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Sample records for aba catabolic gene

  1. A key ABA catabolic gene, OsABA8ox3, is involved in drought stress resistance in rice.

    PubMed

    Cai, Shanlan; Jiang, Guobin; Ye, Nenghui; Chu, Zhizhan; Xu, Xuezhong; Zhang, Jianhua; Zhu, Guohui

    2015-01-01

    Expressions of ABA biosynthesis genes and catabolism genes are generally co-regulated in plant development and responses to environmental stress. Up-regulation of OsNCED3 gene, a key gene in ABA biosynthesis, has been suggested as a way to enhance plant drought resistance but little is known for the role of ABA catabolic genes during drought stress. In this study, we found that OsABA8ox3 was the most highly expressed gene of the OsABA8ox family in rice leaves. Expression of OsABA8ox3 was promptly induced by rehydration after PEG-mimic dehydration, a tendency opposite to the changes of ABA level. We therefore constructed rice OsABA8ox3 silencing (RNA interference, RNAi) and overexpression plants. There were no obvious phenotype differences between the transgenic seedlings and wild type under normal condition. However, OsABA8ox3 RNAi lines showed significant improvement in drought stress tolerance while the overexpression seedlings were hypersensitive to drought stress when compared with wild type in terms of plant survival rates after 10 days of unwatering. Enzyme activity analysis indicated that OsABA8ox3 RNAi plants had higher superoxide dismutase (SOD) and catalase (CAT) activities and less malondialdehyde (MDA) content than those of wild type when the plants were exposed to dehydration treatment, indicating a better anti-oxidative stress capability and less membrane damage. DNA microarray and real-time PCR analysis under dehydration treatment revealed that expressions of a group of stress/drought-related genes, i.e. LEA genes, were enhanced with higher transcript levels in OsABA8ox3 RNAi transgenic seedlings. We therefore conclude that that OsABA8ox3 gene plays an important role in controlling ABA level and drought stress resistance in rice. PMID:25647508

  2. Isolation of a wheat (Triticum aestivum L.) mutant in ABA 8'-hydroxylase gene: effect of reduced ABA catabolism on germination inhibition under field condition.

    PubMed

    Chono, Makiko; Matsunaka, Hitoshi; Seki, Masako; Fujita, Masaya; Kiribuchi-Otobe, Chikako; Oda, Shunsuke; Kojima, Hisayo; Kobayashi, Daisuke; Kawakami, Naoto

    2013-03-01

    Pre-harvest sprouting, the germination of mature seeds on the mother plant under moist condition, is a serious problem in cereals. To investigate the effect of reduced abscisic acid (ABA) catabolism on germination in hexaploid wheat (Triticum aestivum L.), we cloned the wheat ABA 8'-hydroxyase gene which was highly expressed during seed development (TaABA8'OH1) and screened for mutations that lead to reduced ABA catabolism. In a screen for natural variation, one insertion mutation in exon 5 of TaABA8'OH1 on the D genome (TaABA8'OH1-D) was identified in Japanese cultivars including 'Tamaizumi'. However, a single mutation in TaABA8'OH1-D had no clear effect on germination inhibition in double haploid lines. In a screen for a mutation, one deletion mutant lacking the entire TaABA8'OH1 on the A genome (TaABA8'OH1-A), TM1833, was identified from gamma-ray irradiation lines of 'Tamaizumi'. TM1833 (a double mutant in TaABA8'OH1-A and TaABA8'OH1-D) showed lower TaABA8'OH1 expression, higher ABA content in embryos during seed development under field condition and lower germination than those in 'Tamaizumi' (a single mutant in TaABA8'OH1-D). These results indicate that reduced ABA catabolism through mutations in TaABA8'OH1 may be effective in germination inhibition in field-grown wheat.

  3. Isolation of a wheat (Triticum aestivum L.) mutant in ABA 8′-hydroxylase gene: effect of reduced ABA catabolism on germination inhibition under field condition

    PubMed Central

    Chono, Makiko; Matsunaka, Hitoshi; Seki, Masako; Fujita, Masaya; Kiribuchi-Otobe, Chikako; Oda, Shunsuke; Kojima, Hisayo; Kobayashi, Daisuke; Kawakami, Naoto

    2013-01-01

    Pre-harvest sprouting, the germination of mature seeds on the mother plant under moist condition, is a serious problem in cereals. To investigate the effect of reduced abscisic acid (ABA) catabolism on germination in hexaploid wheat (Triticum aestivum L.), we cloned the wheat ABA 8′-hydroxyase gene which was highly expressed during seed development (TaABA8′OH1) and screened for mutations that lead to reduced ABA catabolism. In a screen for natural variation, one insertion mutation in exon 5 of TaABA8′OH1 on the D genome (TaABA8′OH1-D) was identified in Japanese cultivars including ‘Tamaizumi’. However, a single mutation in TaABA8′OH1-D had no clear effect on germination inhibition in double haploid lines. In a screen for a mutation, one deletion mutant lacking the entire TaABA8′OH1 on the A genome (TaABA8′OH1-A), TM1833, was identified from gamma-ray irradiation lines of ‘Tamaizumi’. TM1833 (a double mutant in TaABA8′OH1-A and TaABA8′OH1-D) showed lower TaABA8′OH1 expression, higher ABA content in embryos during seed development under field condition and lower germination than those in ‘Tamaizumi’ (a single mutant in TaABA8′OH1-D). These results indicate that reduced ABA catabolism through mutations in TaABA8′OH1 may be effective in germination inhibition in field-grown wheat. PMID:23641187

  4. PrCYP707A1, an ABA catabolic gene, is a key component of Phelipanche ramosa seed germination in response to the strigolactone analogue GR24

    PubMed Central

    Delavault, Philippe

    2012-01-01

    After a conditioning period, seed dormancy in obligate root parasitic plants is released by a chemical stimulus secreted by the roots of host plants. Using Phelipanche ramosa as the model, experiments conducted in this study showed that seeds require a conditioning period of at least 4 d to be receptive to the synthetic germination stimulant GR24. A cDNA-AFLP procedure on seeds revealed 58 transcript-derived fragments (TDFs) whose expression pattern changed upon GR24 treatment. Among the isolated TDFs, two up-regulated sequences corresponded to an abscisic acid (ABA) catabolic gene, PrCYP707A1, encoding an ABA 8'-hydroxylase. Using the rapid amplification of cDNA ends method, two full-length cDNAs, PrCYP707A1 and PrCYP707A2, were isolated from seeds. Both genes were always expressed at low levels during conditioning during which an initial decline in ABA levels was recorded. GR24 application after conditioning triggered a strong up-regulation of PrCYP707A1 during the first 18h, followed by an 8-fold decrease in ABA levels detectable 3 d after treatment. In situ hybridization experiments on GR24-treated seeds revealed a specific PrCYP707A1 mRNA accumulation in the cells located between the embryo and the micropyle. Abz-E2B, a specific inhibitor of CYP707A enzymes, significantly impeded seed germination, proving to be a non-competitive antagonist of GR24 with reversible inhibitory activity. These results demonstrate that P. ramosa seed dormancy release relies on ABA catabolism mediated by the GR24-dependent activation of PrCYP707A1. In addition, in situ hybridization corroborates the putative location of cells receptive to the germination stimulants in seeds. Abbreviations:ABAabscisic acidAbzabscinazoleAECadenylate energy chargeAFLPamplified fragment length polymorphismRACErapid amplification of cDNA endsSLstrigolactoneTDFtranscript-derived fragment PMID:22859674

  5. Abscisic acid (ABA) regulation of Arabidopsis SR protein gene expression.

    PubMed

    Cruz, Tiago M D; Carvalho, Raquel F; Richardson, Dale N; Duque, Paula

    2014-01-01

    Serine/arginine-rich (SR) proteins are major modulators of alternative splicing, a key generator of proteomic diversity and flexible means of regulating gene expression likely to be crucial in plant environmental responses. Indeed, mounting evidence implicates splicing factors in signal transduction of the abscisic acid (ABA) phytohormone, which plays pivotal roles in the response to various abiotic stresses. Using real-time RT-qPCR, we analyzed total steady-state transcript levels of the 18 SR and two SR-like genes from Arabidopsis thaliana in seedlings treated with ABA and in genetic backgrounds with altered expression of the ABA-biosynthesis ABA2 and the ABA-signaling ABI1 and ABI4 genes. We also searched for ABA-responsive cis elements in the upstream regions of the 20 genes. We found that members of the plant-specific SC35-Like (SCL) Arabidopsis SR protein subfamily are distinctively responsive to exogenous ABA, while the expression of seven SR and SR-related genes is affected by alterations in key components of the ABA pathway. Finally, despite pervasiveness of established ABA-responsive promoter elements in Arabidopsis SR and SR-like genes, their expression is likely governed by additional, yet unidentified cis-acting elements. Overall, this study pinpoints SR34, SR34b, SCL30a, SCL28, SCL33, RS40, SR45 and SR45a as promising candidates for involvement in ABA-mediated stress responses. PMID:25268622

  6. Abscisic Acid (ABA) Regulation of Arabidopsis SR Protein Gene Expression

    PubMed Central

    Cruz, Tiago M. D.; Carvalho, Raquel F.; Richardson, Dale N.; Duque, Paula

    2014-01-01

    Serine/arginine-rich (SR) proteins are major modulators of alternative splicing, a key generator of proteomic diversity and flexible means of regulating gene expression likely to be crucial in plant environmental responses. Indeed, mounting evidence implicates splicing factors in signal transduction of the abscisic acid (ABA) phytohormone, which plays pivotal roles in the response to various abiotic stresses. Using real-time RT-qPCR, we analyzed total steady-state transcript levels of the 18 SR and two SR-like genes from Arabidopsis thaliana in seedlings treated with ABA and in genetic backgrounds with altered expression of the ABA-biosynthesis ABA2 and the ABA-signaling ABI1 and ABI4 genes. We also searched for ABA-responsive cis elements in the upstream regions of the 20 genes. We found that members of the plant-specific SC35-Like (SCL) Arabidopsis SR protein subfamily are distinctively responsive to exogenous ABA, while the expression of seven SR and SR-related genes is affected by alterations in key components of the ABA pathway. Finally, despite pervasiveness of established ABA-responsive promoter elements in Arabidopsis SR and SR-like genes, their expression is likely governed by additional, yet unidentified cis-acting elements. Overall, this study pinpoints SR34, SR34b, SCL30a, SCL28, SCL33, RS40, SR45 and SR45a as promising candidates for involvement in ABA-mediated stress responses. PMID:25268622

  7. Expression of ABA Metabolism-Related Genes Suggests Similarities and Differences Between Seed Dormancy and Bud Dormancy of Peach (Prunus persica)

    PubMed Central

    Wang, Dongling; Gao, Zhenzhen; Du, Peiyong; Xiao, Wei; Tan, Qiuping; Chen, Xiude; Li, Ling; Gao, Dongsheng

    2016-01-01

    Dormancy inhibits seed and bud growth of perennial plants until the environmental conditions are optimal for survival. Previous studies indicated that certain co-regulation pathways exist in seed and bud dormancy. In our study, we found that seed and bud dormancy are similar to some extent but show different reactions to chemical treatments that induce breaking of dormancy. Whether the abscisic acid (ABA) regulatory networks are similar in dormant peach seeds and buds is not well known; however, ABA is generally believed to play a critical role in seed and bud dormancy. In peach, some genes putatively involved in ABA synthesis and catabolism were identified and their expression patterns were studied to learn more about ABA homeostasis and the possible crosstalk between bud dormancy and seed dormancy mechanisms. The analysis demonstrated that two 9-cis-epoxycarotenoid dioxygenase-encoding genes seem to be key in regulating ABA biosynthesis to induce seed and bud dormancy. Three CYP707As play an overlapping role in controlling ABA inactivation, resulting in dormancy-release. In addition, Transcript analysis of ABA metabolism-related genes was much similar demonstrated that ABA pathways was similar in the regulation of vegetative and flower bud dormancy, whereas, expression patterns of ABA metabolism-related genes were different in seed dormancy showed that ABA pathway maybe different in regulating seed dormancy in peach. PMID:26793222

  8. Expression of ABA Metabolism-Related Genes Suggests Similarities and Differences Between Seed Dormancy and Bud Dormancy of Peach (Prunus persica).

    PubMed

    Wang, Dongling; Gao, Zhenzhen; Du, Peiyong; Xiao, Wei; Tan, Qiuping; Chen, Xiude; Li, Ling; Gao, Dongsheng

    2015-01-01

    Dormancy inhibits seed and bud growth of perennial plants until the environmental conditions are optimal for survival. Previous studies indicated that certain co-regulation pathways exist in seed and bud dormancy. In our study, we found that seed and bud dormancy are similar to some extent but show different reactions to chemical treatments that induce breaking of dormancy. Whether the abscisic acid (ABA) regulatory networks are similar in dormant peach seeds and buds is not well known; however, ABA is generally believed to play a critical role in seed and bud dormancy. In peach, some genes putatively involved in ABA synthesis and catabolism were identified and their expression patterns were studied to learn more about ABA homeostasis and the possible crosstalk between bud dormancy and seed dormancy mechanisms. The analysis demonstrated that two 9-cis-epoxycarotenoid dioxygenase-encoding genes seem to be key in regulating ABA biosynthesis to induce seed and bud dormancy. Three CYP707As play an overlapping role in controlling ABA inactivation, resulting in dormancy-release. In addition, Transcript analysis of ABA metabolism-related genes was much similar demonstrated that ABA pathways was similar in the regulation of vegetative and flower bud dormancy, whereas, expression patterns of ABA metabolism-related genes were different in seed dormancy showed that ABA pathway maybe different in regulating seed dormancy in peach.

  9. Mutations in the Arabidopsis Lst8 and Raptor genes encoding partners of the TOR complex, or inhibition of TOR activity decrease abscisic acid (ABA) synthesis.

    PubMed

    Kravchenko, Alena; Citerne, Sylvie; Jéhanno, Isabelle; Bersimbaev, Rakhmetkazhi I; Veit, Bruce; Meyer, Christian; Leprince, Anne-Sophie

    2015-11-27

    The Target of Rapamycin (TOR) kinase regulates essential processes in plant growth and development by modulation of metabolism and translation in response to environmental signals. In this study, we show that abscisic acid (ABA) metabolism is also regulated by the TOR kinase. Indeed ABA hormone level strongly decreases in Lst8-1 and Raptor3g mutant lines as well as in wild-type (WT) Arabidopsis plants treated with AZD-8055, a TOR inhibitor. However the growth and germination of these lines are more sensitive to exogenous ABA. The diminished ABA hormone accumulation is correlated with lower transcript levels of ZEP, NCED3 and AAO3 biosynthetic enzymes, and higher transcript amount of the CYP707A2 gene encoding a key-enzyme in abscisic acid catabolism. These results suggest that the TOR signaling pathway is implicated in the regulation of ABA accumulation in Arabidopsis.

  10. Catabolic gene expression is monitored by bioluminescence in bioreactor studies

    SciTech Connect

    Burlage, R.S.; Kuo, D.; Palumbo, A.V.

    1993-01-01

    In order to study the expression of specific catabolic genes under defined conditions, and to determine whether certain conditions tend to increase or decrease metal catabolic activities, a bioreporter gene can be introduced into the microorganism. Activity from such bioreporter gene would indicate successful bioremediation. Our laboratory has produced several bioreporter strains using the bioluminescent lux genes of Vibrio fischeri. A bioreporter producing visible light when genetic expression is induced. The bioluminescent system include sensitivity of detection, analysis of response in real- time, and on-line capability. We constructed a bioreporter strain aimed at following the degradation of toluene and related compounds in order to study expression of the catabolic genes with various substrates and under optimized bioreactor conditions. We have been able to detect the induction of a specific operon in response to the addition of oxylene, as a gratuitous inducer of the catabolic genes. A strong bioluminescent signal in these studies. We have varied the medium of an induced bioreactor culture of RB1401, and our data suggest that conditions for optimal expression of the catabolic operon might not be identical with optimal growth conditions.

  11. Catabolic gene expression is monitored by bioluminescence in bioreactor studies

    SciTech Connect

    Burlage, R.S.; Kuo, D.; Palumbo, A.V.

    1993-03-01

    In order to study the expression of specific catabolic genes under defined conditions, and to determine whether certain conditions tend to increase or decrease metal catabolic activities, a bioreporter gene can be introduced into the microorganism. Activity from such bioreporter gene would indicate successful bioremediation. Our laboratory has produced several bioreporter strains using the bioluminescent lux genes of Vibrio fischeri. A bioreporter producing visible light when genetic expression is induced. The bioluminescent system include sensitivity of detection, analysis of response in real- time, and on-line capability. We constructed a bioreporter strain aimed at following the degradation of toluene and related compounds in order to study expression of the catabolic genes with various substrates and under optimized bioreactor conditions. We have been able to detect the induction of a specific operon in response to the addition of oxylene, as a gratuitous inducer of the catabolic genes. A strong bioluminescent signal in these studies. We have varied the medium of an induced bioreactor culture of RB1401, and our data suggest that conditions for optimal expression of the catabolic operon might not be identical with optimal growth conditions.

  12. Expression of ABA synthesis and metabolism genes under different irrigation strategies and atmospheric VPDs is associated with stomatal conductance in grapevine (Vitis vinifera L. cv Cabernet Sauvignon).

    PubMed

    Speirs, Jim; Binney, Allan; Collins, Marisa; Edwards, Everard; Loveys, Brian

    2013-04-01

    The influence of different levels of irrigation and of variation in atmospheric vapour pressure deficit (VPD) on the synthesis, metabolism, and transport of abscisic acid (ABA) and the effects on stomatal conductance were examined in field-grown Cabernet Sauvignon grapevines. Xylem sap, leaf tissue, and root tissue were collected at regular intervals during two seasons in conjunction with measurements of leaf water potential (Ψleaf) and stomatal conductance (gs). The different irrigation levels significantly altered the Ψleaf and gs of the vines across both seasons. ABA abundance in the xylem sap was correlated with gs. The expression of genes associated with ABA synthesis, NCED1 and NCED2, was higher in the roots than in the leaves throughout and highest in the roots in mid January, a time when soil moisture declined and VPD was at its highest. Their expression in roots was also inversely related to the levels of irrigation and correlated with ABA abundance in the roots, xylem sap, and leaves. Three genes encoding ABA 8'-hydroxylases were isolated and their identities confirmed by expression in yeast cells. The expression of one of these, Hyd1, was elevated in leaves when VPD was below 2.0-2.5 kPa and minimal at higher VPD levels. The results provide evidence that ABA plays an important role in linking stomatal response to soil moisture status and that changes in ABA catabolism at or near its site of action allows optimization of gas exchange to current environmental conditions. PMID:23630325

  13. A Putative PP2C-Encoding Gene Negatively Regulates ABA Signaling in Populus euphratica

    PubMed Central

    Chen, Jinhuan; Zhang, Dongzhi; Zhang, Chong; Xia, Xinli; Yin, Weilun; Tian, Qianqian

    2015-01-01

    A PP2C homolog gene was cloned from the drought-treated cDNA library of Populus euphratica. Multiple sequence alignment analysis suggested that the gene is a potential ortholog of HAB1. The expression of this HAB1 ortholog (PeHAB1) was markedly induced by drought and moderately induced by ABA. To characterize its function in ABA signaling, we generated transgenic Arabidopsis thaliana plants overexpressing this gene. Transgenic lines exhibited reduced responses to exogenous ABA and reduced tolerance to drought compared to wide-type lines. Yeast two-hybrid analyses indicated that PeHAB1 could interact with the ABA receptor PYL4 in an ABA-independent manner. Taken together; these results indicated that PeHAB1 is a new negative regulator of ABA responses in poplar. PMID:26431530

  14. SlNCED1 and SlCYP707A2: key genes involved in ABA metabolism during tomato fruit ripening.

    PubMed

    Ji, Kai; Kai, Wenbin; Zhao, Bo; Sun, Yufei; Yuan, Bing; Dai, Shengjie; Li, Qian; Chen, Pei; Wang, Ya; Pei, Yuelin; Wang, Hongqing; Guo, Yangdong; Leng, Ping

    2014-10-01

    Abscisic acid (ABA) plays an important role in fruit development and ripening. Here, three NCED genes encoding 9-cis-epoxycarotenoid dioxygenase (NCED, a key enzyme in the ABA biosynthetic pathway) and three CYP707A genes encoding ABA 8'-hydroxylase (a key enzyme in the oxidative catabolism of ABA) were identified in tomato fruit by tobacco rattle virus-induced gene silencing (VIGS). Quantitative real-time PCR showed that VIGS-treated tomato fruits had significant reductions in target gene transcripts. In SlNCED1-RNAi-treated fruits, ripening slowed down, and the entire fruit turned to orange instead of red as in the control. In comparison, the downregulation of SlCYP707A2 expression in SlCYP707A2-silenced fruit could promote ripening; for example, colouring was quicker than in the control. Silencing SlNCED2/3 or SlCYP707A1/3 made no significant difference to fruit ripening comparing RNAi-treated fruits with control fruits. ABA accumulation and SlNCED1transcript levels in the SlNCED1-RNAi-treated fruit were downregulated to 21% and 19% of those in control fruit, respectively, but upregulated in SlCYP707A2-RNAi-treated fruit. Silencing SlNCED1 or SlCYP707A2 by VIGS significantly altered the transcripts of a set of both ABA-responsive and ripening-related genes, including ABA-signalling genes (PYL1, PP2C1, and SnRK2.2), lycopene-synthesis genes (SlBcyc, SlPSY1 and SlPDS), and cell wall-degrading genes (SlPG1, SlEXP, and SlXET) during ripening. These data indicate that SlNCED1 and SlCYP707A2 are key genes in the regulation of ABA synthesis and catabolism, and are involved in fruit ripening as positive and negative regulators, respectively.

  15. SlNCED1 and SlCYP707A2: key genes involved in ABA metabolism during tomato fruit ripening

    PubMed Central

    Ji, Kai; Kai, Wenbin; Zhao, Bo; Sun, Yufei; Yuan, Bing; Dai, Shengjie; Li, Qian; Chen, Pei; Wang, Ya; Pei, Yuelin; Wang, Hongqing; Guo, Yangdong; Leng, Ping

    2014-01-01

    Abscisic acid (ABA) plays an important role in fruit development and ripening. Here, three NCED genes encoding 9-cis-epoxycarotenoid dioxygenase (NCED, a key enzyme in the ABA biosynthetic pathway) and three CYP707A genes encoding ABA 8′-hydroxylase (a key enzyme in the oxidative catabolism of ABA) were identified in tomato fruit by tobacco rattle virus-induced gene silencing (VIGS). Quantitative real-time PCR showed that VIGS-treated tomato fruits had significant reductions in target gene transcripts. In SlNCED1-RNAi-treated fruits, ripening slowed down, and the entire fruit turned to orange instead of red as in the control. In comparison, the downregulation of SlCYP707A2 expression in SlCYP707A2-silenced fruit could promote ripening; for example, colouring was quicker than in the control. Silencing SlNCED2/3 or SlCYP707A1/3 made no significant difference to fruit ripening comparing RNAi-treated fruits with control fruits. ABA accumulation and SlNCED1transcript levels in the SlNCED1-RNAi-treated fruit were downregulated to 21% and 19% of those in control fruit, respectively, but upregulated in SlCYP707A2-RNAi-treated fruit. Silencing SlNCED1 or SlCYP707A2 by VIGS significantly altered the transcripts of a set of both ABA-responsive and ripening-related genes, including ABA-signalling genes (PYL1, PP2C1, and SnRK2.2), lycopene-synthesis genes (SlBcyc, SlPSY1 and SlPDS), and cell wall-degrading genes (SlPG1, SlEXP, and SlXET) during ripening. These data indicate that SlNCED1 and SlCYP707A2 are key genes in the regulation of ABA synthesis and catabolism, and are involved in fruit ripening as positive and negative regulators, respectively. PMID:25039074

  16. Dual Function of NAC072 in ABF3-Mediated ABA-Responsive Gene Regulation in Arabidopsis

    PubMed Central

    Li, Xiaoyun; Li, Xiaoling; Li, Meijuan; Yan, Youcheng; Liu, Xu; Li, Ling

    2016-01-01

    The NAM, ATAF1/2, and CUC2 (NAC) domain proteins play various roles in plant growth and stress responses. Arabidopsis NAC transcription factor NAC072 has been reported as a transcriptional activator in Abscisic acid (ABA)-responsive gene expression. However, the exact function of NAC072 in ABA signaling is still elusive. In this study, we present evidence for the interrelation between NAC072 and ABA-responsive element binding factor 3 (ABF3) that act as a positive regulator of ABA-responsive gene expression in Arabidopsis. The transcript of NAC072 is up-regulated by ABF3 in ABA response, and NAC072 protein interacts with ABF3. Enhanced ABA sensitivity occurs in nac072 mutant plants that overexpressed ABF3. However, overexpression of NAC072 weakened the ABA sensitivity in the abf3 mutant plants, but instead of recovering the ABA sensitivity of abf3. NAC072 and ABF3 cooperate to regulate RD29A expression, but are antagonistic when regulating RD29B expression. Therefore, NAC072 displays a dual function in ABF3-mediated ABA-responsive gene regulation. PMID:27486475

  17. Regulation of the rab17 gene promoter in transgenic Arabidopsis wild-type, ABA-deficient and ABA-insensitive mutants.

    PubMed

    Vilardell, J; Martínez-Zapater, J M; Goday, A; Arenas, C; Pagès, M

    1994-02-01

    The abscisic acid-responsive gene rab17 is induced during maize embryo maturation and in vegetative tissues under water stress conditions. To investigate how ABA is involved in the induction of the rab17 gene, we present here a genetic approach to analyse the transcriptional regulation of the 1.3 kb rab17 promoter fragment in transgenic wild-type Arabidopsis and mutants which are deficient (aba) and insensitive (abi1, abi2 and abi3) to ABA. During seed development the rab17 promoter fragment confers similar temporal and spatial regulation on the reporter gene GUS, both in transgenic wild-type and ABA-deficient and ABA-insensitive mutants. The rab17 promoter was only active in embryo and endosperm during late seed development, although the ABA-deficient embryo mutant showed a reduction in the level of GUS activity. During germination rab17 promoter activity decreases, and GUS activity is not enhanced by water stress in transgenic wild-type and mutant plants. In contrast, transcription of the Arabidopsis endogenous rab gene is stimulated by water stress, both in wild-type and ABA-insensitive mutants. Our data suggest that different molecular mechanisms mediate seed-specific expression and ABA water stress induction of the rab17 gene and indicate strong conservation of the seed-specific regulatory mechanism for rab genes in monocot and dicot plants.

  18. Seed dormancy and ABA signaling

    PubMed Central

    del Carmen Rodríguez-Gacio, María; Matilla-Vázquez, Miguel A

    2009-01-01

    The seed is an important organ in higher plants, it is an important organ for plant survival and species dispersion. The transition between seed dormancy and germination represents a critical stage in the plant life cycle and it is an important ecological and commercial trait. A dynamic balance of synthesis and catabolism of two antagonistic hormones, abscisic acid (ABA) and giberellins (GAs), controls the equilibrium between seed dormancy and germination. Embryonic ABA plays a central role in induction and maintenance of seed dormancy and also inhibits the transition from embryonic to germination growth. Therefore, the ABA metabolism must be highly regulated at both temporal and spatial levels during phase of dessication tolerance. On the other hand, the ABA levels do not depend exclusively on the seeds because sometimes it becomes a strong sink and imports it from the roots and rhizosphere through the xylem and/or phloem. These events are discussed in depth here. Likewise, the role of some recently characterized genes belonging to seeds of woody species and related to ABA signaling are also included. Finally, although four possible ABA receptors have been reported, not much is known about how they mediate ABA signaling transduction. However, new publications seem to show that almost all these receptors lack several properties to consider them as such. PMID:19875942

  19. Bioluminescent reporters for catabolic gene expression and pollutant bioavailability

    SciTech Connect

    Heitzer, A.; DiGrazia, P.M.; Sayler, G.S. . Center for Environmental Biotechnology); Burlage, R.S. )

    1991-01-01

    The application of visualized catabolic nah-gene expression using a luxCDABE gene fusion provides a valuable method to measure quantitatively and specifically naphthalene and salicylate bioavailability. It has been demonstrated that the physiological state of the test culture together with the intrinsic regulation mechanisms of the naphthalene degradation pathway as well as the physiological aspects of the lux gene fusion have to be taken into account. The method presented provides a high potential for in situ bioprocess monitoring. In addition, the results obtained with immobilized cells provide a basis for the development of biosensors for environmental applications in specific pollutant monitoring in waste streams and soil slurry systems but, as a general method, also for more conventional biotechnological process control. 8 refs., 2 figs., 1 tab.

  20. Identification of a gene cluster associated with triclosan catabolism.

    PubMed

    Kagle, Jeanne M; Paxson, Clayton; Johnstone, Precious; Hay, Anthony G

    2015-06-01

    Aerobic degradation of bis-aryl ethers like the antimicrobial triclosan typically proceeds through oxygenase-dependent catabolic pathways. Although several studies have reported on bacteria capable of degrading triclosan aerobically, there are no reports describing the genes responsible for this process. In this study, a gene encoding the large subunit of a putative triclosan oxygenase, designated tcsA was identified in a triclosan-degrading fosmid clone from a DNA library of Sphingomonas sp. RD1. Consistent with tcsA's similarity to two-part dioxygenases, a putative FMN-dependent ferredoxin reductase, designated tcsB was found immediately downstream of tcsA. Both tcsAB were found in the midst of a putative chlorocatechol degradation operon. We show that RD1 produces hydroxytriclosan and chlorocatechols during triclosan degradation and that tcsA is induced by triclosan. This is the first study to report on the genetics of triclosan degradation.

  1. Characterization of genes for chitin catabolism in Haloferax mediterranei.

    PubMed

    Hou, Jing; Han, Jing; Cai, Lei; Zhou, Jian; Lü, Yang; Jin, Cheng; Liu, Jingfang; Xiang, Hua

    2014-02-01

    Chitin is the second most abundant natural polysaccharide after cellulose. But degradation of chitin has never been reported in haloarchaea. In this study, we revealed that Haloferax mediterranei, a metabolically versatile haloarchaeon, could utilize colloidal or powdered chitin for growth and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) accumulation, and the gene cluster (HFX_5025-5039) for the chitin catabolism pathway was experimentally identified. First, reverse transcription polymerase chain reaction results showed that the expression of the genes encoding the four putative chitinases (ChiAHme, ChiBHme, ChiCHme, and ChiDHme, HFX_5036-5039), the LmbE-like deacetylase (DacHme, HFX_5027), and the glycosidase (GlyAHme, HFX_5029) was induced by colloidal or powdered chitin, and chiA Hme, chiB Hme, and chiC Hme were cotranscribed. Knockout of chiABC Hme or chiD Hme had a significant effect on cell growth and PHBV production when chitin was used as the sole carbon source, and the chiABCD Hme knockout mutant lost the capability to utilize chitin. Knockout of dac Hme or glyA Hme also decreased PHBV accumulation on chitin. These results suggested that ChiABCDHme, DacHme, and GlyAHme were indeed involved in chitin degradation in H. mediterranei. Additionally, the chitinase assay showed that each chitinase possessed hydrolytic activity toward colloidal or powdered chitin, and the major product of colloidal chitin hydrolysis by ChiABCDHme was diacetylchitobiose, which was likely further degraded to monosaccharides by DacHme, GlyAHme, and other related enzymes for both cell growth and PHBV biosynthesis. Taken together, this study revealed the genes and enzymes involved in chitin catabolism in haloarchaea for the first time and indicated the potential of H. mediterranei as a whole-cell biocatalyst in chitin bioconversion.

  2. Towards the Identification of New Genes Involved in ABA-Dependent Abiotic Stresses Using Arabidopsis Suppressor Mutants of abh1 Hypersensitivity to ABA during Seed Germination

    PubMed Central

    Daszkowska-Golec, Agata; Chorazy, Edyta; Maluszynski, Miroslaw; Szarejko, Iwona

    2013-01-01

    Abscisic acid plays a pivotal role in the abiotic stress response in plants. Although great progress has been achieved explaining the complexity of the stress and ABA signaling cascade, there are still many questions to answer. Mutants are a valuable tool in the identification of new genes or new alleles of already known genes and in elucidating their role in signaling pathways. We applied a suppressor mutation approach in order to find new components of ABA and abiotic stress signaling in Arabidopsis. Using the abh1 (ABA hypersensitive 1) insertional mutant as a parental line for EMS mutagenesis, we selected several mutants with suppressed hypersensitivity to ABA during seed germination. Here, we present the response to ABA and a wide range of abiotic stresses during the seed germination and young seedling development of two suppressor mutants—soa2 (suppressor of abh1 hypersensitivity to ABA 2) and soa3 (suppressor of abh1 hypersensitivity to ABA 3). Generally, both mutants displayed a suppression of the hypersensitivity of abh1 to ABA, NaCl and mannitol during germination. Both mutants showed a higher level of tolerance than Columbia-0 (Col-0—the parental line of abh1) in high concentrations of glucose. Additionally, soa2 exhibited better root growth than Col-0 in the presence of high ABA concentrations. soa2 and soa3 were drought tolerant and both had about 50% fewer stomata per mm2 than the wild-type but the same number as their parental line—abh1. Taking into account that suppressor mutants had the same genetic background as their parental line—abh1, it was necessary to backcross abh1 with Landsberg erecta four times for the map-based cloning approach. Mapping populations, derived from the cross of abh1 in the Landsberg erecta background with each suppressor mutant, were created. Map based cloning in order to identify the suppressor genes is in progress. PMID:23807502

  3. NADPH oxidase AtrbohD and AtrbohF genes function in ROS-dependent ABA signaling in Arabidopsis.

    PubMed

    Kwak, June M; Mori, Izumi C; Pei, Zhen-Ming; Leonhardt, Nathalie; Torres, Miguel Angel; Dangl, Jeffery L; Bloom, Rachel E; Bodde, Sara; Jones, Jonathan D G; Schroeder, Julian I

    2003-06-01

    Reactive oxygen species (ROS) have been proposed to function as second messengers in abscisic acid (ABA) signaling in guard cells. However, the question whether ROS production is indeed required for ABA signal transduction in vivo has not yet been addressed, and the molecular mechanisms mediating ROS production during ABA signaling remain unknown. Here, we report identification of two partially redundant Arabidopsis guard cell-expressed NADPH oxidase catalytic subunit genes, AtrbohD and AtrbohF, in which gene disruption impairs ABA signaling. atrbohD/F double mutations impair ABA-induced stomatal closing, ABA promotion of ROS production, ABA-induced cytosolic Ca(2+) increases and ABA- activation of plasma membrane Ca(2+)-permeable channels in guard cells. Exogenous H(2)O(2) rescues both Ca(2+) channel activation and stomatal closing in atrbohD/F. ABA inhibition of seed germination and root elongation are impaired in atrbohD/F, suggesting more general roles for ROS and NADPH oxidases in ABA signaling. These data provide direct molecular genetic and cell biological evidence that ROS are rate-limiting second messengers in ABA signaling, and that the AtrbohD and AtrbohF NADPH oxidases function in guard cell ABA signal transduction.

  4. Characterization of purine catabolic pathway genes in coelacanths.

    PubMed

    Forconi, Mariko; Biscotti, Maria Assunta; Barucca, Marco; Buonocore, Francesco; De Moro, Gianluca; Fausto, Anna Maria; Gerdol, Marco; Pallavicini, Alberto; Scapigliati, Giuseppe; Schartl, Manfred; Olmo, Ettore; Canapa, Adriana

    2014-09-01

    Coelacanths are a critically valuable species to explore the gene changes that took place in the transition from aquatic to terrestrial life. One interesting and biologically relevant feature of the genus Latimeria is ureotelism. However not all urea is excreted from the body; in fact high concentrations are retained in plasma and seem to be involved in osmoregulation. The purine catabolic pathway, which leads to urea production in Latimeria, has progressively lost some steps, reflecting an enzyme loss during diversification of terrestrial species. We report the results of analyses of the liver and testis transcriptomes of the Indonesian coelacanth Latimeria menadoensis and of the genome of Latimeria chalumnae, which has recently been fully sequenced in the framework of the coelacanth genome project. We describe five genes, uricase, 5-hydroxyisourate hydrolase, parahox neighbor B, allantoinase, and allantoicase, each coding for one of the five enzymes involved in urate degradation to urea, and report the identification of a putative second form of 5-hydroxyisourate hydrolase that is characteristic of the genus Latimeria. The present data also highlight the activity of the complete purine pathway in the coelacanth liver and suggest its involvement in the maintenance of high plasma urea concentrations.

  5. bHLH122 is important for drought and osmotic stress resistance in Arabidopsis and in the repression of ABA catabolism.

    PubMed

    Liu, Wenwen; Tai, Huanhuan; Li, Songsong; Gao, Wei; Zhao, Meng; Xie, Chuanxiao; Li, Wen-Xue

    2014-03-01

    • Although proteins in the basic helix-loop-helix (bHLH) family are universal transcription factors in eukaryotes, the biological roles of most bHLH family members are not well understood in plants. • The Arabidopsis thaliana bHLH122 transcripts were strongly induced by drought, NaCl and osmotic stresses, but not by ABA treatment. Promoter::GUS analysis showed that bHLH122 was highly expressed in vascular tissues and guard cells. Compared with wild-type (WT) plants, transgenic plants overexpressing bHLH122 displayed greater resistance to drought, NaCl and osmotic stresses. In contrast, the bhlh122 loss-of-function mutant was more sensitive to NaCl and osmotic stresses than were WT plants. • Microarray analysis indicated that bHLH122 was important for the expression of a number of abiotic stress-responsive genes. In electrophoretic mobility shift assay and chromatin immunoprecipitation assays, bHLH122 could bind directly to the G-box/E-box cis-elements in the CYP707A3 promoter, and repress its expression. Further, up-regulation of bHLH122 substantially increased cellular ABA levels. • These results suggest that bHLH122 functions as a positive regulator of drought, NaCl and osmotic signaling. PMID:24261563

  6. An ABA-mimicking ligand that reduces water loss and promotes drought resistance in plants

    PubMed Central

    Cao, Minjie; Liu, Xue; Zhang, Yan; Xue, Xiaoqian; Zhou, X Edward; Melcher, Karsten; Gao, Pan; Wang, Fuxing; Zeng, Liang; Zhao, Yang; Zhao, Yang; Deng, Pan; Zhong, Dafang; Zhu, Jian-Kang; Xu, H Eric; Xu, Yong

    2013-01-01

    Abscisic acid (ABA) is the most important hormone for plants to resist drought and other abiotic stresses. ABA binds directly to the PYR/PYL family of ABA receptors, resulting in inhibition of type 2C phosphatases (PP2C) and activation of downstream ABA signaling. It is envisioned that intervention of ABA signaling by small molecules could help plants to overcome abiotic stresses such as drought, cold and soil salinity. However, chemical instability and rapid catabolism by plant enzymes limit the practical application of ABA itself. Here we report the identification of a small molecule ABA mimic (AM1) that acts as a potent activator of multiple members of the family of ABA receptors. In Arabidopsis, AM1 activates a gene network that is highly similar to that induced by ABA. Treatments with AM1 inhibit seed germination, prevent leaf water loss, and promote drought resistance. We solved the crystal structure of AM1 in complex with the PYL2 ABA receptor and the HAB1 PP2C, which revealed that AM1 mediates a gate-latch-lock interacting network, a structural feature that is conserved in the ABA-bound receptor/PP2C complex. Together, these results demonstrate that a single small molecule ABA mimic can activate multiple ABA receptors and protect plants from water loss and drought stress. Moreover, the AM1 complex crystal structure provides a structural basis for designing the next generation of ABA-mimicking small molecules. PMID:23835477

  7. Methanesulfonate (MSA) Catabolic Genes from Marine and Estuarine Bacteria

    PubMed Central

    Henriques, Ana C.; De Marco, Paolo

    2015-01-01

    Quantitatively, methanesulfonate (MSA) is a very relevant compound in the global biogeochemical sulfur cycle. Its utilization by bacteria as a source of carbon and energy has been described and a specific enzyme, methanesulfonate monooxygenase (MSAMO), has been found to perform the first catabolic step of its oxidation. Other proteins seemingly involved in the import of MSA into bacterial cells have been reported. In this study, we obtained novel sequences of genes msmA and msmE from marine, estuary and soil MSA-degraders (encoding the large subunit of the MSAMO enzyme and the periplasmic component of the import system, respectively). We also obtained whole-genome sequences of two novel marine Filomicrobium strains, Y and W, and annotated two full msm operons in these genomes. Furthermore, msmA and msmE sequences were amplified from North Atlantic seawater and analyzed. Good conservation of the MsmA deduced protein sequence was observed in both cultured strains and metagenomic clones. A long spacer sequence in the Rieske-type [2Fe-2S] cluster-binding motif within MsmA was found to be conserved in all instances, supporting the hypothesis that this feature is specific to the large (α) subunit of the MSAMO enzyme. The msmE gene was more difficult to amplify, from both cultivated isolates and marine metagenomic DNA. However, 3 novel msmE sequences were obtained from isolated strains and one directly from seawater. With both genes, our results combined with previous metagenomic analyses seem to imply that moderate to high-GC strains are somehow favored during enrichment and isolation of MSA-utilizing bacteria, while the majority of msm genes obtained by cultivation-independent methods have low levels of GC%, which is a clear example of the misrepresentation of natural populations that culturing, more often than not, entails. Nevertheless, the data obtained in this work show that MSA-degrading bacteria are abundant in surface seawater, which suggests ecological

  8. Substrate-induced gene-expression screening of environmental metagenome libraries for isolation of catabolic genes.

    PubMed

    Uchiyama, Taku; Abe, Takashi; Ikemura, Toshimichi; Watanabe, Kazuya

    2005-01-01

    Recent awareness that most microorganisms in the environment are resistant to cultivation has prompted scientists to directly clone useful genes from environmental metagenomes. Two screening methods are currently available for the metagenome approach, namely, nucleotide sequence-based screening and enzyme activity-based screening. Here we have introduced and optimized a third option for the isolation of novel catabolic operons, that is, substrate-induced gene expression screening (SIGEX). This method is based on the knowledge that catabolic-gene expression is generally induced by relevant substrates and, in many cases, controlled by regulatory elements situated proximate to catabolic genes. For SIGEX to be high throughput, we constructed an operon-trap gfp-expression vector available for shotgun cloning that allows for the selection of positive clones in liquid cultures by fluorescence-activated cell sorting. The utility of SIGEX was demonstrated by the cloning of aromatic hydrocarbon-induced genes from a groundwater metagenome library and subsequent genome-informatics analysis.

  9. Reduced ABA Accumulation in the Root System is Caused by ABA Exudation in Upland Rice (Oryza sativa L. var. Gaoshan1) and this Enhanced Drought Adaptation.

    PubMed

    Shi, Lu; Guo, Miaomiao; Ye, Nenghui; Liu, Yinggao; Liu, Rui; Xia, Yiji; Cui, Suxia; Zhang, Jianhua

    2015-05-01

    Lowland rice (Nipponbare) and upland rice (Gaoshan 1) that are comparable under normal and moderate drought conditions showed dramatic differences in severe drought conditions, both naturally occurring long-term drought and simulated rapid water deficits. We focused on their root response and found that enhanced tolerance of upland rice to severe drought conditions was mainly due to the lower level of ABA in its roots than in those of the lowland rice. We first excluded the effect of ABA biosynthesis and catabolism on root-accumulated ABA levels in both types of rice by monitoring the expression of four OsNCED genes and two OsABA8ox genes. Next, we excluded the impact of the aerial parts on roots by suppressing leaf-biosynthesized ABA with fluridone and NDGA (nordihydroguaiaretic acid), and measuring the ABA level in detached roots. Instead, we proved that upland rice had the ability to export considerably more root-sourced ABA than lowland rice under severe drought, which improved ABA-dependent drought adaptation. The investigation of apoplastic pH in root cells and root anatomy showed that ABA leakage in the root system of upland rice was related to high apoplastic pH and the absence of Casparian bands in the sclerenchyma layer. Finally, taking some genes as examples, we predicted that different ABA levels in rice roots stimulated distinct ABA perception and signaling cascades, which influenced its response to water stress.

  10. The Gene Cluster for para-Nitrophenol Catabolism Is Responsible for 2-Chloro-4-Nitrophenol Degradation in Burkholderia sp. Strain SJ98

    PubMed Central

    Min, Jun; Zhang, Jun-Jie

    2014-01-01

    Burkholderia sp. strain SJ98 (DSM 23195) utilizes 2-chloro-4-nitrophenol (2C4NP) or para-nitrophenol (PNP) as a sole source of carbon and energy. Here, by genetic and biochemical analyses, a 2C4NP catabolic pathway different from those of all other 2C4NP utilizers was identified with chloro-1,4-benzoquinone (CBQ) as an intermediate. Reverse transcription-PCR analysis showed that all of the pnp genes in the pnpABA1CDEF cluster were located in a single operon, which is significantly different from the genetic organization of all other previously reported PNP degradation gene clusters, in which the structural genes were located in three different operons. All of the Pnp proteins were purified to homogeneity as His-tagged proteins. PnpA, a PNP 4-monooxygenase, was found to be able to catalyze the monooxygenation of 2C4NP to CBQ. PnpB, a 1,4-benzoquinone reductase, has the ability to catalyze the reduction of CBQ to chlorohydroquinone. Moreover, PnpB is also able to enhance PnpA activity in vitro in the conversion of 2C4NP to CBQ. Genetic analyses indicated that pnpA plays an essential role in the degradation of both 2C4NP and PNP by gene knockout and complementation. In addition to being responsible for the lower pathway of PNP catabolism, PnpCD, PnpE, and PnpF were also found to be likely involved in that of 2C4NP catabolism. These results indicated that the catabolism of 2C4NP and that of PNP share the same gene cluster in strain SJ98. These findings fill a gap in our understanding of the microbial degradation of 2C4NP at the molecular and biochemical levels. PMID:25085488

  11. Ti plasmid and chromosomal ornithine catabolism genes of Agrobacterium tumefaciens C58.

    PubMed Central

    Schardl, C L; Kado, C I

    1983-01-01

    The pTiC58 plasmid noc genes of Agrobacterium tumefaciens C58 code for nopaline oxidase (nocC), nopaline permease (nocP), the inducible periplasmic protein n1 (nocB), and a function(s) required for ornithine catabolism (nocA). In addition, strains C58 and Ach-5 of A. tumefaciens have chromosomal ornithine catabolism genes. The chromosomal orc gene codes for ornithine dehydrogenase. Strain C58 is normally orc, but orc+ mutants can be selected. We have characterized both chromosomal orc and pTiC58 nocA plasmid genes. Complementation of most chromosomal orc mutants by pTiC58 restored growth on both nopaline and L-ornithine but did not restore ornithine dehydrogenase activity. We conclude that ornithine is an intermediate of nopaline degradation and that the Ti plasmid and chromosome both code for ornithine-degradative enzymes. A model for nopaline catabolism is presented. PMID:6305908

  12. Comparative Transcriptional Profiling of Melatonin Synthesis and Catabolic Genes Indicates the Possible Role of Melatonin in Developmental and Stress Responses in Rice

    PubMed Central

    Wei, Yunxie; Zeng, Hongqiu; Hu, Wei; Chen, Lanzhen; He, Chaozu; Shi, Haitao

    2016-01-01

    As a well-known animal hormone, melatonin (N-acetyl-5-methoxytryptamine) is also involved in multiple plant biological processes, especially in various stress responses. Rice is one of the most important crops, and melatonin is taken in by many people everyday from rice. However, the transcriptional profiling of melatonin-related genes in rice is largely unknown. In this study, the expression patterns of 11 melatonin related genes in rice in different periods, tissues, in response to different treatments were synthetically analyzed using published microarray data. These results suggest that the melatonin-related genes may play important and dual roles in rice developmental stages. We highlight the commonly regulation of rice melatonin-related genes by abscisic acid (ABA), jasmonic acid (JA), various abiotic stresses and pathogen infection, indicating the possible role of these genes in multiple stress responses and underlying crosstalks of plant hormones, especially ABA and JA. Taken together, this study may provide insight into the association among melatonin biosynthesis and catabolic pathway, plant development and stress responses in rice. The profile analysis identified candidate genes for further functional characterization in circadian rhythm and specific stress responses. PMID:27242875

  13. ABA gene expression during kernel development in relation to pre-harvest sprouting in wheat and triticale.

    PubMed

    Sarah, De Laethauwer; Jan, De Riek; Geert, Haesaert

    2014-01-01

    Pre-harvest sprouting (PHS) during wet and cool harvest periods remains a serious problem in the production of cereals like barley, wheat and triticale. Being involved in dormancy induction and maintenance during seed development, abscisic acid (ABA) may play a key role to improve dormancy level and hence PHS-tolerance in these grains. In this study, we investigated the ABA levels and expression profiles of ABA biosynthesis and degradation genes during kernel development to explore the potential of these genes for improving PHS-tolerance in wheat and triticale. Plants of a PHS-tolerant and a PHS-susceptible variety of both wheat and triticale were grown under controlled conditions from flowering to harvest. At regular time points, kernels were harvested for ABA analysis and RNA extraction. RNA extracts were used in an RT-qPCR assay to obtain expression profiles of the ABA synthesis genes ZEP, NCED1 and NCED2 and the ABA degradation genes CYP707A1 and CYP707A2. In contrast to reports in Arabidopsis, the ZEP gene was predominantly expressed towards harvest maturity in both wheat and triticale. NCED1 expression coincided well with the observed ABA levels during kernel development, while NCED2 expression was mainly detected in early development, indicating a potential role for dormancy induction. ABA degradation towards harvest maturity was mainly associated with increased CYP707A1 expression, whereas CYP707A2 expression appeared to correlate with the regulation of ABA levels during kernel development. However, no differential expression of the investigated genes was detected between PHS-tolerant and PHS-susceptible varieties.

  14. Bioremediation of petroleum hydrocarbons: catabolic genes, microbial communities, and applications.

    PubMed

    Fuentes, Sebastián; Méndez, Valentina; Aguila, Patricia; Seeger, Michael

    2014-06-01

    Bioremediation is an environmental sustainable and cost-effective technology for the cleanup of hydrocarbon-polluted soils and coasts. In spite of that longer times are usually required compared with physicochemical strategies, complete degradation of the pollutant can be achieved, and no further confinement of polluted matrix is needed. Microbial aerobic degradation is achieved by the incorporation of molecular oxygen into the inert hydrocarbon molecule and funneling intermediates into central catabolic pathways. Several families of alkane monooxygenases and ring hydroxylating dioxygenases are distributed mainly among Proteobacteria, Actinobacteria, Firmicutes and Fungi strains. Catabolic routes, regulatory networks, and tolerance/resistance mechanisms have been characterized in model hydrocarbon-degrading bacteria to understand and optimize their metabolic capabilities, providing the basis to enhance microbial fitness in order to improve hydrocarbon removal. However, microbial communities taken as a whole play a key role in hydrocarbon pollution events. Microbial community dynamics during biodegradation is crucial for understanding how they respond and adapt to pollution and remediation. Several strategies have been applied worldwide for the recovery of sites contaminated with persistent organic pollutants, such as polycyclic aromatic hydrocarbons and petroleum derivatives. Common strategies include controlling environmental variables (e.g., oxygen availability, hydrocarbon solubility, nutrient balance) and managing hydrocarbon-degrading microorganisms, in order to overcome the rate-limiting factors that slow down hydrocarbon biodegradation.

  15. In vivo cloning of Erwinia carotovora genes involved in the catabolism of hexuronates.

    PubMed Central

    Van Gijsegem, F; Toussaint, A

    1983-01-01

    Using the RP4::mini-Mu pULB113 plasmid, an RP4 derivative carrying a deleted Mu prophage which allows the plasmid to pick up any chromosomal DNA segment to form R' plasmids, we cloned all of the genes of Erwinia carotovora involved in the catabolism of the hexuronates and in the transport of these substrates. With the R' plasmids we isolated, we performed complementation analysis and found that, in the Erwinia carotovora strain we used, the genes involved in the catabolism of the hexuronates are clustered in four regions of the chromosome. This genetic organization is compared with that of Escherichia coli K-12. Images PMID:6853444

  16. DNA sequence and spatial expression pattern of a drought- and ABA-induced gene in tomato

    SciTech Connect

    Plant, A.L.; Cohen, A.; Moses, M.S.; Bray, E.A. )

    1991-05-01

    The genomic and cDNA sequence for the previously characterized drought- and ABA-induced gene pLE16 are presented. The single open reading frame contained within the gene has the capacity to encode a polypeptide of 12.7 kD with a predicted pI of 8.73. The amino-terminus is highly hydrophobic and is characteristic of signal sequences which target polypeptides for export from the cytoplasm. There is considerable homology (51.3% identity) between the amino-terminus of pLE16 and the amino-terminal domains of a group of proteins that comprise the phospholipid transfer proteins. Although this homology breaks down at the carboxy-terminal half of pLE16, the homology that exists suggests that pLE16 may be associated with membranes and may therefore play a role in maintaining membrane integrity during drought-stress. pLE16 is expressed in drought-stressed leaf, petiole and stem tissue and to a much lower extent in the seeds and pericarp of mature green tomato fruit. No expression was detected in the seeds or pericarp of red fruit or drought-stressed roots. Expression of pLE16 is induced in leaf tissue by a variety of other environmental stresses including PEG-mediated water deficit, salt, cold stress and heat stress. These stresses did not however induce expression of pLE16 in the roots. Examination of the 5{prime} flanking DNA sequences for this gene did not reveal the presence of the consensus ABA responsive element (ABRE), implicated in ABA induction of gene expression and so far common to the 5{prime} flanking DNA sequences of many genes that are ABA responsive. The expression of pLE16 in response to drought-stress and other environmental stresses in vegetative tissue, together with the lack of a consensus ABRE, suggests that the regulation of this gene by ABA may differ from those that are seed-specific.

  17. Transcriptional regulation of genes encoding ABA metabolism enzymes during the fruit development and dehydration stress of pear 'Gold Nijisseiki'.

    PubMed

    Dai, Shengjie; Li, Ping; Chen, Pei; Li, Qian; Pei, Yuelin; He, Suihuan; Sun, Yufei; Wang, Ya; Kai, Wenbin; Zhao, Bo; Liao, Yalan; Leng, Ping

    2014-09-01

    To investigate the contribution of abscisic acid (ABA) in pear 'Gold Nijisseiki' during fruit ripening and under dehydration stress, two cDNAs (PpNCED1 and PpNCED2) which encode 9-cis-epoxycarotenoid dioxygenase (NCED) (a key enzyme in ABA biosynthesis), two cDNAs (PpCYP707A1 and PpCYP707A2) which encode 8'-hydroxylase (a key enzyme in the oxidative catabolism of ABA), one cDNA (PpACS3) which encodes 1-aminocyclopropane-1-carboxylic acid (ACC), and one cDNA (PpACO1) which encodes ACC oxidase involved in ethylene biosynthesis were cloned from 'Gold Nijisseiki' fruit. In the pulp, peel and seed, expressions of PpNCED1 and PpNCED2 rose in two stages which corresponded with the increase of ABA levels. The expression of PpCYP707A1 dramatically declined after 60-90 days after full bloom (DAFB) in contrast to the changes of ABA levels during this period, while PpCYP707A2 stayed low during the whole development of fruit. Application of exogenous ABA at 100 DAFB increased the soluble sugar content and the ethylene release but significantly decreased the titratable acid and chlorophyll contents in fruits. When fruits harvested at 100 DAFB were stored in the laboratory (25 °C, 50% relative humidity), the ABA content and the expressions of PpNCED1/2 and PpCYP707A1 in the pulp, peel and seed increased significantly, while ethylene reached its highest value after the maximum peak of ABA accompanied with the expressions of PpACS3 and PpACO1. In sum the endogenous ABA may play an important role in the fruit ripening and dehydration of pear 'Gold Nijisseiki' and the ABA level was regulated mainly by the dynamics of PpNCED1, PpNCED2 and PpCYP707A1 at the transcriptional level.

  18. Effects of molybdenum on expression of cold-responsive genes in abscisic acid (ABA)-dependent and ABA-independent pathways in winter wheat under low-temperature stress

    PubMed Central

    Sun, Xuecheng; Hu, Chengxiao; Tan, Qilin; Liu, Jinshan; Liu, Hongen

    2009-01-01

    Background and Aims Molybdenum (Mo) is an essential trace element for higher plants. It has been shown that application of Mo enhances the cold resistance of winter wheat. In order to improve our understanding of the molecular mechanisms of cold resistance arising from application of Mo in winter wheat, investigations were made regarding the transcription of cold-responsive (COR) genes in abscisic acid (ABA)-dependent and ABA-independent pathways in winter wheat regulated by Mo application under low-temperature stress. Methods Two cultivars of winter wheat (Triticum aestivum), Mo-efficient cultivar ‘97003’ and Mo-inefficient cultivar ‘97014’, were grown in control (−Mo) and Mo fertilizer (+Mo) treatments for 40 d at 15/12 °C (day/night), and the temperature was then reduced to 5/2 °C (day/night) to create low-temperature stress. Aldehyde oxidase (AO) activities, ABA contents, the transcripts of basic leucine zipper (bZIP)-type transcription factor (TF) genes, ABA-dependent COR genes, CBF/DREB transcription factor genes and ABA-independent COR genes were investigated at 0, 3, 6 and 48 h post cold stress. Key Results Mo application significantly increased AO activity, ABA levels, and expression of bZIP-type TF genes (Wlip19 and Wabi5) and ABA-dependent COR genes (Wrab15, Wrab17, Wrab18 and Wrab19). Mo application increased expression levels of CBF/DREB transcription factor genes (TaCBF and Wcbf2-1) and ABA-independent COR genes (Wcs120, Wcs19, Wcor14 and Wcor15) after 3 and 6 h exposure to low temperature. Conclusions Mo might regulate the expression of ABA-dependent COR genes through the pathway: Mo → AO → ABA → bZIP → ABA-dependent COR genes in winter wheat. The response of the ABA-dependent pathway to Mo was prior to that of the ABA-independent pathway. Similarities and differences between the Mo-efficient and Mo-inefficient wheat cultivars in response to Mo under cold stress are discussed. PMID:19491090

  19. Characterization of genes involved in erythritol catabolism in Rhizobium leguminosarum bv. viciae.

    PubMed

    Yost, Christopher K; Rath, Amber M; Noel, Tanya C; Hynes, Michael F

    2006-07-01

    A genetic locus encoding erythritol uptake and catabolism genes was identified in Rhizobium leguminosarum bv. viciae, and shown to be plasmid encoded in a wide range of R. leguminosarum strains. A Tn5-B22 mutant (19B-3) unable to grow on erythritol was isolated from a mutant library of R. leguminosarum strain VF39SM. The mutated gene eryF was cloned and partially sequenced, and determined to have a high homology to permease genes of ABC transporters. A cosmid complementing the mutation (pCos42) was identified and was shown to carry all the genes necessary to restore the ability to grow on erythritol to a VF39SM strain cured of pRleVF39f. In the genomic DNA sequence of strain 3841, the gene linked to the mutation in 19B-3 is flanked by a cluster of genes with high homology to the known erythritol catabolic genes from Brucella spp. Through mutagenesis studies, three distinct operons on pCos42 that are required for growth on erythritol were identified: an ABC-transporter operon (eryEFG), a catabolic operon (eryABCD) and an operon (deoR-tpiA2-rpiB) that encodes a gene with significant homology to triosephosphate isomerase (tpiA2). These genes all share high sequence identity to genes in the erythritol catabolism region of Brucella spp., and clustalw alignments suggest that horizontal transfer of the erythritol locus may have occurred between R. leguminosarum and Brucella. Transcription of the eryABCD operon is repressed by EryD and is induced by the presence of erythritol. Mutant 19B-3 was impaired in its ability to compete against wild-type for nodulation of pea plants but was still capable of forming nitrogen-fixing nodules.

  20. Identification of Agrobacterium tumefaciens genes that direct the complete catabolism of octopine.

    PubMed

    Cho, K; Fuqua, C; Martin, B S; Winans, S C

    1996-04-01

    Agrobacterium tumefaciens R10 was mutagenized by using the promoter probe transposon Tn5-gusA7, and a library of approximately 5,000 transcriptional fusions was screened for octopine-inducible patterns of gene expression. Twenty-one mutants carrying strongly inducible gusA fusions, 20 of which showed defects in the catabolism of octopine or its metabolites, were obtained. One group of mutants could not use octopine as a carbon source, while a second group of mutants could not utilize arginine or ornithine and a third group could not utilize octopine, arginine, ornithine, or proline as a carbon source. Utilization of these compounds as nitrogen sources showed similar but not identical patterns. Fifteen fusions were subcloned together with adjacent DNA. Sequence analysis and further genetic analysis indicated that insertions of the first group are localized in the occ region of the Ti plasmid. Insertions of the second group were localized to a gene encoding ornithine cyclodeaminase. This gene is very similar to, but distinct from, a homolog located on the Ti plasmid. This gene is located immediately downstream from a gene encoding an arginase. Genetic experiments indicated that this arginase gene is essential for octopine and arginine catabolism. Insertions of the third group was localized to a gene whose product is required for degradation of proline. We therefore have identified all steps required for the catabolism of octopine to glutamate. PMID:8606160

  1. Sialic acid catabolism and transport gene clusters are lineage specific in Vibrio vulnificus.

    PubMed

    Lubin, Jean-Bernard; Kingston, Joseph J; Chowdhury, Nityananda; Boyd, E Fidelma

    2012-05-01

    Sialic or nonulosonic acids are nine-carbon alpha ketosugars that are present in all vertebrate mucous membranes. Among bacteria, the ability to catabolize sialic acid as a carbon source is present mainly in pathogenic and commensal species of animals. Previously, it was shown that several Vibrio species carry homologues of the genes required for sialic acid transport and catabolism, which are genetically linked. In Vibrio cholerae on chromosome I, these genes are carried on the Vibrio pathogenicity island-2 region, which is confined to pathogenic isolates. We found that among the three sequenced Vibrio vulnificus clinical strains, these genes are present on chromosome II and are not associated with a pathogenicity island. To determine whether the sialic acid transport (SAT) and catabolism (SAC) region is universally present within V. vulnificus, we examined 67 natural isolates whose phylogenetic relationships are known. We found that the region was present predominantly among lineage I of V. vulnificus, which is comprised mainly of clinical isolates. We demonstrate that the isolates that contain this region can catabolize sialic acid as a sole carbon source. Two putative transporters are genetically linked to the region in V. vulnificus, the tripartite ATP-independent periplasmic (TRAP) transporter SiaPQM and a component of an ATP-binding cassette (ABC) transporter. We constructed an in-frame deletion mutation in siaM, a component of the TRAP transporter, and demonstrate that this transporter is essential for sialic acid uptake in this species. Expression analysis of the SAT and SAC genes indicates that sialic acid is an inducer of expression. Overall, our study demonstrates that the ability to catabolize and transport sialic acid is predominately lineage specific in V. vulnificus and that the TRAP transporter is essential for sialic acid uptake.

  2. Organization and control of genes encoding catabolic enzymes in Rhizobiaceae

    SciTech Connect

    Parke, D.; Ornston, L.N.

    1993-03-01

    Rhizobiaceae, a diverse bacterial group comprising rhizobia and agrobacteria, symbiotic partnership with plants form nitrogen-fixing nodules on plant roots or are plant pathogens. Phenolic compounds produced by plants serve as inducers of rhizobial nodulation genes and agrobacterial virulence genes reflect their capacity to utilize numerous aromatics, including phenolics, as a source of carbon and energy. In many microbes the aerobic degradation of numerous aromatic compounds to tricarboxylic acid cycle intermediates is achieved by the [beta]-ketoadipate pathway. Our initial studies focused on the organization and regulation of the ketoadipate pathway in Agrobacterium tumefaciens. We have cloned, identified and characterized a novel regulatory gene that modulates expression of an adjacent pca (protocatechuate) structural gene, pcaD. Regulation of pcaD is mediated by the regulatory gene, termed pcaQ, in concert with the intermediate [beta]-carboxy-cis,cis-muconate. [beta]-carboxy-cis,cismuconate is an unstable chemical, not marketed commercially, and it is unlikely to permeate Escherichia coli cells if supplied in media. Because of these factors, characterization of pcaQ in E. coli required an in vivo delivery system for [beta]-carboxycis,cis-muconate. This was accomplished by designing an E. coli strain that expressed an Acinetobacter calcoaceticus pcaA gene for conversion of protocatechuate to [beta]-carboxy-cis,cis-muconate.

  3. Molecular detection of catabolic genes for polycyclic aromatic hydrocarbons in the reed rhizosphere of Sunchon Bay.

    PubMed

    Kahng, Hyung-Yeel; Oh, Kye-Heon

    2005-12-01

    This study focused on detecting catabolic genes for polycyclic aromatic hydrocarbons (PAHs) distributed in the reed rhizosphere of Sunchon Bay, Korea. These marsh and mud environments were severely affected by human activities, including agriculture and fisheries. Our previous study on microbial roles in natural decontamination displayed the possibility that PAH-degrading bacteria, such as Achromobacter sp., Alcaligenes sp., Burkholderia sp. and Pseudomonas sp. play an important decontamination role in a reed rhizosphere. In order to gain further fundamental knowledge on the natural decontamination process, catabolic genes for PAH metabolism were investigated through PCR amplification of dioxygenase genes using soil genomic DNA and sequencing. Comparative analysis of predicted amino acid sequences from 50 randomly selected dioxygenase clones capable of hydroxylating inactivated aromatic nuclei indicated that these were divided into three groups, two of which might be originated from PAH-degrading bacteria. Amino acid sequences of each dioxygenase clone were a part of the genes encoding enzymes for initial catabolism of naphthalene, phenanthrene, or pyrene that might be originated from bacteria in the reed rhizosphere of Sunchon Bay.

  4. Correlating denitrifying catabolic genes with N2O and N2 emissions from swine slurry composting.

    PubMed

    Angnes, G; Nicoloso, R S; da Silva, M L B; de Oliveira, P A V; Higarashi, M M; Mezzari, M P; Miller, P R M

    2013-07-01

    This work evaluated N dynamics that occurs over time within swine slurry composting piles. Real-time quantitative PCR (qPCR) analyzes were conducted to estimate concentrations of bacteria community harboring specific catabolic nitrifying-ammonium monooxygenase (amoA), and denitrifying nitrate- (narG), nitrite- (nirS and nirG), nitric oxide- (norB) and nitrous oxide reductases (nosZ) genes. NH3-N, N2O-N, N2-N emissions represented 15.4 ± 1.9%, 5.4 ± 0.9%, and 79.1 ± 2.0% of the total nitrogen losses, respectively. Among the genes tested, temporal distribution of narG, nirS, and nosZ concentration correlated significantly (p<0.05) with the estimated N2 emissions. Denitrifying catabolic gene ratio (cnorB+qnorB)/nosZ ≥ 100 was indicative of N2O emission potential from the compost pile. Considering our current empirical limitations to accurately measure N2 emissions from swine slurry composting at field scale the use of these catabolic genes could represent a promising monitoring tool to aid minimize our uncertainties on biological N mass balances in these systems.

  5. Frequent, independent transfers of a catabolic gene from bacteria to contrasted filamentous eukaryotes.

    PubMed

    Bruto, Maxime; Prigent-Combaret, Claire; Luis, Patricia; Moënne-Loccoz, Yvan; Muller, Daniel

    2014-08-22

    Even genetically distant prokaryotes can exchange genes between them, and these horizontal gene transfer events play a central role in adaptation and evolution. While this was long thought to be restricted to prokaryotes, certain eukaryotes have acquired genes of bacterial origin. However, gene acquisitions in eukaryotes are thought to be much less important in magnitude than in prokaryotes. Here, we describe the complex evolutionary history of a bacterial catabolic gene that has been transferred repeatedly from different bacterial phyla to stramenopiles and fungi. Indeed, phylogenomic analysis pointed to multiple acquisitions of the gene in these filamentous eukaryotes-as many as 15 different events for 65 microeukaryotes. Furthermore, once transferred, this gene acquired introns and was found expressed in mRNA databases for most recipients. Our results show that effective inter-domain transfers and subsequent adaptation of a prokaryotic gene in eukaryotic cells can happen at an unprecedented magnitude.

  6. Rhizobium meliloti Genes Encoding Catabolism of Trigonelline Are Induced under Symbiotic Conditions.

    PubMed Central

    Boivin, C; Camut, S; Malpica, CA; Truchet, G; Rosenberg, C

    1990-01-01

    Rhizobium meliloti trc genes controlling the catabolism of trigonelline, a plant secondary metabolite often abundant in legumes, are closely linked to nif-nod genes on the symbiotic megaplasmid pSym [Boivin, C., Malpica, C., Rosenberg, C., Denarie, J., Goldman, A., Fleury, V., Maille, M., Message, B., and Tepfer, D. (1989). In Molecular Signals in the Microbe-Plant Symbiotic and Pathogenic Systems. (Berlin: Springer-Verlag), pp. 401-407]. To investigate the role of trigonelline catabolism in the Rhizobium-legume interaction, we studied the regulation of trc gene expression in free-living and in endosymbiotic bacteria using Escherichia coli lacZ as a reporter gene. Experiments performed with free-living bacteria indicated that trc genes were organized in at least four transcription units and that the substrate trigonelline was a specific inducer for three of them. Noninducing trigonelline-related compounds such as betaines appeared to antagonize the inducing effect of trigonelline. None of the general or symbiotic regulatory genes ntrA, dctB/D, or nodD seemed to be involved in trigonelline catabolism. trc fusions exhibiting a low basal and a high induced [beta]-galactosidase activity when present on pSym were used to monitor trc gene expression in alfalfa tissue under symbiotic conditions. Results showed that trc genes are induced during all the symbiotic steps, i.e., in the rhizosphere, infection threads, and bacteroids of alfalfa, suggesting that trigonelline is a nutrient source throughout the Rhizobium-legume association. PMID:12354952

  7. ABA crosstalk with ethylene and nitric oxide in seed dormancy and germination

    PubMed Central

    Arc, Erwann; Sechet, Julien; Corbineau, Françoise; Rajjou, Loïc; Marion-Poll, Annie

    2013-01-01

    Dormancy is an adaptive trait that enables seed germination to coincide with favorable environmental conditions. It has been clearly demonstrated that dormancy is induced by abscisic acid (ABA) during seed development on the mother plant. After seed dispersal, germination is preceded by a decline in ABA in imbibed seeds, which results from ABA catabolism through 8′-hydroxylation. The hormonal balance between ABA and gibberellins (GAs) has been shown to act as an integrator of environmental cues to maintain dormancy or activate germination. The interplay of ABA with other endogenous signals is however less documented. In numerous species, ethylene counteracts ABA signaling pathways and induces germination. In Brassicaceae seeds, ethylene prevents the inhibitory effects of ABA on endosperm cap weakening, thereby facilitating endosperm rupture and radicle emergence. Moreover, enhanced seed dormancy in Arabidopsis ethylene-insensitive mutants results from greater ABA sensitivity. Conversely, ABA limits ethylene action by down-regulating its biosynthesis. Nitric oxide (NO) has been proposed as a common actor in the ABA and ethylene crosstalk in seed. Indeed, convergent evidence indicates that NO is produced rapidly after seed imbibition and promotes germination by inducing the expression of the ABA 8′-hydroxylase gene, CYP707A2, and stimulating ethylene production. The role of NO and other nitrogen-containing compounds, such as nitrate, in seed dormancy breakage and germination stimulation has been reported in several species. This review will describe our current knowledge of ABA crosstalk with ethylene and NO, both volatile compounds that have been shown to counteract ABA action in seeds and to improve dormancy release and germination. PMID:23531630

  8. ABA crosstalk with ethylene and nitric oxide in seed dormancy and germination.

    PubMed

    Arc, Erwann; Sechet, Julien; Corbineau, Françoise; Rajjou, Loïc; Marion-Poll, Annie

    2013-01-01

    Dormancy is an adaptive trait that enables seed germination to coincide with favorable environmental conditions. It has been clearly demonstrated that dormancy is induced by abscisic acid (ABA) during seed development on the mother plant. After seed dispersal, germination is preceded by a decline in ABA in imbibed seeds, which results from ABA catabolism through 8'-hydroxylation. The hormonal balance between ABA and gibberellins (GAs) has been shown to act as an integrator of environmental cues to maintain dormancy or activate germination. The interplay of ABA with other endogenous signals is however less documented. In numerous species, ethylene counteracts ABA signaling pathways and induces germination. In Brassicaceae seeds, ethylene prevents the inhibitory effects of ABA on endosperm cap weakening, thereby facilitating endosperm rupture and radicle emergence. Moreover, enhanced seed dormancy in Arabidopsis ethylene-insensitive mutants results from greater ABA sensitivity. Conversely, ABA limits ethylene action by down-regulating its biosynthesis. Nitric oxide (NO) has been proposed as a common actor in the ABA and ethylene crosstalk in seed. Indeed, convergent evidence indicates that NO is produced rapidly after seed imbibition and promotes germination by inducing the expression of the ABA 8'-hydroxylase gene, CYP707A2, and stimulating ethylene production. The role of NO and other nitrogen-containing compounds, such as nitrate, in seed dormancy breakage and germination stimulation has been reported in several species. This review will describe our current knowledge of ABA crosstalk with ethylene and NO, both volatile compounds that have been shown to counteract ABA action in seeds and to improve dormancy release and germination.

  9. Up-regulating the abscisic acid inactivation gene ZmABA8ox1b contributes to seed germination heterosis by promoting cell expansion

    PubMed Central

    Li, Yangyang; Wang, Cheng; Liu, Xinye; Song, Jian; Li, Hongjian; Sui, Zhipeng; Zhang, Ming; Fang, Shuang; Chu, Jinfang; Xin, Mingming; Xie, Chaojie; Zhang, Yirong; Sun, Qixin; Ni, Zhongfu

    2016-01-01

    Heterosis has been widely used in agriculture, but the underlying molecular principles are still largely unknown. During seed germination, we observed that maize (Zea mays) hybrid B73/Mo17 was less sensitive than its parental inbred lines to exogenous abscisic acid (ABA), and endogenous ABA content in hybrid embryos decreased more rapidly than in the parental inbred lines. ZmABA8ox1b, an ABA inactivation gene, was consistently more highly up-regulated in hybrid B73/Mo17 than in its parental inbred lines at early stages of seed germination. Moreover, ectopic expression of ZmABA8ox1b obviously promoted seed germination in Arabidopsis. Remarkably, microscopic observation revealed that cell expansion played a major role in the ABA-mediated maize seed germination heterosis, which could be attributed to the altered expression of cell wall-related genes. PMID:27034328

  10. Up-regulating the abscisic acid inactivation gene ZmABA8ox1b contributes to seed germination heterosis by promoting cell expansion.

    PubMed

    Li, Yangyang; Wang, Cheng; Liu, Xinye; Song, Jian; Li, Hongjian; Sui, Zhipeng; Zhang, Ming; Fang, Shuang; Chu, Jinfang; Xin, Mingming; Xie, Chaojie; Zhang, Yirong; Sun, Qixin; Ni, Zhongfu

    2016-04-01

    Heterosis has been widely used in agriculture, but the underlying molecular principles are still largely unknown. During seed germination, we observed that maize (Zea mays) hybrid B73/Mo17 was less sensitive than its parental inbred lines to exogenous abscisic acid (ABA), and endogenous ABA content in hybrid embryos decreased more rapidly than in the parental inbred lines. ZmABA8ox1b, an ABA inactivation gene, was consistently more highly up-regulated in hybrid B73/Mo17 than in its parental inbred lines at early stages of seed germination. Moreover, ectopic expression of ZmABA8ox1b obviously promoted seed germination in Arabidopsis Remarkably, microscopic observation revealed that cell expansion played a major role in the ABA-mediated maize seed germination heterosis, which could be attributed to the altered expression of cell wall-related genes.

  11. Effect of grain colour gene (R) on grain dormancy and sensitivity of the embryo to abscisic acid (ABA) in wheat.

    PubMed

    Himi, Eiko; Mares, Daryl J; Yanagisawa, Akira; Noda, Kazuhiko

    2002-07-01

    The level of grain dormancy and sensitivity to ABA of the embryo, a key factor in grain dormancy, were examined in developing grains of a white-grained wheat line, Novosibirskaya 67 (NS-67), and its red-grained near-isogenic lines (ANK-1A to -1D); a red-grained line, AUS 1490, and its white-grained mutant line (EMS-AUS). ANK lines showed higher levels of grain dormancy than NS-67 at harvest maturity. AUS 1490 grain also showed higher dormancy than EMS-AUS grain. These results suggest that the R gene for grain colour can enhance grain dormancy. However, the dormancy effect conferred by the R gene was not large, suggesting that it plays a minor role in the development of grain dormancy. Water extracts of AUS 1490 and EMS-AUS bran contained germination inhibitors equivalent to 1-10 microM ABA, although there was no difference in the amount of inhibitors between AUS 1490 and EMS-AUS. Thus, the grain colour gene of AUS 1490 did not appear to enhance the level of grain dormancy by accumulating germination inhibitors in its bran. Sensitivity to ABA of embryos was higher in grains collected around harvest-maturity for ANK lines and AUS 1490, compared with NS-67 and EMS-AUS. The R gene might enhance grain dormancy by increasing the sensitivity of embryos to ABA.

  12. The phn Genes of Burkholderia sp. Strain RP007 Constitute a Divergent Gene Cluster for Polycyclic Aromatic Hydrocarbon Catabolism

    PubMed Central

    Laurie, Andrew D.; Lloyd-Jones, Gareth

    1999-01-01

    Cloning and molecular ecological studies have underestimated the diversity of polycyclic aromatic hydrocarbon (PAH) catabolic genes by emphasizing classical nah-like (nah, ndo, pah, and dox) sequences. Here we report the description of a divergent set of PAH catabolic genes, the phn genes, which although isofunctional to the classical nah-like genes, show very low homology. This phn locus, which contains nine open reading frames (ORFs), was isolated on an 11.5-kb HindIII fragment from phenanthrene-degrading Burkholderia sp. strain RP007. The phn genes are significantly different in sequence and gene order from previously characterized genes for PAH degradation. They are transcribed by RP007 when grown at the expense of either naphthalene or phenanthrene, while in Escherichia coli the recombinant phn enzymes have been shown to be capable of oxidizing both naphthalene and phenanthrene to predicted metabolites. The locus encodes iron sulfur protein α and β subunits of a PAH initial dioxygenase but lacks the ferredoxin and reductase components. The dihydrodiol dehydrogenase of the RP007 pathway, PhnB, shows greater similarity to analogous dehydrogenases from described biphenyl pathways than to those characterized from naphthalene/phenanthrene pathways. An unusual extradiol dioxygenase, PhnC, shows no similarity to other extradiol dioxygenases for naphthalene or biphenyl oxidation but is the first member of the recently proposed class III extradiol dioxygenases that is specific for polycyclic arene diols. Upstream of the phn catabolic genes are two putative regulatory genes, phnR and phnS. Sequence homology suggests that phnS is a LysR-type transcriptional activator and that phnR, which is divergently transcribed with respect to phnSFECDAcAdB, is a member of the ς54-dependent family of positive transcriptional regulators. Reverse transcriptase PCR experiments suggest that this gene cluster is coordinately expressed and is under regulatory control which may involve

  13. Overexpression of an ABA biosynthesis gene using a stress inducible promoter enhances drought resistance in petunia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plants respond to drought stress by closing their stomata and reducing transpirational water loss. The plant hormone abscisic acid (ABA) regulates growth and stomatal closure particularly when the plant is under environmental stresses. One of the key enzymes in the ABA biosynthesis of higher plants ...

  14. The naphthalene catabolic (nag) genes of Polaromonas naphthalenivorans CJ2: Evolutionary implications for two gene clusters and novel regulatory control

    SciTech Connect

    Jeon, C.O.; Park, M.; Ro, H.S.; Park, W.; Madsen, E.L.

    2006-02-15

    Polaromonas naphthalenivorans CJ2, found to be responsible for the degradation of naphthalene in situ at a coal tar waste-contaminated site, is able to grow on mineral salts agar media with naphthalene as the sole carbon source. Beginning from a 484-bp nagAc-like region, we used a genome walking strategy to sequence genes encoding the entire naphthalene degradation pathway and additional flanking regions. We found that the naphthalene catabolic genes in P. naphthalenivorans CJ2 were divided into one large and one small gene cluster, separated by an unknown distance. The large gene cluster is bounded by a LysR-type regulator (nagR). The small cluster is bounded by a MarR-type regulator (nagR2). The catabolic genes of P. naphthalenivorans CJ2 were homologous to many of those of Ralstonia U2, which uses the gentisate pathway to convert naphthalene to central metabolites. However, three open reading frames (nagY, nagM, and nagN), present in Ralstonia U2, were absent. Also, P. naphthalenivorans carries two copies of gentisate dioxygenase (nagI) with 77.4% DNA sequence identity to one another and 82% amino acid identity to their homologue in Ralstonia sp. strain U2. Investigation of the operons using reverse transcription PCR showed that each cluster was controlled independently by its respective promoter. Insertional inactivation and lacZ reporter assays showed that nagR2 is a negative regulator and that expression of the small cluster is not induced by naphthalene, salicylate, or gentisate. Association of two putative Azoarcus-related transposases with the large cluster and one Azoarcus-related putative salicylate 5-hydroxylase gene (ORF2) in the small cluster suggests that mobile genetic elements were likely involved in creating the novel arrangement of catabolic and regulatory genes in P. naphthalenivorans.

  15. Identification of new ABA- and MEJA-activated sugarcane bZIP genes by data mining in the SUCEST database.

    PubMed

    Schlögl, Paulo Sérgio; Nogueira, Fábio Tebaldi S; Drummond, Rodrigo; Felix, Juliana M; De Rosa, Vicente E; Vicentini, Renato; Leite, Adilson; Ulian, Eugênio C; Menossi, Marcelo

    2008-02-01

    Sugarcane is generally propagated by cuttings of the stalk containing one or more lateral buds, which will develop into a new plant. The transition from the dormant into the active stage constitutes a complex phenomenon characterized by changes in accumulation of phytohormones and several other physiological aspects. Abscisic acid (ABA) and methyl-jasmonate (MeJA) are major signaling molecules, which influence plant development and stress responses. These plant regulators modulate gene expression with the participation of many transcriptional factors. Basic leucine zipper proteins (bZIPs) form a large family of transcriptional factors involved in a variety of plant physiological processes, such as development and responses to stress. Query sequences consisting of full-length protein sequence of each of the Arabidopsis bZIP families were utilized to screen the sugarcane EST database (SUCEST) and 86 sugarcane assembled sequences (SAS) coding for bZIPs were identified. cDNA arrays and RNA-gel blots were used to study the expression of these sugarcane bZIP genes during early plantlet development and in response to ABA and MeJA. Six bZIP genes were found to be differentially expressed during development. ABA and MeJA modulated the expression of eight sugarcane bZIP genes. Our findings provide novel insights into the expression of this large protein family of transcriptional factors in sugarcane.

  16. The Mg-Chelatase H Subunit of Arabidopsis Antagonizes a Group of WRKY Transcription Repressors to Relieve ABA-Responsive Genes of Inhibition[W][OA

    PubMed Central

    Shang, Yi; Yan, Lu; Liu, Zhi-Qiang; Cao, Zheng; Mei, Chao; Xin, Qi; Wu, Fu-Qing; Wang, Xiao-Fang; Du, Shu-Yuan; Jiang, Tao; Zhang, Xiao-Feng; Zhao, Rui; Sun, Hai-Li; Liu, Rui; Yu, Yong-Tao; Zhang, Da-Peng

    2010-01-01

    The phytohormone abscisic acid (ABA) plays a vital role in plant development and response to environmental challenges, but the complex networks of ABA signaling pathways are poorly understood. We previously reported that a chloroplast protein, the magnesium-protoporphyrin IX chelatase H subunit (CHLH/ABAR), functions as a receptor for ABA in Arabidopsis thaliana. Here, we report that ABAR spans the chloroplast envelope and that the cytosolic C terminus of ABAR interacts with a group of WRKY transcription factors (WRKY40, WRKY18, and WRKY60) that function as negative regulators of ABA signaling in seed germination and postgermination growth. WRKY40, a central negative regulator, inhibits expression of ABA-responsive genes, such as ABI5. In response to a high level of ABA signal that recruits WRKY40 from the nucleus to the cytosol and promotes ABAR–WRKY40 interaction, ABAR relieves the ABI5 gene of inhibition by repressing WRKY40 expression. These findings describe a unique ABA signaling pathway from the early signaling events to downstream gene expression. PMID:20543028

  17. CmWRKY1 Enhances the Dehydration Tolerance of Chrysanthemum through the Regulation of ABA-Associated Genes.

    PubMed

    Fan, Qingqing; Song, Aiping; Jiang, Jiafu; Zhang, Ting; Sun, Hainan; Wang, Yinjie; Chen, Sumei; Chen, Fadi

    2016-01-01

    WRKY transcription factors serve as antagonistic or synergistic regulators in a variety of abiotic stress responses in plants. Here, we show that CmWRKY1, a member of the group IIb WRKY family isolated from Chrysanthemum morifolium, exhibits no transcriptional activation in yeast cells. The subcellular localization examination showed that CmWRKY1 localizes to the nucleus in vivo. Furthermore, CmWRKY1-overexpressing transgenic lines exhibit enhanced dehydration tolerance in response to polyethylene glycol (PEG) treatment compared with wild-type plants. We further confirmed that the transgenic plants exhibit suppressed expression levels of genes negatively regulated by ABA, such as PP2C, ABI1 and ABI2, and activated expression levels of genes positively regulated by ABA, such as PYL2, SnRK2.2, ABF4, MYB2, RAB18, and DREB1A. Taken together, our results indicate that CmWRKY1 plays an important role in the response to drought in chrysanthemum through an ABA-mediated pathway. PMID:26938878

  18. Feedback Regulation of ABA Signaling and Biosynthesis by a bZIP Transcription Factor Targets Drought-Resistance-Related Genes.

    PubMed

    Zong, Wei; Tang, Ning; Yang, Jun; Peng, Lei; Ma, Siqi; Xu, Yan; Li, Guoliang; Xiong, Lizhong

    2016-08-01

    The OsbZIP23 transcription factor has been characterized for its essential role in drought resistance in rice (Oryza sativa), but the mechanism is unknown. In this study, we first investigated the transcriptional activation of OsbZIP23. A homolog of SnRK2 protein kinase (SAPK2) was found to interact with and phosphorylate OsbZIP23 for its transcriptional activation. SAPK2 also interacted with OsPP2C49, an ABI1 homolog, which deactivated the SAPK2 to inhibit the transcriptional activation activity of OsbZIP23. Next, we performed genome-wide identification of OsbZIP23 targets by immunoprecipitation sequencing and RNA sequencing analyses in the OsbZIP23-overexpression, osbzip23 mutant, and wild-type rice under normal and drought stress conditions. OsbZIP23 directly regulates a large number of reported genes that function in stress response, hormone signaling, and developmental processes. Among these targets, we found that OsbZIP23 could positively regulate OsPP2C49, and overexpression of OsPP2C49 in rice resulted in significantly decreased sensitivity of the abscisic acid (ABA) response and rapid dehydration. Moreover, OsNCED4 (9-cis-epoxycarotenoid dioxygenase4), a key gene in ABA biosynthesis, was also positively regulated by OsbZIP23. Together, our results suggest that OsbZIP23 acts as a central regulator in ABA signaling and biosynthesis, and drought resistance in rice. PMID:27325665

  19. CmWRKY1 Enhances the Dehydration Tolerance of Chrysanthemum through the Regulation of ABA-Associated Genes

    PubMed Central

    Fan, Qingqing; Song, Aiping; Jiang, Jiafu; Zhang, Ting; Sun, Hainan; Wang, Yinjie; Chen, Sumei; Chen, Fadi

    2016-01-01

    WRKY transcription factors serve as antagonistic or synergistic regulators in a variety of abiotic stress responses in plants. Here, we show that CmWRKY1, a member of the group IIb WRKY family isolated from Chrysanthemum morifolium, exhibits no transcriptional activation in yeast cells. The subcellular localization examination showed that CmWRKY1 localizes to the nucleus in vivo. Furthermore, CmWRKY1-overexpressing transgenic lines exhibit enhanced dehydration tolerance in response to polyethylene glycol (PEG) treatment compared with wild-type plants. We further confirmed that the transgenic plants exhibit suppressed expression levels of genes negatively regulated by ABA, such as PP2C, ABI1 and ABI2, and activated expression levels of genes positively regulated by ABA, such as PYL2, SnRK2.2, ABF4, MYB2, RAB18, and DREB1A. Taken together, our results indicate that CmWRKY1 plays an important role in the response to drought in chrysanthemum through an ABA-mediated pathway. PMID:26938878

  20. γ-Resorcylate Catabolic-Pathway Genes in the Soil Actinomycete Rhodococcus jostii RHA1

    PubMed Central

    Kasai, Daisuke; Araki, Naoto; Motoi, Kota; Yoshikawa, Shota; Iino, Toju; Imai, Shunsuke; Masai, Eiji

    2015-01-01

    The Rhodococcus jostii RHA1 gene cluster required for γ-resorcylate (GRA) catabolism was characterized. The cluster includes tsdA, tsdB, tsdC, tsdD, tsdR, tsdT, and tsdX, which encode GRA decarboxylase, resorcinol 4-hydroxylase, hydroxyquinol 1,2-dioxygenase, maleylacetate reductase, an IclR-type regulator, a major facilitator superfamily transporter, and a putative hydrolase, respectively. The tsdA gene conferred GRA decarboxylase activity on Escherichia coli. Purified TsdB oxidized NADH in the presence of resorcinol, suggesting that tsdB encodes a unique NADH-specific single-component resorcinol 4-hydroxylase. Mutations in either tsdA or tsdB resulted in growth deficiency on GRA. The tsdC and tsdD genes conferred hydroxyquinol 1,2-dioxygenase and maleylacetate reductase activities, respectively, on E. coli. Inactivation of tsdT significantly retarded the growth of RHA1 on GRA. The growth retardation was partially suppressed under acidic conditions, suggesting the involvement of tsdT in GRA uptake. Reverse transcription-PCR analysis revealed that the tsd genes constitute three transcriptional units, the tsdBADC and tsdTX operons and tsdR. Transcription of the tsdBADC and tsdTX operons was induced during growth on GRA. Inactivation of tsdR derepressed transcription of the tsdBADC and tsdTX operons in the absence of GRA, suggesting that tsd gene transcription is negatively regulated by the tsdR-encoded regulator. Binding of TsdR to the tsdR-tsdB and tsdT-tsdR intergenic regions was inhibited by the addition of GRA, indicating that GRA interacts with TsdR as an effector molecule. PMID:26319878

  1. The rose (Rosa hybrida) NAC transcription factor 3 gene, RhNAC3, involved in ABA signaling pathway both in rose and Arabidopsis.

    PubMed

    Jiang, Guimei; Jiang, Xinqiang; Lü, Peitao; Liu, Jitao; Gao, Junping; Zhang, Changqing

    2014-01-01

    Plant transcription factors involved in stress responses are generally classified by their involvement in either the abscisic acid (ABA)-dependent or the ABA-independent regulatory pathways. A stress-associated NAC gene from rose (Rosa hybrida), RhNAC3, was previously found to increase dehydration tolerance in both rose and Arabidopsis. However, the regulatory mechanism involved in RhNAC3 action is still not fully understood. In this study, we isolated and analyzed the upstream regulatory sequence of RhNAC3 and found many stress-related cis-elements to be present in the promoter, with five ABA-responsive element (ABRE) motifs being of particular interest. Characterization of Arabidopsis thaliana plants transformed with the putative RhNAC3 promoter sequence fused to the β-glucuronidase (GUS) reporter gene revealed that RhNAC3 is expressed at high basal levels in leaf guard cells and in vascular tissues. Moreover, the ABRE motifs in the RhNAC3 promoter were observed to have a cumulative effect on the transcriptional activity of this gene both in the presence and absence of exogenous ABA. Overexpression of RhNAC3 in A. thaliana resulted in ABA hypersensitivity during seed germination and promoted leaf closure after ABA or drought treatments. Additionally, the expression of 11 ABA-responsive genes was induced to a greater degree by dehydration in the transgenic plants overexpressing RhNAC3 than control lines transformed with the vector alone. Further analysis revealed that all these genes contain NAC binding cis-elements in their promoter regions, and RhNAC3 was found to partially bind to these putative NAC recognition sites. We further found that of 219 A. thaliana genes previously shown by microarray analysis to be regulated by heterologous overexpression RhNAC3, 85 are responsive to ABA. In rose, the expression of genes downstream of the ABA-signaling pathways was also repressed in RhNAC3-silenced petals. Taken together, we propose that the rose RhNAC3 protein

  2. The Rose (Rosa hybrida) NAC Transcription Factor 3 Gene, RhNAC3, Involved in ABA Signaling Pathway Both in Rose and Arabidopsis

    PubMed Central

    Lü, Peitao; Liu, Jitao; Gao, Junping; Zhang, Changqing

    2014-01-01

    Plant transcription factors involved in stress responses are generally classified by their involvement in either the abscisic acid (ABA)-dependent or the ABA-independent regulatory pathways. A stress-associated NAC gene from rose (Rosa hybrida), RhNAC3, was previously found to increase dehydration tolerance in both rose and Arabidopsis. However, the regulatory mechanism involved in RhNAC3 action is still not fully understood. In this study, we isolated and analyzed the upstream regulatory sequence of RhNAC3 and found many stress-related cis-elements to be present in the promoter, with five ABA-responsive element (ABRE) motifs being of particular interest. Characterization of Arabidopsis thaliana plants transformed with the putative RhNAC3 promoter sequence fused to the β-glucuronidase (GUS) reporter gene revealed that RhNAC3 is expressed at high basal levels in leaf guard cells and in vascular tissues. Moreover, the ABRE motifs in the RhNAC3 promoter were observed to have a cumulative effect on the transcriptional activity of this gene both in the presence and absence of exogenous ABA. Overexpression of RhNAC3 in A. thaliana resulted in ABA hypersensitivity during seed germination and promoted leaf closure after ABA or drought treatments. Additionally, the expression of 11 ABA-responsive genes was induced to a greater degree by dehydration in the transgenic plants overexpressing RhNAC3 than control lines transformed with the vector alone. Further analysis revealed that all these genes contain NAC binding cis-elements in their promoter regions, and RhNAC3 was found to partially bind to these putative NAC recognition sites. We further found that of 219 A. thaliana genes previously shown by microarray analysis to be regulated by heterologous overexpression RhNAC3, 85 are responsive to ABA. In rose, the expression of genes downstream of the ABA-signaling pathways was also repressed in RhNAC3-silenced petals. Taken together, we propose that the rose RhNAC3 protein

  3. Role of abscisic acid (ABA) and Arabidopsis thaliana ABA-insensitive loci in low water potential-induced ABA and proline accumulation.

    PubMed

    Verslues, Paul E; Bray, Elizabeth A

    2006-01-01

    The mechanisms by which plants respond to reduced water availability (low water potential) include both ABA-dependent and ABA-independent processes. Pro accumulation and osmotic adjustment are two important traits for which the mechanisms of regulation by low water potential, and the involvement of ABA, is not well understood. The ABA-deficient mutant, aba2-1, was used to investigate the regulatory role of ABA in low water potential-induced Pro accumulation and osmotic adjustment in seedlings of Arabidopsis thaliana. Low water potential-induced Pro accumulation required wild-type levels of ABA, as well as a change in ABA sensitivity or ABA-independent events. Osmotic adjustment, in contrast, occurred independently of ABA accumulation in aba2-1. Quantification of low water potential-induced ABA and Pro accumulation in five ABA-insensitive mutants, abi1-1, abi2-1, abi3, abi4, and abi5, revealed that abi4 had increased Pro accumulation at low water potential, but a reduced response to exogenous ABA. Both of these responses were modified by sucrose treatment, indicating that ABI4 has a role in connecting ABA and sugar in regulating Pro accumulation. Of the other abi mutants, only abi1 had reduced Pro accumulation in response to low water potential and ABA application. It was also observed that abi1-1 and abi2-1 had increased ABA accumulation. The involvement of these loci in feedback regulation of ABA accumulation may occur through an effect on ABA catabolism or conjugation. These data provide new information on the function of ABA in seedlings exposed to low water potential and define new roles for three of the well-studied abi loci.

  4. T cells stimulate catabolic gene expression by the stromal cells from giant cell tumor of bone

    SciTech Connect

    Cowan, Robert W.; Ghert, Michelle; Singh, Gurmit

    2012-03-23

    Highlights: Black-Right-Pointing-Pointer Two T cell lines stimulate PTHrP, RANKL, MMP13 gene expression in GCT cell cultures. Black-Right-Pointing-Pointer CD40 expressed by stromal cells; CD40L detected in whole tumor but not cultures. Black-Right-Pointing-Pointer Effect of CD40L treatment on GCT cells increased PTHrP and MMP13 gene expression. Black-Right-Pointing-Pointer PTHrP treatment increased MMP13 expression, while inhibition decreased expression. Black-Right-Pointing-Pointer T cells may stimulate GCT stromal cells and promote the osteolysis of the tumor. -- Abstract: The factors that promote the localized bone resorption by giant cell tumor of bone (GCT) are not fully understood. We investigated whether T cells could contribute to bone resorption by stimulating expression of genes for parathyroid hormone-related protein (PTHrP), matrix metalloproteinase (MMP)-13, and the receptor activator of nuclear-factor {kappa}B ligand (RANKL). Two cell lines, Jurkat clone E6-1 and D1.1, were co-cultured with isolated GCT stromal cells. Real-time PCR analyses demonstrated a significant increase of all three genes following 48 h incubation, and PTHrP and MMP-13 gene expression was also increased at 24 h. Further, we examined the expression of CD40 ligand (CD40L), a protein expressed by activated T cells, and its receptor, CD40, in GCT. Immunohistochemistry results revealed expression of the CD40 receptor in both the stromal cells and giant cells of the tumor. RNA collected from whole GCT tissues showed expression of CD40LG, which was absent in cultured stromal cells, and suggests that CD40L is expressed within GCT. Stimulation of GCT stromal cells with CD40L significantly increased expression of the PTHrP and MMP-13 genes. Moreover, we show that inhibition of PTHrP with neutralizing antibodies significantly decreased MMP13 expression by the stromal cells compared to IgG-matched controls, whereas stimulation with PTHrP (1-34) increased MMP-13 gene expression. These

  5. Salicylic acid mediates antioxidant defense system and ABA pathway related gene expression in Oryza sativa against quinclorac toxicity.

    PubMed

    Wang, Jian; Lv, Mengting; Islam, Faisal; Gill, Rafaqat A; Yang, Chong; Ali, Basharat; Yan, Guijun; Zhou, Weijun

    2016-11-01

    The auxin herbicide quinclorac is widely used for controlling weeds in transplanted and direct-seeded rice fields. However, its phytotoxic responses on rice are still unknown. Therefore, in the present investigation we studied the effects of different concentrations (0, 0.1 and 0.5g/L) of quinclorac herbicide on the physiological and biochemical changes of two rice cultivars (XS 134 and ZJ 88) and further analyzed the ameliorating role of salicylic acid (SA) on quinclorac toxicity in rice plants. The results revealed that exogenous application of SA significantly increased plant biomass and total chlorophyll contents in herbicide stressed plants. The lipid peroxidation and ROS (H2O2, O2(-.), (-)OH) production were significantly increased in roots and leaves of both rice cultivars under quinclorac stress, demonstrating an oxidative burst in rice plants. Whereas, application of SA significantly lowered ROS contents under quinclorac stress. Further, exogenous SA treatment significantly modulated antioxidant enzymes and enhanced GSH concentration in stress plants. Anatomical observations of leaf and root revealed that herbicide affected internal structures, while SA played a vital role in protection from toxic effects. Expression analysis of stress hormone ABA genes (OsABA8oxs, OsNCEDs) revealed that quinclorac application enhanced stress condition in cultivar ZJ 88, while SA treatment downregulated ABA genes more in cultivar XS 134, which correlated with the enhanced tolerance to quinclorac induced oxidative stress in this cultivar. The present study delineated that SA played a critical role under quinclorac stress in both rice cultivars by regulating antioxidant defense system, reducing ROS formation and preventing the degradation of internal cell organelles.

  6. Salicylic acid mediates antioxidant defense system and ABA pathway related gene expression in Oryza sativa against quinclorac toxicity.

    PubMed

    Wang, Jian; Lv, Mengting; Islam, Faisal; Gill, Rafaqat A; Yang, Chong; Ali, Basharat; Yan, Guijun; Zhou, Weijun

    2016-11-01

    The auxin herbicide quinclorac is widely used for controlling weeds in transplanted and direct-seeded rice fields. However, its phytotoxic responses on rice are still unknown. Therefore, in the present investigation we studied the effects of different concentrations (0, 0.1 and 0.5g/L) of quinclorac herbicide on the physiological and biochemical changes of two rice cultivars (XS 134 and ZJ 88) and further analyzed the ameliorating role of salicylic acid (SA) on quinclorac toxicity in rice plants. The results revealed that exogenous application of SA significantly increased plant biomass and total chlorophyll contents in herbicide stressed plants. The lipid peroxidation and ROS (H2O2, O2(-.), (-)OH) production were significantly increased in roots and leaves of both rice cultivars under quinclorac stress, demonstrating an oxidative burst in rice plants. Whereas, application of SA significantly lowered ROS contents under quinclorac stress. Further, exogenous SA treatment significantly modulated antioxidant enzymes and enhanced GSH concentration in stress plants. Anatomical observations of leaf and root revealed that herbicide affected internal structures, while SA played a vital role in protection from toxic effects. Expression analysis of stress hormone ABA genes (OsABA8oxs, OsNCEDs) revealed that quinclorac application enhanced stress condition in cultivar ZJ 88, while SA treatment downregulated ABA genes more in cultivar XS 134, which correlated with the enhanced tolerance to quinclorac induced oxidative stress in this cultivar. The present study delineated that SA played a critical role under quinclorac stress in both rice cultivars by regulating antioxidant defense system, reducing ROS formation and preventing the degradation of internal cell organelles. PMID:27448955

  7. Copper suppresses abscisic acid catabolism and catalase activity, and inhibits seed germination of rice.

    PubMed

    Ye, Nenghui; Li, Haoxuan; Zhu, Guohui; Liu, Yinggao; Liu, Rui; Xu, Weifeng; Jing, Yu; Peng, Xinxiang; Zhang, Jianhua

    2014-11-01

    Although copper (Cu) is an essential micronutrient for plants, a slight excess of Cu in soil can be harmful to plants. Unfortunately, Cu contamination is a growing problem all over the world due to human activities, and poses a soil stress to plant development. As one of the most important biological processes, seed germination is sensitive to Cu stress. However, little is known about the mechanism of Cu-induced inhibition of seed germination. In the present study, we investigated the relationship between Cu and ABA which is the predominant regulator of seed germination. Cu at a concentration of 30 µM effectively inhibited germination of rice caryopsis. ABA content in germinating seeds under copper stress was also higher than that under control conditions. Quantitative real-time PCR (qRT-PCR) revealed that Cu treatment reduced the expression of OsABA8ox2, a key gene of ABA catabolism in rice seeds. In addition, both malondialdehyde (MDA) and H2O2 contents were increased by Cu stress in the germinating seeds. Antioxidant enzyme assays revealed that only catalase activity was reduced by excess Cu, which was consistent with the mRNA profile of OsCATa during seed germination under Cu stress. Together, our results demonstrate that suppression of ABA catabolism and catalase (CAT) activity by excess Cu leads to the inhibition of seed germination of rice.

  8. Gene expression and biochemical analysis of cheese-ripening yeasts: focus on catabolism of L-methionine, lactate, and lactose.

    PubMed

    Cholet, Orianne; Hénaut, Alain; Casaregola, Serge; Bonnarme, Pascal

    2007-04-01

    DNA microarrays of 86 genes from the yeasts Debaryomyces hansenii, Kluyveromyces marxianus, and Yarrowia lipolytica were developed to determine which genes were expressed in a medium mimicking a cheese-ripening environment. These genes were selected for potential involvement in lactose/lactate catabolism and the biosynthesis of sulfur-flavored compounds. Hybridization conditions to follow specifically the expression of homologous genes belonging to different species were set up. The microarray was first validated on pure cultures of each yeast; no interspecies cross-hybridization was observed. Expression patterns of targeted genes were studied in pure cultures of each yeast, as well as in coculture, and compared to biochemical data. As expected, a high expression of the LAC genes of K. marxianus was observed. This is a yeast that efficiently degrades lactose. Several lactate dehydrogenase-encoding genes were also expressed essentially in D. hansenii and K. marxianus, which are two efficient deacidifying yeasts in cheese ripening. A set of genes possibly involved in l-methionine catabolism was also used on the array. Y. lipolytica, which efficiently assimilates l-methionine, also exhibited a high expression of the Saccharomyces cerevisiae orthologs BAT2 and ARO8, which are involved in the l-methionine degradation pathway. Our data provide the first evidence that the use of a multispecies microarray could be a powerful tool to investigate targeted metabolism and possible metabolic interactions between species within microbial cocultures. PMID:17308183

  9. Identification and functional characterization of the pepper CaDRT1 gene involved in the ABA-mediated drought stress response.

    PubMed

    Baek, Woonhee; Lim, Sohee; Lee, Sung Chul

    2016-05-01

    Plants are constantly challenged by various environmental stresses, including high salinity and drought, and they have evolved defense mechanisms to counteract the deleterious effects of these stresses. The plant hormone abscisic acid (ABA) regulates plant growth and developmental processes and mediates abiotic stress responses. Here, we identified the Capsicum annuum DRought Tolerance 1 (CaDRT1) gene from pepper leaves treated with ABA. CaDRT1 was strongly expressed in pepper leaves in response to environmental stresses and after ABA treatment, suggesting that the CaDRT1 protein functions in the abiotic stress response. Knockdown expression of CaDRT1 via virus-induced gene silencing resulted in a high level of drought susceptibility, and this was characterized by increased transpirational water loss via decreased stomatal closure. CaDRT1-overexpressing (OX) Arabidopsis plants exhibited an ABA-hypersensitive phenotype during the germinative, seedling, and adult stages. Additionally, these CaDRT1-OX plants exhibited a drought-tolerant phenotype characterized by low levels of transpirational water loss, high leaf temperatures, increased stomatal closure, and enhanced expression levels of drought-responsive genes. Taken together, our results suggest that CaDRT1 is a positive regulator of the ABA-mediated drought stress response.

  10. Identification and functional characterization of the pepper CaDRT1 gene involved in the ABA-mediated drought stress response.

    PubMed

    Baek, Woonhee; Lim, Sohee; Lee, Sung Chul

    2016-05-01

    Plants are constantly challenged by various environmental stresses, including high salinity and drought, and they have evolved defense mechanisms to counteract the deleterious effects of these stresses. The plant hormone abscisic acid (ABA) regulates plant growth and developmental processes and mediates abiotic stress responses. Here, we identified the Capsicum annuum DRought Tolerance 1 (CaDRT1) gene from pepper leaves treated with ABA. CaDRT1 was strongly expressed in pepper leaves in response to environmental stresses and after ABA treatment, suggesting that the CaDRT1 protein functions in the abiotic stress response. Knockdown expression of CaDRT1 via virus-induced gene silencing resulted in a high level of drought susceptibility, and this was characterized by increased transpirational water loss via decreased stomatal closure. CaDRT1-overexpressing (OX) Arabidopsis plants exhibited an ABA-hypersensitive phenotype during the germinative, seedling, and adult stages. Additionally, these CaDRT1-OX plants exhibited a drought-tolerant phenotype characterized by low levels of transpirational water loss, high leaf temperatures, increased stomatal closure, and enhanced expression levels of drought-responsive genes. Taken together, our results suggest that CaDRT1 is a positive regulator of the ABA-mediated drought stress response. PMID:26869261

  11. Functional characterization of diverse ring-hydroxylating oxygenases and induction of complex aromatic catabolic gene clusters in Sphingobium sp. PNB

    PubMed Central

    Khara, Pratick; Roy, Madhumita; Chakraborty, Joydeep; Ghosal, Debajyoti; Dutta, Tapan K.

    2014-01-01

    Sphingobium sp. PNB, like other sphingomonads, has multiple ring-hydroxylating oxygenase (RHO) genes. Three different fosmid clones have been sequenced to identify the putative genes responsible for the degradation of various aromatics in this bacterial strain. Comparison of the map of the catabolic genes with that of different sphingomonads revealed a similar arrangement of gene clusters that harbors seven sets of RHO terminal components and a sole set of electron transport (ET) proteins. The presence of distinctly conserved amino acid residues in ferredoxin and in silico molecular docking analyses of ferredoxin with the well characterized terminal oxygenase components indicated the structural uniqueness of the ET component in sphingomonads. The predicted substrate specificities, derived from the phylogenetic relationship of each of the RHOs, were examined based on transformation of putative substrates and their structural homologs by the recombinant strains expressing each of the oxygenases and the sole set of available ET proteins. The RHO AhdA1bA2b was functionally characterized for the first time and was found to be capable of transforming ethylbenzene, propylbenzene, cumene, p-cymene and biphenyl, in addition to a number of polycyclic aromatic hydrocarbons. Overexpression of aromatic catabolic genes in strain PNB, revealed by real-time PCR analyses, is a way forward to understand the complex regulation of degradative genes in sphingomonads. PMID:24918041

  12. Transcriptome Analysis Reveals Regulation of Gene Expression for Lipid Catabolism in Young Broilers by Butyrate Glycerides

    PubMed Central

    Yin, Fugui; Yu, Hai; Lepp, Dion; Shi, Xuejiang; Yang, Xiaojian; Hu, Jielun; Leeson, Steve; Yang, Chengbo; Nie, Shaoping; Hou, Yongqing; Gong, Joshua

    2016-01-01

    indicated that dietary BG intervention induced 79 and 205 characterized DEGs in the jejunum and liver, respectively. In addition, 255 and 165 TSEGs were detected in the liver and jejunum of BG-fed group, while 162 and 211 TSEGs genes were observed in the liver and jejunum of BD-fed birds, respectively. Bioinformatic analysis with both IPA and DAVID-BR further revealed a significant enrichment of DEGs and TSEGs in the biological processes for reducing the synthesis, storage, transportation and secretion of lipids in the jejunum, while those in the liver were for enhancing the oxidation of ingested lipids and fatty acids. In particular, transcriptional regulators of THRSP and EGR-1 as well as several DEGs involved in the PPAR-α signaling pathway were significantly induced by dietary BG intervention for lipid catabolism. Conclusions Our results demonstrate that BG reduces body fat deposition via regulation of gene expression, which is involved in the biological events relating to the reduction of synthesis, storage, transportation and secretion, and improvement of oxidation of lipids and fatty acids. PMID:27508934

  13. Carotenoid Biosynthetic and Catabolic Pathways: Gene Expression and Carotenoid Content in Grains of Maize Landraces

    PubMed Central

    Messias, Rafael da Silva; Galli, Vanessa; Silva, Sérgio Delmar dos Anjos e; Rombaldi, Cesar Valmor

    2014-01-01

    Plant carotenoids have been implicated in preventing several age-related diseases, and they also provide vitamin A precursors; therefore, increasing the content of carotenoids in maize grains is of great interest. It is not well understood, however, how the carotenoid biosynthetic pathway is regulated. Fortunately, the maize germplasm exhibits a high degree of genetic diversity that can be exploited for this purpose. Here, the accumulation of carotenoids and the expression of genes from carotenoid metabolic and catabolic pathways were investigated in several maize landraces. The carotenoid content in grains varied from 10.03, in the white variety MC5, to 61.50 μg·g−1, in the yellow-to-orange variety MC3, and the major carotenoids detected were lutein and zeaxanthin. PSY1 (phythoene synthase) expression showed a positive correlation with the total carotenoid content. Additionally, the PSY1 and HYD3 (ferredoxin-dependent di-iron monooxygenase) expression levels were positively correlated with β-cryptoxanthin and zeaxanthin, while CYP97C (cytochrome P450-type monooxygenase) expression did not correlate with any of the carotenoids. In contrast, ZmCCD1 (carotenoid dioxygenase) was more highly expressed at the beginning of grain development, as well as in the white variety, and its expression was inversely correlated with the accumulation of several carotenoids, suggesting that CCD1 is also an important enzyme to be considered when attempting to improve the carotenoid content in maize. The MC27 and MC1 varieties showed the highest HYD3/CYP97C ratios, suggesting that they are promising candidates for increasing the zeaxanthin content; in contrast, MC14 and MC7 showed low HYD3/CYP97C, suggesting that they may be useful in biofortification efforts aimed at promoting the accumulation of provitamin A. The results of this study demonstrate the use of maize germplasm to provide insight into the regulation of genes involved in the carotenoid pathway, which would thus better

  14. Changes in expression of proteolytic genes in response to anabolic and catabolic signals in rainbow trout

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rates of protein accrual are largely affected by rates of protein degradation. Determining how proteolytic pathways are affected by catabolic and anabolic signals will contribute to the understanding of the impact and regulation these pathways have on protein turnover. Real time RT-PCR was used to...

  15. Biodegradation Ability and Catabolic Genes of Petroleum-Degrading Sphingomonas koreensis Strain ASU-06 Isolated from Egyptian Oily Soil

    PubMed Central

    Mostafa, Yasser M.; Shoreit, Ahmed

    2014-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are serious pollutants and health hazards. In this study, 15 PAHs-degrading bacteria were isolated from Egyptian oily soil. Among them, one Gram-negative strain (ASU-06) was selected and biodegradation ability and initial catabolic genes of petroleum compounds were investigated. Comparison of 16S rRNA gene sequence of strain ASU-06 to published sequences in GenBank database as well as phylogenetic analysis identified ASU-06 as Sphingomonas koreensis. Strain ASU-06 degraded 100, 99, 98, and 92.7% of 100 mg/L naphthalene, phenanthrene, anthracene, and pyrene within 15 days, respectively. When these PAHs present in a mixed form, the enhancement phenomenon appeared, particularly in the degradation of pyrene, whereas the degradation rate was 98.6% within the period. This is the first report showing the degradation of different PAHs by this species. PCR experiments with specific primers for catabolic genes alkB, alkB1, nahAc, C12O, and C23O suggested that ASU-06 might possess genes for aliphatic and PAHs degradation, while PAH-RHDαGP gene was not detected. Production of biosurfactants and increasing cell-surface hydrophobicity were investigated. GC/MS analysis of intermediate metabolites of studied PAHs concluded that this strain utilized these compounds via two main pathways, and phthalate was the major constant product that appeared in each day of the degradation period. PMID:25177681

  16. The ARF2-ANT-COR15A gene cascade regulates ABA-signaling-mediated resistance of large seeds to drought in Arabidopsis.

    PubMed

    Meng, Lai-Sheng; Wang, Zhi-Bo; Yao, Shun-Qiao; Liu, Aizhong

    2015-11-01

    Seedlings of large-seeded plants are considered to be able to withstand abiotic stresses efficiently. The molecular mechanisms that underlie the involved signaling crosstalk between the large-seeded trait and abiotic tolerance are, however, largely unknown. Here, we demonstrate the molecular link that integrates plant abscisic acid (ABA) responses to drought stress into the regulation of seed mass. Both loss-of-function mutants of the Auxin Response Factor 2 (ARF2 encoding a transcription factor) and lines overexpressing AINTEGUMENTA (ANT; a transcription factor) under the 35S promoter exhibited large seed and drought-tolerant phenotypes as a result of abnormal ABA-auxin crosstalk signaling pathways in Arabidopsis. The target gene COLD-REGULATED15A (COR15a) was identified as participating in the regulation of seed development with ABA signaling through a negative regulation mechanism that is mediated by ANT. The molecular and genetic evidence presented indicate that ARF2, ANT and COR15A form an ABA-mediated signaling pathway to link modulation of seed mass with drought tolerance. These observations indicate that the ARF2 transcription factor serves as a molecular link that integrates plant ABA responses to drought stress into the regulation of seed mass. PMID:26395398

  17. ABA may promote or delay peach fruit ripening through modulation of ripening- and hormone-related gene expression depending on the developmental stage.

    PubMed

    Soto, Alvaro; Ruiz, Karina B; Ravaglia, Daniela; Costa, Guglielmo; Torrigiani, Patrizia

    2013-03-01

    Peach (Prunus persica laevis L. Batsch) was chosen as a model to further clarify the physiological role of ABA during fruit ripening. To this aim, branches bearing one fruit at mid-S3, S3/S4 and S4 stages of fruit development and characterized by a different ripening index (I(AD)), as revealed by a non-destructive device called a DA-meter, were treated with ABA (0.02 mM) for 1 and 5 days. Exogenously applied ABA interfered with the progression of ripening leading to less ripe or riper fruit depending on the physiological stage. To better understand the molecular basis of ABA interference with ripening, the time-course changes in the expression of ethylene-, cell wall-, and auxin-related genes as well as other genes (NCED, PIP, LOX, AOS and SOT) was evaluated in the fruit mesocarp. Real-time PCR analyses revealed that in mid-S3 fruit transcript levels of ethylene biosynthesis and signaling (ACS1, ACO1, ETR2, ERF2), cell wall softening-related (PG, PMEI, EXP1, EXP2) and auxin biosynthesis, conjugation, transport and perception (TRPB, IGPS, Aux/IAA, GH3, PIN1 and TIR1) genes were substantially down-regulated on day 5 indicating a ripening delay. On the contrary, in more advanced stages (S3/S4 and S4) the same genes were early (day 1) up-regulated suggesting an acceleration of ripening. Transcript profiling of other ripening-related genes revealed changes that were in accord with a ripening delay (mid-S3) or acceleration (S3/S4 and S4). Thus, in peach fruit, ABA appears to modulate ripening through interference not only with ethylene and cell wall but also with auxin-related genes.

  18. Characterization of new bacterial catabolic genes and mobile genetic elements by high throughput genetic screening of a soil metagenomic library.

    PubMed

    Jacquiod, Samuel; Demanèche, Sandrine; Franqueville, Laure; Ausec, Luka; Xu, Zhuofei; Delmont, Tom O; Dunon, Vincent; Cagnon, Christine; Mandic-Mulec, Ines; Vogel, Timothy M; Simonet, Pascal

    2014-11-20

    A mix of oligonucleotide probes was used to hybridize soil metagenomic DNA from a fosmid clone library spotted on high density membranes. The pooled radio-labeled probes were designed to target genes encoding glycoside hydrolases GH18, dehalogenases, bacterial laccases and mobile genetic elements (integrases from integrons and insertion sequences). Positive hybridizing spots were affiliated to the corresponding clones in the library and the metagenomic inserts were sequenced. After assembly and annotation, new coding DNA sequences related to genes of interest were identified with low protein similarity against the closest hits in databases. This work highlights the sensitivity of DNA/DNA hybridization techniques as an effective and complementary way to recover novel genes from large metagenomic clone libraries. This study also supports that some of the identified catabolic genes might be associated with horizontal transfer events.

  19. Cross-species approaches to seed dormancy and germination: conservation and biodiversity of ABA-regulated mechanisms and the Brassicaceae DOG1 genes.

    PubMed

    Graeber, Kai; Linkies, Ada; Müller, Kerstin; Wunchova, Andrea; Rott, Anita; Leubner-Metzger, Gerhard

    2010-05-01

    Seed dormancy is genetically determined with substantial environmental influence mediated, at least in part, by the plant hormone abscisic acid (ABA). The ABA-related transcription factor ABI3/VP1 (ABA INSENSITIVE3/VIVIPAROUS1) is widespread among green plants. Alternative splicing of its transcripts appears to be involved in regulating seed dormancy, but the role of ABI3/VP1 goes beyond seeds and dormancy. In contrast, DOG1 (DELAY OF GERMINATION 1), a major quantitative trait gene more specifically involved in seed dormancy, was so far only known from Arabidopsis thaliana (AtDOG1) and whether it also has roles during the germination of non-dormant seeds was not known. Seed germination of Lepidium sativum ('garden cress') is controlled by ABA and its antagonists gibberellins and ethylene and involves the production of apoplastic hydroxyl radicals. We found orthologs of AtDOG1 in the Brassicaceae relatives L. sativum (LesaDOG1) and Brassica rapa (BrDOG1) and compared their gene structure and the sequences of their transcripts expressed in seeds. Tissue-specific analysis of LesaDOG1 transcript levels in L. sativum seeds showed that they are degraded upon imbibition in the radicle and the micropylar endosperm. ABA inhibits germination in that it delays radicle protrusion and endosperm weakening and it increased LesaDOG1 transcript levels during early germination due to enhanced transcription and/or inhibited degradation. A reduced decrease in LesaDOG1 transcript levels upon ABA treatment is evident in the late germination phase in both tissues. This temporal and ABA-related transcript expression pattern suggests a role for LesaDOG1 in the control of germination timing of non-dormant L. sativum seeds. The possible involvement of the ABA-related transcription factors ABI3 and ABI5 in the regulation of DOG1 transcript expression is discussed. Other species of the monophyletic genus Lepidium showed coat or embryo dormancy and are therefore highly suited for comparative

  20. The N‐acetylglucosamine catabolic gene cluster in Trichoderma reesei is controlled by the Ndt80‐like transcription factor RON1

    PubMed Central

    Kappel, Lisa; Gaderer, Romana; Flipphi, Michel

    2015-01-01

    Summary Chitin is an important structural constituent of fungal cell walls composed of N‐acetylglucosamine (GlcNAc) monosaccharides, but catabolism of GlcNAc has not been studied in filamentous fungi so far. In the yeast C andida albicans, the genes encoding the three enzymes responsible for stepwise conversion of GlcNAc to fructose‐6‐phosphate are clustered. In this work, we analysed GlcNAc catabolism in ascomycete filamentous fungi and found that the respective genes are also clustered in these fungi. In contrast to C . albicans, the cluster often contains a gene for an Ndt80‐like transcription factor, which we named RON1 (regulator of N‐acetylglucosamine catabolism 1). Further, a gene for a glycoside hydrolase 3 protein related to bacterial N‐acetylglucosaminidases can be found in the GlcNAc gene cluster in filamentous fungi. Functional analysis in T richoderma reesei showed that the transcription factor RON1 is a key activator of the GlcNAc gene cluster and essential for GlcNAc catabolism. Furthermore, we present an evolutionary analysis of Ndt80‐like proteins in Ascomycota. All GlcNAc cluster genes, as well as the GlcNAc transporter gene ngt1, and an additional transcriptional regulator gene, csp2, encoding the homolog of N eurospora crassa  CSP2/GRHL, were functionally characterised by gene expression analysis and phenotypic characterisation of knockout strains in T . reesei. PMID:26481444

  1. Molecular detection of atrazine catabolism gene atzA in coastal waters of Georgia, Puerto Rico and Trinidad.

    PubMed

    Sherchan, Samendra P; Bachoon, D S; Otero, Ernesto; Ramsubhag, Adesh

    2013-04-15

    In this study, quantitative polymerase chain reaction targeting the atrazine catabolism gene, atzA, was used to detect the presence of atrazine degrading bacteria as an indicator of atrazine contamination in 11 sites in Georgia, nine coastal sites in Puerto Rico and 11 coastal sites in Trinidad. The atzA gene was detected in five stations in Georgia (Oak Grove Island entrance, Blythe Island Recreation Park, Jekyll Island., Village Creek Landing and Dunbar Creek Sea Island Rd Bridge). In Puerto Rico gene was detected in five sites (Boquilla, Oro Creek, Fishers Association, Ceiba Creek and Sabalos Creek) while seven sites in Trinidad (Carli Bay, Las Cuevas Bay, Quinam Bay, Salybia River, Salybia Bay, Maracas River and Maracas Bay) showed the presence of atzA.

  2. Characterization of biphenyl catabolic genes of gram-positive polychlorinated biphenyl degrader rhodococcus sp. strain RHA1

    SciTech Connect

    Masai, Eiji; Hatta, Takashi; Kimbara, Kazuhide

    1995-06-01

    Rhodococcus sp. strain RHA1 is a gram-positive polychlorinated biphenyl (PCB) degrader which can degrade 10 ppm of PCB-48 (equivalent to Aroclor 1248), including tri-, tetra-, and pentachlorobiphenyls, in a few days. We isolated the 7.6-kb EcoRI-BamHI fragment carrying the biphenyl catabolic genes of RHA1 and determined their nucleotide sequence. On the basis of deduced amino acid sequence homology, we identified six bph genes, bphA1A2A3A4, bphB, and bphC, that are responsible for the initial three steps of biphenyl degradation. The order of bph genes in RHA1 is bphA1A2A3A4-bphC-bphB. This gene order differs from that of other PCB degraders reported previously. The amino acid sequences deduced from the RHA1 bph genes have a higher degree of homology with the tod genes from Pseudomonas putida F1 (49 to 79%) than with the bph genes of Pseudomonas sp. strains KF707 and KKS102 (30-65%). FIn Escherichia coli, bphA gene activity was not observed even when expression vectors were used. The activities of bphB and bphC, however, were confirmed by observing the transformation of biphenyl to a meta-cleavage compound with the aid of benzene dioxygenase activity that complemented the bphA gene activity (S. Irie, S. Djoi, T. Yorifuji, M. Takagi, and K. Yano, J. Bacteriol. 169:5174-5179, 1987). The expected products of the cloned bph genes, except bphA3, were observed in E. coli in an in vitro transcription-translation system. Insertion mutations of bphA1 and bphC of Rhodococcus sp. strain RHA1 were constructed by gene replacement with cloned gene fragments. The bphA1 and bphC insertion mutants lost the ability to grow on biphenyl, demonstrating that the cloned bph genes are essential for biphenyl catabolism in this strain. 31 refs., 5 figs., 2 tabs.

  3. Catabolism of Phenol and Its Derivatives in Bacteria: Genes, Their Regulation, and Use in the Biodegradation of Toxic Pollutants.

    PubMed

    Nešvera, Jan; Rucká, Lenka; Pátek, Miroslav

    2015-01-01

    Phenol and its derivatives (alkylphenols, halogenated phenols, nitrophenols) are natural or man-made aromatic compounds that are ubiquitous in nature and in human-polluted environments. Many of these substances are toxic and/or suspected of mutagenic, carcinogenic, and teratogenic effects. Bioremediation of the polluted soil and water using various bacteria has proved to be a promising option for the removal of these compounds. In this review, we describe a number of peripheral pathways of aerobic and anaerobic catabolism of various natural and xenobiotic phenolic compounds, which funnel these substances into a smaller number of central catabolic pathways. Finally, the metabolites are used as carbon and energy sources in the citric acid cycle. We provide here the characteristics of the enzymes that convert the phenolic compounds and their catabolites, show their genes, and describe regulatory features. The genes, which encode these enzymes, are organized on chromosomes and plasmids of the natural bacterial degraders in various patterns. The accumulated data on similarities and the differences of the genes, their varied organization, and particularly, an astonishingly broad range of intricate regulatory mechanism may be read as an exciting adventurous book on divergent evolutionary processes and horizontal gene transfer events inscribed in the bacterial genomes. In the end, the use of this wealth of bacterial biodegradation potential and the manipulation of its genetic basis for purposes of bioremediation is exemplified. It is envisioned that the integrated high-throughput techniques and genome-level approaches will enable us to manipulate systems rather than separated genes, which will give birth to systems biotechnology.

  4. Identification of an L-arabinose reductase gene in Aspergillus niger and its role in L-arabinose catabolism.

    PubMed

    Mojzita, Dominik; Penttilä, Merja; Richard, Peter

    2010-07-30

    The first enzyme in the pathway for l-arabinose catabolism in eukaryotic microorganisms is a reductase, reducing l-arabinose to l-arabitol. The enzymes catalyzing this reduction are in general nonspecific and would also reduce d-xylose to xylitol, the first step in eukaryotic d-xylose catabolism. It is not clear whether microorganisms use different enzymes depending on the carbon source. Here we show that Aspergillus niger makes use of two different enzymes. We identified, cloned, and characterized an l-arabinose reductase, larA, that is different from the d-xylose reductase, xyrA. The larA is up-regulated on l-arabinose, while the xyrA is up-regulated on d-xylose. There is however an initial up-regulation of larA also on d-xylose but that fades away after about 4 h. The deletion of the larA gene in A. niger results in a slow growth phenotype on l-arabinose, whereas the growth on d-xylose is unaffected. The l-arabinose reductase can convert l-arabinose and d-xylose to their corresponding sugar alcohols but has a higher affinity for l-arabinose. The K(m) for l-arabinose is 54 + or - 6 mm and for d-xylose 155 + or - 15 mm.

  5. (+)-Abscisic Acid Metabolism, 3-Ketoacyl-Coenzyme A Synthase Gene Expression, and Very-Long-Chain Monounsaturated Fatty Acid Biosynthesis in Brassica napus Embryos1

    PubMed Central

    Qi, Qungang; Rose, Patricia A.; Abrams, Garth D.; Taylor, David C.; Abrams, Suzanne R.; Cutler, Adrian J.

    1998-01-01

    Microspore-derived embryos of Brassica napus cv Reston were used to examine the effects of exogenous (+)-abscisic acid (ABA) and related compounds on the accumulation of very-long-chain monounsaturated fatty acids (VLCMFAs), VLCMFA elongase complex activity, and induction of the 3-ketoacyl-coenzyme A synthase (KCS) gene encoding the condensing enzyme of the VLCMFA elongation system. Of the concentrations tested, (+)-ABA at 10 μm showed the strongest effect. Maximum activity of the elongase complex, observed 6 h after 10 μm (+)-ABA treatment, was 60% higher than that of the untreated embryos at 24 h. The transcript of the KCS gene was induced by 10 μm (+)-ABA within 1 h and further increased up to 6 h. The VLCMFAs eicosenoic acid (20:1) and erucoic acid (22:1) increased by 1.5- to 2-fold in embryos treated with (+)-ABA for 72 h. Also, (+)-8′-methylene ABA, which is metabolized more slowly than ABA, had a stronger ABA-like effect on the KCS gene transcription, elongase complex activity (28% higher), and level of VLCMFAs (25–30% higher) than ABA. After 24 h approximately 60% of the added (+)-[3H]ABA (10 μm) was metabolized, yielding labeled phaseic and dihydrophaseic acid. This study demonstrates that (+)-ABA promotes VLCMFA biosynthesis via increased expression of the KCS gene and that reducing ABA catabolism would increase VLCMFAs in microspore-derived embryos. PMID:9662540

  6. D-galactose catabolism in Penicillium chrysogenum: Expression analysis of the structural genes of the Leloir pathway.

    PubMed

    Jónás, Ágota; Fekete, Erzsébet; Németh, Zoltán; Flipphi, Michel; Karaffa, Levente

    2016-09-01

    In this study, we analyzed the expression of the structural genes encoding the five enzymes comprising the Leloir pathway of D-galactose catabolism in the industrial cell factory Penicillium chrysogenum on various carbon sources. The genome of P. chrysogenum contains a putative galactokinase gene at the annotated locus Pc13g10140, the product of which shows strong structural similarity to yeast galactokinase that was expressed on lactose and D-galactose only. The expression profile of the galactose-1-phosphate uridylyl transferase gene at annotated locus Pc15g00140 was essentially similar to that of galactokinase. This is in contrast to the results from other fungi such as Aspergillus nidulans, Trichoderma reesei and A. niger, where the ortholog galactokinase and galactose-1-phosphate uridylyl transferase genes were constitutively expressed. As for the UDP-galactose-4-epimerase encoding gene, five candidates were identified. We could not detect Pc16g12790, Pc21g12170 and Pc20g06140 expression on any of the carbon sources tested, while for the other two loci (Pc21g10370 and Pc18g01080) transcripts were clearly observed under all tested conditions. Like the 4-epimerase specified at locus Pc21g10370, the other two structural Leloir pathway genes - UDP-glucose pyrophosphorylase (Pc21g12790) and phosphoglucomutase (Pc18g01390) - were expressed constitutively at high levels as can be expected from their indispensable function in fungal cell wall formation. PMID:27630054

  7. Inspection of the Grapevine BURP Superfamily Highlights an Expansion of RD22 Genes with Distinctive Expression Features in Berry Development and ABA-Mediated Stress Responses

    PubMed Central

    Matus, José Tomás; Aquea, Felipe; Espinoza, Carmen; Vega, Andrea; Cavallini, Erika; Santo, Silvia Dal; Cañón, Paola; de la Guardia, Amparo Rodríguez-Hoces; Serrano, Jennifer; Tornielli, Giovanni Battista; Arce-Johnson, Patricio

    2014-01-01

    The RESPONSIVE TO DEHYDRATION 22 (RD22) gene is a molecular link between abscisic acid (ABA) signalling and abiotic stress responses. Its expression has been used as a reliable ABA early response marker. In Arabidopsis, the single copy RD22 gene possesses a BURP domain also located at the C-terminus of USP embryonic proteins and the beta subunit of polygalacturonases. In grapevine, a RD22 gene has been identified but putative paralogs are also found in the grape genome, possibly forming a large RD22 family in this species. In this work, we searched for annotations containing BURP domains in the Vitis vinifera genome. Nineteen proteins were defined by a comparative analysis between the two genome predictions and RNA-Seq data. These sequences were compared to other plant BURPs identified in previous genome surveys allowing us to reconceive group classifications based on phylogenetic relationships and protein motif occurrence. We observed a lineage-specific evolution of the RD22 family, with the biggest expansion in grapevine and poplar. In contrast, rice, sorghum and maize presented highly expanded monocot-specific groups. The Vitis RD22 group may have expanded from segmental duplications as most of its members are confined to a region in chromosome 4. The inspection of transcriptomic data revealed variable expression of BURP genes in vegetative and reproductive organs. Many genes were induced in specific tissues or by abiotic and biotic stresses. Three RD22 genes were further studied showing that they responded oppositely to ABA and to stress conditions. Our results show that the inclusion of RNA-Seq data is essential while describing gene families and improving gene annotations. Robust phylogenetic analyses including all BURP members from other sequenced species helped us redefine previous relationships that were erroneously established. This work provides additional evidence for RD22 genes serving as marker genes for different organs or stresses in grapevine. PMID

  8. Imaging B. anthracis heme catabolism in mice using the IFP1.4 gene reporter

    NASA Astrophysics Data System (ADS)

    Zhu, Banghe; Robinson, Holly; Wilganowski, Nathaniel; Nobles, Christopher L.; Sevick-Muraca, Eva; Maresso, Anthony

    2012-03-01

    B. anthracis is a gram-positive, spore-forming bacterium which likes all pathogenic bacteria, survive by sequestering heme from its host. To image B. anthracis heme catabolism in vivo, we stably transfect new red excitable fluorescent protein, IFP1.4, that requires the heme catabolism product biliverdin (BV). IFP1.4 reporter has favorable excitation and emission characteristics, which has an absorption peak at 685 nm and an emission peak at 708 nm. Therefore, IFP1.4 reporter can be imaged deeply into the tissue with less contamination from tissue autofluorescence. However, the excitation light "leakage" through optical filters can limit detection and sensitivity of IFP1.4 reporter due to the small Stoke's shift of IFP1.4 fluorescence. To minimize the excitation light leakage, an intensified CCD (ICCD) based infrared fluorescence imaging device was optimized using two band pass filters separated by a focus lens to increase the optical density at the excitation wavelength. In this study, a mouse model (DBA/J2) was first injected with B. anthracis bacteria expressing IFP1.4, 150 μl s.c., on the ventral side of the left thigh. Then mouse was given 250 μl of a 1mM BV solution via I.V. injection. Imaging was conducted as a function of time after infection under light euthanasia, excised tissues were imaged and IFP1.4 fluorescence correlated with standard culture measurements of colony forming units (CFU). The work demonstrates the use of IFP1.4 as a reporter of bacterial utilization of host heme and may provide an important tool for understanding the pathogenesis of bacterial infection and developing new anti-bacterial therapeutics.

  9. Feedback Regulation of ABA Signaling and Biosynthesis by a bZIP Transcription Factor Targets Drought-Resistance-Related Genes1[OPEN

    PubMed Central

    Tang, Ning; Yang, Jun; Peng, Lei; Ma, Siqi; Xu, Yan; Li, Guoliang

    2016-01-01

    The OsbZIP23 transcription factor has been characterized for its essential role in drought resistance in rice (Oryza sativa), but the mechanism is unknown. In this study, we first investigated the transcriptional activation of OsbZIP23. A homolog of SnRK2 protein kinase (SAPK2) was found to interact with and phosphorylate OsbZIP23 for its transcriptional activation. SAPK2 also interacted with OsPP2C49, an ABI1 homolog, which deactivated the SAPK2 to inhibit the transcriptional activation activity of OsbZIP23. Next, we performed genome-wide identification of OsbZIP23 targets by immunoprecipitation sequencing and RNA sequencing analyses in the OsbZIP23-overexpression, osbzip23 mutant, and wild-type rice under normal and drought stress conditions. OsbZIP23 directly regulates a large number of reported genes that function in stress response, hormone signaling, and developmental processes. Among these targets, we found that OsbZIP23 could positively regulate OsPP2C49, and overexpression of OsPP2C49 in rice resulted in significantly decreased sensitivity of the abscisic acid (ABA) response and rapid dehydration. Moreover, OsNCED4 (9-cis-epoxycarotenoid dioxygenase4), a key gene in ABA biosynthesis, was also positively regulated by OsbZIP23. Together, our results suggest that OsbZIP23 acts as a central regulator in ABA signaling and biosynthesis, and drought resistance in rice. PMID:27325665

  10. Transcriptional regulation of 9-cis-epoxycarotenoid dioxygenase (NCED) gene by putrescine accumulation positively modulates ABA synthesis and drought tolerance in Lotus tenuis plants.

    PubMed

    Espasandin, Fabiana D; Maiale, Santiago J; Calzadilla, Pablo; Ruiz, Oscar A; Sansberro, Pedro A

    2014-03-01

    The accumulation of putrescine (Put) and increased arginine decarboxylase (ADC, EC 4.1.1.19) activity levels in response to osmotic stress has been reported; however, the biological meaning of this increase remains unclear. To obtain new insights into these questions, we studied the drought response of a transgenic Lotus tenuis line that expresses the oat ADC gene, which is driven by the stress-inducible pRD29A promoter. This line contains high levels of Put with no changes in spermidine and spermine contents, even under water deficits. Our results indicate that the biochemical and morphological responses to dehydration correlate with the Put level and provide evidence that Put controls the ABA content in response to drought by modulating ABA biosynthesis at the transcriptional level. PMID:24448322

  11. Overexpression of Glucocorticoid Receptor β Enhances Myogenesis and Reduces Catabolic Gene Expression.

    PubMed

    Hinds, Terry D; Peck, Bailey; Shek, Evan; Stroup, Steven; Hinson, Jennifer; Arthur, Susan; Marino, Joseph S

    2016-01-01

    Unlike the glucocorticoid receptor α (GRα), GR β (GRβ) has a truncated ligand-binding domain that prevents glucocorticoid binding, implicating GRα as the mediator of glucocorticoid-induced skeletal muscle loss. Because GRβ causes glucocorticoid resistance, targeting GRβ may be beneficial in impairing muscle loss as a result of GRα activity. The purpose of this study was to determine how the overexpression of GRβ affects myotube formation and dexamethasone (Dex) responsiveness. We measured GR isoform expression in C₂C12 muscle cells in response to Dex and insulin, and through four days of myotube formation. Next, lentiviral-mediated overexpression of GRβ in C₂C12 was performed, and these cells were characterized for cell fusion and myotube formation, as well as sensitivity to Dex via the expression of ubiquitin ligases. GRβ overexpression increased mRNA levels of muscle regulatory factors and enhanced proliferation in myoblasts. GRβ overexpressing myotubes had an increased fusion index. Myotubes overexpressing GRβ had lower forkhead box O3 (Foxo3a) mRNA levels and a blunted muscle atrophy F-box/Atrogen-1 (MAFbx) and muscle ring finger 1 (MuRF1) response to Dex. We showed that GRβ may serve as a pharmacological target for skeletal muscle growth and protection from glucocorticoid-induced catabolic signaling. Increasing GRβ levels in skeletal muscle may cause a state of glucocorticoid resistance, stabilizing muscle mass during exposure to high doses of glucocorticoids. PMID:26875982

  12. Overexpression of Glucocorticoid Receptor β Enhances Myogenesis and Reduces Catabolic Gene Expression

    PubMed Central

    Hinds, Terry D.; Peck, Bailey; Shek, Evan; Stroup, Steven; Hinson, Jennifer; Arthur, Susan; Marino, Joseph S.

    2016-01-01

    Unlike the glucocorticoid receptor α (GRα), GR β (GRβ) has a truncated ligand-binding domain that prevents glucocorticoid binding, implicating GRα as the mediator of glucocorticoid-induced skeletal muscle loss. Because GRβ causes glucocorticoid resistance, targeting GRβ may be beneficial in impairing muscle loss as a result of GRα activity. The purpose of this study was to determine how the overexpression of GRβ affects myotube formation and dexamethasone (Dex) responsiveness. We measured GR isoform expression in C2C12 muscle cells in response to Dex and insulin, and through four days of myotube formation. Next, lentiviral-mediated overexpression of GRβ in C2C12 was performed, and these cells were characterized for cell fusion and myotube formation, as well as sensitivity to Dex via the expression of ubiquitin ligases. GRβ overexpression increased mRNA levels of muscle regulatory factors and enhanced proliferation in myoblasts. GRβ overexpressing myotubes had an increased fusion index. Myotubes overexpressing GRβ had lower forkhead box O3 (Foxo3a) mRNA levels and a blunted muscle atrophy F-box/Atrogen-1 (MAFbx) and muscle ring finger 1 (MuRF1) response to Dex. We showed that GRβ may serve as a pharmacological target for skeletal muscle growth and protection from glucocorticoid-induced catabolic signaling. Increasing GRβ levels in skeletal muscle may cause a state of glucocorticoid resistance, stabilizing muscle mass during exposure to high doses of glucocorticoids. PMID:26875982

  13. Sequential Alterations in Catabolic and Anabolic Gene Expression Parallel Pathological Changes during Progression of Monoiodoacetate-Induced Arthritis

    PubMed Central

    Liu, Jie; Rath, Bjoern; Deschner, James; Gassner, Robert; Butterfield, Timothy A.; Agarwal, Sudha

    2011-01-01

    Chronic inflammation is one of the major causes of cartilage destruction in osteoarthritis. Here, we systematically analyzed the changes in gene expression associated with the progression of cartilage destruction in monoiodoacetate-induced arthritis (MIA) of the rat knee. Sprague Dawley female rats were given intra-articular injection of monoiodoacetate in the knee. The progression of MIA was monitored macroscopically, microscopically and by micro-computed tomography. Grade 1 damage was observed by day 5 post-monoiodoacetate injection, progressively increasing to Grade 2 by day 9, and to Grade 3–3.5 by day 21. Affymetrix GeneChip was utilized to analyze the transcriptome-wide changes in gene expression, and the expression of salient genes was confirmed by real-time-PCR. Functional networks generated by Ingenuity Pathways Analysis (IPA) from the microarray data correlated the macroscopic/histologic findings with molecular interactions of genes/gene products. Temporal changes in gene expression during the progression of MIA were categorized into five major gene clusters. IPA revealed that Grade 1 damage was associated with upregulation of acute/innate inflammatory responsive genes (Cluster I) and suppression of genes associated with musculoskeletal development and function (Cluster IV). Grade 2 damage was associated with upregulation of chronic inflammatory and immune trafficking genes (Cluster II) and downregulation of genes associated with musculoskeletal disorders (Cluster IV). The Grade 3 to 3.5 cartilage damage was associated with chronic inflammatory and immune adaptation genes (Cluster III). These findings suggest that temporal regulation of discrete gene clusters involving inflammatory mediators, receptors, and proteases may control the progression of cartilage destruction. In this process, IL-1β, TNF-α, IL-15, IL-12, chemokines, and NF-κB act as central nodes of the inflammatory networks, regulating catabolic processes. Simultaneously, upregulation of

  14. Overexpression of an ABA biosynthesis gene using a stress-inducible promoter enhances drought resistance in petunia.

    PubMed

    Estrada-Melo, Alejandro C; Chao; Reid, Michael S; Jiang, Cai-Zhong

    2015-01-01

    The response of plants to drought stress includes reduced transpiration as stomates close in response to increased abscisic acid (ABA) concentrations. Constitutive overexpression of 9-cis-epoxycarotenoid dioxygenase (NCED), a key enzyme in ABA biosynthesis, increases drought resistance, but causes negative pleiotropic effects on plant growth and development. We overexpressed the tomato NCED (LeNCED1) in petunia plants under the control of a stress-inducible promoter, rd29A. Under water stress, the transgenic plants had increased transcripts of NCED mRNA, elevated leaf ABA concentrations, increased concentrations of proline, and a significant increase in drought resistance. The transgenic plants also displayed the expected decreases in stomatal conductance, transpiration, and photosynthesis. After 14 days without water, the control plants were dead, but the transgenic plants, though wilted, recovered fully when re-watered. Well-watered transgenic plants grew like non-transformed control plants and there was no effect of the transgene on seed dormancy. PMID:26504568

  15. RNA-Seq and Gene Network Analysis Uncover Activation of an ABA-Dependent Signalosome During the Cork Oak Root Response to Drought

    PubMed Central

    Magalhães, Alexandre P.; Verde, Nuno; Reis, Francisca; Martins, Inês; Costa, Daniela; Lino-Neto, Teresa; Castro, Pedro H.; Tavares, Rui M.; Azevedo, Herlânder

    2016-01-01

    Quercus suber (cork oak) is a West Mediterranean species of key economic interest, being extensively explored for its ability to generate cork. Like other Mediterranean plants, Q. suber is significantly threatened by climatic changes, imposing the need to quickly understand its physiological and molecular adaptability to drought stress imposition. In the present report, we uncovered the differential transcriptome of Q. suber roots exposed to long-term drought, using an RNA-Seq approach. 454-sequencing reads were used to de novo assemble a reference transcriptome, and mapping of reads allowed the identification of 546 differentially expressed unigenes. These were enriched in both effector genes (e.g., LEA, chaperones, transporters) as well as regulatory genes, including transcription factors (TFs) belonging to various different classes, and genes associated with protein turnover. To further extend functional characterization, we identified the orthologs of differentially expressed unigenes in the model species Arabidopsis thaliana, which then allowed us to perform in silico functional inference, including gene network analysis for protein function, protein subcellular localization and gene co-expression, and in silico enrichment analysis for TFs and cis-elements. Results indicated the existence of extensive transcriptional regulatory events, including activation of ABA-responsive genes and ABF-dependent signaling. We were then able to establish that a core ABA-signaling pathway involving PP2C-SnRK2-ABF components was induced in stressed Q. suber roots, identifying a key mechanism in this species’ response to drought. PMID:26793200

  16. RNA-Seq and Gene Network Analysis Uncover Activation of an ABA-Dependent Signalosome During the Cork Oak Root Response to Drought.

    PubMed

    Magalhães, Alexandre P; Verde, Nuno; Reis, Francisca; Martins, Inês; Costa, Daniela; Lino-Neto, Teresa; Castro, Pedro H; Tavares, Rui M; Azevedo, Herlânder

    2015-01-01

    Quercus suber (cork oak) is a West Mediterranean species of key economic interest, being extensively explored for its ability to generate cork. Like other Mediterranean plants, Q. suber is significantly threatened by climatic changes, imposing the need to quickly understand its physiological and molecular adaptability to drought stress imposition. In the present report, we uncovered the differential transcriptome of Q. suber roots exposed to long-term drought, using an RNA-Seq approach. 454-sequencing reads were used to de novo assemble a reference transcriptome, and mapping of reads allowed the identification of 546 differentially expressed unigenes. These were enriched in both effector genes (e.g., LEA, chaperones, transporters) as well as regulatory genes, including transcription factors (TFs) belonging to various different classes, and genes associated with protein turnover. To further extend functional characterization, we identified the orthologs of differentially expressed unigenes in the model species Arabidopsis thaliana, which then allowed us to perform in silico functional inference, including gene network analysis for protein function, protein subcellular localization and gene co-expression, and in silico enrichment analysis for TFs and cis-elements. Results indicated the existence of extensive transcriptional regulatory events, including activation of ABA-responsive genes and ABF-dependent signaling. We were then able to establish that a core ABA-signaling pathway involving PP2C-SnRK2-ABF components was induced in stressed Q. suber roots, identifying a key mechanism in this species' response to drought.

  17. Arabidopsis histone demethylases LDL1 and LDL2 control primary seed dormancy by regulating DELAY OF GERMINATION 1 and ABA signaling-related genes

    PubMed Central

    Zhao, Minglei; Yang, Songguang; Liu, Xuncheng; Wu, Keqiang

    2015-01-01

    Seed dormancy controls germination and plays a critical role in regulating the beginning of the life cycle of plants. Seed dormancy is established and maintained during seed maturation and is gradually broken during dry storage (after-ripening). The plant hormone abscisic acid (ABA) and DELAY OF GERMINATION1 (DOG1) protein are essential regulators of seed dormancy. Recent studies revealed that chromatin modifications are also involved in the transcription regulation of seed dormancy. Here, we showed that two Arabidopsis histone demethylases, LYSINESPECIFIC DEMETHYLASE LIKE 1 and 2 (LDL1 and LDL2) act redundantly in repressing of seed dormancy. LDL1 and LDL2 are highly expressed in the early silique developing stage. The ldl1 ldl2 double mutant displays increased seed dormancy, whereas overexpression of LDL1 or LDL2 in Arabidopsis causes reduced dormancy. Furthermore, we showed that LDL1 and LDL2 repress the expression of seed dormancy-related genes, including DOG1, ABA2 and ABI3 during seed dormancy establishment. Furthermore, genetic analysis revealed that the repression of seed dormancy by LDL1 and LDL2 requires DOG1, ABA2, and ABI3. Taken together, our findings revealed that LDL1 and LDL2 play an essential role in seed dormancy. PMID:25852712

  18. Mechanical Loading of Cartilage Explants with Compression and Sliding Motion Modulates Gene Expression of Lubricin and Catabolic Enzymes

    PubMed Central

    Marková, Michala; Torzilli, Peter A.; Gallo, Luigi M.

    2015-01-01

    Objective Translation of the contact zone in articulating joints is an important component of joint kinematics, yet rarely investigated in a biological context. This study was designed to investigate how sliding contact areas affect cartilage mechanobiology. We hypothesized that higher sliding speeds would lead to increased extracellular matrix mechanical stress and the expression of catabolic genes. Design A cylindrical Teflon indenter was used to apply 50 or 100 N normal forces at 10, 40, or 70 mm/s sliding speed. Mechanical parameters were correlated with gene expressions using a multiple linear regression model. Results In both loading groups there was no significant effect of sliding speed on any of the mechanical parameters (strain, stress, modulus, tangential force). However, an increase in vertical force (from 50 to 100 N) led to a significant increase in extracellular matrix strain and stress. For 100 N, significant correlations between gene expression and mechanical parameters were found for TIMP-3 (r2 = 0.89), ADAMTS-5 (r2 = 0.73), and lubricin (r2 = 0.73). Conclusions The sliding speeds applied do not have an effect on the mechanical response of the cartilage, this could be explained by a partial attainment of the “elastic limit” at and above a sliding speed of 10 mm/s. Nevertheless, we still found a relationship between sliding speed and gene expression when the tissue was loaded with 100 N normal force. Thus despite the absence of speed-dependent mechanical changes (strain, stress, modulus, tangential force), the sliding speed had an influence on gene expression. PMID:26175864

  19. Genetic Interaction of Aspergillus nidulans galR, xlnR and araR in Regulating D-Galactose and L-Arabinose Release and Catabolism Gene Expression

    PubMed Central

    Kowalczyk, Joanna E.; Gruben, Birgit S.; Battaglia, Evy; Wiebenga, Ad; Majoor, Eline; de Vries, Ronald P.

    2015-01-01

    In Aspergillus nidulans, the xylanolytic regulator XlnR and the arabinanolytic regulator AraR co-regulate pentose catabolism. In nature, the pentose sugars D-xylose and L-arabinose are both main building blocks of the polysaccharide arabinoxylan. In pectin and arabinogalactan, these two monosaccharides are found in combination with D-galactose. GalR, the regulator that responds to the presence of D-galactose, regulates the D-galactose catabolic pathway. In this study we investigated the possible interaction between XlnR, AraR and GalR in pentose and/or D-galactose catabolism in A. nidulans. Growth phenotypes and metabolic gene expression profiles were studied in single, double and triple disruptant A. nidulans strains of the genes encoding these paralogous transcription factors. Our results demonstrate that AraR and XlnR not only control pentose catabolic pathway genes, but also genes of the oxido-reductive D-galactose catabolic pathway. This suggests an interaction between three transcriptional regulators in D-galactose catabolism. Conversely, GalR is not involved in regulation of pentose catabolism, but controls only genes of the oxido-reductive D-galactose catabolic pathway. PMID:26580075

  20. Genetic Interaction of Aspergillus nidulans galR, xlnR and araR in Regulating D-Galactose and L-Arabinose Release and Catabolism Gene Expression.

    PubMed

    Kowalczyk, Joanna E; Gruben, Birgit S; Battaglia, Evy; Wiebenga, Ad; Majoor, Eline; de Vries, Ronald P

    2015-01-01

    In Aspergillus nidulans, the xylanolytic regulator XlnR and the arabinanolytic regulator AraR co-regulate pentose catabolism. In nature, the pentose sugars D-xylose and L-arabinose are both main building blocks of the polysaccharide arabinoxylan. In pectin and arabinogalactan, these two monosaccharides are found in combination with D-galactose. GalR, the regulator that responds to the presence of D-galactose, regulates the D-galactose catabolic pathway. In this study we investigated the possible interaction between XlnR, AraR and GalR in pentose and/or D-galactose catabolism in A. nidulans. Growth phenotypes and metabolic gene expression profiles were studied in single, double and triple disruptant A. nidulans strains of the genes encoding these paralogous transcription factors. Our results demonstrate that AraR and XlnR not only control pentose catabolic pathway genes, but also genes of the oxido-reductive D-galactose catabolic pathway. This suggests an interaction between three transcriptional regulators in D-galactose catabolism. Conversely, GalR is not involved in regulation of pentose catabolism, but controls only genes of the oxido-reductive D-galactose catabolic pathway.

  1. Fruit load induces changes in global gene expression and in abscisic acid (ABA) and indole acetic acid (IAA) homeostasis in citrus buds

    PubMed Central

    Shalom, Liron; Samuels, Sivan; Zur, Naftali; Shlizerman, Lyudmila; Doron-Faigenboim, Adi; Blumwald, Eduardo; Sadka, Avi

    2014-01-01

    Many fruit trees undergo cycles of heavy fruit load (ON-Crop) in one year, followed by low fruit load (OFF-Crop) the following year, a phenomenon known as alternate bearing (AB). The mechanism by which fruit load affects flowering induction during the following year (return bloom) is still unclear. Although not proven, it is commonly accepted that the fruit or an organ which senses fruit presence generates an inhibitory signal that moves into the bud and inhibits apical meristem transition. Indeed, fruit removal from ON-Crop trees (de-fruiting) induces return bloom. Identification of regulatory or metabolic processes modified in the bud in association with altered fruit load might shed light on the nature of the AB signalling process. The bud transcriptome of de-fruited citrus trees was compared with those of ON- and OFF-Crop trees. Fruit removal resulted in relatively rapid changes in global gene expression, including induction of photosynthetic genes and proteins. Altered regulatory mechanisms included abscisic acid (ABA) metabolism and auxin polar transport. Genes of ABA biosynthesis were induced; however, hormone analyses showed that the ABA level was reduced in OFF-Crop buds and in buds shortly following fruit removal. Additionally, genes associated with Ca2+-dependent auxin polar transport were remarkably induced in buds of OFF-Crop and de-fruited trees. Hormone analyses showed that auxin levels were reduced in these buds as compared with ON-Crop buds. In view of the auxin transport autoinhibition theory, the possibility that auxin distribution plays a role in determining bud fate is discussed. PMID:24706719

  2. Fruit load induces changes in global gene expression and in abscisic acid (ABA) and indole acetic acid (IAA) homeostasis in citrus buds.

    PubMed

    Shalom, Liron; Samuels, Sivan; Zur, Naftali; Shlizerman, Lyudmila; Doron-Faigenboim, Adi; Blumwald, Eduardo; Sadka, Avi

    2014-07-01

    Many fruit trees undergo cycles of heavy fruit load (ON-Crop) in one year, followed by low fruit load (OFF-Crop) the following year, a phenomenon known as alternate bearing (AB). The mechanism by which fruit load affects flowering induction during the following year (return bloom) is still unclear. Although not proven, it is commonly accepted that the fruit or an organ which senses fruit presence generates an inhibitory signal that moves into the bud and inhibits apical meristem transition. Indeed, fruit removal from ON-Crop trees (de-fruiting) induces return bloom. Identification of regulatory or metabolic processes modified in the bud in association with altered fruit load might shed light on the nature of the AB signalling process. The bud transcriptome of de-fruited citrus trees was compared with those of ON- and OFF-Crop trees. Fruit removal resulted in relatively rapid changes in global gene expression, including induction of photosynthetic genes and proteins. Altered regulatory mechanisms included abscisic acid (ABA) metabolism and auxin polar transport. Genes of ABA biosynthesis were induced; however, hormone analyses showed that the ABA level was reduced in OFF-Crop buds and in buds shortly following fruit removal. Additionally, genes associated with Ca(2+)-dependent auxin polar transport were remarkably induced in buds of OFF-Crop and de-fruited trees. Hormone analyses showed that auxin levels were reduced in these buds as compared with ON-Crop buds. In view of the auxin transport autoinhibition theory, the possibility that auxin distribution plays a role in determining bud fate is discussed.

  3. Catabolic cytokines disrupt the circadian clock and the expression of clock-controlled genes in cartilage via an NFкB-dependent pathway

    PubMed Central

    Guo, B.; Yang, N.; Borysiewicz, E.; Dudek, M.; Williams, J.L.; Li, J.; Maywood, E.S.; Adamson, A.; Hastings, M.H.; Bateman, J.F.; White, M.R.H.; Boot-Handford, R.P.; Meng, Q.J.

    2015-01-01

    Summary Objective To define how the catabolic cytokines (Interleukin 1 (IL-1) and tumor necrosis factor alpha (TNFα)) affect the circadian clock mechanism and the expression of clock-controlled catabolic genes within cartilage, and to identify the downstream pathways linking the cytokines to the molecular clock within chondrocytes. Methods Ex vivo cartilage explants were isolated from the Cry1-luc or PER2::LUC clock reporter mice. Clock gene dynamics were monitored in real-time by bioluminescence photon counting. Gene expression changes were studied by qRT-PCR. Functional luc assays were used to study the function of the core Clock/BMAL1 complex in SW-1353 cells. NFкB pathway inhibitor and fluorescence live-imaging of cartilage were performed to study the underlying mechanisms. Results Exposure to IL-1β severely disrupted circadian gene expression rhythms in cartilage. This effect was reversed by an anti-inflammatory drug dexamethasone, but not by other clock synchronizing agents. Circadian disruption mediated by IL-1β was accompanied by disregulated expression of endogenous clock genes and clock-controlled catabolic pathways. Mechanistically, NFкB signalling was involved in the effect of IL-1β on the cartilage clock in part through functional interference with the core Clock/BMAL1 complex. In contrast, TNFα had little impact on the circadian rhythm and clock gene expression in cartilage. Conclusion In our experimental system (young healthy mouse cartilage), we demonstrate that IL-1β (but not TNFα) abolishes circadian rhythms in Cry1-luc and PER2::LUC gene expression. These data implicate disruption of the chondrocyte clock as a novel aspect of the catabolic responses of cartilage to pro-inflammatory cytokines, and provide an additional mechanism for how chronic joint inflammation may contribute to osteoarthritis (OA). PMID:26521744

  4. Organization and control of genes encoding catabolic enzymes in Rhizobiaceae. Progress report, March 1993

    SciTech Connect

    Parke, D.; Ornston, L.N.

    1993-03-01

    Rhizobiaceae, a diverse bacterial group comprising rhizobia and agrobacteria, symbiotic partnership with plants form nitrogen-fixing nodules on plant roots or are plant pathogens. Phenolic compounds produced by plants serve as inducers of rhizobial nodulation genes and agrobacterial virulence genes reflect their capacity to utilize numerous aromatics, including phenolics, as a source of carbon and energy. In many microbes the aerobic degradation of numerous aromatic compounds to tricarboxylic acid cycle intermediates is achieved by the {beta}-ketoadipate pathway. Our initial studies focused on the organization and regulation of the ketoadipate pathway in Agrobacterium tumefaciens. We have cloned, identified and characterized a novel regulatory gene that modulates expression of an adjacent pca (protocatechuate) structural gene, pcaD. Regulation of pcaD is mediated by the regulatory gene, termed pcaQ, in concert with the intermediate {beta}-carboxy-cis,cis-muconate. {beta}-carboxy-cis,cismuconate is an unstable chemical, not marketed commercially, and it is unlikely to permeate Escherichia coli cells if supplied in media. Because of these factors, characterization of pcaQ in E. coli required an in vivo delivery system for {beta}-carboxycis,cis-muconate. This was accomplished by designing an E. coli strain that expressed an Acinetobacter calcoaceticus pcaA gene for conversion of protocatechuate to {beta}-carboxy-cis,cis-muconate.

  5. ABA and cytokinins: challenge and opportunity for plant stress research.

    PubMed

    Verslues, Paul E

    2016-08-01

    Accumulation of the stress hormone abscisic acid (ABA) induces many cellular mechanisms associated with drought resistance. Recent years have seen a rapid advance in our knowledge of how increased ABA levels are perceived by ABA receptors, particularly the PYL/RCAR receptors, but there has been relatively less new information about how ABA accumulation is controlled and matched to stress severity. ABA synthesis and catabolism, conjugation and deconjugation to glucose, and ABA transport all are involved in controlling ABA levels. This highly buffered system of ABA metabolism represents both a challenge and opportunity in developing a mechanistic understanding of how plants detect and respond to drought. Recent data have also shown that direct manipulation of cytokinin levels in transgenic plants has dramatic effect on drought phenotypes and prompted new interest in the role of cytokinins and cytokinin signaling in drought. Both ABA and cytokinins will continue to be major foci of drought research but likely with different trajectories both in terms of basic research and in translational research aimed at increasing plant performance during drought. PMID:26910054

  6. Cloning and characterization of the ferulic acid catabolic genes of Sphingomonas paucimobilis SYK-6.

    PubMed

    Masai, Eiji; Harada, Kyo; Peng, Xue; Kitayama, Hirotaka; Katayama, Yoshihiro; Fukuda, Masao

    2002-09-01

    Sphingomonas paucimobilis SYK-6 degrades ferulic acid to vanillin, and it is further metabolized through the protocatechuate 4,5-cleavage pathway. We obtained a Tn5 mutant of SYK-6, FA2, which was able to grow on vanillic acid but not on ferulic acid. A cosmid which complemented the growth deficiency of FA2 on ferulic acid was isolated. The 5.2-kb BamHI-EcoRI fragment in this cosmid conferred the transformation activity of ferulic acid to vanillin on Escherichia coli host cells. A sequencing analysis revealed the genes ferB and ferA in this fragment; these genes consist of 852- and 2,127-bp open reading frames, respectively. The deduced amino acid sequence of ferB showed 40 to 48% identity with that of the feruloyl-coenzyme A (CoA) hydratase/lyase genes of Pseudomonas and Amycolatopsis ferulic acid degraders. On the other hand, the deduced amino acid sequence of ferA showed no significant similarity to the feruloyl-CoA synthetase genes of other ferulic acid degraders. However, the deduced amino acid sequence of ferA did show 31% identity with pimeloyl-CoA synthetase of Pseudomonas mendocina 35, which has been classified as a new superfamily of acyl-CoA synthetase (ADP forming) with succinyl-CoA synthetase (L. B. Sánchez, M. Y. Galperin, and M. Müller, J. Biol. Chem. 275:5794-5803, 2000). On the basis of the enzyme activity of E. coli carrying each of these genes, ferA and ferB were shown to encode a feruloyl-CoA synthetase and feruloyl-CoA hydratase/lyase, respectively. p-coumaric acid, caffeic acid, and sinapinic acid were converted to their corresponding benzaldehyde derivatives by the cell extract containing FerA and FerB, thereby indicating their broad substrate specificities. We found a ferB homolog, ferB2, upstream of a 5-carboxyvanillic acid decarboxylase gene (ligW) involved in the degradation of 5,5'-dehydrodivanillic acid. The deduced amino acid sequence of ferB2 showed 49% identity with ferB, and its gene product showed feruloyl-CoA hydratase

  7. Homologous gene clusters of nicotine catabolism, including a new ω-amidase for α-ketoglutaramate, in species of three genera of Gram-positive bacteria.

    PubMed

    Cobzaru, Cristina; Ganas, Petra; Mihasan, Marius; Schleberger, Paula; Brandsch, Roderich

    2011-04-01

    Gram-positive soil bacteria Arthrobacter nicotinovorans, Nocardioides sp. JS614 and Rhodococcus opacus were shown to contain similarly organized clusters of homologous genes for nicotine catabolism. An uncharacterized gene of a predicted nitrilase within these gene clusters was cloned from A. nicotinovorans and biochemical data unexpectedly showed that the protein exhibited ω-amidase activity toward α-ketoglutaramate. Structural modelling of the protein suggested the presence of the catalytic triad Cys-Glu-Lys, characteristic of this class of enzymes, and supported α-ketoglutaramate as substrate. A-ketoglutaramate could be generated by hydrolytic cleavage of the C-N bond of the trihydroxypyridine ring produced by nicotine catabolism in these bacteria. This ω-amidase, together with glutamate dehydrogenase, may form a physiologically relevant enzyme couple, leading to transformation of metabolically inert α-ketoglutaramate derived from trihydroxypyridine into glutamate, a central compound of nitrogen metabolism.

  8. Linking Microbial Community and Catabolic Gene Structures during the Adaptation of Three Contaminated Soils under Continuous Long-Term Pollutant Stress

    PubMed Central

    Lima-Morales, Daiana; Jáuregui, Ruy; Camarinha-Silva, Amelia; Geffers, Robert; Vilchez-Vargas, Ramiro

    2016-01-01

    Three types of contaminated soil from three geographically different areas were subjected to a constant supply of benzene or benzene/toluene/ethylbenzene/xylenes (BTEX) for a period of 3 months. Different from the soil from Brazil (BRA) and Switzerland (SUI), the Czech Republic (CZE) soil which was previously subjected to intensive in situ bioremediation displayed only negligible changes in community structure. BRA and SUI soil samples showed a clear succession of phylotypes. A rapid response to benzene stress was observed, whereas the response to BTEX pollution was significantly slower. After extended incubation, actinobacterial phylotypes increased in relative abundance, indicating their superior fitness to pollution stress. Commonalities but also differences in the phylotypes were observed. Catabolic gene surveys confirmed the enrichment of actinobacteria by identifying the increase of actinobacterial genes involved in the degradation of pollutants. Proteobacterial phylotypes increased in relative abundance in SUI microcosms after short-term stress with benzene, and catabolic gene surveys indicated enriched metabolic routes. Interestingly, CZE soil, despite staying constant in community structure, showed a change in the catabolic gene structure. This indicates that a highly adapted community, which had to adjust its gene pool to meet novel challenges, has been enriched. PMID:26850298

  9. Transcriptional regulation and locations of Agrobacterium tumefaciens genes required for complete catabolism of octopine.

    PubMed

    Cho, K; Fuqua, C; Winans, S C

    1997-01-01

    By screening for octopine-inducible gene expression, we previously identified all the genes required for utilization of octopine as a source of carbon, nitrogen, and energy. They are (i) octopine oxidase, which converts octopine to arginine and pyruvate and is encoded by the ooxAB operon, (ii) arginase, which converts arginine to ornithine and urea and is encoded by arcA, (iii) ornithine cyclodeaminase, which converts ornithine to proline and ammonia and is encoded by the homologous arcB and ocd genes, and (iv) proline dehydrogenase, which converts proline to glutamate and is encoded by putA. Here we describe the regulation and localization of each of these genes. The ooxA-ooxB-ocd operon was previously shown to reside on the Ti plasmid and to be directly inducible by octopine. The arcAB operon is directly inducible by arginine, while it is induced by octopine only in strains that can convert octopine to arginine. Ornithine may also be a direct inducer of arcAB. putA is directly inducible by proline, while induction by octopine and by arginine (and probably by ornithine) requires their conversion to proline. Genetic studies indicate that arcAB and putA are localized on a conjugal genetic element. This element can be transferred to other Agrobacterium tumefaciens strains by a mechanism that does not require recA-dependent homologous recombination. Transfer of this genetic element from A. tumefaciens R10 requires at least one tra gene found on its Ti plasmid, indicating that this element is not self-transmissible but is mobilizable by the Ti plasmid. The DNA containing the arcAB and putA genes comigrates with a 243-kb linear molecular weight standard on field inversion electrophoretic gels. PMID:8981973

  10. Positive feedback regulation of a Lycium chinense-derived VDE gene by drought-induced endogenous ABA, and over-expression of this VDE gene improve drought-induced photo-damage in Arabidopsis.

    PubMed

    Guan, Chunfeng; Ji, Jing; Zhang, Xuqiang; Li, Xiaozhou; Jin, Chao; Guan, Wenzhu; Wang, Gang

    2015-03-01

    Violaxanthin de-epoxidase (VDE) plays an important role in protecting the photosynthetic apparatus from photo-damage by dissipating excessively absorbed light energy as heat, via the conversion of violaxanthin (V) to intermediate product antheraxanthin (A) and final product zeaxanthin (Z) under light stress. We have cloned a VDE gene (LcVDE) from Lycium chinense, a deciduous woody perennial halophyte, which can grow in a large variety of soil types. The amino acid sequence of LcVDE has high homology with VDEs in other plants. Under drought stress, relative expression of LcVDE and the de-epoxidation ratio (Z+0.5A)/(V+A+Z) increased rapidly, and non-photochemical quenching (NPQ) also rose. Interestingly, these elevations induced by drought stress were reduced by the topical administration of abamine SG, a potent ABA inhibitor via inhibition of NCED in the ABA synthesis pathway. Until now, little has been done to explore the relationship between endogenous ABA and the expression of VDE genes. Since V serves as a common precursor for ABA, these data support the possible involvement of endogenous ABA in the positive feedback regulation of LcVDE gene expression in L. chinense under drought stress. Moreover, the LcVDE may be involved in modulating the level of photosynthesis damage caused by drought stress. Furthermore, the ratio of (Z+0.5A)/(V+A+Z) and NPQ increased more in transgenic Arabidopsis over-expressing LcVDE gene than the wild types under drought stress. The maximum quantum yield of primary photochemistry of PSII (Fv/Fm) in transgenic Arabidopsis decreased more slowly during the stressed period than that in wild types under the same conditions. Furthermore, transgenic Arabidopsis over-expressing LcVDE showed increased tolerance to drought stress.

  11. Chemical inhibition of potato ABA-8'-hydroxylase activity alters in vitro and in vivo ABA metabolism and endogenous ABA levels but does not affect potato microtuber dormancy duration.

    PubMed

    Suttle, Jeffrey C; Abrams, Suzanne R; De Stefano-Beltrán, Luis; Huckle, Linda L

    2012-09-01

    The effects of azole-type P450 inhibitors and two metabolism-resistant abscisic acid (ABA) analogues on in vitro ABA-8'-hydroxylase activity, in planta ABA metabolism, endogenous ABA content, and tuber meristem dormancy duration were examined in potato (Solanum tuberosum L. cv. Russet Burbank). When functionally expressed in yeast, three potato CYP707A genes were demonstrated to encode enzymatically active ABA-8'-hydroxylases with micromolar affinities for (+)-ABA. The in vitro activity of the three enzymes was inhibited by the P450 azole-type inhibitors ancymidol, paclobutrazol, diniconazole, and tetcyclasis, and by the 8'-acetylene- and 8'-methylene-ABA analogues, with diniconazole and tetcyclasis being the most potent inhibitors. The in planta metabolism of [(3)H](±)-ABA to phaseic acid and dihydrophaseic acid in tuber meristems was inhibited by diniconazole, tetcyclasis, and to a lesser extent by 8'-acetylene- and 8'-methylene-ABA. Continuous exposure of in vitro generated microtubers to diniconazole resulted in a 2-fold increase in endogenous ABA content and a decline in dihydrophaseic acid content after 9 weeks of development. Similar treatment with 8'-acetylene-ABA had no effects on the endogenous contents of ABA or phaseic acid but reduced the content of dihydrophaseic acid. Tuber meristem dormancy progression was determined ex vitro in control, diniconazole-, and 8'-acetylene-ABA-treated microtubers following harvest. Continuous exposure to diniconazole during microtuber development had no effects on subsequent sprouting at any time point. Continuous exposure to 8'-acetylene-ABA significantly increased the rate of microtuber sprouting. The results indicate that, although a decrease in ABA content is a hallmark of tuber dormancy progression, the decline in ABA levels is not a prerequisite for dormancy exit and the onset of tuber sprouting.

  12. Genes involved in the benzoate catabolic pathway in Acinetobacter calcoaceticus PHEA-2.

    PubMed

    Zhan, Yuhua; Yu, Haiying; Yan, Yongliang; Chen, Ming; Lu, Wei; Li, Shuying; Peng, Zixin; Zhang, Wei; Ping, Shuzhen; Wang, Jin; Lin, Min

    2008-12-01

    A putative benM gene encoding a LysR-type regulator located upstream from the benA gene was found in Acinetobacter calcoaceticus PHEA-2. Disruption of benM or benA destroyed the ability of PHEA-2 to utilize benzoate. The benM mutant was used to construct a genomic library for isolation of the complete gene cluster responsible for benzoate degradation. Sequence analysis showed that the cluster has three putative operons: benM, benABCDE, and benKP. Unlike many well-characterized benzoate-degrading bacteria, muconate is unable to induce in vivo transcription of the PHEA-2 ben cluster. Reverse transcriptase-polymerase chain reaction (RT-PCR) results showed that the benABCDE operon is activated by the BenM protein in the presence of benzoate. Moreover, a gel-retardation assay demonstrated that BenM binds to the promotor region of the benA gene. The activities of catechol 1,2-dioxygenase (C12O) and catechol 2,3-dioxygenase (C23O) showed that PHEA-2 converted benzoate to catechol for further degradation, possibly via an ortho-cleavage pathway.

  13. PLASTID MOVEMENT IMPAIRED1 mediates ABA sensitivity during germination and implicates ABA in light-mediated Chloroplast movements.

    PubMed

    Rojas-Pierce, Marcela; Whippo, Craig W; Davis, Phillip A; Hangarter, Roger P; Springer, Patricia S

    2014-10-01

    The plant hormone abscisic acid (ABA) controls many aspects of plant growth and development, including seed development, germination and responses to water-deficit stress. A complex ABA signaling network integrates environmental signals including water availability and light intensity and quality to fine-tune the response to a changing environment. To further define the regulatory pathways that control water-deficit and ABA responses, we carried out a gene-trap tagging screen for water-deficit-regulated genes in Arabidopsis thaliana. This screen identified PLASTID MOVEMENT IMPAIRED1 (PMI1), a gene involved in blue-light-induced chloroplast movement, as functioning in ABA-response pathways. We provide evidence that PMI1 is involved in the regulation of seed germination by ABA, acting upstream of the intersection between ABA and low-glucose signaling pathways. Furthermore, PMI1 participates in the regulation of ABA accumulation during periods of water deficit at the seedling stage. The combined phenotypes of pmi1 mutants in chloroplast movement and ABA responses indicate that ABA signaling may modulate chloroplast motility. This result was further supported by the detection of altered chloroplast movements in the ABA mutants aba1-6, aba2-1 and abi1-1.

  14. Detection of genes for alkane and naphthalene catabolism in Rhodococcus sp. strain 1BN.

    PubMed

    Andreoni, V; Bernasconi, S; Colombo, M; van Beilen, J B; Cavalca, L

    2000-10-01

    Rhodococcus sp. 1BN was isolated from a contaminated site and showed various biodegradative capabilities. Besides naphthalene, strain 1BN degraded medium- (C6) and long-chain alkanes (C16-C28), benzene and toluene, alone or when the hydrocarbons were mixed in equal proportions. The nucleotide sequence of an alk polymerase chain reaction (PCR) fragment revealed a 59% nucleotide homology to the Pseudomonas oleovorans alkB gene. The nar fragments were highly homologous to genes coding for large and small subunits of cis-naphthalene 1,2-dioxygenase (narAa and narAb) and to cis-naphthalene dihydrodiol dehydrogenase (narB) from other rhodococci. The oxidation of indene to cis-(1S,2R)-1,2-dihydroxyindan by toluene-induced cells allows to hypothesize that strain 1BN also carries a toluene dioxygenase-like system. PMID:11233165

  15. Identification and characterization of cis-acting elements involved in the regulation of ABA- and/or GA-mediated LuPLR1 gene expression and lignan biosynthesis in flax (Linum usitatissimum L.) cell cultures.

    PubMed

    Corbin, Cyrielle; Renouard, Sullivan; Lopez, Tatiana; Lamblin, Frédéric; Lainé, Eric; Hano, Christophe

    2013-03-15

    Pinoresinol lariciresinol reductase 1, encoded by the LuPLR1 gene in flax (Linum usitatissimum L.), is responsible for the biosynthesis of (+)-secoisolariciresinol, a cancer chemopreventive phytoestrogenic lignan accumulated in high amount in the hull of flaxseed. Our recent studies have demonstrated a key role of abscisic acid (ABA) in the regulation of LuPLR1 gene expression and thus of the (+)-secoisolariciresinol synthesis during the flax seedcoat development. It is well accepted that gibberellins (GA) and ABA play antagonistic roles in the regulation of numerous developmental processes; therefore it is of interest to clarify their respective effects on lignan biosynthesis. Herein, using flax cell suspension cultures, we demonstrate that LuPLR1 gene expression and (+)-secoisolariciresinol synthesis are up-regulated by ABA and down-regulated by GA. The LuPLR1 gene promoter analysis and mutation experiments allow us to identify and characterize two important cis-acting sequences (ABRE and MYB2) required for these regulations. These results imply that a cross-talk between ABA and GA signaling orchestrated by transcription factors is involved in the regulation of lignan biosynthesis. This is particularly evidenced in the case of the ABRE cis-regulatory sequence of LuPLR1 gene promoter that appears to be a common target sequence of GA and ABA signals.

  16. Positive regulation of phenolic catabolism in Agrobacterium tumefaciens by the pcaQ gene in response to beta-carboxy-cis,cis-muconate.

    PubMed Central

    Parke, D

    1993-01-01

    An Escherichia coli system for generating a commercially unavailable catabolite in vivo was developed and was used to facilitate molecular genetic studies of phenolic catabolism. Introduction of the plasmid-borne Acinetobacter pcaHG genes, encoding the 3,4-dioxygenase which acts on protocatechuate, into E. coli resulted in bioconversion of exogenously supplied protocatechuate into beta-carboxy-cis,cis-muconate. This compound has been shown to be an inducer of the protocatechuate (pca) genes required for catabolism of protocatechuate to tricarboxylic acid cycle intermediates in Rhizobium leguminosarum biovar trifolii. The E. coli bioconversion system was used to explore regulation of the pca genes in a related bacterium, Agrobacterium tumefaciens. The pcaD gene, which encodes beta-ketoadipate enol-lactone hydrolase, from A. tumefaciens A348 was cloned and was shown to be adjacent to a regulatory region which responds strongly to beta-carboxy-cis,cis-muconate in E. coli. Site-specific insertional mutagenesis of the regulatory region eliminated expression of the pcaD gene in E. coli. When the mutation was incorporated into the A. tumefaciens chromosome, it eliminated expression of the pcaD gene and at least three other pca genes as well. The regulatory region was shown to activate gene expression in trans. The novel regulatory gene was termed pcaQ to differentiate it from pca regulatory genes identified in other microbes, which bind different metabolites. PMID:8501056

  17. Degradation of Benzene by Pseudomonas veronii 1YdBTEX2 and 1YB2 Is Catalyzed by Enzymes Encoded in Distinct Catabolism Gene Clusters.

    PubMed

    de Lima-Morales, Daiana; Chaves-Moreno, Diego; Wos-Oxley, Melissa L; Jáuregui, Ruy; Vilchez-Vargas, Ramiro; Pieper, Dietmar H

    2015-10-16

    Pseudomonas veronii 1YdBTEX2, a benzene and toluene degrader, and Pseudomonas veronii 1YB2, a benzene degrader, have previously been shown to be key players in a benzene-contaminated site. These strains harbor unique catabolic pathways for the degradation of benzene comprising a gene cluster encoding an isopropylbenzene dioxygenase where genes encoding downstream enzymes were interrupted by stop codons. Extradiol dioxygenases were recruited from gene clusters comprising genes encoding a 2-hydroxymuconic semialdehyde dehydrogenase necessary for benzene degradation but typically absent from isopropylbenzene dioxygenase-encoding gene clusters. The benzene dihydrodiol dehydrogenase-encoding gene was not clustered with any other aromatic degradation genes, and the encoded protein was only distantly related to dehydrogenases of aromatic degradation pathways. The involvement of the different gene clusters in the degradation pathways was suggested by real-time quantitative reverse transcription PCR.

  18. Degradation of Benzene by Pseudomonas veronii 1YdBTEX2 and 1YB2 Is Catalyzed by Enzymes Encoded in Distinct Catabolism Gene Clusters

    PubMed Central

    de Lima-Morales, Daiana; Chaves-Moreno, Diego; Wos-Oxley, Melissa L.; Jáuregui, Ruy; Vilchez-Vargas, Ramiro

    2015-01-01

    Pseudomonas veronii 1YdBTEX2, a benzene and toluene degrader, and Pseudomonas veronii 1YB2, a benzene degrader, have previously been shown to be key players in a benzene-contaminated site. These strains harbor unique catabolic pathways for the degradation of benzene comprising a gene cluster encoding an isopropylbenzene dioxygenase where genes encoding downstream enzymes were interrupted by stop codons. Extradiol dioxygenases were recruited from gene clusters comprising genes encoding a 2-hydroxymuconic semialdehyde dehydrogenase necessary for benzene degradation but typically absent from isopropylbenzene dioxygenase-encoding gene clusters. The benzene dihydrodiol dehydrogenase-encoding gene was not clustered with any other aromatic degradation genes, and the encoded protein was only distantly related to dehydrogenases of aromatic degradation pathways. The involvement of the different gene clusters in the degradation pathways was suggested by real-time quantitative reverse transcription PCR. PMID:26475106

  19. pAO1 of Arthrobacter nicotinovorans and the spread of catabolic traits by horizontal gene transfer in gram-positive soil bacteria.

    PubMed

    Mihasan, Marius; Brandsch, Roderich

    2013-08-01

    The 165-kb megaplasmid pAO1 of Arthrobacter nicotinovorans carries two large gene clusters, one involved in nicotine catabolism (nic-gene cluster) and one in carbohydrate utilization (ch-gene cluster). Here, we propose that both gene clusters were acquired by A. nicotinovorans by horizontal gene transfer mediated by pAO1. Protein-protein blast search showed that none of the published Arthrobacter genomes contains nic-genes, but Rhodococcus opacus carries on its chromosome a nic-gene cluster highly similar to that of pAO1. Analysis of the nic-genes in the two species suggested a recombination event between their nic-gene clusters. Apparently, there was a gene exchange between pAO1, or a precursor plasmid, and a nic-gene cluster of an as yet unidentified Arthrobacter specie or other soil bacterium, possibly related to Rhodococcus, leading to the transfer by pAO1 of this catabolic trait to A. nicotinovorans. Analysis of the pAO1 ch-gene cluster revealed a virtually identical counterpart on the chromosome of Arthrobacter phenanthrenivorans. Moreover, the sequence analysis of the genes flanking the ch-gene cluster suggested that it was acquired by pAO1 by Xer-related site directed recombination and transferred via the plasmid to A. nicotinovorans. The G+C content, the level of sequence identity, gene co-linearity of nic- and ch-gene clusters as well as the signs of recombination events clearly supports the notion of pAO1 and its precursor plasmids as vehicles in HGT among Gram + soil bacteria.

  20. Gene Expression and Biochemical Analysis of Cheese-Ripening Yeasts: Focus on Catabolism of l-Methionine, Lactate, and Lactose▿ †

    PubMed Central

    Cholet, Orianne; Hénaut, Alain; Casaregola, Serge; Bonnarme, Pascal

    2007-01-01

    DNA microarrays of 86 genes from the yeasts Debaryomyces hansenii, Kluyveromyces marxianus, and Yarrowia lipolytica were developed to determine which genes were expressed in a medium mimicking a cheese-ripening environment. These genes were selected for potential involvement in lactose/lactate catabolism and the biosynthesis of sulfur-flavored compounds. Hybridization conditions to follow specifically the expression of homologous genes belonging to different species were set up. The microarray was first validated on pure cultures of each yeast; no interspecies cross-hybridization was observed. Expression patterns of targeted genes were studied in pure cultures of each yeast, as well as in coculture, and compared to biochemical data. As expected, a high expression of the LAC genes of K. marxianus was observed. This is a yeast that efficiently degrades lactose. Several lactate dehydrogenase-encoding genes were also expressed essentially in D. hansenii and K. marxianus, which are two efficient deacidifying yeasts in cheese ripening. A set of genes possibly involved in l-methionine catabolism was also used on the array. Y. lipolytica, which efficiently assimilates l-methionine, also exhibited a high expression of the Saccharomyces cerevisiae orthologs BAT2 and ARO8, which are involved in the l-methionine degradation pathway. Our data provide the first evidence that the use of a multispecies microarray could be a powerful tool to investigate targeted metabolism and possible metabolic interactions between species within microbial cocultures. PMID:17308183

  1. Overexpression of the phosphatidylinositol synthase gene (ZmPIS) conferring drought stress tolerance by altering membrane lipid composition and increasing ABA synthesis in maize.

    PubMed

    Liu, Xiuxia; Zhai, Shumei; Zhao, Yajie; Sun, Baocheng; Liu, Cheng; Yang, Aifang; Zhang, Juren

    2013-05-01

    Phosphatidylinositol (PtdIns) synthase is a key enzyme in the phospholipid pathway and catalyses the formation of PtdIns. PtdIns is not only a structural component of cell membranes, but also the precursor of the phospholipid signal molecules that regulate plant response to environment stresses. Here, we obtained transgenic maize constitutively overexpressing or underexpressing PIS from maize (ZmPIS) under the control of a maize ubiquitin promoter. Transgenic plants were confirmed by PCR, Southern blotting analysis and real-time RT-PCR assay. The electrospray ionization tandem mass spectrometry (ESI-MS/MS)-based lipid profiling analysis showed that, under drought stress conditions, the overexpression of ZmPIS in maize resulted in significantly elevated levels of most phospholipids and galactolipids in leaves compared with those in wild type (WT). At the same time, the expression of some genes involved in the phospholipid metabolism pathway and the abscisic acid (ABA) biosynthesis pathway including ZmPLC, ZmPLD, ZmDGK1, ZmDGK3, ZmPIP5K9, ZmABA1, ZmNCED, ZmAAO1, ZmAAO2 and ZmSCA1 was markedly up-regulated in the overexpression lines after drought stress. Consistent with these results, the drought stress tolerance of the ZmPIS sense transgenic plants was enhanced significantly at the pre-flowering stages compared with WT maize plants. These results imply that ZmPIS regulates the plant response to drought stress through altering membrane lipid composition and increasing ABA synthesis in maize.

  2. GEm-Related 5 (GER5), an ABA and stress-responsive GRAM domain protein regulating seed development and inflorescence architecture.

    PubMed

    Baron, Kevin N; Schroeder, Dana F; Stasolla, Claudio

    2014-06-01

    We have identified an abscisic acid (ABA) and stress-responsive GRAM (Glucosyltransferases, Rab-like GTPase activators and Myotubularins) domain protein GER5 (GEm-Related 5) closely related to GEM (GLABRA2 Expression Modulator), a novel regulator of cell division and cell fate determination in epidermal cells. A loss-of-function T-DNA line (ger5-2) and transgenic lines silencing (GER5(RNAi)) or overexpressing (GER5(OE)) GER5 displayed several defects in reproductive development affecting seed and embryo development. RNA in situ studies revealed GER5 and related GRAM genes (GEM and GEm-Related 1 (GER1)) have both overlapping and unique expression domains in male and female reproductive organs. Hormone immunolocalization experiments further indicate GER5 transcripts preferentially localize to reproductive tissues which accumulate ABA. Expression analysis revealed members of the GRAM family (GER5, GER1, GEM) display tissue-specific expression patterns and are responsive to phytohormones and abiotic stress, in addition to genetic lesions (aba1, aba2, ctr1) affecting ABA biosynthesis or ethylene signalling. Mature seeds of ger5-2 mutants also exhibit reduced sensitivity to ABA during seed germination assays. Microarray analysis of aborting and developing seeds isolated from ger5-2 mutants revealed underlying transcriptional changes in carbohydrate metabolism, hormone signalling and catabolic processes (e.g. protein degradation, autophagy). Taken together, our results indicate ABA-responsive GRAM genes play a novel role in regulating the reproductive development of plants, and raise intriguing questions regarding the functional relationship between members of the GRAM gene family.

  3. ABA-Mediated Inhibition of Germination Is Related to the Inhibition of Genes Encoding Cell-Wall Biosynthetic and Architecture: Modifying Enzymes and Structural Proteins in Medicago truncatula Embryo Axis

    PubMed Central

    Gimeno-Gilles, Christine; Lelièvre, Eric; Viau, Laure; Malik-Ghulam, Mustafa; Ricoult, Claudie; Niebel, Andreas; Leduc, Nathalie; Limami, Anis M.

    2009-01-01

    Radicle emergence and reserves mobilization are two distinct programmes that are thought to control germination. Both programs are influenced by abscissic acid (ABA) but how this hormone controls seed germination is still poorly known. Phenotypic and microscopic observations of the embryo axis of Medicago truncatula during germination in mitotic inhibition condition triggered by 10 μM oryzalin showed that cell division was not required to allow radicle emergence. A suppressive subtractive hybridization showed that more than 10% of up-regulated genes in the embryo axis encoded proteins related to cell-wall biosynthesis. The expression of α-expansins, pectin-esterase, xylogucan-endotransglycosidase, cellulose synthase, and extensins was monitored in the embryo axis of seeds germinated on water, constant and transitory ABA. These genes were overexpressed before completion of germination in the control and strongly inhibited by ABA. The expression was re-established in the ABA transitory-treatment after the seeds were transferred back on water and proceeded to germination. This proves these genes as contributors to the completion of germination and strengthen the idea that cell-wall loosening and remodeling in relation to cell expansion in the embryo axis is a determinant feature in germination. Our results also showed that ABA controls germination through the control of radicle emergence, namely by inhibiting cell-wall loosening and expansion. PMID:19529818

  4. Melatonin promotes seed germination under high salinity by regulating antioxidant systems, ABA and GA₄ interaction in cucumber (Cucumis sativus L.).

    PubMed

    Zhang, Hai-Jun; Zhang, Na; Yang, Rong-Chao; Wang, Li; Sun, Qian-Qian; Li, Dian-Bo; Cao, Yun-Yun; Weeda, Sarah; Zhao, Bing; Ren, Shuxin; Guo, Yang-Dong

    2014-10-01

    Although previous studies have found that melatonin can promote seed germination, the mechanisms involved in perceiving and signaling melatonin remain poorly understood. In this study, it was found that melatonin was synthesized during cucumber seed germination with a peak in melatonin levels occurring 14 hr into germination. This is indicative of a correlation between melatonin synthesis and seed germination. Meanwhile, seeds pretreated with exogenous melatonin (1 μM) showed enhanced germination rates under 150 mM NaCl stress compared to water-pretreated seeds under salinity stress. There are two apparent mechanisms by which melatonin alleviated salinity-induced inhibition of seed germination. Exogenous melatonin decreased oxidative damage induced by NaCl stress by enhancing gene expression of antioxidants. Under NaCl stress, compared to untreated control, the activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) were significantly increased by approximately 1.3-5.0-fold, with a concomitant 1.4-2.0-fold increase of CsCu-ZnSOD, CsFe-ZnSOD, CsCAT, and CsPOD in melatonin-pretreated seeds. Melatonin also alleviated salinity stress by affecting abscisic acid (ABA) and gibberellin acid (GA) biosynthesis and catabolism during seed germination. Compared to NaCl treatment, melatonin significantly up-regulated ABA catabolism genes (e.g., CsCYP707A1 and CsCYP707A2, 3.5 and 105-fold higher than NaCl treatment at 16 hr, respectively) and down-regulated ABA biosynthesis genes (e.g., CsNECD2, 0.29-fold of CK2 at 16 hr), resulting in a rapid decrease of ABA content during the early stage of germination. At the same time, melatonin positively up-regulated GA biosynthesis genes (e.g., GA20ox and GA3ox, 2.3 and 3.9-fold higher than NaCl treatment at 0 and 12 hr, respectively), contributing to a significant increase of GA (especially GA4) content. In this study, we provide new evidence suggesting that melatonin alleviates the

  5. Genes for the catabolism and synthesis of an opine-like compound in Rhizobium meliloti are closely linked and on the Sym plasmid

    PubMed Central

    Murphy, Peter J.; Heycke, Nina; Banfalvi, Zsofia; Tate, Max E.; de Bruijn, Frans; Kondorosi, Adam; Tempé, Jacques; Schell, Jeff

    1987-01-01

    In alfalfa nodules induced by Rhizobium meliloti strain L5-30 the compound L-3-O-methyl-scyllo-inosamine (3-O-MSI) is synthesized. This compound is also catabolized specifically by this strain. Its biological properties are therefore similar to the Agrobacterium opines. To answer the question whether opine-like compounds (“Rhizopines”) play a role in a plant symbiotic interaction, we isolated the genes for the catabolism of 3-O-MSI (moc genes) and for the induction of its synthesis in the nodule [mos gene(s)]. moc and mos genes were shown to be closely linked and located on the Sym plasmid of L5-30, suggesting that they have co-evolved and may be important in symbiosis. These genes have been cloned into a broad host-range vector that can be mobilized into other R. meliloti strains where they are expressed. The location of the mos genes in the bacteria extends the opine concept, initially developed for a plant pathological interaction, to a symbiotic one. Images PMID:16593802

  6. Characterization of genes for synthesis and catabolism of a new rhizopine induced in nodules by Rhizobium meliloti Rm220-3: extension of the rhizopine concept.

    PubMed Central

    Saint, C P; Wexler, M; Murphy, P J; Tempé, J; Tate, M E; Murphy, P J

    1993-01-01

    Rhizopines are selective growth substrates synthesized in nodules only by strains of rhizobia capable of their catabolism. We report the isolation and study of genes for the synthesis and catabolism of a new rhizopine, scyllo-inosamine (sIa), from alfalfa nodules induced by Rhizobium meliloti Rm220-3. This compound is similar in structure to the previously described rhizopine 3-O-methyl-scyllo-inosamine from R. meliloti L5-30 (P.J. Murphy, N. Heycke, Z. Banfalvi, M.E. Tate, F.J. de Bruijn, A. Kondorosi, J. Tempé, and J. Schell, Proc. Natl. Acad. Sci. USA 84:493-497, 1987). The synthesis (mos) and catabolism (moc) genes for the Rm220-3 rhizopine are closely linked and located on the nod-nif Sym plasmid. The mos genes are directly controlled by the NifA/NtrA regulatory system. A comparison of the sequence of the 5' regions of the two mos loci shows very extensive conservation of sequence as well as strong homology to the nifH coding region. Restriction mapping and hybridization to DNA from the four open reading frames (ORFs) of the L5-30 mos locus indicate the absence of mosA and presence of the other three ORFs (ORF1 and mosB and -C) in Rm220-3. We suggest that the L5-30 mosA gene product is involved in the conversion of scyllo-inosamine to 3-O-methyl-scyllo-inosamine. Restriction fragment length polymorphism analysis of the moc regions of both strains shows that they are very similar. Regulation studies indicate that the moc region is not controlled by the common regulatory gene nifA, ntrA, and ntrC. We discuss the striking similarities in gene structure, location, and regulation between these two rhizopine loci in relation to the rhizopine concept. Images PMID:8349560

  7. H2O2 and ABA signaling are responsible for the increased Na+ efflux and water uptake in Gossypium hirsutum L. roots in the non-saline side under non-uniform root zone salinity.

    PubMed

    Kong, Xiangqiang; Luo, Zhen; Dong, Hezhong; Eneji, A Egrinya; Li, Weijiang

    2016-04-01

    Non-uniform root salinity increases the Na(+)efflux, water use, and growth of the root in non-saline side, which may be regulated by some form of signaling induced by the high-salinity side. However, the signaling and its specific function have remained unknown. Using a split-root system to simulate a non-uniform root zone salinity in Gossypium hirsutum L., we showed that the up-regulated expression of sodium efflux-related genes (SOS1, SOS2, PMA1, and PMA2) and water uptake-related genes (PIP1 and PIP2) was possibly involved in the elevated Na(+) efflux and water use in the the roots in the non-saline side. The increased level of indole acetic acid (IAA) in the non-saline side was the likely cause of the increased root growth. Also, the abscisic acid (ABA) and H2O2 contents in roots in the non-saline side increased, possibly due to the increased expression of their key biosynthesis genes, NCED and RBOHC, and the decreased expression of ABA catabolic CYP707A genes. Exogenous ABA added to the non-saline side induced H2O2 generation by up-regulating the RBOHC gene, but this was decreased by exogenous fluridone. Exogenous H2O2 added to the non-saline side reduced the ABA content by down-regulating NCED genes, which can be induced by diphenylene iodonium (DPI) treatment in the non-saline side, suggesting a feedback mechanism between ABA and H2O2.Both exogenous ABA and H2O2 enhanced the expression of SOS1, PIP1;7 ,PIP2;2, and PIP2;10 genes, but these were down-regulated by fluridone and DPI, suggesting that H2O2 and ABA are important signals for increasing root Na(+) efflux and water uptake in the roots in the non-saline side.

  8. Role of protein farnesylation events in the ABA-mediated regulation of the Pinoresinol-Lariciresinol Reductase 1 (LuPLR1) gene expression and lignan biosynthesis in flax (Linum usitatissimum L.).

    PubMed

    Corbin, Cyrielle; Decourtil, Cédric; Marosevic, Djurdjica; Bailly, Marlène; Lopez, Tatiana; Renouard, Sullivan; Doussot, Joël; Dutilleul, Christelle; Auguin, Daniel; Giglioli-Guivarc'h, Nathalie; Lainé, Eric; Lamblin, Frédéric; Hano, Christophe

    2013-11-01

    A Linum usitatissimum LuERA1 gene encoding a putative ortholog of the ERA1 (Enhanced Response to ABA 1) gene of Arabidopsis thaliana (encoding the beta subunit of a farnesyltransferase) was analyzed in silico and for its expression in flax. The gene and the protein sequences are highly similar to other sequences already characterized in plants and all the features of a farnesyltransferase were detected. Molecular modeling of LuERA1 protein confirmed its farnesyltransferase nature. LuERA1 is expressed in the vegetative organs and also in the outer seedcoat of the flaxseed, where it could modulate the previously observed regulation operated by ABA on lignan synthesis. This effect could be mediated by the regulation of the transcription of a key gene for lignan synthesis in flax, the LuPLR1 gene, encoding a pinoresinol lariciresinol reductase. The positive effect of manumycin A, a specific inhibitor of farnesyltransferase, on lignan biosynthesis in flax cell suspension systems supports the hypothesis of the involvement of such an enzyme in the negative regulation of ABA action. In Arabidopsis, ERA1 is able to negatively regulate the ABA effects and the mutant era1 has an enhanced sensitivity to ABA. When expressed in an Arabidopsis cell suspension (heterologous system) LuERA1 is able to reverse the effect of the era1 mutation. RNAi experiments in flax targeting the farnesyltransferase β-subunit encoded by the LuERA1 gene led to an increase LuPLR1 expression level associated with an increased content of lignan in transgenic calli. Altogether these results strongly suggest a role of the product of this LuERA1 gene in the ABA-mediated upregulation of lignan biosynthesis in flax cells through the activation of LuPLR1 promoter. This ABA signaling pathway involving ERA1 probably acts through the ABRE box found in the promoter sequence of LuPLR1, a key gene for lignan synthesis in flax, as demonstrated by LuPLR1 gene promoter-reporter experiments in flax cells using wild

  9. Tryptophan catabolism via kynurenine production in Streptomyces coelicolor: identification of three genes coding for the enzymes of tryptophan to anthranilate pathway.

    PubMed

    Zummo, F P; Marineo, S; Pace, A; Civiletti, F; Giardina, A; Puglia, A M

    2012-05-01

    Most enzymes involved in tryptophan catabolism via kynurenine formation are highly conserved in Prokaryotes and Eukaryotes. In humans, alterations of this pathway have been related to different pathologies mainly involving the central nervous system. In Bacteria, tryptophan and some of its derivates are important antibiotic precursors. Tryptophan degradation via kynurenine formation involves two different pathways: the eukaryotic kynurenine pathway, also recently found in some bacteria, and the tryptophan-to-anthranilate pathway, which is widespread in microorganisms. The latter produces anthranilate using three enzymes also involved in the kynurenine pathway: tryptophan 2,3-dioxygenase (TDO), kynureninase (KYN), and kynurenine formamidase (KFA). In Streptomyces coelicolor, where it had not been demonstrated which genes code for these enzymes, tryptophan seems to be important for the calcium- dependent antibiotic (CDA) production. In this study, we describe three adjacent genes of S. coelicolor (SCO3644, SCO3645, and SCO3646), demonstrating their involvement in the tryptophan-to-anthranilate pathway: SCO3644 codes for a KFA, SCO3645 for a KYN and SCO3646 for a TDO. Therefore, these genes can be considered as homologous respectively to kynB, kynU, and kynA of other microorganisms and belong to a constitutive catabolic pathway in S. coelicolor, which expression increases during the stationary phase of a culture grown in the presence of tryptophan. Moreover, the S. coelicolor ΔkynU strain, in which SCO3645 gene is deleted, produces higher amounts of CDA compared to the wild-type strain. Overall, these results describe a pathway, which is used by S. coelicolor to catabolize tryptophan and that could be inactivated to increase antibiotic production.

  10. Loss of nitrate reductases NIA1 and NIA2 impairs stomatal closure by altering genes of core ABA signaling components in Arabidopsis.

    PubMed

    Zhao, Chenchen; Cai, Shengguan; Wang, Yizhou; Chen, Zhong-Hua

    2016-06-01

    Nitrate reductases NIA1 and NIA2 determine NO production in plants and are critical to abscisic acid (ABA)-induced stomatal closure. However, the role for NIA1 and NIA2 in ABA signaling has not been paid much attention in nitrate reductase loss-of-function mutant nia1nia2. Recently, we have demonstrated that ABA-inhibited K(+)in current and ABA-enhanced slow anion current were absent in nia1nia2. Exogenous NO restored regulation of these channels for stomatal closure in nia1nia2. In this study, we found that mutating NIA1 and NIA2 impaired nearly all the key components of guard cell ABA signaling pathway in Arabidopsis. We also propose a simplified model for ABA signaling in the nia1nia2 mutant.

  11. Loss of nitrate reductases NIA1 and NIA2 impairs stomatal closure by altering genes of core ABA signaling components in Arabidopsis

    PubMed Central

    Zhao, Chenchen; Cai, Shengguan; Wang, Yizhou; Chen, Zhong-Hua

    2016-01-01

    ABSTRACT Nitrate reductases NIA1 and NIA2 determine NO production in plants and are critical to abscisic acid (ABA)-induced stomatal closure. However, the role for NIA1 and NIA2 in ABA signaling has not been paid much attention in nitrate reductase loss-of-function mutant nia1nia2. Recently, we have demonstrated that ABA-inhibited K+in current and ABA-enhanced slow anion current were absent in nia1nia2. Exogenous NO restored regulation of these channels for stomatal closure in nia1nia2. In this study, we found that mutating NIA1 and NIA2 impaired nearly all the key components of guard cell ABA signaling pathway in Arabidopsis. We also propose a simplified model for ABA signaling in the nia1nia2 mutant. PMID:27171851

  12. The Pseudomonas aeruginosa liuE gene encodes the 3-hydroxy-3-methylglutaryl coenzyme A lyase, involved in leucine and acyclic terpene catabolism.

    PubMed

    Chávez-Avilés, Mauricio; Díaz-Pérez, Alma Laura; Reyes-de la Cruz, Homero; Campos-García, Jesús

    2009-07-01

    The enzymes involved in the catabolism of leucine are encoded by the liu gene cluster in Pseudomonas aeruginosa PAO1. A mutant in the liuE gene (ORF PA2011) of P. aeruginosa was unable to utilize both leucine/isovalerate and acyclic terpenes as the carbon source. The liuE mutant grown in culture medium with citronellol accumulated metabolites of the acyclic terpene pathway, suggesting an involvement of liuE in both leucine/isovalerate and acyclic terpene catabolic pathways. The LiuE protein was expressed as a His-tagged recombinant polypeptide purified by affinity chromatography in Escherichia coli. LiuE showed a mass of 33 kDa under denaturing and 79 kDa under nondenaturing conditions. Protein sequence alignment and fingerprint sequencing suggested that liuE encodes 3-hydroxy-3-methylglutaryl-coenzyme A lyase (HMG-CoA lyase), which catalyzes the cleavage of HMG-CoA to acetyl-CoA and acetoacetate. LiuE showed HMG-CoA lyase optimal activity at a pH of 7.0 and 37 degrees C, an apparent K(m) of 100 microM for HMG-CoA and a V(max) of 21 micromol min(-1) mg(-1). These results demonstrate that the liuE gene of P. aeruginosa encodes for the HMG-CoA lyase, an essential enzyme for growth in both leucine and acyclic terpenes.

  13. The RhaS activator controls the Erwinia chrysanthemi 3937 genes rhiN, rhiT and rhiE involved in rhamnogalacturonan catabolism.

    PubMed

    Hugouvieux-Cotte-Pattat, Nicole

    2004-03-01

    Erwinia chrysanthemi causes soft-rot diseases of various plants by enzymatic degradation of the pectin in plant cell walls. The linear regions of pectin are composed of an acidic sugar, D-galacturonic acid. The ramified regions of pectin also include neutral sugars, and are rich in L-rhamnose residues. E. chrysanthemi is able to degrade these polysaccharides, polygalacturonate and rhamnogalacturonate. In E. chrysanthemi, the production of pectinases acting on linear regions is induced in the presence of polygalacturonate by a mechanism involving the repressor KdgR. The induction of the two adjacent E. chrysanthemi genes, designated rhiT and rhiN, is maximal after the simultaneous addition of both polygalacturonate and L-rhamnose. The rhiT product is homologous to the oligogalacturonide transporter TogT of E. chrysanthemi. The rhiN product is homologous to various proteins of unknown function, including a protein encoded by the plant-inducible locus picA of Agrobacterium tumefaciens. Both rhiT and rhiN are highly induced during plant infection. Various data suggest that RhiT and RhiN are involved in rhamnogalacturonate catabolism. RhiN is able to degrade the oligomers liberated by the rhamnogalacturonate lyase RhiE. The induction of the rhiTN operon in the presence of polygalacturonate results from control by the repressor KdgR. The additional induction of these genes by rhamnose is directly mediated by RhaS, a protein homologous to the activator of rhamnose catabolism in Escherichia coli. The virulence of an E. chrysanthemi rhaS mutant towards different host plants was clearly reduced. In this phytopathogenic bacterial species, RhaS positively regulates the transcription of the rhaBAD operon, involved in rhamnose catabolism, of the rhiE gene and of the rhiTN operon. The regulator RhaS plays a larger role in E. chrysanthemi than in other enterobacteria. Indeed, the RhaS control is not restricted to the catabolism of rhamnose but is extended to the degradation of

  14. Cloning of new members of heat shock protein HSP101 gene family in wheat (Triticum aestivum (L.) Moench) inducible by heat, dehydration, and ABA(1).

    PubMed

    Campbell, J L; Klueva, N Y; Zheng, H G; Nieto-Sotelo, J; Ho, T D; Nguyen, H T

    2001-01-26

    We have cloned two cDNAs, TaHSP101B and TaHSP101C, encoding two heat stress-inducible members of HSP101/ClpB family in bread wheat (Triticum aestivum (L.) Moench.). Proteins encoded by these cDNAs are highly similar at the primary sequence level and diverged from the previously reported TaHSP101 (designated TaHSP101A) both in the consensus ATP/GTP-binding region II and in the carboxy terminal region. The HSP101 gene was determined to be a single copy gene or a member of a small gene family in hexaploid wheat. Messages encoding HSP101 proteins were inducible by heat stress treatments in both wheat leaves and roots. Accumulation of the TaHSP101C mRNA was less abundant than that of TaHSP101B mRNA. We are showing for the first time that in addition to heat stress, expression of HSP101 mRNAs in wheat leaves was induced by a 2-h dehydration and a treatment with 5x10(-5)M ABA, but not affected by chilling or wounding, indicating that HSP101 proteins may be involved in both heat and drought responses in wheat. PMID:11342108

  15. Jasmonic acid promotes degreening via MYC2/3/4- and ANAC019/055/072-mediated regulation of major chlorophyll catabolic genes.

    PubMed

    Zhu, Xiaoyu; Chen, Junyi; Xie, Zuokun; Gao, Jiong; Ren, Guodong; Gao, Shan; Zhou, Xin; Kuai, Benke

    2015-11-01

    Degreening caused by rapid chlorophyll (Chl) degradation is a characteristic event during green organ senescence or maturation. Pheophorbide a oxygenase gene (PAO) encodes a key enzyme of Chl degradation, yet its transcriptional regulation remains largely unknown. Using yeast one-hybrid screening, coupled with in vitro and in vivo assays, we revealed that Arabidopsis MYC2/3/4 basic helix-loop-helix proteins directly bind to PAO promoter. Overexpression of the MYCs significantly enhanced the transcriptional activity of PAO promoter in Arabidopsis protoplasts, and methyl jasmonate (MeJA) treatment greatly induced PAO expression in wild-type Arabidopsis plants, but the induction was abolished in myc2 myc3 myc4. In addition, MYC2/3/4 proteins could promote the expression of another Chl catabolic enzyme gene, NYC1, as well as a key regulatory gene of Chl degradation, NYE1/SGR1, by directly binding to their promoters. More importantly, the myc2 myc3 myc4 triple mutant showed a severe stay-green phenotype, whereas the lines overexpressing the MYCs showed accelerated leaf yellowing upon MeJA treatment. These results suggest that MYC2/3/4 proteins may mediate jasmonic acid (JA)-induced Chl degradation by directly activating these Chl catabolic genes (CCGs). Three NAC family proteins, ANAC019/055/072, downstream from MYC2/3/4 proteins, could also directly promote the expression of a similar set of CCGs (NYE1/SGR1, NYE2/SGR2 and NYC1) during Chl degradation. In particular, anac019 anac055 anac072 triple mutant displayed a severe stay-green phenotype after MeJA treatment. Finally, we revealed that MYC2 and ANAC019 may interact with each other and synergistically enhance NYE1 expression. Together, our study reveals a hierarchical and coordinated regulatory network of JA-induced Chl degradation.

  16. DNA sequence determination of the TOL plasmid (pWWO) xylGFJ genes of Pseudomonas putida: implications for the evolution of aromatic catabolism.

    PubMed

    Horn, J M; Harayama, S; Timmis, K N

    1991-10-01

    The meta operon of the Pseudomonas putida TOL plasmid (pWWO) encodes all enzymes of a meta-cleavage pathway for the metabolism of benzoic acids to Krebs-cycle intermediates. We have determined and analysed the nucleic acid sequence of a 3442 bp region of the meta operon containing the xyl-GFJ genes whose products are involved in the post meta-ring fission transformation of catechols. Homology analysis of the xylGFJ gene products revealed evidence of biochemical relatedness, suggested enzymatic mechanisms, and permitted us to propose evolutionary events which may have generated the current variety of aromatic degradative pathways. The xylG gene, which specifies 2-hydroxymuconic semialdehyde dehydrogenase (HMSD), was found to encode a protein of 51.7 kDa. The predicted protein sequence exhibits significant homology to eukaryotic aldehyde dehydrogenases (ADHs) and to the products of two other Pseudomonas catabolic genes, i.e. xylC and alkH. Expansion of the ADH superfamily to include these prokaryotic enzymes permitted a broader analysis of functionally critical ADH residues and phylogenetic relationships among superfamily members. The importance of three regions of these enzymes previously thought to be critical to ADH activity was reinforced by this analysis. However glutamine-487, also thought to be critical, is less well conserved. The revised ADH phylogeny proposed here suggests early catabolic ADH divergence with subsequent interkingdom gene exchange. The xylF gene, which specifies 2-hydroxymuconic semialdehyde hydrolase (HMSH), was delineated by N-terminal sequence analysis of the purified gene product and is shown to encode a protein of 30.6 kDa. Homology analysis revealed sequence similarity to a chromosomally encoded serine hydrolase, especially in the region of the previously identified active-site serine residue, suggesting that HMSH may also possess a serine hydrolytic enzymatic mechanism. Likewise, the xylJ gene, which specifies 2-hydroxy-pent-2

  17. GenR, an IclR-type regulator, activates and represses the transcription of gen genes involved in 3-hydroxybenzoate and gentisate catabolism in Corynebacterium glutamicum.

    PubMed

    Chao, Hongjun; Zhou, Ning-Yi

    2013-04-01

    The genes required for 3-hydroxybenzoate and gentisate catabolism in Corynebacterium glutamicum are closely clustered in three operons. GenR, an IclR-type regulator, can activate the transcription of genKH and genDFM operons in response to 3-hydroxybenzoate and gentisate, and it can repress its own expression. Footprinting analyses demonstrated that GenR bound to four sites with different affinities. Two GenR-binding sites (DFMn01 and DFMn02) were found to be located between positions --41 and --84 upstream of the --35 and --10 regions of the genDFM promoter, which was involved in positive regulation of genDFM transcription. The GenR binding site R-KHn01 (located between positions --47 and --16) overlapped the --35 region of the genKH promoter sequence and is involved in positive regulation of its transcription. The binding site R-KHn02, at which GenR binds to its own promoter, was found within a footprint extending from position --44 to --67. It appeared to be involved in negative regulation of the activity of the genR promoter. A consensus motif with a 5-bp imperfect palindromic sequence [ATTCC-N(7(5))-GGAAT] was identified among all four GenR binding sites and found to be necessary to GenR regulation through site-directed mutagenesis. The results reveal a new regulatory function of the IclR family in the catabolism of aromatic compounds.

  18. Lesions in the mRNA cap-binding gene ABA HYPERSENSITIVE 1 suppress FRIGIDA-mediated delayed flowering in Arabidopsis.

    PubMed

    Bezerra, Isabel C; Michaels, Scott D; Schomburg, Fritz M; Amasino, Richard M

    2004-10-01

    Recessive mutations that suppress the late-flowering phenotype conferred by FRIGIDA (FRI) and FLOWERING LOCUS C (FLC) and which also result in serrated leaf morphology were identified in T-DNA and fast-neutron mutant populations. Molecular analysis showed that the mutations are caused by lesions in the gene encoding the large subunit of the nuclear mRNA cap-binding protein, ABH1 (ABA hypersensitive1). The suppression of late flowering is caused by the inability of FRI to increase FLC mRNA levels in the abh1 mutant background. The serrated leaf morphology of abh1 is similar to the serrate (se) mutant and, like abh1, se is also a suppressor of FRI-mediated late flowering although it is a weaker suppressor than abh1. Unlike se, in abh1 the rate of leaf production and the number of juvenile leaves are not altered. The abh1 lesion affects several developmental processes, perhaps because the processing of certain mRNAs in these pathways is more sensitive to loss of cap-binding activity than the majority of cellular mRNAs. PMID:15361145

  19. Lesions in the mRNA cap-binding gene ABA HYPERSENSITIVE 1 suppress FRIGIDA-mediated delayed flowering in Arabidopsis.

    PubMed

    Bezerra, Isabel C; Michaels, Scott D; Schomburg, Fritz M; Amasino, Richard M

    2004-10-01

    Recessive mutations that suppress the late-flowering phenotype conferred by FRIGIDA (FRI) and FLOWERING LOCUS C (FLC) and which also result in serrated leaf morphology were identified in T-DNA and fast-neutron mutant populations. Molecular analysis showed that the mutations are caused by lesions in the gene encoding the large subunit of the nuclear mRNA cap-binding protein, ABH1 (ABA hypersensitive1). The suppression of late flowering is caused by the inability of FRI to increase FLC mRNA levels in the abh1 mutant background. The serrated leaf morphology of abh1 is similar to the serrate (se) mutant and, like abh1, se is also a suppressor of FRI-mediated late flowering although it is a weaker suppressor than abh1. Unlike se, in abh1 the rate of leaf production and the number of juvenile leaves are not altered. The abh1 lesion affects several developmental processes, perhaps because the processing of certain mRNAs in these pathways is more sensitive to loss of cap-binding activity than the majority of cellular mRNAs.

  20. Gene order of the TOL catabolic plasmid upper pathway operon and oxidation of both toluene and benzyl alcohol by the xylA product

    SciTech Connect

    Harayama, S.; Leppik, R.A.; Rekik, M.; Mermod, N.; Lehrbach, P.R.; Reineke, W.; Timmis, K.N.

    1986-08-01

    TOL plasmid pWW0 specifies enzymes for the oxidative catabolism of toluene and xylenes. The upper pathway converts the aromatic hydrocarbons to aromatic carboxylic acids via corresponding alcohols and aldehydes and involves three enzymes: xylene oxygenase, benzyl alcohol dehydrogenase, and benzaldehyde dehydrogenase. The synthesis of these enzymes is positively regulated by the product of xylR. Determination of upper pathway enzyme levels in bacteria carrying Tn5 insertion mutant derivatives of plasmid pWW0-161 has shown that the genes for upper pathway enzymes are organized in an operon with the following order: promoter-xylC (benzaldehyde dehydrogenase gene(s))-xylA (xylene oxygenase gene(s))-xylB (benzyl alcohol dehydrogenase gene). Subcloning of the upper pathway genes in a lambda p/sub L/ promoter-containing vector and analysis of their expression in Escherichia coli K-12 confirmed this order. Two distinct enzymes were found to attack benzyl alcohol, namely, xylene oxygenase and benzyl alcohol dehydrogenase; and their catalytic activities were additive in the conversion of benzyl alcohol to benzaldehyde. The fact that benzyl alcohol is both a product and a substrate of xylene oxygenase indicates that this enzyme has a relaxed substrate specificity.

  1. Plasmids Responsible for Horizontal Transfer of Naphthalene Catabolism Genes between Bacteria at a Coal Tar-Contaminated Site Are Homologous to pDTG1 from Pseudomonas putida NCIB 9816-4

    PubMed Central

    Stuart-Keil, K. G.; Hohnstock, A. M.; Drees, K. P.; Herrick, J. B.; Madsen, E. L.

    1998-01-01

    The presence of a highly conserved nahAc allele among phylogenetically diverse bacteria carrying naphthalene-catabolic plasmids provided evidence for in situ horizontal gene transfer at a coal tar-contaminated site (J. B. Herrick, K. G. Stuart-Keil, W. C. Ghiorse, and E. L. Madsen, Appl. Environ. Microbiol. 63:2330–2337, 1997). The objective of the present study was to identify and characterize the different-sized naphthalene-catabolic plasmids in order to determine the probable mechanism of horizontal transfer of the nahAc gene in situ. Filter matings between naphthalene-degrading bacterial isolates and their cured progeny revealed that the naphthalene-catabolic plasmids were self-transmissible. Limited interstrain transfer was also found. Analysis of the restriction fragment length polymorphism (RFLP) patterns indicated that catabolic plasmids from 12 site-derived isolates were closely related to each other and to the naphthalene-catabolic plasmid (pDTG1) of Pseudomonas putida NCIB 9816-4, which was isolated decades ago in Bangor, Wales. The similarity among all site-derived naphthalene-catabolic plasmids and pDTG1 was confirmed by using the entire pDTG1 plasmid as a probe in Southern hybridizations. Two distinct but similar naphthalene-catabolic plasmids were retrieved directly from the microbial community indigenous to the contaminated site in a filter mating by using a cured, rifampin-resistant site-derived isolate as the recipient. RFLP patterns and Southern hybridization showed that both of these newly retrieved plasmids, like the isolate-derived plasmids, were closely related to pDTG1. These data indicate that a pDTG1-like plasmid is the mobile genetic element responsible for transferring naphthalene-catabolic genes among bacteria in situ. The pervasiveness and persistence of this naphthalene-catabolic plasmid suggest that it may have played a role in the adaptation of this microbial community to the coal tar contamination at our study site. PMID:9758778

  2. Cloning and expression of lipoxygenase genes and enzyme activity in ripening persimmon fruit in response to GA and ABA treatment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two genes of the lipoxygenase (LOX) family, DkLox1 and DkLox3 (GenBank accession No. JF436951 and JF436950), were cloned from persimmon fruit (Diospyros kaki L. ‘Fuping Jianshi’). Sequence analysis indicated that they belong to the 9-LOX sub-group. Heterologous expression of DkLox1 in E. coli produc...

  3. GenR, an IclR-Type Regulator, Activates and Represses the Transcription of gen Genes Involved in 3-Hydroxybenzoate and Gentisate Catabolism in Corynebacterium glutamicum

    PubMed Central

    Chao, Hongjun

    2013-01-01

    The genes required for 3-hydroxybenzoate and gentisate catabolism in Corynebacterium glutamicum are closely clustered in three operons. GenR, an IclR-type regulator, can activate the transcription of genKH and genDFM operons in response to 3-hydroxybenzoate and gentisate, and it can repress its own expression. Footprinting analyses demonstrated that GenR bound to four sites with different affinities. Two GenR-binding sites (DFMn01 and DFMn02) were found to be located between positions −41 and −84 upstream of the −35 and −10 regions of the genDFM promoter, which was involved in positive regulation of genDFM transcription. The GenR binding site R-KHn01 (located between positions −47 and −16) overlapped the −35 region of the genKH promoter sequence and is involved in positive regulation of its transcription. The binding site R-KHn02, at which GenR binds to its own promoter, was found within a footprint extending from position −44 to −67. It appeared to be involved in negative regulation of the activity of the genR promoter. A consensus motif with a 5-bp imperfect palindromic sequence [ATTCC-N7(5)-GGAAT] was identified among all four GenR binding sites and found to be necessary to GenR regulation through site-directed mutagenesis. The results reveal a new regulatory function of the IclR family in the catabolism of aromatic compounds. PMID:23354754

  4. ABA-deficiency results in reduced plant and fruit size in tomato.

    PubMed

    Nitsch, L; Kohlen, W; Oplaat, C; Charnikhova, T; Cristescu, S; Michieli, P; Wolters-Arts, M; Bouwmeester, H; Mariani, C; Vriezen, W H; Rieu, I

    2012-06-15

    Abscisic acid (ABA) deficient mutants, such as notabilis and flacca, have helped elucidating the role of ABA during plant development and stress responses in tomato (Solanum lycopersicum L.). However, these mutants have only moderately decreased ABA levels. Here we report on plant and fruit development in the more strongly ABA-deficient notabilis/flacca (not/flc) double mutant. We observed that plant growth, leaf-surface area, drought-induced wilting and ABA-related gene expression in the different genotypes were strongly correlated with the ABA levels and thus most strongly affected in the not/flc double mutants. These mutants also had reduced fruit size that was caused by an overall smaller cell size. Lower ABA levels in fruits did not correlate with changes in auxin levels, but were accompanied by higher ethylene evolution rates. This suggests that in a wild-type background ABA stimulates cell enlargement during tomato fruit growth via a negative effect on ethylene synthesis.

  5. Arabidopsis DREB2C modulates ABA biosynthesis during germination.

    PubMed

    Je, Jihyun; Chen, Huan; Song, Chieun; Lim, Chae Oh

    2014-09-12

    Plant dehydration-responsive element binding factors (DREBs) are transcriptional regulators of the APETELA2/Ethylene Responsive element-binding Factor (AP2/ERF) family that control expression of abiotic stress-related genes. We show here that under conditions of mild heat stress, constitutive overexpression seeds of transgenic DREB2C overexpression Arabidopsis exhibit delayed germination and increased abscisic acid (ABA) content compared to untransformed wild-type (WT). Treatment with fluridone, an inhibitor of the ABA biosynthesis abrogated these effects. Expression of an ABA biosynthesis-related gene, 9-cis-epoxycarotenoid dioxygenase 9 (NCED9) was up-regulated in the DREB2C overexpression lines compared to WT. DREB2C was able to trans-activate expression of NCED9 in Arabidopsis leaf protoplasts in vitro. Direct and specific binding of DREB2C to a complete DRE on the NCED9 promoter was observed in electrophoretic mobility shift assays. Exogenous ABA treatment induced DREB2C expression in germinating seeds of WT. Vegetative growth of transgenic DREB2C overexpression lines was more strongly inhibited by exogenous ABA compared to WT. These results suggest that DREB2C is a stress- and ABA-inducible gene that acts as a positive regulator of ABA biosynthesis in germinating seeds through activating NCED9 expression.

  6. The transcriptional activators AraR and XlnR from Aspergillus niger regulate expression of pentose catabolic and pentose phosphate pathway genes.

    PubMed

    Battaglia, Evy; Zhou, Miaomiao; de Vries, Ronald P

    2014-09-01

    The pentose catabolic pathway (PCP) and the pentose phosphate pathway (PPP) are required for the conversion of pentose sugars in fungi and are linked via d-xylulose-5-phosphate. Previously, it was shown that the PCP is regulated by the transcriptional activators XlnR and AraR in Aspergillus niger. Here we assessed whether XlnR and AraR also regulate the PPP. Expression of two genes, rpiA and talB, was reduced in the ΔaraR/ΔxlnR strain and increased in the xylulokinase negative strain (xkiA1) on d-xylose and/or l-arabinose. Bioinformatic analysis of the 1 kb promoter regions of rpiA and talB showed the presence of putative XlnR binding sites. Combining all results in this study, it strongly suggests that these two PPP genes are under regulation of XlnR in A. niger.

  7. Patchwork assembly of nag-like nitroarene dioxygenase genes and the 3-chlorocatechol degradation cluster for evolution of the 2-chloronitrobenzene catabolism pathway in Pseudomonas stutzeri ZWLR2-1.

    PubMed

    Liu, Hong; Wang, Shu-Jun; Zhang, Jun-Jie; Dai, Hui; Tang, Huiru; Zhou, Ning-Yi

    2011-07-01

    Pseudomonas stutzeri ZWLR2-1 utilizes 2-chloronitrobenzene (2CNB) as a sole source of carbon, nitrogen, and energy. To identify genes involved in this pathway, a 16.2-kb DNA fragment containing putative 2CNB dioxygenase genes was cloned and sequenced. Of the products from the 19 open reading frames that resulted from this fragment, CnbAc and CnbAd exhibited striking identities to the respective α and β subunits of the Nag-like ring-hydroxylating dioxygenases involved in the metabolism of nitrotoluene, nitrobenzene, and naphthalene. The encoding genes were also flanked by two copies of insertion sequence IS6100. CnbAa and CnbAb are similar to the ferredoxin reductase and ferredoxin for anthranilate 1,2-dioxygenase from Burkholderia cepacia DBO1. Escherichia coli cells expressing cnbAaAbAcAd converted 2CNB to 3-chlorocatechol with concomitant nitrite release. Cell extracts of E. coli/pCNBC exhibited chlorocatechol 1,2-dioxygenase activity. The cnbCDEF gene cluster, homologous to a 3-chlorocatechol degradation cluster in Sphingomonas sp. strain TFD44, probably contains all of the genes necessary for the conversion of 3-chlorocatechol to 3-oxoadipate. The patchwork-like structure of this catabolic cluster suggests that the cnb cluster for 2CNB degradation evolved by recruiting two catabolic clusters encoding a nitroarene dioxygenase and a chlorocatechol degradation pathway. This provides another example to help elucidate the bacterial evolution of catabolic pathways in response to xenobiotic chemicals.

  8. Genome-wide study of KNOX regulatory network reveals brassinosteroid catabolic genes important for shoot meristem function in rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In flowering plants, knotted1-like homeobox (KNOX) transcription factors play crucial roles in establishment and maintenance of the shoot apical meristem (SAM), from which aerial organs such as leaves, stems, and flowers initiate. We report that a rice (Oryza sativa) KNOX gene Oryza sativa homeobox1...

  9. EIN3 and ORE1 Accelerate Degreening during Ethylene-Mediated Leaf Senescence by Directly Activating Chlorophyll Catabolic Genes in Arabidopsis.

    PubMed

    Qiu, Kai; Li, Zhongpeng; Yang, Zhen; Chen, Junyi; Wu, Shouxin; Zhu, Xiaoyu; Gao, Shan; Gao, Jiong; Ren, Guodong; Kuai, Benke; Zhou, Xin

    2015-07-01

    Degreening, caused by chlorophyll degradation, is the most obvious symptom of senescing leaves. Chlorophyll degradation can be triggered by endogenous and environmental cues, and ethylene is one of the major inducers. ETHYLENE INSENSITIVE3 (EIN3) is a key transcription factor in the ethylene signaling pathway. It was previously reported that EIN3, miR164, and a NAC (NAM, ATAF, and CUC) transcription factor ORE1/NAC2 constitute a regulatory network mediating leaf senescence. However, how this network regulates chlorophyll degradation at molecular level is not yet elucidated. Here we report a feed-forward regulation of chlorophyll degradation that involves EIN3, ORE1, and chlorophyll catabolic genes (CCGs). Gene expression analysis showed that the induction of three major CCGs, NYE1, NYC1 and PAO, by ethylene was largely repressed in ein3 eil1 double mutant. Dual-luciferase assay revealed that EIN3 significantly enhanced the promoter activity of NYE1, NYC1 and PAO in Arabidopsis protoplasts. Furthermore, Electrophoretic mobility shift assay (EMSA) indicated that EIN3 could directly bind to NYE1, NYC1 and PAO promoters. These results reveal that EIN3 functions as a positive regulator of CCG expression during ethylene-mediated chlorophyll degradation. Interestingly, ORE1, a senescence regulator which is a downstream target of EIN3, could also activate the expression of NYE1, NYC1 and PAO by directly binding to their promoters in EMSA and chromatin immunoprecipitation (ChIP) assays. In addition, EIN3 and ORE1 promoted NYE1 and NYC1 transcriptions in an additive manner. These results suggest that ORE1 is also involved in the direct regulation of CCG transcription. Moreover, ORE1 activated the expression of ACS2, a major ethylene biosynthesis gene, and subsequently promoted ethylene production. Collectively, our work reveals that EIN3, ORE1 and CCGs constitute a coherent feed-forward loop involving in the robust regulation of ethylene-mediated chlorophyll degradation

  10. MBF1s regulate ABA-dependent germination of Arabidopsis seeds.

    PubMed

    Di Mauro, María Florencia; Iglesias, María José; Arce, Débora Pamela; Valle, Estela Marta; Arnold, Roberto Benech; Tsuda, Kenichi; Yamazaki, Ken-ichi; Casalongué, Claudia Anahí; Godoy, Andrea Verónica

    2012-02-01

    Transcriptional co-activators of the multiprotein bridging factor 1 (MBF1) controls gene expression by connecting transcription factors and the basal transcription machinery. In Arabidopsis thaliana functions of MBF1 genes have been related to stress tolerance and developmental alterations. Endogenous ABA plays a major role in the regulation of Arabidopsis seed dormancy and germination. Seed dormancy and ABA sensitivity are enhanced in ethylene insensitive mutants suggesting that ethylene signal transduction pathway is necessary to fully develop ABA-dependent germination. In this report we showed that a triple knock-down mutant for Arabidopsis MBF1 genes (abc-) has enhanced seed dormancy and displays hypersensitivity to exogenous ABA. In addition, higher ABA contents were detected in abc- seeds after imbibition. These evidences suggest a negative role of MBF1s genes in ABA-dependent inhibition of germination. The participation of MBF1s in ethylene signal transduction pathway is also discussed.

  11. ABA receptor PYL9 promotes drought resistance and leaf senescence.

    PubMed

    Zhao, Yang; Chan, Zhulong; Gao, Jinghui; Xing, Lu; Cao, Minjie; Yu, Chunmei; Hu, Yuanlei; You, Jun; Shi, Haitao; Zhu, Yingfang; Gong, Yuehua; Mu, Zixin; Wang, Haiqing; Deng, Xin; Wang, Pengcheng; Bressan, Ray A; Zhu, Jian-Kang

    2016-02-16

    Drought stress is an important environmental factor limiting plant productivity. In this study, we screened drought-resistant transgenic plants from 65 promoter-pyrabactin resistance 1-like (PYL) abscisic acid (ABA) receptor gene combinations and discovered that pRD29A::PYL9 transgenic lines showed dramatically increased drought resistance and drought-induced leaf senescence in both Arabidopsis and rice. Previous studies suggested that ABA promotes senescence by causing ethylene production. However, we found that ABA promotes leaf senescence in an ethylene-independent manner by activating sucrose nonfermenting 1-related protein kinase 2s (SnRK2s), which subsequently phosphorylate ABA-responsive element-binding factors (ABFs) and Related to ABA-Insensitive 3/VP1 (RAV1) transcription factors. The phosphorylated ABFs and RAV1 up-regulate the expression of senescence-associated genes, partly by up-regulating the expression of Oresara 1. The pyl9 and ABA-insensitive 1-1 single mutants, pyl8-1pyl9 double mutant, and snrk2.2/3/6 triple mutant showed reduced ABA-induced leaf senescence relative to the WT, whereas pRD29A::PYL9 transgenic plants showed enhanced ABA-induced leaf senescence. We found that leaf senescence may benefit drought resistance by helping to generate an osmotic potential gradient, which is increased in pRD29A::PYL9 transgenic plants and causes water to preferentially flow to developing tissues. Our results uncover the molecular mechanism of ABA-induced leaf senescence and suggest an important role of PYL9 and leaf senescence in promoting resistance to extreme drought stress. PMID:26831097

  12. ABA receptor PYL9 promotes drought resistance and leaf senescence

    PubMed Central

    Zhao, Yang; Chan, Zhulong; Gao, Jinghui; Xing, Lu; Cao, Minjie; Yu, Chunmei; Hu, Yuanlei; You, Jun; Shi, Haitao; Zhu, Yingfang; Gong, Yuehua; Mu, Zixin; Wang, Haiqing; Deng, Xin; Wang, Pengcheng; Bressan, Ray A.; Zhu, Jian-Kang

    2016-01-01

    Drought stress is an important environmental factor limiting plant productivity. In this study, we screened drought-resistant transgenic plants from 65 promoter-pyrabactin resistance 1-like (PYL) abscisic acid (ABA) receptor gene combinations and discovered that pRD29A::PYL9 transgenic lines showed dramatically increased drought resistance and drought-induced leaf senescence in both Arabidopsis and rice. Previous studies suggested that ABA promotes senescence by causing ethylene production. However, we found that ABA promotes leaf senescence in an ethylene-independent manner by activating sucrose nonfermenting 1-related protein kinase 2s (SnRK2s), which subsequently phosphorylate ABA-responsive element-binding factors (ABFs) and Related to ABA-Insensitive 3/VP1 (RAV1) transcription factors. The phosphorylated ABFs and RAV1 up-regulate the expression of senescence-associated genes, partly by up-regulating the expression of Oresara 1. The pyl9 and ABA-insensitive 1-1 single mutants, pyl8-1pyl9 double mutant, and snrk2.2/3/6 triple mutant showed reduced ABA-induced leaf senescence relative to the WT, whereas pRD29A::PYL9 transgenic plants showed enhanced ABA-induced leaf senescence. We found that leaf senescence may benefit drought resistance by helping to generate an osmotic potential gradient, which is increased in pRD29A::PYL9 transgenic plants and causes water to preferentially flow to developing tissues. Our results uncover the molecular mechanism of ABA-induced leaf senescence and suggest an important role of PYL9 and leaf senescence in promoting resistance to extreme drought stress. PMID:26831097

  13. ABA receptor PYL9 promotes drought resistance and leaf senescence.

    PubMed

    Zhao, Yang; Chan, Zhulong; Gao, Jinghui; Xing, Lu; Cao, Minjie; Yu, Chunmei; Hu, Yuanlei; You, Jun; Shi, Haitao; Zhu, Yingfang; Gong, Yuehua; Mu, Zixin; Wang, Haiqing; Deng, Xin; Wang, Pengcheng; Bressan, Ray A; Zhu, Jian-Kang

    2016-02-16

    Drought stress is an important environmental factor limiting plant productivity. In this study, we screened drought-resistant transgenic plants from 65 promoter-pyrabactin resistance 1-like (PYL) abscisic acid (ABA) receptor gene combinations and discovered that pRD29A::PYL9 transgenic lines showed dramatically increased drought resistance and drought-induced leaf senescence in both Arabidopsis and rice. Previous studies suggested that ABA promotes senescence by causing ethylene production. However, we found that ABA promotes leaf senescence in an ethylene-independent manner by activating sucrose nonfermenting 1-related protein kinase 2s (SnRK2s), which subsequently phosphorylate ABA-responsive element-binding factors (ABFs) and Related to ABA-Insensitive 3/VP1 (RAV1) transcription factors. The phosphorylated ABFs and RAV1 up-regulate the expression of senescence-associated genes, partly by up-regulating the expression of Oresara 1. The pyl9 and ABA-insensitive 1-1 single mutants, pyl8-1pyl9 double mutant, and snrk2.2/3/6 triple mutant showed reduced ABA-induced leaf senescence relative to the WT, whereas pRD29A::PYL9 transgenic plants showed enhanced ABA-induced leaf senescence. We found that leaf senescence may benefit drought resistance by helping to generate an osmotic potential gradient, which is increased in pRD29A::PYL9 transgenic plants and causes water to preferentially flow to developing tissues. Our results uncover the molecular mechanism of ABA-induced leaf senescence and suggest an important role of PYL9 and leaf senescence in promoting resistance to extreme drought stress.

  14. pH regulates genes for flagellar motility, catabolism, and oxidative stress in Escherichia coli K-12.

    PubMed

    Maurer, Lisa M; Yohannes, Elizabeth; Bondurant, Sandra S; Radmacher, Michael; Slonczewski, Joan L

    2005-01-01

    Gene expression profiles of Escherichia coli K-12 W3110 were compared as a function of steady-state external pH. Cultures were grown to an optical density at 600 nm of 0.3 in potassium-modified Luria-Bertani medium buffered at pH 5.0, 7.0, and 8.7. For each of the three pH conditions, cDNA from RNA of five independent cultures was hybridized to Affymetrix E. coli arrays. Analysis of variance with an alpha level of 0.001 resulted in 98% power to detect genes showing a twofold difference in expression. Normalized expression indices were calculated for each gene and intergenic region (IG). Differential expression among the three pH classes was observed for 763 genes and 353 IGs. Hierarchical clustering yielded six well-defined clusters of pH profiles, designated Acid High (highest expression at pH 5.0), Acid Low (lowest expression at pH 5.0), Base High (highest at pH 8.7), Base Low (lowest at pH 8.7), Neutral High (highest at pH 7.0, lower in acid or base), and Neutral Low (lowest at pH 7.0, higher at both pH extremes). Flagellar and chemotaxis genes were repressed at pH 8.7 (Base Low cluster), where the cell's transmembrane proton potential is diminished by the maintenance of an inverted pH gradient. High pH also repressed the proton pumps cytochrome o (cyo) and NADH dehydrogenases I and II. By contrast, the proton-importing ATP synthase F1Fo and the microaerophilic cytochrome d (cyd), which minimizes proton export, were induced at pH 8.7. These observations are consistent with a model in which high pH represses synthesis of flagella, which expend proton motive force, while stepping up electron transport and ATPase components that keep protons inside the cell. Acid-induced genes, on the other hand, were coinduced by conditions associated with increased metabolic rate, such as oxidative stress. All six pH-dependent clusters included envelope and periplasmic proteins, which directly experience external pH. Overall, this study showed that (i) low pH accelerates acid

  15. Metagenomic survey of methanesulfonic acid (MSA) catabolic genes in an Atlantic Ocean surface water sample and in a partial enrichment

    PubMed Central

    Henriques, Ana C.; Azevedo, Rui M.S.

    2016-01-01

    Methanesulfonic acid (MSA) is a relevant intermediate of the biogeochemical cycle of sulfur and environmental microorganisms assume an important role in the mineralization of this compound. Several methylotrophic bacterial strains able to grow on MSA have been isolated from soil or marine water and two conserved operons, msmABCD coding for MSA monooxygenase and msmEFGH coding for a transport system, have been repeatedly encountered in most of these strains. Homologous sequences have also been amplified directly from the environment or observed in marine metagenomic data, but these showed a base composition (G + C content) very different from their counterparts from cultivated bacteria. The aim of this study was to understand which microorganisms within the coastal surface oceanic microflora responded to MSA as a nutrient and how the community evolved in the early phases of an enrichment by means of metagenome and gene-targeted amplicon sequencing. From the phylogenetic point of view, the community shifted significantly with the disappearance of all signals related to the Archaea, the Pelagibacteraceae and phylum SAR406, and the increase in methylotroph-harboring taxa, accompanied by other groups so far not known to comprise methylotrophs such as the Hyphomonadaceae. At the functional level, the abundance of several genes related to sulfur metabolism and methylotrophy increased during the enrichment and the allelic distribution of gene msmA diagnostic for MSA monooxygenase altered considerably. Even more dramatic was the disappearance of MSA import-related gene msmE, which suggests that alternative transporters must be present in the enriched community and illustrate the inadequacy of msmE as an ecofunctional marker for MSA degradation at sea. PMID:27761315

  16. Identification of mannose uptake and catabolism genes in Corynebacterium glutamicum and genetic engineering for simultaneous utilization of mannose and glucose.

    PubMed

    Sasaki, Miho; Teramoto, Haruhiko; Inui, Masayuki; Yukawa, Hideaki

    2011-03-01

    Here, focus is on Corynebacterium glutamicum mannose metabolic genes with the aim to improve this industrially important microorganism's ability to ferment mannose present in mixed sugar substrates. cgR_0857 encodes C. glutamicum's protein with 36% amino acid sequence identity to mannose 6-phosphate isomerase encoded by manA of Escherichia coli. Its deletion mutant did not grow on mannose and exhibited noticeably reduced growth on glucose as sole carbon sources. In effect, C. glutamicum manA is not only essential for growth on mannose but also important in glucose metabolism. A double deletion mutant of genes encoding glucose and fructose permeases (ptsG and ptsF, respectively) of the phosphoenolpyruvate-dependent phosphotransferase system (PTS) was not able to grow on mannose unlike the respective single deletion mutants with mannose utilization ability. A mutant deficient in ptsH, a general PTS gene, did not utilize mannose. These indicate that the glucose-PTS and fructose-PTS are responsible for mannose uptake in C. glutamicum. When cultured with a glucose and mannose mixture, mannose utilization of manA-overexpressing strain CRM1 was significantly higher than that of its wild-type counterpart, but with a strong preference for glucose. ptsF-overexpressing strain CRM2 co-utilized mannose and glucose, but at a total sugar consumption rate much lower than that of the wild-type strain and CRM1. Strain CRM3 overexpressing both manA and ptsF efficiently co-utilized mannose and glucose. Under oxygen-deprived conditions, high volumetric productivity of organic acids concomitant with the simultaneous consumption of the mixed sugars was achieved by the densely packed growth-arrested CRM3 cells.

  17. Genes involved in lactose catabolism and organic acid production during growth of Lactobacillus delbrueckii UFV H2b20 in skimmed milk.

    PubMed

    Do Carmo, A P; De Oliveira, M N V; Da Silva, D F; Castro, S B; Borges, A C; De Carvalho, A F; De Moraes, C A

    2012-03-01

    There are three main reasons for using lactic acid bacteria (LAB) as starter cultures in industrial food fermentation processes: food preservation due to lactic acid production; flavour formation due to a range of organic molecules derived from sugar, lipid and protein catabolism; and probiotic properties attributed to some strains of LAB, mainly of lactobacilli. The aim of this study was to identify some genes involved in lactose metabolism of the probiotic Lactobacillus delbrueckii UFV H2b20, and analyse its organic acid production during growth in skimmed milk. The following genes were identified, encoding the respective enzymes: ldh - lactate dehydrogenase, adhE - Ldb1707 acetaldehyde dehydrogenase, and ccpA-pepR1 - catabolite control protein A. It was observed that L. delbrueckii UFV H2b20 cultivated in different media has the unexpected ability to catabolyse galactose, and to produce high amounts of succinic acid, which was absent in the beginning, raising doubts about the subspecies in question. The phylogenetic analyses showed that this strain can be compared physiologically to L. delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis, which are able to degrade lactose and can grow in milk. L. delbrueckii UFV H2b20 sequences have grouped with L. delbrueckii subsp. bulgaricus ATCC 11842 and L. delbrueckii subsp. bulgaricus ATCC BAA-365, strengthening the classification of this probiotic strain in the NCFM group proposed by a previous study. Additionally, L. delbrueckii UFV H2b20 presented an evolutionary pattern closer to that of probiotic Lactobacillus acidophilus NCFM, corroborating the suggestion that this strain might be considered as a new and unusual subspecies among L. delbrueckii subspecies, the first one identified as a probiotic. In addition, its unusual ability to metabolise galactose, which was significantly consumed in the fermentation medium, might be exploited to produce low-browning probiotic Mozzarella cheeses, a desirable property

  18. Membrane-associated transcription factor peptidase, site-2 protease, antagonizes ABA signaling in Arabidopsis.

    PubMed

    Zhou, Shun-Fan; Sun, Le; Valdés, Ana Elisa; Engström, Peter; Song, Ze-Ting; Lu, Sun-Jie; Liu, Jian-Xiang

    2015-10-01

    Abscisic acid plays important roles in maintaining seed dormancy while gibberellins (GA) and other phytohormones antagonize ABA to promote germination. However, how ABA signaling is desensitized during the transition from dormancy to germination is still poorly understood. We functionally characterized the role of membrane-associated transcription factor peptidase, site-2 protease (S2P), in ABA signaling during seed germination in Arabidopsis. Genetic analysis showed that loss-of-function of S2P conferred high ABA sensitivity during seed germination, and expression of the activated form of membrane-associated transcription factor bZIP17, in which the transmembrane domain and endoplasmic reticulum (ER) lumen-facing C-terminus were deleted, in the S2P mutant rescued its ABA-sensitive phenotype. MYC and green fluorescent protein (GFP)-tagged bZIP17 were processed and translocated from the ER to the nucleus in response to ABA treatment. Furthermore, genes encoding negative regulators of ABA signaling, such as the transcription factor ATHB7 and its target genes HAB1, HAB2, HAI1 and AHG3, were up-regulated in seeds of the wild-type upon ABA treatment; this up-regulation was impaired in seeds of S2P mutants. Our results suggest that S2P desensitizes ABA signaling during seed germination through regulating the activation of the membrane-associated transcription factor bZIP17 and therefore controlling the expression level of genes encoding negative regulators of ABA signaling. PMID:25919792

  19. Catabolism of Hexuronides, Hexuronates, Aldonates, and Aldarates.

    PubMed

    Mandrand-Berthelot, M-A; Condemine, G; Hugouvieux-Cotte-Pattat, N

    2004-12-01

    Following elucidation of the regulation of the lactose operon in Escherichia coli, studies on the metabolism of many sugars were initiated in the early 1960s. The catabolic pathways of D-gluconate and of the two hexuronates, D-glucuronate and D-galacturonate, were investigated. The post genomic era has renewed interest in the study of these sugar acids and allowed the complete characterization of the D-gluconate pathway and the discovery of the catabolic pathways for L-idonate, D-glucarate, galactarate, and ketogluconates. Among the various sugar acids that are utilized as sole carbon and energy sources to support growth of E. coli, galacturonate, glucuronate, and gluconate were shown to play an important role in the colonization of the mammalian large intestine. In the case of sugar acid degradation, the regulators often mediate negative control and are inactivated by interaction with a specific inducer, which is either the substrate or an intermediate of the catabolism. These regulators coordinate the synthesis of all the proteins involved in the same pathway and, in some cases, exert crosspathway control between related catabolic pathways. This is particularly well illustrated in the case of hexuronide and hexuronate catabolism. The structural genes encoding the different steps of hexuronate catabolism were identified by analysis of numerous mutants affected for growth with galacturonate or glucuronate. E. coli is able to use the diacid sugars D-glucarate and galactarate (an achiral compound) as sole carbon source for growth. Pyruvate and 2-phosphoglycerate are the final products of the D-glucarate/galactarate catabolism. PMID:26443361

  20. Function of ABA in Stomatal Defense against Biotic and Drought Stresses.

    PubMed

    Lim, Chae Woo; Baek, Woonhee; Jung, Jangho; Kim, Jung-Hyun; Lee, Sung Chul

    2015-01-01

    The plant hormone abscisic acid (ABA) regulates many key processes involved in plant development and adaptation to biotic and abiotic stresses. Under stress conditions, plants synthesize ABA in various organs and initiate defense mechanisms, such as the regulation of stomatal aperture and expression of defense-related genes conferring resistance to environmental stresses. The regulation of stomatal opening and closure is important to pathogen defense and control of transpirational water loss. Recent studies using a combination of approaches, including genetics, physiology, and molecular biology, have contributed considerably to our understanding of ABA signal transduction. A number of proteins associated with ABA signaling and responses--especially ABA receptors--have been identified. ABA signal transduction initiates signal perception by ABA receptors and transfer via downstream proteins, including protein kinases and phosphatases. In the present review, we focus on the function of ABA in stomatal defense against biotic and abiotic stresses, through analysis of each ABA signal component and the relationships of these components in the complex network of interactions. In particular, two ABA signal pathway models in response to biotic and abiotic stress were proposed, from stress signaling to stomatal closure, involving the pyrabactin resistance (PYR)/PYR-like (PYL) or regulatory component of ABA receptor (RCAR) family proteins, 2C-type protein phosphatases, and SnRK2-type protein kinases. PMID:26154766

  1. Arabidopsis PYL8 Plays an Important Role for ABA Signaling and Drought Stress Responses.

    PubMed

    Lim, Chae Woo; Baek, Woonhee; Han, Sang-Wook; Lee, Sung Chul

    2013-12-01

    Plants are frequently exposed to numerous environmental stresses such as dehydration and high salinity, and have developed elaborate mechanisms to counteract the deleterious effects of stress. The phytohormone abscisic acid (ABA) plays a critical role as an integrator of plant responses to water-limited condition to activate ABA signal transduction pathway. Although perception of ABA has been suggested to be important, the function of each ABA receptor remains elusive in dehydration condition. Here, we show that ABA receptor, pyrabactin resistance-like protein 8 (PYL8), functions in dehydration conditions. Transgenic plants overexpressing PYL8 exhibited hypersensitive phenotype to ABA in seed germination, seedling growth and establishment. We found that hypersensitivity to ABA of transgenic plants results in high degrees of stomatal closure in response to ABA leading to low transpiration rates and ultimately more vulnerable to drought than the wild-type plants. In addition, high expression of ABA maker genes also contributes to altered drought tolerance phenotype. Overall, this work emphasizes the importance of ABA signaling by ABA receptor in stomata during defense response to drought stress. PMID:25288979

  2. Increased ABA sensitivity results in higher seed dormancy in soft white spring wheat cultivar 'Zak'.

    PubMed

    Schramm, Elizabeth C; Nelson, Sven K; Kidwell, Kimberlee K; Steber, Camille M

    2013-03-01

    As a strategy to increase the seed dormancy of soft white wheat, mutants with increased sensitivity to the plant hormone abscisic acid (ABA) were identified in mutagenized grain of soft white spring wheat "Zak". Lack of seed dormancy is correlated with increased susceptibility to preharvest sprouting in wheat, especially those cultivars with white kernels. ABA induces seed dormancy during embryo maturation and inhibits the germination of mature grain. Three mutant lines called Zak ERA8, Zak ERA19A, and Zak ERA19B (Zak ENHANCED RESPONSE to ABA) were recovered based on failure to germinate on 5 μM ABA. All three mutants resulted in increased ABA sensitivity over a wide range of concentrations such that a phenotype can be detected at very low ABA concentrations. Wheat loses sensitivity to ABA inhibition of germination with extended periods of dry after-ripening. All three mutants recovered required more time to after-ripen sufficiently to germinate in the absence of ABA and to lose sensitivity to 5 μM ABA. However, an increase in ABA sensitivity could be detected after as long as 3 years of after-ripening using high ABA concentrations. The Zak ERA8 line showed the strongest phenotype and segregated as a single semi-dominant mutation. This mutation resulted in no obvious decrease in yield and is a good candidate gene for breeding preharvest sprouting tolerance. PMID:23212773

  3. Function of ABA in Stomatal Defense against Biotic and Drought Stresses

    PubMed Central

    Lim, Chae Woo; Baek, Woonhee; Jung, Jangho; Kim, Jung-Hyun; Lee, Sung Chul

    2015-01-01

    The plant hormone abscisic acid (ABA) regulates many key processes involved in plant development and adaptation to biotic and abiotic stresses. Under stress conditions, plants synthesize ABA in various organs and initiate defense mechanisms, such as the regulation of stomatal aperture and expression of defense-related genes conferring resistance to environmental stresses. The regulation of stomatal opening and closure is important to pathogen defense and control of transpirational water loss. Recent studies using a combination of approaches, including genetics, physiology, and molecular biology, have contributed considerably to our understanding of ABA signal transduction. A number of proteins associated with ABA signaling and responses—especially ABA receptors—have been identified. ABA signal transduction initiates signal perception by ABA receptors and transfer via downstream proteins, including protein kinases and phosphatases. In the present review, we focus on the function of ABA in stomatal defense against biotic and abiotic stresses, through analysis of each ABA signal component and the relationships of these components in the complex network of interactions. In particular, two ABA signal pathway models in response to biotic and abiotic stress were proposed, from stress signaling to stomatal closure, involving the pyrabactin resistance (PYR)/PYR-like (PYL) or regulatory component of ABA receptor (RCAR) family proteins, 2C-type protein phosphatases, and SnRK2-type protein kinases. PMID:26154766

  4. The unique mode of action of a divergent member of the ABA-receptor protein family in ABA and stress signaling

    PubMed Central

    Zhao, Yang; Chan, Zhulong; Xing, Lu; Liu, Xiaodong; Hou, Yueh-Ju; Chinnusamy, Viswanathan; Wang, Pengcheng; Duan, Chengguo; Zhu, Jian-Kang

    2013-01-01

    Proteins in the PYR/PYL/RCAR family (PYLs) are known as receptors for the phytohormone ABA. Upon ABA binding, PYL adopts a conformation that allows it to interact with and inhibit clade A protein phosphatase 2Cs (PP2Cs), which are known as the co-receptors for ABA. Inhibition of the PP2Cs then leads to the activation of the SnRK2 family protein kinases that phosphorylate and activate downstream effectors in ABA response pathways. The PYL family has 14 members in Arabidopsis, 13 of which have been demonstrated to function as ABA receptors. The function of PYL13, a divergent member of the family, has been enigmatic. We report here that PYL13 differs from the other PYLs in three key residues that affect ABA perception, and mutations in these three residues can convert PYL13 into a partially functional ABA receptor. Transgenic plants overexpressing PYL13 show increased ABA sensitivity in seed germination and postgermination seedling establishment as well as decreased stomatal conductance, increased water-use efficiency, accelerated stress-responsive gene expression, and enhanced drought resistance. pyl13 mutant plants are less sensitive to ABA inhibition of postgermination seedling establishment. PYL13 interacts with and inhibits some members of clade A PP2Cs (PP2CA in particular) in an ABA-independent manner. PYL13 also interacts with the other PYLs and antagonizes their function as ABA receptors. Our results show that PYL13 is not an ABA receptor but can modulate the ABA pathway by interacting with and inhibiting both the PYL receptors and the PP2C co-receptors. PMID:24189045

  5. Bioinformatic evaluation of L-arginine catabolic pathways in 24 cyanobacteria and transcriptional analysis of genes encoding enzymes of L-arginine catabolism in the cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Schriek, Sarah; Rückert, Christian; Staiger, Dorothee; Pistorius, Elfriede K; Michel, Klaus-Peter

    2007-01-01

    Background So far very limited knowledge exists on L-arginine catabolism in cyanobacteria, although six major L-arginine-degrading pathways have been described for prokaryotes. Thus, we have performed a bioinformatic analysis of possible L-arginine-degrading pathways in cyanobacteria. Further, we chose Synechocystis sp. PCC 6803 for a more detailed bioinformatic analysis and for validation of the bioinformatic predictions on L-arginine catabolism with a transcript analysis. Results We have evaluated 24 cyanobacterial genomes of freshwater or marine strains for the presence of putative L-arginine-degrading enzymes. We identified an L-arginine decarboxylase pathway in all 24 strains. In addition, cyanobacteria have one or two further pathways representing either an arginase pathway or L-arginine deiminase pathway or an L-arginine oxidase/dehydrogenase pathway. An L-arginine amidinotransferase pathway as a major L-arginine-degrading pathway is not likely but can not be entirely excluded. A rather unusual finding was that the cyanobacterial L-arginine deiminases are substantially larger than the enzymes in non-photosynthetic bacteria and that they are membrane-bound. A more detailed bioinformatic analysis of Synechocystis sp. PCC 6803 revealed that three different L-arginine-degrading pathways may in principle be functional in this cyanobacterium. These are (i) an L-arginine decarboxylase pathway, (ii) an L-arginine deiminase pathway, and (iii) an L-arginine oxidase/dehydrogenase pathway. A transcript analysis of cells grown either with nitrate or L-arginine as sole N-source and with an illumination of 50 μmol photons m-2 s-1 showed that the transcripts for the first enzyme(s) of all three pathways were present, but that the transcript levels for the L-arginine deiminase and the L-arginine oxidase/dehydrogenase were substantially higher than that of the three isoenzymes of L-arginine decarboxylase. Conclusion The evaluation of 24 cyanobacterial genomes revealed that

  6. Implication for the regulation of catabolism drawn from the single insulin-like growth factor binding domain protein (SIBD) gene in the mud crab, Scylla paramamosain.

    PubMed

    Huang, Xiaoshuai; Ye, Haihui; Huang, Huiyang; Liu, An; Feng, Biyun

    2015-05-15

    Insulin-like growth factor (IGF) signaling system holds a central position in regulating growth and metabolism in vertebrates. As critical components of this system, the IGF-binding proteins (IGFBPs) play important roles in regulating the biological activities of IGFs. Recently, the single IGF-binding domain protein (SIBD) was identified in invertebrates and its sequence was highly homologous with the N-terminal domain of IGFBP. In view of the possible role as counterparts of vertebrate IGFBPs, SIBDs have attracted the ever-increasing attention. This study reports the identification of a 1284bp SIBD gene (Sp-SIBD) from a member of commercially important family of Portunidae. The tissue distribution analysis showed that Sp-SIBD was mainly expressed in the nervous tissues and hepatopancreas. RNA in situ hybridization analysis showed that the positive signals were predominantly distributed in the secretory cells of the hepatopancreas. Subsequently, we examined the effects of various stresses, including hyperosmotic stress, hyperthermia, activated stress and fasting, on glucose levels in the hemolymph and Sp-SIBD expressions in the hepatopancreas. Interestingly, we found that Sp-SIBD expression was strongly up-regulated in response to these catabolic circumstances. Given the previous findings of insulin-like peptides (ILPs) in invertebrates, we speculate that invertebrate ILPs and SIBDs promise to serve as a pair of counterparts of IGFs and IGFBPs from vertebrate species respectively. In this context, the combined results suggested, by analogy with IGFBP 1 from vertebrates, for the first time that SIBD might play a key physiological role by sequestering ILPs to inhibit energy-expensive growth until conditions are more favorable.

  7. EIN3 and ORE1 Accelerate Degreening during Ethylene-Mediated Leaf Senescence by Directly Activating Chlorophyll Catabolic Genes in Arabidopsis

    PubMed Central

    Qiu, Kai; Li, Zhongpeng; Yang, Zhen; Chen, Junyi; Wu, Shouxin; Zhu, Xiaoyu; Gao, Shan; Gao, Jiong; Ren, Guodong; Kuai, Benke; Zhou, Xin

    2015-01-01

    Degreening, caused by chlorophyll degradation, is the most obvious symptom of senescing leaves. Chlorophyll degradation can be triggered by endogenous and environmental cues, and ethylene is one of the major inducers. ETHYLENE INSENSITIVE3 (EIN3) is a key transcription factor in the ethylene signaling pathway. It was previously reported that EIN3, miR164, and a NAC (NAM, ATAF, and CUC) transcription factor ORE1/NAC2 constitute a regulatory network mediating leaf senescence. However, how this network regulates chlorophyll degradation at molecular level is not yet elucidated. Here we report a feed-forward regulation of chlorophyll degradation that involves EIN3, ORE1, and chlorophyll catabolic genes (CCGs). Gene expression analysis showed that the induction of three major CCGs, NYE1, NYC1 and PAO, by ethylene was largely repressed in ein3 eil1 double mutant. Dual-luciferase assay revealed that EIN3 significantly enhanced the promoter activity of NYE1, NYC1 and PAO in Arabidopsis protoplasts. Furthermore, Electrophoretic mobility shift assay (EMSA) indicated that EIN3 could directly bind to NYE1, NYC1 and PAO promoters. These results reveal that EIN3 functions as a positive regulator of CCG expression during ethylene-mediated chlorophyll degradation. Interestingly, ORE1, a senescence regulator which is a downstream target of EIN3, could also activate the expression of NYE1, NYC1 and PAO by directly binding to their promoters in EMSA and chromatin immunoprecipitation (ChIP) assays. In addition, EIN3 and ORE1 promoted NYE1 and NYC1 transcriptions in an additive manner. These results suggest that ORE1 is also involved in the direct regulation of CCG transcription. Moreover, ORE1 activated the expression of ACS2, a major ethylene biosynthesis gene, and subsequently promoted ethylene production. Collectively, our work reveals that EIN3, ORE1 and CCGs constitute a coherent feed-forward loop involving in the robust regulation of ethylene-mediated chlorophyll degradation

  8. Importance of ABA homeostasis under terminal drought stress in regulating grain filling events.

    PubMed

    Govind, Geetha; Seiler, Christiane; Wobus, Ulrich; Sreenivasulu, Nese

    2011-08-01

    Recent studies suggest that abscisic acid (ABA) at its basal level plays an important role during seed set and grain filling events. Under drought stress ABA levels were found to be significantly enhanced in the developing seed. Until now we lack an understanding of (A) ABA homeostasis in developing seeds under terminal drought and (B) the interactive role of ABA in regulating the starch biosynthesis pathway in developing grains under terminal drought. We have recently reported the possible regulation of ABA homeostasis in source (flag leaf) and sink (developing grains) tissues under post-anthesis drought stress in barley and concluded that significantly enhanced ABA levels in developing grains are due to strong activation of the ABA deconjugation pathway and fine regulation of the ABA biosynthesis-degradation pathway.1 Additionally, we provided evidence for the role of ABA in differential regulation of starch biosynthesis genes and a significant upregulation of starch degradation beta amylase genes under drought, i.e. ABA not only influences the rate of starch accumulation but also starch quality.

  9. Type One Protein Phosphatase 1 and Its Regulatory Protein Inhibitor 2 Negatively Regulate ABA Signaling

    PubMed Central

    Zhao, Yang; Xie, Shaojun; Batelli, Giorgia; Wang, Bangshing; Duan, Cheng-Guo; Wang, Xingang; Xing, Lu; Lei, Mingguang; Yan, Jun; Zhu, Xiaohong; Zhu, Jian-Kang

    2016-01-01

    The phytohormone abscisic acid (ABA) regulates plant growth, development and responses to biotic and abiotic stresses. The core ABA signaling pathway consists of three major components: ABA receptor (PYR1/PYLs), type 2C Protein Phosphatase (PP2C) and SNF1-related protein kinase 2 (SnRK2). Nevertheless, the complexity of ABA signaling remains to be explored. To uncover new components of ABA signal transduction pathways, we performed a yeast two-hybrid screen for SnRK2-interacting proteins. We found that Type One Protein Phosphatase 1 (TOPP1) and its regulatory protein, At Inhibitor-2 (AtI-2), physically interact with SnRK2s and also with PYLs. TOPP1 inhibited the kinase activity of SnRK2.6, and this inhibition could be enhanced by AtI-2. Transactivation assays showed that TOPP1 and AtI-2 negatively regulated the SnRK2.2/3/6-mediated activation of the ABA responsive reporter gene RD29B, supporting a negative role of TOPP1 and AtI-2 in ABA signaling. Consistent with these findings, topp1 and ati-2 mutant plants displayed hypersensitivities to ABA and salt treatments, and transcriptome analysis of TOPP1 and AtI-2 knockout plants revealed an increased expression of multiple ABA-responsive genes in the mutants. Taken together, our results uncover TOPP1 and AtI-2 as negative regulators of ABA signaling. PMID:26943172

  10. Conformationally restricted 3'-modified ABA analogs for controlling ABA receptors.

    PubMed

    Takeuchi, Jun; Ohnishi, Toshiyuki; Okamoto, Masanori; Todoroki, Yasushi

    2015-04-14

    The physiological functions of abscisic acid (ABA) are regulated by a signal transduction pathway involving cytosolic ABA receptors, which include 14 PYR/PYL/RCAR (PYL) proteins in Arabidopsis. The development of a PYL antagonist could be a valuable tool to improve our understanding of the roles of ABA. We previously developed 3'-hexylsulfanyl-ABA (AS6), whose S-hexyl chain blocks protein phosphatase 2C (PP2C) binding by steric hindrance. This finding not only validated our structure-based approach to the design of a PYL antagonist, but also provided a basis for the development of a more potent or subclass/subtype selective PYL antagonist. In the present study, we synthesized a conformationally restricted analog of AS6, namely propenyl-ABA with an O-butyl chain (PAO4), to improve the affinity for PYL proteins by reducing the entropic penalty for binding to the receptors. In seed germination assays, (+)-PAO4 was a slightly stronger antagonist than AS6 in Arabidopsis and a significantly stronger antagonist in lettuce. Analysis of the thermodynamic parameters associated with the formation of the Arabidopsis PYL-(+)-PAO4 complex revealed that (+)-PAO4 binds more strongly to PYL5 than AS6 owing to an entropic advantage. In PP2C assays, this enhancement effect was observed only for the monomeric PYL subclass containing PYL5, suggesting that (+)-PAO4 is more effective than AS6 in physiological events involving monomeric PYL proteins as ABA receptors. PMID:25758810

  11. Monitoring in Situ Anaerobic Alkylbenzene Biodegradation Based on Mass Spectrometric Detection of Unique Metabolites or Real-Time PCR Detection of a Catabolic Gene

    NASA Astrophysics Data System (ADS)

    Beller, H. R.; Kane, S. R.

    2002-12-01

    anaerobic methylbenzene-degrading bacteria in aquifer sediment. The method targets a catabolic gene (bssA) associated with the first step of anaerobic toluene and xylene degradation. The method proved to be sensitive (detection limit ca. 5 gene copies) and had a linear range of > 7 orders of magnitude. In microcosm experiments involving toluene degradation under denitrifying conditions, population trends were generally consistent with observed toluene degradation activity. In the microcosms with the most rapid toluene degradation, numbers of bssA copies increased 100- to 1000-fold over the first four days of incubation, during which time most of the toluene had been consumed. These results were supported by slot blot analyses with unamplified DNA and by cloning and sequencing of putative bssA amplicons.

  12. ABA-HYPERSENSITIVE BTB/POZ PROTEIN 1 functions as a negative regulator in ABA-mediated inhibition of germination in Arabidopsis.

    PubMed

    Kim, Hani; Kim, Soon-Hee; Seo, Dong Hye; Chung, Sunglan; Kim, Sang-Woo; Lee, Jeong-Soo; Kim, Woo Taek; Lee, Jae-Hoon

    2016-02-01

    To elucidate the contribution of CRL3-ABA-mediated responses, we attempted to find CRL3 substrate receptors involved in ABA signaling. One gene named ABA-HYPERSENSITIVE BTB/POZ PROTEIN 1 (AHT1) was upregulated more than 2.5 times by ABA, and its coding region possessed a BTB/POZ domain, which is the common feature of CRL3 substrate receptors. Loss of AHT1 led to retardation of the germination process, not inhibition of root growth. AHT1 transcripts also increased in response to mannitol, NaCl and drought treatments at the seedling stage and in dry seeds. High expression of AHT1 in dry seeds was inhibited by the defect of ABA signaling components such as ABI1, ABI3 and SRKs indicating that the expression of AHT1 is dependent on ABA signaling. Among bZIP transcription factors participating in ABA signaling, the losses of ABI5/DPBF1, AREB1/ABF2, EEL/DPBF4 and DPBF2/bZIP67 resulted in reduced AHT1 expression, showing that these transcription factors play a positive role in ABA-induced AHT1 expression. While loss of AHT1 did not affect the expression pattern of NCED3, ABI2, SRKs and AREB/ABF genes, it led to hyperinduction of ABI5/DPBF genes such as ABI5/DPBF1, EEL/DPBF4 and AREB3/DPBF3, which are mainly involved in seed development and germination, as well as ABA-inducible genes transactivated by ABI5. Overall, these findings indicate that AHT1 negatively regulates ABA-mediated inhibition of germination, possibly by repressing the expression of a subset of ABI5/DPBF subfamily genes, and that AHT1 may be regulated by a negative feedback process through its linkage with a part of ABI5/DPBF proteins. PMID:26667153

  13. Comprehensive Analysis of ABA Effects on Ethylene Biosynthesis and Signaling during Tomato Fruit Ripening

    PubMed Central

    Bu, Jianwen; Jiang, Yuanyuan; Khan, Zia Ullah; Luo, Zisheng; Mao, Linchun; Ying, Tiejin

    2016-01-01

    ABA has been widely acknowledged to regulate ethylene biosynthesis and signaling during fruit ripening, but the molecular mechanism underlying the interaction between these two hormones are largely unexplored. In the present study, exogenous ABA treatment obviously promoted fruit ripening as well as ethylene emission, whereas NDGA (Nordihydroguaiaretic acid, an inhibitor of ABA biosynthesis) application showed the opposite biological effects. Combined RNA-seq with time-course RT-PCR analysis, our study not only helped to illustrate how ABA regulated itself at the transcription level, but also revealed that ABA can facilitate ethylene production and response probably by regulating some crucial genes such as LeACS4, LeACO1, GR and LeETR6. In addition, investigation on the fruits treated with 1-MCP immediately after ABA exposure revealed that ethylene might be essential for the induction of ABA biosynthesis and signaling at the onset of fruit ripening. Furthermore, some specific transcription factors (TFs) known as regulators of ethylene synthesis and sensibility (e.g. MADS-RIN, TAGL1, CNR and NOR) were also observed to be ABA responsive, which implied that ABA influenced ethylene action possibly through the regulation of these TFs expression. Our comprehensive physiological and molecular-level analysis shed light on the mechanism of cross-talk between ABA and ethylene during the process of tomato fruit ripening. PMID:27100326

  14. Abscisic acid (ABA) sensitivity regulates desiccation tolerance in germinated Arabidopsis seeds.

    PubMed

    Maia, Julio; Dekkers, Bas J W; Dolle, Miranda J; Ligterink, Wilco; Hilhorst, Henk W M

    2014-07-01

    During germination, orthodox seeds lose their desiccation tolerance (DT) and become sensitive to extreme drying. Yet, DT can be rescued, in a well-defined developmental window, by the application of a mild osmotic stress before dehydration. A role for abscisic acid (ABA) has been implicated in this stress response and in DT re-establishment. However, the path from the sensing of an osmotic cue and its signaling to DT re-establishment is still largely unknown. Analyses of DT, ABA sensitivity, ABA content and gene expression were performed in desiccation-sensitive (DS) and desiccation-tolerant Arabidopsis thaliana seeds. Furthermore, loss and re-establishment of DT in germinated Arabidopsis seeds was studied in ABA-deficient and ABA-insensitive mutants. We demonstrate that the developmental window in which DT can be re-established correlates strongly with the window in which ABA sensitivity is still present. Using ABA biosynthesis and signaling mutants, we show that this hormone plays a key role in DT re-establishment. Surprisingly, re-establishment of DT depends on the modulation of ABA sensitivity rather than enhanced ABA content. In addition, the evaluation of several ABA-insensitive mutants, which can still produce normal desiccation-tolerant seeds, but are impaired in the re-establishment of DT, shows that the acquisition of DT during seed development is genetically different from its re-establishment during germination.

  15. Essential role of tissue-specific proline synthesis and catabolism in growth and redox balance at low water potential.

    PubMed

    Sharma, Sandeep; Villamor, Joji Grace; Verslues, Paul E

    2011-09-01

    To better define the still unclear role of proline (Pro) metabolism in drought resistance, we analyzed Arabidopsis (Arabidopsis thaliana) Δ(1)-pyrroline-5-carboxylate synthetase1 (p5cs1) mutants deficient in stress-induced Pro synthesis as well as proline dehydrogenase (pdh1) mutants blocked in Pro catabolism and found that both Pro synthesis and catabolism were required for optimal growth at low water potential (ψ(w)). The abscisic acid (ABA)-deficient mutant aba2-1 had similar reduction in root elongation as p5cs1 and p5cs1/aba2-1 double mutants. However, the reduced growth of aba2-1 but not p5cs1/aba2-1 could be complemented by exogenous ABA, indicating that Pro metabolism was required for ABA-mediated growth protection at low ψ(w). PDH1 maintained high expression in the root apex and shoot meristem at low ψ(w) rather than being repressed, as in the bulk of the shoot tissue. This, plus a reduced oxygen consumption and buildup of Pro in the root apex of pdh1-2, indicated that active Pro catabolism was needed to sustain growth at low ψ(w). Conversely, P5CS1 expression was most highly induced in shoot tissue. Both p5cs1-4 and pdh1-2 had a more reduced NADP/NADPH ratio than the wild type at low ψ(w). These results indicate a new model of Pro metabolism at low ψ(w) whereby Pro synthesis in the photosynthetic tissue regenerates NADP while Pro catabolism in meristematic and expanding cells is needed to sustain growth. Tissue-specific differences in Pro metabolism and function in maintaining a favorable NADP/NADPH ratio are relevant to understanding metabolic adaptations to drought and efforts to enhance drought resistance.

  16. Transcriptional regulation of SlPYL, SlPP2C, and SlSnRK2 gene families encoding ABA signal core components during tomato fruit development and drought stress

    PubMed Central

    Sun, Liang; Wang, Yan-Ping; Chen, Pei; Ren, Jie; Ji, Kai; Li, Qian; Li, Ping; Dai, Sheng-Jie; Leng, Ping

    2011-01-01

    In order to characterize the potential transcriptional regulation of core components of abscisic acid (ABA) signal transduction in tomato fruit development and drought stress, eight SlPYL (ABA receptor), seven SlPP2C (type 2C protein phosphatase), and eight SlSnRK2 (subfamily 2 of SNF1-related kinases) full-length cDNA sequences were isolated from the tomato nucleotide database of NCBI GenBank. All SlPYL, SlPP2C, and SlSnRK2 genes obtained are homologous to Arabidopsis AtPYL, AtPP2C, and AtSnRK2 genes, respectively. Based on phylogenetic analysis, SlPYLs and SlSnRK2s were clustered into three subfamilies/subclasses, and all SlPP2Cs belonged to PP2C group A. Within the SlPYL gene family, SlPYL1, SlPYL2, SlPYL3, and SlPYL6 were the major genes involved in the regulation of fruit development. Among them, SlPYL1 and SlPYL2 were expressed at high levels throughout the process of fruit development and ripening; SlPYL3 was strongly expressed at the immature green (IM) and mature green (MG) stages, while SlPYL6 was expressed strongly at the IM and red ripe (RR) stages. Within the SlPP2C gene family, the expression of SlPP2C, SlPP2C3, and SlPP2C4 increased after the MG stage; SlPP2C1 and SlPP2C5 peaked at the B3 stage, while SlPP2C2 and SlPP2C6 changed little during fruit development. Within the SlSnRK2 gene family, the expression of SlSnRK2.2, SlSnRK2.3, SlSnRK2.4, and SlSnRK2C was higher than that of other members during fruit development. Additionally, most SlPYL genes were down-regulated, while most SlPP2C and SlSnRK2 genes were up-regulated by dehydration in tomato leaf. PMID:21873532

  17. Melatonin mediates the regulation of ABA metabolism, free-radical scavenging, and stomatal behaviour in two Malus species under drought stress.

    PubMed

    Li, Chao; Tan, Dun-Xian; Liang, Dong; Chang, Cong; Jia, Dongfeng; Ma, Fengwang

    2015-02-01

    Melatonin pre-treatment significantly increases the tolerance of both drought-tolerant Malus prunifolia and drought-sensitive M. hupehensis plants. Its beneficial effects include better water conservation in leaves, less electrolyte leakage, steady chlorophyll contents, and greater photosynthetic performance under stress conditions. Melatonin selectively down-regulates MdNCED3, an abscisic acid (ABA) synthesis gene, and up-regulates its catabolic genes, MdCYP707A1 and MdCYP707A2, thereby reducing ABA contents in drought-stressed plants. Melatonin also directly scavenges H2O2 and enhances the activities of antioxidant enzymes to detoxify H2O2 indirectly. These two mechanisms work synergistically to improve the functions of stomata, i.e. causing them to re-open. Plants can effectively regulate their water balance under drought conditions by up-regulating the expression of melatonin synthesis genes MdTDC1, MdAANAT2, MdT5H4, and MdASMT1. Therefore, inducing melatonin production is an important mechanism by which plants can counteract the influence of this abiotic stressor. PMID:25481689

  18. Melatonin mediates the regulation of ABA metabolism, free-radical scavenging, and stomatal behaviour in two Malus species under drought stress.

    PubMed

    Li, Chao; Tan, Dun-Xian; Liang, Dong; Chang, Cong; Jia, Dongfeng; Ma, Fengwang

    2015-02-01

    Melatonin pre-treatment significantly increases the tolerance of both drought-tolerant Malus prunifolia and drought-sensitive M. hupehensis plants. Its beneficial effects include better water conservation in leaves, less electrolyte leakage, steady chlorophyll contents, and greater photosynthetic performance under stress conditions. Melatonin selectively down-regulates MdNCED3, an abscisic acid (ABA) synthesis gene, and up-regulates its catabolic genes, MdCYP707A1 and MdCYP707A2, thereby reducing ABA contents in drought-stressed plants. Melatonin also directly scavenges H2O2 and enhances the activities of antioxidant enzymes to detoxify H2O2 indirectly. These two mechanisms work synergistically to improve the functions of stomata, i.e. causing them to re-open. Plants can effectively regulate their water balance under drought conditions by up-regulating the expression of melatonin synthesis genes MdTDC1, MdAANAT2, MdT5H4, and MdASMT1. Therefore, inducing melatonin production is an important mechanism by which plants can counteract the influence of this abiotic stressor.

  19. The Citrus ABA signalosome: identification and transcriptional regulation during sweet orange fruit ripening and leaf dehydration

    PubMed Central

    Rodrigo, María J.

    2012-01-01

    The abscisic acid (ABA) signalling core in plants include the cytosolic ABA receptors (PYR/PYL/RCARs), the clade-A type 2C protein phosphatases (PP2CAs), and the subclass III SNF1-related protein kinases 2 (SnRK2s). The aim of this work was to identify these ABA perception system components in sweet orange and to determine the influence of endogenous ABA on their transcriptional regulation during fruit development and ripening, taking advantage of the comparative analysis between a wild-type and a fruit-specific ABA-deficient mutant. Transcriptional changes in the ABA signalosome during leaf dehydration were also studied. Six PYR/PYL/RCAR, five PP2CA, and two subclass III SnRK2 genes, homologous to those of Arabidopsis, were identified in the Citrus genome. The high degree of homology and conserved motifs for protein folding and for functional activity suggested that these Citrus proteins are bona fide core elements of ABA perception in orange. Opposite expression patterns of CsPYL4 and CsPYL5 and ABA accumulation were found during ripening, although there were few differences between varieties. In contrast, changes in expression of CsPP2CA genes during ripening paralleled those of ABA content and agreeed with the relevant differences between wild-type and mutant fruit transcript accumulation. CsSnRK2 gene expression continuously decreased with ripening and no remarkable differences were found between cultivars. Overall, dehydration had a minor effect on CsPYR/PYL/RCAR and CsSnRK2 expression in vegetative tissue, whereas CsABI1, CsAHG1, and CsAHG3 were highly induced by water stress. The global results suggest that responsiveness to ABA changes during citrus fruit ripening, and leaf dehydration was higher in the CsPP2CA gene negative regulators than in the other ABA signalosome components. PMID:22888124

  20. The Citrus ABA signalosome: identification and transcriptional regulation during sweet orange fruit ripening and leaf dehydration.

    PubMed

    Romero, Paco; Lafuente, María T; Rodrigo, María J

    2012-08-01

    The abscisic acid (ABA) signalling core in plants include the cytosolic ABA receptors (PYR/PYL/RCARs), the clade-A type 2C protein phosphatases (PP2CAs), and the subclass III SNF1-related protein kinases 2 (SnRK2s). The aim of this work was to identify these ABA perception system components in sweet orange and to determine the influence of endogenous ABA on their transcriptional regulation during fruit development and ripening, taking advantage of the comparative analysis between a wild-type and a fruit-specific ABA-deficient mutant. Transcriptional changes in the ABA signalosome during leaf dehydration were also studied. Six PYR/PYL/RCAR, five PP2CA, and two subclass III SnRK2 genes, homologous to those of Arabidopsis, were identified in the Citrus genome. The high degree of homology and conserved motifs for protein folding and for functional activity suggested that these Citrus proteins are bona fide core elements of ABA perception in orange. Opposite expression patterns of CsPYL4 and CsPYL5 and ABA accumulation were found during ripening, although there were few differences between varieties. In contrast, changes in expression of CsPP2CA genes during ripening paralleled those of ABA content and agreeed with the relevant differences between wild-type and mutant fruit transcript accumulation. CsSnRK2 gene expression continuously decreased with ripening and no remarkable differences were found between cultivars. Overall, dehydration had a minor effect on CsPYR/PYL/RCAR and CsSnRK2 expression in vegetative tissue, whereas CsABI1, CsAHG1, and CsAHG3 were highly induced by water stress. The global results suggest that responsiveness to ABA changes during citrus fruit ripening, and leaf dehydration was higher in the CsPP2CA gene negative regulators than in the other ABA signalosome components. PMID:22888124

  1. Bacterial Catabolism of Dimethylsulfoniopropionate (DMSP)

    PubMed Central

    Reisch, Chris R.; Moran, Mary Ann; Whitman, William B.

    2011-01-01

    Dimethylsulfoniopropionate (DMSP) is a metabolite produced primarily by marine phytoplankton and is the main precursor to the climatically important gas dimethylsulfide (DMS). DMS is released upon bacterial catabolism of DMSP, but it is not the only possible fate of DMSP sulfur. An alternative demethylation/demethiolation pathway results in the eventual release of methanethiol, a highly reactive volatile sulfur compound that contributes little to the atmospheric sulfur flux. The activity of these pathways control the natural flux of sulfur released to the atmosphere. Although these biochemical pathways and the factors that regulate them are of great interest, they are poorly understood. Only recently have some of the genes and pathways responsible for DMSP catabolism been elucidated. Thus far, six different enzymes have been identified that catalyze the cleavage of DMSP, resulting in the release of DMS. In addition, five of these enzymes appear to produce acrylate, while one produces 3-hydroxypropionate. In contrast, only one enzyme, designated DmdA, has been identified that catalyzes the demethylation reaction producing methylmercaptopropionate (MMPA). The metabolism of MMPA is performed by a series of three coenzyme-A mediated reactions catalyzed by DmdB, DmdC, and DmdD. Interestingly, Candidatus Pelagibacter ubique, a member of the SAR11 clade of Alphaproteobacteria that is highly abundant in marine surface waters, possessed functional DmdA, DmdB, and DmdC enzymes. Microbially mediated transformations of both DMS and methanethiol are also possible, although many of the biochemical and molecular genetic details are still unknown. This review will focus on the recent discoveries in the biochemical pathways that mineralize and assimilate DMSP carbon and sulfur, as well as the areas for which a comprehensive understanding is still lacking. PMID:21886640

  2. Ethylene-dependent/ethylene-independent ABA regulation of tomato plants colonized by arbuscular mycorrhiza fungi.

    PubMed

    Martín-Rodríguez, José Ángel; León-Morcillo, Rafael; Vierheilig, Horst; Ocampo, Juan Antonio; Ludwig-Müller, Jutta; García-Garrido, José Manuel

    2011-04-01

    We investigated the relationship between ABA and ethylene regulating the formation of the arbuscular mycorrhiza (AM) symbiosis in tomato (Solanum lycopersicum) plants and tried to define the specific roles played by each of these phytohormones in the mycorrhization process. We analysed the impact of ABA biosynthesis inhibition on mycorrhization by Glomus intraradices in transgenic tomato plants with an altered ethylene pathway. We also studied the effects on mycorrhization in sitiens plants treated with the aminoethoxyvinyl glycine hydrochloride (AVG) ethylene biosynthesis inhibitor and supplemented with ABA. In addition, the expression of plant and fungal genes involved in the mycorrhization process was studied. ABA biosynthesis inhibition qualitatively altered the parameters of mycorrhization in accordance with the plant's ethylene perception and ethylene biosynthesis abilities. Inhibition of ABA biosynthesis in wild-type plants negatively affected all the mycorrhization parameters studied, while tomato mutants impaired in ethylene synthesis only showed a reduced arbuscular abundance in mycorrhizal roots. Inhibition of ethylene synthesis in ABA-deficient sitiens plants increased the intensity of mycorrhiza development, while ABA application rescued arbuscule abundance in the root's mycorrhizal zones. The results of our study show an antagonistic interaction between ABA and ethylene, and different roles of each of the two hormones during AM formation. This suggests that a dual ethylene-dependent/ethylene-independent mechanism is involved in ABA regulation of AM formation.

  3. Arabidopsis CPR5 Independently Regulates Seed Germination and Postgermination Arrest of Development through LOX Pathway and ABA Signaling

    PubMed Central

    Yang, Xiang; Wang, Yaqin; Su, Xiaojun; Du, Jinju; Yang, Chengwei

    2011-01-01

    The phytohormone abscisic acid (ABA) and the lipoxygenases (LOXs) pathway play important roles in seed germination and seedling growth and development. Here, we reported on the functional characterization of Arabidopsis CPR5 in the ABA signaling and LOX pathways. The cpr5 mutant was hypersensitive to ABA in the seed germination, cotyledon greening and root growth, whereas transgenic plants overexpressing CPR5 were insensitive. Genetic analysis demonstrated that CPR5 gene may be located downstream of the ABI1 in the ABA signaling pathway. However, the cpr5 mutant showed an ABA independent drought-resistant phenotype. It was also found that the cpr5 mutant was hypersensitive to NDGA and NDGA treatment aggravated the ABA-induced delay in the seed germination and cotyledon greening. Taken together, these results suggest that the CPR5 plays a regulatory role in the regulation of seed germination and early seedling growth through ABA and LOX pathways independently. PMID:21556325

  4. Comparison of Four Comamonas Catabolic Plasmids Reveals the Evolution of pBHB To Catabolize Haloaromatics

    PubMed Central

    Chen, Kai; Xu, Xihui; Zhang, Long; Gou, Zhenjiu; Li, Shunpeng

    2015-01-01

    Comamonas plasmids play important roles in shaping the phenotypes of their hosts and the adaptation of these hosts to changing environments, and understanding the evolutionary strategy of these plasmids is thus of great concern. In this study, the sequence of the 119-kb 3,5-dibromo-4-hydroxybenzonitrile-catabolizing plasmid pBHB from Comamonas sp. strain 7D-2 was studied and compared with those of three other Comamonas haloaromatic catabolic plasmids. Incompatibility group determination based on a phylogenetic analysis of 24 backbone gene proteins, as well as TrfA, revealed that these four plasmids all belong to the IncP-1β subgroup. Comparison of the four plasmids revealed a conserved backbone region and diverse genetic-load regions. The four plasmids share a core genome consisting of 40 genes (>50% similarities) and contain 12 to 50 unique genes each, most of which are xenobiotic-catabolic genes. Two functional reductive dehalogenase gene clusters are specifically located on pBHB, showing distinctive evolution of pBHB for haloaromatics. The higher catabolic ability of the bhbA2B2 cluster than the bhbAB cluster may be due to the transcription levels and the character of the dehalogenase gene itself rather than that of its extracytoplasmic binding receptor gene. The plasmid pBHB is riddled with transposons and insertion sequence (IS) elements, and ISs play important roles in the evolution of pBHB. The analysis of the origin of the bhb genes on pBHB suggested that these accessory genes evolved independently. Our work provides insights into the evolutionary strategies of Comamonas plasmids, especially into the adaptation mechanism employed by pBHB for haloaromatics. PMID:26682859

  5. Comparison of Four Comamonas Catabolic Plasmids Reveals the Evolution of pBHB To Catabolize Haloaromatics.

    PubMed

    Chen, Kai; Xu, Xihui; Zhang, Long; Gou, Zhenjiu; Li, Shunpeng; Freilich, Shiri; Jiang, Jiandong

    2015-12-18

    Comamonas plasmids play important roles in shaping the phenotypes of their hosts and the adaptation of these hosts to changing environments, and understanding the evolutionary strategy of these plasmids is thus of great concern. In this study, the sequence of the 119-kb 3,5-dibromo-4-hydroxybenzonitrile-catabolizing plasmid pBHB from Comamonas sp. strain 7D-2 was studied and compared with those of three other Comamonas haloaromatic catabolic plasmids. Incompatibility group determination based on a phylogenetic analysis of 24 backbone gene proteins, as well as TrfA, revealed that these four plasmids all belong to the IncP-1β subgroup. Comparison of the four plasmids revealed a conserved backbone region and diverse genetic-load regions. The four plasmids share a core genome consisting of 40 genes (>50% similarities) and contain 12 to 50 unique genes each, most of which are xenobiotic-catabolic genes. Two functional reductive dehalogenase gene clusters are specifically located on pBHB, showing distinctive evolution of pBHB for haloaromatics. The higher catabolic ability of the bhbA2B2 cluster than the bhbAB cluster may be due to the transcription levels and the character of the dehalogenase gene itself rather than that of its extracytoplasmic binding receptor gene. The plasmid pBHB is riddled with transposons and insertion sequence (IS) elements, and ISs play important roles in the evolution of pBHB. The analysis of the origin of the bhb genes on pBHB suggested that these accessory genes evolved independently. Our work provides insights into the evolutionary strategies of Comamonas plasmids, especially into the adaptation mechanism employed by pBHB for haloaromatics.

  6. Biochemical characterization of the aba2 and aba3 mutants in Arabidopsis thaliana.

    PubMed

    Schwartz, S H; Léon-Kloosterziel, K M; Koornneef, M; Zeevaart, J A

    1997-05-01

    Abscisic acid (ABA)-deficient mutants in a variety of species have been identified by screening for precocious germination and a wilty phenotype. Mutants at two new loci, aba2 and aba3, have recently been isolated in Arabidopsis thaliana (L.) Hynh. (K.M. Léon-Kloosterziel, M. Alvarez-Gil, G.J. Ruijs, S.E. Jacobsen, N.E. Olszewski, S.H. Schwartz, J.A.D. Zeevaart, M. Koornneef [1996] Plant J 10: 655-661), and the biochemical characterization of these mutants is presented here. Protein extracts from aba2 and aba3 plants displayed a greatly reduced ability to convert xanthoxin to ABA relative to the wild type. The next putative intermediate in ABA synthesis, ABA-aldehyde, was efficiently converted to ABA by extracts from aba2 but not by extracts from aba3 plants. This indicates that the aba2 mutant is blocked in the conversion of xanthoxin to ABA-aldehyde and that aba3 is impaired in the conversion of ABA-aldehyde to ABA. Extracts from the aba3 mutant also lacked additional activities that require a molybdenum cofactor (Moco). Nitrate reductase utilizes a Moco but its activity was unaffected in extracts from aba3 plants. Moco hydroxylases in animals require a desulfo moiety of the cofactor. A sulfido ligand can be added to the Moco by treatment with Na2S and dithionite. Treatment of aba3 extracts with Na2S restored ABA-aldehyde oxidase activity. Therefore, the genetic lesion in aba3 appears to be in the introduction of S into the Moco. PMID:9159947

  7. A rice F-box gene, OsFbx352, is involved in glucose-delayed seed germination in rice

    PubMed Central

    Zhang, Wen-Hao

    2012-01-01

    F-box proteins play diverse roles in regulating numerous physiological processes in plants. This study isolated a gene (OsFbx352) from rice encoding an F-box domain protein and characterized its role in seed germination. Expression of OsFbx352 was upregulated by abscisic acid (ABA). The transcripts of OsFbx352 were increased upon imbibition of rice seeds and the increase was markedly suppressed by glucose. Germination of seeds with overexpression of OsFbx352 was less suppressed by glucose than that of wild-type seeds, while glucose had greater inhibition for germination of seeds with knockdown of OsFbx352 by RNA interference (RNAi) than that of wild-type seeds. The differential response of germination of the transgenic and wild-type seeds to glucose may be accounted for by differences in ABA content among overexpressing, RNAi, and wild-type seeds such that overexpression of OsFbx352 and knockdown of OsFbx352 led to lower and higher ABA contents, respectively, than that of wild-type seeds in the presence of glucose. Overexpression of OsFbx352 led to a reduction in expression of genes responsible for ABA synthesis (OsNced2, OsNced3) and an increase in expression of genes encoding ABA catabolism (OsAba-ox2, OsAba-ox3) in the presence of glucose. These findings indicate that OsFbx352 plays a regulatory role in the regulation of glucose-induced suppression of seed germination by targeting ABA metabolism. PMID:22859682

  8. Control of hydroxyproline catabolism in Sinorhizobium meliloti.

    PubMed

    White, Catharine E; Gavina, Jennilee M A; Morton, Richard; Britz-McKibbin, Philip; Finan, Turlough M

    2012-09-01

    Hydroxyproline (Hyp) in decaying organic matter is a rich source of carbon and nitrogen for microorganisms. A bacterial pathway for Hyp catabolism is known; however, genes and function relationships are not established. In the pathway, trans-4-hydroxy-L-proline (4-L-Hyp) is epimerized to cis-4-hydroxy-D-proline (4-D-Hyp), and then, in three enzymatic reactions, the D-isomer is converted via Δ-pyrroline-4-hydroxy-2-carboxylate (HPC) and α-ketoglutarate semialdehyde (KGSA) to α-ketoglutarate (KG). Here a transcriptional analysis of cells growing on 4-L-Hyp, and the regulation and functions of genes from a Hyp catabolism locus of the legume endosymbiont Sinorhizobium meliloti are reported. Fourteen hydroxyproline catabolism genes (hyp), in five transcripts hypR, hypD, hypH, hypST and hypMNPQO(RE)XYZ, were negatively regulated by hypR. hypRE was shown to encode 4-hydroxyproline 2-epimerase and a hypRE mutant grew with 4-D-Hyp but not 4-L-Hyp. hypO, hypD and hypH are predicted to encode 4-D-Hyp oxidase, HPC deaminase and α-KGSA dehydrogenase respectively. The functions for hypS, hypT, hypX, hypY and hypZ remain to be determined. The data suggest 4-Hyp is converted to the tricarboxylic acid cycle intermediate α-ketoglutarate via the pathway established biochemically for Pseudomonas. This report describes the first molecular characterization of a Hyp catabolism locus.

  9. Identification of acoR, a regulatory gene for the expression of genes essential for acetoin catabolism in Alcaligenes eutrophus H16.

    PubMed Central

    Krüger, N; Steinbüchel, A

    1992-01-01

    Two hundred thirty-nine base pairs upstream from acoXABC, which encodes the Alcaligenes eutrophus H16 structural genes essential for cleavage of acetoin, the 2,004-bp acoR gene was identified. acoR encodes a protein of 668 amino acids with a molecular mass of 72.9 kDa. The amino acid sequence deduced from acoR exhibited homologies to the primary structures of transcriptional activators such as NifA of Azotobacter vinelandii, NtrC of Klebsiella pneumoniae, and HoxA of A. eutrophus. Striking similarities to the central domain of these proteins and the presence of a typical nucleotide-binding site (GETGSGK) as well as of a C-terminal helix-turn-helix motif as a DNA-binding site were revealed. Between acoR and acoXABC, two different types of sequences with dual rotational symmetry [CAC-(N11 to N18)-GTG and TGT-(N10 to N14)-ACA] were found; these sequences are similar to NtrC and NifA upstream activator sequences, respectively. Determination of the N-terminal amino acid sequence of an acoR'-'lacZ gene fusion identified the translational start of acoR. S1 nuclease protection assay identified the transcriptional start site 109 bp upstream of acoR. The promoter region (TTGCGC-N18-TACATT) resembled the sigma 70 consensus sequence of Escherichia coli. Analysis of an acoR'-'lacZ fusion and primer extension studies revealed that acoR was expressed at a low level under all culture conditions, whereas acoXABC was expressed only in acetoin-grown cells. The insertions of Tn5 in six transposon-induced acetoin-negative mutants of A. eutrophus were mapped within acoR. On the basis of these studies, it is probable that AcoR represents a regulatory protein which is required for sigma 54-dependent transcription of acoXABC. Images PMID:1378052

  10. Increased ABA sensitivity results in higher seed dormancy in soft white spring wheat cultivar ‘Zak’

    PubMed Central

    Schramm, Elizabeth C.; Nelson, Sven K.; Kidwell, Kimberlee K.

    2014-01-01

    As a strategy to increase the seed dormancy of soft white wheat, mutants with increased sensitivity to the plant hormone abscisic acid (ABA) were identified in mutagenized grain of soft white spring wheat “Zak”. Lack of seed dormancy is correlated with increased susceptibility to preharvest sprouting in wheat, especially those cultivars with white kernels. ABA induces seed dormancy during embryo maturation and inhibits the germination of mature grain. Three mutant lines called Zak ERA8, Zak ERA19A, and Zak ERA19B (Zak ENHANCED RESPONSE to ABA) were recovered based on failure to germinate on 5 µM ABA. All three mutants resulted in increased ABA sensitivity over a wide range of concentrations such that a phenotype can be detected at very low ABA concentrations. Wheat loses sensitivity to ABA inhibition of germination with extended periods of dry after-ripening. All three mutants recovered required more time to after-ripen sufficiently to germinate in the absence of ABA and to lose sensitivity to 5 µM ABA. However, an increase in ABA sensitivity could be detected after as long as 3 years of after-ripening using high ABA concentrations. The Zak ERA8 line showed the strongest phenotype and segregated as a single semi-dominant mutation. This mutation resulted in no obvious decrease in yield and is a good candidate gene for breeding preharvest sprouting tolerance. PMID:23212773

  11. Effects of lipopolysaccharide on the catabolic activity of macrophages

    SciTech Connect

    Cluff, C.; Ziegler, H.K.

    1986-03-05

    The ability of macrophages to degrade and catabolize antigens is of relevance both as a means to process complex antigens prior to presentation to T cells, as well as a way to down regulate immune responses by destroying the antigenicity of polypeptides. With these considerations, the authors have investigated the regulation of macrophage catabolic activity by lipopolysaccharide (LPS). Catabolic activity was quantitated by following the distribution and molecular form of /sup 125/-I labelled surface components of heat-killed Listeria monocytogenes (HKLM) subsequent to their uptake by macrophages. They have compared the catabolic activity of macrophages from peritoneal exudates of mice injected i.p. with saline or LPS and have found that LPS-elicited macrophages display a greatly enhanced (3 fold) rate of catabolism. This increase in catabolic activity peaks 3 days after LPS injection and steadily declines thereafter, approaching a baseline level after 3 weeks. The enhancement of catabolic activity is under LPS gene control. LPS-elicited macrophages rapidly destroy the antigenicity of bacterial antigens and function poorly as antigen presenting cells in vitro. These results suggest that LPS elicits a macrophage population specialized for antigen degradation functions with negative regulatory effects on the induction of specific immune responses.

  12. Involvement of plant endogenous ABA in Bacillus megaterium PGPR activity in tomato plants

    PubMed Central

    2014-01-01

    Background Plant growth-promoting rhizobacteria (PGPR) are naturally occurring soil bacteria which benefit plants by improving plant productivity and immunity. The mechanisms involved in these processes include the regulation of plant hormone levels such as ethylene and abscisic acid (ABA). The aim of the present study was to determine whether the activity of Bacillus megaterium PGPR is affected by the endogenous ABA content of the host plant. The ABA-deficient tomato mutants flacca and sitiens and their near-isogenic wild-type parental lines were used. Growth, stomatal conductance, shoot hormone concentration, competition assay for colonization of tomato root tips, and root expression of plant genes expected to be modulated by ABA and PGPR were examined. Results Contrary to the wild-type plants in which PGPR stimulated growth rates, PGPR caused growth inhibition in ABA-deficient mutant plants. PGPR also triggered an over accumulation of ethylene in ABA-deficient plants which correlated with a higher expression of the pathogenesis-related gene Sl-PR1b. Conclusions Positive correlation between over-accumulation of ethylene and a higher expression of Sl-PR1b in ABA-deficient mutant plants could indicate that maintenance of normal plant endogenous ABA content may be essential for the growth promoting action of B. megaterium by keeping low levels of ethylene production. PMID:24460926

  13. Overexpression of the Artemisia Orthologue of ABA Receptor, AaPYL9, Enhances ABA Sensitivity and Improves Artemisinin Content in Artemisia annua L

    PubMed Central

    Zhang, Fangyuan; Lu, Xu; Lv, Zongyou; Zhang, Ling; Zhu, Mengmeng; Jiang, Weiming; Wang, Guofeng; Sun, Xiaofen; Tang, Kexuan

    2013-01-01

    The phytohormone abscisic acid (ABA) plays an important role in plant development and environmental stress response. In this study, we cloned an ABA receptor orthologue, AaPYL9, from Artemisia annua L. AaPYL9 is expressed highly in leaf and flower. AaPYL9 protein can be localized in both nucleus and cytoplasm. Yeast two-hybrid assay shows AaPYL9 can specifically interact with AtABI1 but not with AtABI2, AtHAB1 or AtHAB2. ABA can enhance the interaction between AaPYL9 and AtABI1 while AaPYL9-89 Pro→Ser and AaPYL9-116 His→Ala point mutations abolishes the interaction. BiFC assay shows that AaPYL9 interacts with AtABI1 in nucleus in planta. Transgenic Arabidopsis plants over-expressing AaPYL9 are more sensitive to ABA in the seed germination and primary root growth than wild type. Consistent with this, ABA report genes have higher expression in AaPYL9 overexpressing plants compared to wild type after ABA treatment. Moreover, overexpression of AaPYL9 in A. annua increases not only drought tolerance, but also artemisinin content after ABA treatment, with significant enhancement of the expression of key genes in artemisinin biosynthesis. This study provides a way to develop A. annua with high-yielding artemisinin and high drought resistance. PMID:23437216

  14. Isolation and Characterization of ScGluD2, a New Sugarcane beta-1,3-Glucanase D Family Gene Induced by Sporisorium scitamineum, ABA, H2O2, NaCl, and CdCl2 Stresses

    PubMed Central

    Su, Yachun; Wang, Zhuqing; Liu, Feng; Li, Zhu; Peng, Qiong; Guo, Jinlong; Xu, Liping; Que, Youxiong

    2016-01-01

    Beta-1,3-glucanases (EC 3.2.1.39), commonly known as pathogenesis-related (PR) proteins, play an important role not only in plant defense against fungal pathogens but also in plant physiological and developmental processes. However, only a limited number of sugarcane beta-1,3-glucanase genes have been isolated. In the present study, we identified and characterized a new beta-1,3-glucanase gene ScGluD2 (GenBank Acc No. KF664181) from sugarcane. An X8 domain was present at the C terminal region of ScGluD2, suggesting beta-1,3-glucan-binding function. Phylogenetic analysis showed that the predicted ScGluD2 protein was classified into subfamily D beta-1,3-glucanase. Localization of the ScGluD2 protein in the plasma membrane was determined by tagging it with green fluorescent protein. The expression of ScGluD2 was more up-regulated in sugarcane smut-resistant cultivars in the early stage (1 or 3 days) than in the susceptible ones after being challenged by the smut pathogen, revealing that ScGluD2 may be involved in defense against the invasion of Sporisorium scitamineum. Transient overexpression of ScGluD2 in Nicotiana benthamiana leaves induced a defense response and exhibited antimicrobial action on the tobacco pathogens Pseudomonas solanacearum and Botrytis cinerea, further demonstrating that ScGluD2 was related to the resistance to plant pathogens. However, the transcripts of ScGluD2 partially increased (12 h) under NaCl stress, and were steadily up-regulated from 6 to 24 h upon ABA, H2O2, and CdCl2 treatments, suggesting that ABA may be a signal molecule regulating oxidative stress and play a role in the salt and heavy metal stress-induced stimulation of ScGluD2 transcripts. Taken together, ScGluD2, a novel member of subfamily D beta-1,3-glucanase, was a stress-related gene of sugarcane involved in plant defense against smut pathogen attack and salt and heavy metal stresses.

  15. Isolation and Characterization of ScGluD2, a New Sugarcane beta-1,3-Glucanase D Family Gene Induced by Sporisorium scitamineum, ABA, H2O2, NaCl, and CdCl2 Stresses.

    PubMed

    Su, Yachun; Wang, Zhuqing; Liu, Feng; Li, Zhu; Peng, Qiong; Guo, Jinlong; Xu, Liping; Que, Youxiong

    2016-01-01

    Beta-1,3-glucanases (EC 3.2.1.39), commonly known as pathogenesis-related (PR) proteins, play an important role not only in plant defense against fungal pathogens but also in plant physiological and developmental processes. However, only a limited number of sugarcane beta-1,3-glucanase genes have been isolated. In the present study, we identified and characterized a new beta-1,3-glucanase gene ScGluD2 (GenBank Acc No. KF664181) from sugarcane. An X8 domain was present at the C terminal region of ScGluD2, suggesting beta-1,3-glucan-binding function. Phylogenetic analysis showed that the predicted ScGluD2 protein was classified into subfamily D beta-1,3-glucanase. Localization of the ScGluD2 protein in the plasma membrane was determined by tagging it with green fluorescent protein. The expression of ScGluD2 was more up-regulated in sugarcane smut-resistant cultivars in the early stage (1 or 3 days) than in the susceptible ones after being challenged by the smut pathogen, revealing that ScGluD2 may be involved in defense against the invasion of Sporisorium scitamineum. Transient overexpression of ScGluD2 in Nicotiana benthamiana leaves induced a defense response and exhibited antimicrobial action on the tobacco pathogens Pseudomonas solanacearum and Botrytis cinerea, further demonstrating that ScGluD2 was related to the resistance to plant pathogens. However, the transcripts of ScGluD2 partially increased (12 h) under NaCl stress, and were steadily up-regulated from 6 to 24 h upon ABA, H2O2, and CdCl2 treatments, suggesting that ABA may be a signal molecule regulating oxidative stress and play a role in the salt and heavy metal stress-induced stimulation of ScGluD2 transcripts. Taken together, ScGluD2, a novel member of subfamily D beta-1,3-glucanase, was a stress-related gene of sugarcane involved in plant defense against smut pathogen attack and salt and heavy metal stresses. PMID:27642288

  16. Isolation and Characterization of ScGluD2, a New Sugarcane beta-1,3-Glucanase D Family Gene Induced by Sporisorium scitamineum, ABA, H2O2, NaCl, and CdCl2 Stresses

    PubMed Central

    Su, Yachun; Wang, Zhuqing; Liu, Feng; Li, Zhu; Peng, Qiong; Guo, Jinlong; Xu, Liping; Que, Youxiong

    2016-01-01

    Beta-1,3-glucanases (EC 3.2.1.39), commonly known as pathogenesis-related (PR) proteins, play an important role not only in plant defense against fungal pathogens but also in plant physiological and developmental processes. However, only a limited number of sugarcane beta-1,3-glucanase genes have been isolated. In the present study, we identified and characterized a new beta-1,3-glucanase gene ScGluD2 (GenBank Acc No. KF664181) from sugarcane. An X8 domain was present at the C terminal region of ScGluD2, suggesting beta-1,3-glucan-binding function. Phylogenetic analysis showed that the predicted ScGluD2 protein was classified into subfamily D beta-1,3-glucanase. Localization of the ScGluD2 protein in the plasma membrane was determined by tagging it with green fluorescent protein. The expression of ScGluD2 was more up-regulated in sugarcane smut-resistant cultivars in the early stage (1 or 3 days) than in the susceptible ones after being challenged by the smut pathogen, revealing that ScGluD2 may be involved in defense against the invasion of Sporisorium scitamineum. Transient overexpression of ScGluD2 in Nicotiana benthamiana leaves induced a defense response and exhibited antimicrobial action on the tobacco pathogens Pseudomonas solanacearum and Botrytis cinerea, further demonstrating that ScGluD2 was related to the resistance to plant pathogens. However, the transcripts of ScGluD2 partially increased (12 h) under NaCl stress, and were steadily up-regulated from 6 to 24 h upon ABA, H2O2, and CdCl2 treatments, suggesting that ABA may be a signal molecule regulating oxidative stress and play a role in the salt and heavy metal stress-induced stimulation of ScGluD2 transcripts. Taken together, ScGluD2, a novel member of subfamily D beta-1,3-glucanase, was a stress-related gene of sugarcane involved in plant defense against smut pathogen attack and salt and heavy metal stresses. PMID:27642288

  17. ABA Receptors: Past, Present and Future

    SciTech Connect

    Guo, Jianjun; Yang, Xiaohan; Weston, David; Chen, Jay

    2011-01-01

    Abscisic acid (ABA) is the key plant stress hormone. Consistent with the earlier studies in support of the presence of both membrane- and cytoplasm-localized ABA receptors, recent studies have identified multiple ABA receptors located in various subcellular locations. These include a chloroplast envelope-localized receptor (the H subunit of Chloroplast Mg2+-chelatase/ABA Receptor), two plasma membrane-localized receptors (G-protein Coupled Receptor 2 and GPCR-type G proteins), and one cytosol/nucleus-localized Pyrabactin Resistant (PYR)/PYR-Like (PYL)/Regulatory Component of ABA Receptor 1 (RCAR). Although the downstream molecular events for most of the identified ABA receptors are currently unknown, one of them, PYR/PYL/RACR was found to directly bind and regulate the activity of a long-known central regulator of ABA signaling, the A-group protein phosphatase 2C (PP2C). Together with the Sucrose Non-fermentation Kinase Subfamily 2 (SnRK2s) protein kinases, a central signaling complex (ABA-PYR-PP2Cs-SnRK2s) that is responsible for ABA signal perception and transduction is supported by abundant genetic, physiological, biochemical and structural evidence. The identification of multiple ABA receptors has advanced our understanding of ABA signal perception and transduction while adding an extra layer of complexity.

  18. ABA-alcohol is an intermediate in abscisic acid biosynthesis

    SciTech Connect

    Rock, C.D.; Zeevaart, J.A.D. )

    1990-05-01

    It has been established that ABA-aldehyde is a precursor to ABA. The ABA-deficient flacca and sitiens mutants of tomato are blocked in the conversion of ABA-aldehyde to ABA, and accumulate trans-ABA-alcohol. {sup 18}O-Labeling studies of ABA in flacca and sitiens show that these mutants synthesize a large percentage of ({sup 18}O)ABA which contains two {sup 18}O atoms in the carboxyl group. Furthermore, the mutants synthesize much greater amounts of trans-ABA-glucose ester (t-ABA-GE) compared with the wild type, and this ({sup 18}O)t-ABA-GE is also double labeled in the carboxyl group. Our interpretation of these data is that the {sup 18}O in ABA-aldehyde is trapped in the side chain by reduction to ({sup 18}O)ABA-alcohol, followed by isomerization to ({sup 18}O)t-ABA-alcohol and oxidation with {sup 18}O{sub 2} to ({sup 18}O)t-ABA. The ({sup 18}O)t-ABA is then rapidly converted to ({sup 18}O)t-ABA-GE. Because ({sup 18}O)ABA doubly labeled in the carboxyl group has been observed in small amounts in labeling experiments with several species, and various species have been shown to convert ABA-aldehyde to ABA-alcohol and t-ABA-alcohol, we propose that ABA-alcohol is an ABA intermediate in a shunt pathway.

  19. The role of ABA in triggering ethylene biosynthesis and ripening of tomato fruit

    PubMed Central

    Zhang, Mei; Yuan, Bing; Leng, Ping

    2009-01-01

    In order to understand more details about the role of abscisic acid (ABA) in fruit ripening and senescence of tomato, two cDNAs (LeNCED1 and LeNCED2) which encode 9-cis-epoxycarotenoid dioxygenase (NCED) as a key enzyme in ABA biosynthesis, two cDNAs (LeACS2 and LeACS4) which encode 1-aminocyclopropane-1-carboxylic acid (ACC) synthase, and one cDNA (LeACO1) which encodes ACC oxidase involved in ethylene biosynthesis were cloned from tomato fruit using a reverse transcription-PCR (RT-PCR) approach. The relationship between ABA and ethylene during ripening was also investigated. Among six sampling times in tomato fruits, the LeNCED1 gene was highly expressed only at the breaker stage when the ABA content becomes high. After this, the LeACS2, LeACS4, and LeACO1 genes were expressed with some delay. The change in pattern of ACO activity was in accordance with ethylene production reaching its peak at the pink stage. The maximum ABA content preceded ethylene production in both the seeds and the flesh. The peak value of ABA, ACC, and ACC oxidase activity, and ethylene production all started to increase earlier in seeds than in flesh tissues, although they occurred at different ripening stages. Exogenous ABA treatment increased the ABA content in both flesh and seed, inducing the expression of both ACS and ACO genes, and promoting ethylene synthesis and fruit ripening, while treatment with fluridone or nordihydroguaiaretic acid (NDGA) inhibited them, delaying fruit ripening and softening. Based on the results obtained in this study, it was concluded that LeNCED1 initiates ABA biosynthesis at the onset of fruit ripening, and might act as an original inducer, and ABA accumulation might play a key role in the regulation of ripeness and senescence of tomato fruit. PMID:19246595

  20. Tryptophan-catabolizing enzymes - party of three.

    PubMed

    Ball, Helen J; Jusof, Felicita F; Bakmiwewa, Supun M; Hunt, Nicholas H; Yuasa, Hajime J

    2014-01-01

    Indoleamine 2,3-dioxygenase (IDO) and tryptophan 2,3-dioxygenase (TDO) are tryptophan-degrading enzymes that have independently evolved to catalyze the first step in tryptophan catabolism via the kynurenine pathway (KP). The depletion of tryptophan and formation of KP metabolites modulates the activity of the mammalian immune, reproductive, and central nervous systems. IDO and TDO enzymes can have overlapping or distinct functions depending on their expression patterns. The expression of TDO and IDO enzymes in mammals differs not only by tissue/cellular localization but also by their induction by distinct stimuli. To add to the complexity, these genes also have undergone duplications in some organisms leading to multiple isoforms of IDO or TDO. For example, many vertebrates, including all mammals, have acquired two IDO genes via gene duplication, although the IDO1-like gene has been lost in some lower vertebrate lineages. Gene duplications can allow the homologs to diverge and acquire different properties to the original gene. There is evidence for IDO enzymes having differing enzymatic characteristics, signaling properties, and biological functions. This review analyzes the evolutionary convergence of IDO and TDO enzymes as tryptophan-catabolizing enzymes and the divergent evolution of IDO homologs to generate an enzyme family with diverse characteristics not possessed by TDO enzymes, with an emphasis on the immune system. PMID:25346733

  1. ABA-induced CCCH tandem zinc finger protein OsC3H47 decreases ABA sensitivity and promotes drought tolerance in Oryza sativa.

    PubMed

    Wang, Wenyi; Liu, Bohan; Xu, Mengyun; Jamil, Muhammad; Wang, Guoping

    2015-08-14

    Water deficit causes multiple negative impacts on plants, such as reactive oxygen species (ROS) accumulation, abscisic acid (ABA) induction, stomatal closure, and decreased photosynthesis. Here, we characterized OsC3H47, which belongs to CCCH zinc-finger families, as a drought-stress response gene. It can be strongly induced by NaCl, PEG, ABA, and drought conditions. Overexpression of OsC3H47 significantly enhanced tolerance to drought and salt stresses in rice seedlings, which indicates that OsC3H47 plays important roles in post-stress recovery. However, overexpression of OsC3H47 reduced the ABA sensitivity of rice seedlings. This suggests that OsC3H47 is a newly discovered gene that can control rice drought-stress response, and it may play an important role in ABA feedback and post-transcription processes. PMID:26047696

  2. The Role of MAPK Modules and ABA during Abiotic Stress Signaling.

    PubMed

    de Zelicourt, Axel; Colcombet, Jean; Hirt, Heribert

    2016-08-01

    To respond to abiotic stresses, plants have developed specific mechanisms that allow them to rapidly perceive and respond to environmental changes. The phytohormone abscisic acid (ABA) was shown to be a pivotal regulator of abiotic stress responses in plants, triggering major changes in plant physiology. The ABA core signaling pathway largely relies on the activation of SnRK2 kinases to mediate several rapid responses, including gene regulation, stomatal closure, and plant growth modulation. Mitogen-activated protein kinases (MAPKs) have also been implicated in ABA signaling, but an entire ABA-activated MAPK module was uncovered only recently. In this review, we discuss the evidence for a role of MAPK modules in the context of different plant ABA signaling pathways. PMID:27143288

  3. Novel inositol catabolic pathway in Thermotoga maritima.

    PubMed

    Rodionova, Irina A; Leyn, Semen A; Burkart, Michael D; Boucher, Nathalie; Noll, Kenneth M; Osterman, Andrei L; Rodionov, Dmitry A

    2013-08-01

    myo-inositol (MI) is a key sugar alcohol component of various metabolites, e.g. phosphatidylinositol-based phospholipids that are abundant in animal and plant cells. The seven-step pathway of MI degradation was previously characterized in various soil bacteria including Bacillus subtilis. Through a combination of bioinformatics and experimental techniques we identified a novel variant of the MI catabolic pathway in the marine hyperthermophilic bacterium Thermotoga maritima. By using in vitro biochemical assays with purified recombinant proteins we characterized four inositol catabolic enzymes encoded in the TM0412-TM0416 chromosomal gene cluster. The novel catabolic pathway in T. maritima starts as the conventional route using the myo-inositol dehydrogenase IolG followed by three novel reactions. The first 2-keto-myo-inositol intermediate is oxidized by another, previously unknown NAD-dependent dehydrogenase TM0412 (named IolM), and a yet unidentified product of this reaction is further hydrolysed by TM0413 (IolN) to form 5-keto-l-gluconate. The fourth step involves epimerization of 5-keto-l-gluconate to d-tagaturonate by TM0416 (IolO). T. maritima is unable to grow on myo-inositol as a single carbon source. The determined in vitro specificity of the InoEFGK (TM0418-TM0421) transporter to myo-inositol-phosphate suggests that the novel pathway in Thermotoga utilizes a phosphorylated derivative of inositol.

  4. Molecular dissection of bacterial acrylate catabolism--unexpected links with dimethylsulfoniopropionate catabolism and dimethyl sulfide production.

    PubMed

    Todd, Jonathan D; Curson, Andrew R J; Nikolaidou-Katsaraidou, Nefeli; Brearley, Charles A; Watmough, Nicholas J; Chan, Yohan; Page, Philip C B; Sun, Lei; Johnston, Andrew W B

    2010-02-01

    A bacterium in the genus Halomonas that grew on dimethylsulfoniopropionate (DMSP) or acrylate as sole carbon sources and that liberated the climate-changing gas dimethyl sulfide in media containing DMSP was obtained from the phylloplane of the macroalga Ulva. We identified a cluster that contains genes specifically involved in DMSP catabolism (dddD, dddT) or in degrading acrylate (acuN, acuK) or that are required to break down both substrates (dddC, dddA). Using NMR and HPLC analyses to trace 13C- or 14C-labelled acrylate and DMSP in strains of Escherichia coli with various combinations of cloned ddd and/or acu genes, we deduced that DMSP is imported by the BCCT-type transporter DddT, then converted by DddD to 3-OH-propionate (3HP), liberating dimethyl sulfide in the process. As DddD is a predicted acyl CoA transferase, there may be an earlier, unidentified catabolite of DMSP. Acrylate is also converted to 3HP, via a CoA transferase (AcuN) and a hydratase (AcuK). The 3HP is predicted to be catabolized by an alcohol dehydrogenase, DddA, to malonate semialdehyde, thence by an aldehyde dehydrogenase, DddC, to acyl CoA plus CO2. The regulation of the ddd and acu genes is unusual, as a catabolite, 3HP, was a co-inducer of their transcription. This first description of genes involved in acrylate catabolism in any organism shows that the relationship between the catabolic pathways of acrylate and DMSP differs from that which had been suggested in other bacteria.

  5. Genome-Wide Analysis of the bZIP Gene Family Identifies Two ABI5-Like bZIP Transcription Factors, BrABI5a and BrABI5b, as Positive Modulators of ABA Signalling in Chinese Cabbage.

    PubMed

    Bai, Yili; Zhu, Wenbo; Hu, Xiaochen; Sun, Congcong; Li, Yanlin; Wang, Dandan; Wang, Qinhu; Pei, Guoliang; Zhang, Yanfeng; Guo, Aiguang; Zhao, Huixian; Lu, Haibin; Mu, Xiaoqian; Hu, Jingjiang; Zhou, Xiaona; Xie, Chang Gen

    2016-01-01

    bZIP (basic leucine zipper) transcription factors coordinate plant growth and development and control responses to environmental stimuli. The genome of Chinese cabbage (Brassica rapa) encodes 136 putative bZIP transcription factors. The bZIP transcription factors in Brassica rapa (BrbZIP) are classified into 10 subfamilies. Phylogenetic relationship analysis reveals that subfamily A consists of 23 BrbZIPs. Two BrbZIPs within subfamily A, Bra005287 and Bra017251, display high similarity to ABI5 (ABA Insensitive 5). Expression of subfamily A BrbZIPs, like BrABI5a (Bra005287/BrbZIP14) and BrABI5b (Bra017251/BrbZIP13), are significantly induced by the plant hormone ABA. Subcellular localization assay reveal that both BrABI5a and BrABI5b have a nuclear localization. BrABI5a and BrABI5b could directly stimulate ABA Responsive Element-driven HIS (a HIS3 reporter gene, which confers His prototrophy) or LUC (LUCIFERASE) expression in yeast and Arabidopsis protoplast. Deletion of the bZIP motif abolished BrABI5a and BrABI5b transcriptional activity. The ABA insensitive phenotype of Arabidopsis abi5-1 is completely suppressed in transgenic lines expressing BrABI5a or BrABI5b. Overall, these results suggest that ABI5 orthologs, BrABI5a and BrABI5b, have key roles in ABA signalling in Chinese cabbage.

  6. Genome-Wide Analysis of the bZIP Gene Family Identifies Two ABI5-Like bZIP Transcription Factors, BrABI5a and BrABI5b, as Positive Modulators of ABA Signalling in Chinese Cabbage

    PubMed Central

    Hu, Xiaochen; Sun, Congcong; Li, Yanlin; Wang, Dandan; Wang, Qinhu; Pei, Guoliang; Zhang, Yanfeng; Guo, Aiguang; Zhao, Huixian; Lu, Haibin; Mu, Xiaoqian; Hu, Jingjiang; Zhou, Xiaona; Xie, Chang Gen

    2016-01-01

    bZIP (basic leucine zipper) transcription factors coordinate plant growth and development and control responses to environmental stimuli. The genome of Chinese cabbage (Brassica rapa) encodes 136 putative bZIP transcription factors. The bZIP transcription factors in Brassica rapa (BrbZIP) are classified into 10 subfamilies. Phylogenetic relationship analysis reveals that subfamily A consists of 23 BrbZIPs. Two BrbZIPs within subfamily A, Bra005287 and Bra017251, display high similarity to ABI5 (ABA Insensitive 5). Expression of subfamily A BrbZIPs, like BrABI5a (Bra005287/BrbZIP14) and BrABI5b (Bra017251/BrbZIP13), are significantly induced by the plant hormone ABA. Subcellular localization assay reveal that both BrABI5a and BrABI5b have a nuclear localization. BrABI5a and BrABI5b could directly stimulate ABA Responsive Element-driven HIS (a HIS3 reporter gene, which confers His prototrophy) or LUC (LUCIFERASE) expression in yeast and Arabidopsis protoplast. Deletion of the bZIP motif abolished BrABI5a and BrABI5b transcriptional activity. The ABA insensitive phenotype of Arabidopsis abi5-1 is completely suppressed in transgenic lines expressing BrABI5a or BrABI5b. Overall, these results suggest that ABI5 orthologs, BrABI5a and BrABI5b, have key roles in ABA signalling in Chinese cabbage. PMID:27414644

  7. Genome-Wide Analysis of the bZIP Gene Family Identifies Two ABI5-Like bZIP Transcription Factors, BrABI5a and BrABI5b, as Positive Modulators of ABA Signalling in Chinese Cabbage.

    PubMed

    Bai, Yili; Zhu, Wenbo; Hu, Xiaochen; Sun, Congcong; Li, Yanlin; Wang, Dandan; Wang, Qinhu; Pei, Guoliang; Zhang, Yanfeng; Guo, Aiguang; Zhao, Huixian; Lu, Haibin; Mu, Xiaoqian; Hu, Jingjiang; Zhou, Xiaona; Xie, Chang Gen

    2016-01-01

    bZIP (basic leucine zipper) transcription factors coordinate plant growth and development and control responses to environmental stimuli. The genome of Chinese cabbage (Brassica rapa) encodes 136 putative bZIP transcription factors. The bZIP transcription factors in Brassica rapa (BrbZIP) are classified into 10 subfamilies. Phylogenetic relationship analysis reveals that subfamily A consists of 23 BrbZIPs. Two BrbZIPs within subfamily A, Bra005287 and Bra017251, display high similarity to ABI5 (ABA Insensitive 5). Expression of subfamily A BrbZIPs, like BrABI5a (Bra005287/BrbZIP14) and BrABI5b (Bra017251/BrbZIP13), are significantly induced by the plant hormone ABA. Subcellular localization assay reveal that both BrABI5a and BrABI5b have a nuclear localization. BrABI5a and BrABI5b could directly stimulate ABA Responsive Element-driven HIS (a HIS3 reporter gene, which confers His prototrophy) or LUC (LUCIFERASE) expression in yeast and Arabidopsis protoplast. Deletion of the bZIP motif abolished BrABI5a and BrABI5b transcriptional activity. The ABA insensitive phenotype of Arabidopsis abi5-1 is completely suppressed in transgenic lines expressing BrABI5a or BrABI5b. Overall, these results suggest that ABI5 orthologs, BrABI5a and BrABI5b, have key roles in ABA signalling in Chinese cabbage. PMID:27414644

  8. [Role of NO signal in ABA-induced phenolic acids accumulation in Salvia miltiorrhiza hairy roots].

    PubMed

    Shen, Lihong; Ren, Jiahui; Jin, Wenfang; Wang, Ruijie; Ni, Chunhong; Tong, Mengjiao; Liang, Zongsuo; Yang, Dongfeng

    2016-02-01

    To investigate roles of nitric oxide (NO) signal in accumulations of phenolic acids in abscisic.acid (ABA)-induced Salvia miltiorrhiza hairy roots, S. miltiorrhiza hairy roots were treated with different concentrations of sodium nitroprusside (SNP)-an exogenous NO donor, for 6 days, and contents of phenolic acids in the hairy roots are determined. Then with treatment of ABA and NO scavenger (2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylimidazoline-1- oxyl-3-oxide, c-PTIO) or NO synthase inhibitor (NG-nitro-L-arginine methyl ester, L-NAME), contents of phenolic acids and expression levels of three key genes involved in phenolic acids biosynthesis were detected. Phenolic acids production in S. miltiorrhiza hairy roots was most significantly improved by 100 µmoL/L SNP. Contents of RA and salvianolic acid B increased by 3 and 4 folds. ABA significantly improved transcript levels of PAL (phenylalanine ammonia lyase), TAT (tyrosine aminotransferase) and RAS (rosmarinic acid synthase), and increased phenolic acids accumulations. However, with treatments of ABA+c-PTIO or ABA+L-NAME, accumulations of phenolic acids and expression levels of the three key genes were significantly inhibited. Both NO and ABA can increase accumulations of phenolic acids in S. miltiorrhiza hairy roots. NO signal probably mediates the ABA-induced phenolic acids production. PMID:27382772

  9. AbaA Regulates Conidiogenesis in the Ascomycete Fungus Fusarium graminearum

    PubMed Central

    Son, Hokyoung; Kim, Myung-Gu; Min, Kyunghun; Seo, Young-Su; Lim, Jae Yun; Choi, Gyung Ja; Kim, Jin-Cheol; Chae, Suhn-Kee; Lee, Yin-Won

    2013-01-01

    Fusarium graminearum (teleomorph Gibberella zeae) is a prominent pathogen that infects major cereal crops such as wheat, barley, and maize. Both sexual (ascospores) and asexual (conidia) spores are produced in F. graminearum. Since conidia are responsible for secondary infection in disease development, our objective of the present study was to reveal the molecular mechanisms underlying conidiogenesis in F. graminearum based on the framework previously described in Aspergillus nidulans. In this study, we firstly identified and functionally characterized the ortholog of AbaA, which is involved in differentiation from vegetative hyphae to conidia and known to be absent in F. graminearum. Deletion of abaA did not affect vegetative growth, sexual development, or virulence, but conidium production was completely abolished and thin hyphae grew from abnormally shaped phialides in abaA deletion mutants. Overexpression of abaA resulted in pleiotropic defects such as impaired sexual and asexual development, retarded conidium germination, and reduced trichothecene production. AbaA localized to the nuclei of phialides and terminal cells of mature conidia. Successful interspecies complementation using A. nidulans AbaA and the conserved AbaA-WetA pathway demonstrated that the molecular mechanisms responsible for AbaA activity are conserved in F. graminearum as they are in A. nidulans. Results from RNA-sequencing analysis suggest that AbaA plays a pivotal role in conidiation by regulating cell cycle pathways and other conidiation-related genes. Thus, the conserved roles of the AbaA ortholog in both A. nidulans and F. graminearum give new insight into the genetics of conidiation in filamentous fungi. PMID:24039821

  10. Structural Biology of Proline Catabolism

    PubMed Central

    2009-01-01

    Summary The proline catabolic enzymes proline dehydrogenase and Δ1-pyrroline-5-carboxylate dehydrogenase catalyze the 4-electron oxidation of proline to glutamate. These enzymes play important roles in cellular redox control, superoxide generation, apoptosis and cancer. In some bacteria, the two enzymes are fused into the bifunctional enzyme, proline utilization A. Here we review the three-dimensional structural information that is currently available for proline catabolic enzymes. Crystal structures have been determined for bacterial monofunctional proline dehydrogenase and Δ1-pyrroline-5-carboxylate dehydrogenase, as well as the proline dehydrogenase and DNA-binding domains of proline utilization A. Some of the functional insights provided by analyses of these structures are discussed, including substrate recognition, catalytic mechanism, biochemical basis of inherited proline catabolic disorders and DNA recognition by proline utilization A. PMID:18369526

  11. Identification of low Ca(2+) stress-induced embryo apoptosis response genes in Arachis hypogaea by SSH-associated library lift (SSHaLL).

    PubMed

    Chen, Hua; Zhang, Chong; Cai, Tie Cheng; Deng, Ye; Zhou, Shuangbiao; Zheng, Yixiong; Ma, Shiwei; Tang, Ronghua; Varshney, Rajeev K; Zhuang, Weijian

    2016-02-01

    Calcium is a universal signal in the regulation of wide aspects in biology, but few are known about the function of calcium in the control of early embryo development. Ca(2+) deficiency in soil induces early embryo abortion in peanut, producing empty pods, which is a general problem; however, the underlying mechanism remains unclear. In this study, embryo abortion was characterized to be caused by apoptosis marked with cell wall degradation. Using a method of SSH cDNA libraries associated with library lift (SSHaLL), 62 differentially expressed genes were isolated from young peanut embryos. These genes were classified to be stress responses, catabolic process, carbohydrate and lipid metabolism, embryo morphogenesis, regulation, etc. The cell retardation with cell wall degradation was caused by up-regulated cell wall hydrolases and down-regulated cellular synthases genes. HsfA4a, which was characterized to be important to embryo development, was significantly down-regulated under Ca(2+) -deficient conditions from 15 days after pegging (DAP) to 30 DAP. Two AhCYP707A4 genes, encoding abscisic acid (ABA) 8'-hydroxylases, key enzymes for ABA catabolism, were up-regulated by 21-fold under Ca(2+) -deficient conditions upstream of HsfA4a, reducing the ABA level in early embryos. Over-expression of AhCYP707A4 in Nicotiana benthamiana showed a phenotype of low ABA content with high numbers of aborted embryos, small pods and less seeds, which confirms that AhCYP707A4 is a key player in regulation of Ca(2+) deficiency-induced embryo abortion via ABA-mediated apoptosis. The results elucidated the mechanism of low Ca(2+) -induced embryo abortion and described the method for other fields of study.

  12. ABA Affects Brassinosteroid-Induced Antioxidant Defense via ZmMAP65-1a in Maize Plants.

    PubMed

    Zhu, Yuan; Liu, Weijuan; Sheng, Yu; Zhang, Juan; Chiu, Tsanyu; Yan, Jingwei; Jiang, Mingyi; Tan, Mingpu; Zhang, Aying

    2015-07-01

    Brassinosteroids (BRs) and ABA co-ordinately regulate water deficit tolerance in maize leaves. ZmMAP65-1a, a maize microtubule-associated protein (MAP) which plays an essential role in BR-induced antioxidant defense, has been characterized previously. However, the interactions among BR, ABA and ZmMAP65-1a in water deficit tolerance remain unexplored. In this study, we demonstrated that ABA was required for BR-induced antioxidant defense via ZmMAP65-1a by using biochemical blocking and ABA biosynthetic mutants. The expression of ZmMAP65-1a in maize leaves and mesophyll protoplasts could be increased under polyethylene glycol- (PEG) stimulated water deficit and ABA treatments. Furthermore, the importance of ABA in the early pathway of BR-induced water deficit tolerance was demonstrated by limiting ABA availability. Blocking ABA biosynthesis biochemically or by a null mutation inhibited the downstream gene expression of ZmMAP65-1a and the activity of ZmMAPK5 in the pathway. It also affected the activities of BR-induced antioxidant defense-related enzymes, namely ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), superoxide dismutase (SOD) and NADPH oxidase. In addition, combining results from transiently overexpressed or silenced ZmMAP65-1a in mesophyll protoplasts, we discovered that ZmMAP65-1a mediated the ABA-induced gene expression and activities of APX and SOD. Surprisingly, silencing of ZmMAP65-1a in mesophyll protoplasts did not alter the gene expression of ZmCCaMK and vice versa in response to ABA. Taken together, our data indicate that water deficit-induced ABA is a key mediator in BR-induced antioxidant defense via ZmMAP65-1a in maize.

  13. The Arabidopsis transcription factor ABIG1 relays ABA signaled growth inhibition and drought induced senescence

    PubMed Central

    Liu, Tie; Longhurst, Adam D; Talavera-Rauh, Franklin; Hokin, Samuel A; Barton, M Kathryn

    2016-01-01

    Drought inhibits plant growth and can also induce premature senescence. Here we identify a transcription factor, ABA INSENSITIVE GROWTH 1 (ABIG1) required for abscisic acid (ABA) mediated growth inhibition, but not for stomatal closure. ABIG1 mRNA levels are increased both in response to drought and in response to ABA treatment. When treated with ABA, abig1 mutants remain greener and produce more leaves than comparable wild-type plants. When challenged with drought, abig1 mutants have fewer yellow, senesced leaves than wild-type. Induction of ABIG1 transcription mimics ABA treatment and regulates a set of genes implicated in stress responses. We propose a model in which drought acts through ABA to increase ABIG1 transcription which in turn restricts new shoot growth and promotes leaf senescence. The results have implications for plant breeding: the existence of a mutant that is both ABA resistant and drought resistant points to new strategies for isolating drought resistant genetic varieties. DOI: http://dx.doi.org/10.7554/eLife.13768.001 PMID:27697148

  14. Endodermal ABA signaling promotes lateral root quiescence during salt stress in Arabidopsis seedlings.

    PubMed

    Duan, Lina; Dietrich, Daniela; Ng, Chong Han; Chan, Penny Mei Yeen; Bhalerao, Rishikesh; Bennett, Malcolm J; Dinneny, José R

    2013-01-01

    The endodermal tissue layer is found in the roots of vascular plants and functions as a semipermeable barrier, regulating the transport of solutes from the soil into the vascular stream. As a gateway for solutes, the endodermis may also serve as an important site for sensing and responding to useful or toxic substances in the environment. Here, we show that high salinity, an environmental stress widely impacting agricultural land, regulates growth of the seedling root system through a signaling network operating primarily in the endodermis. We report that salt stress induces an extended quiescent phase in postemergence lateral roots (LRs) whereby the rate of growth is suppressed for several days before recovery begins. Quiescence is correlated with sustained abscisic acid (ABA) response in LRs and is dependent upon genes necessary for ABA biosynthesis, signaling, and transcriptional regulation. We use a tissue-specific strategy to identify the key cell layers where ABA signaling acts to regulate growth. In the endodermis, misexpression of the ABA insensitive1-1 mutant protein, which dominantly inhibits ABA signaling, leads to a substantial recovery in LR growth under salt stress conditions. Gibberellic acid signaling, which antagonizes the ABA pathway, also acts primarily in the endodermis, and we define the crosstalk between these two hormones. Our results identify the endodermis as a gateway with an ABA-dependent guard, which prevents root growth into saline environments.

  15. Loss of ACS7 confers abiotic stress tolerance by modulating ABA sensitivity and accumulation in Arabidopsis.

    PubMed

    Dong, Hui; Zhen, Zhiqin; Peng, Jinying; Chang, Li; Gong, Qingqiu; Wang, Ning Ning

    2011-10-01

    The phytohormones ethylene and abscisic acid (ABA) play essential roles in the abiotic stress adaptation of plants, with both cross-talk of ethylene signalling and ABA biosynthesis and signalling reported. Any reciprocal effects on each other's biosynthesis, however, remain elusive. ACC synthase (ACS) acts as the key enzyme in ethylene biosynthesis. A pilot study on changes in ACS promoter activities in response to abiotic stresses revealed the unique involvement in abiotic stress responses of the only type 3 ACC synthase, ACS7, among all nine ACSs of Arabidopsis. Hence an acs7 mutant was characterized and its abiotic stress responses were analysed. The acs7 mutant germinated slightly faster than the wild type and subsequently maintained a higher growth rate at the vegetative growth stage. Ethylene emission of acs7 was merely one-third of that of the wild type. acs7 exhibited enhanced tolerance to salt, osmotic, and heat stresses. Furthermore, acs7 seeds were hypersensitive to both ABA and glucose during germination. Transcript analyses revealed that acs7 had elevated transcript levels of the stress-responsive genes involved in the ABA-dependent pathway under salt stress. The ABA level was also higher in acs7 following salt treatment. Our data suggest that ACS7 acts as a negative regulator of ABA sensitivity and accumulation under stress and appears as a node in the cross-talk between ethylene and ABA.

  16. Functional analysis of 14 genes that constitute the purine catabolic pathway in Bacillus subtilis and evidence for a novel regulon controlled by the PucR transcription activator.

    PubMed

    Schultz, A C; Nygaard, P; Saxild, H H

    2001-06-01

    The soil bacterium Bacillus subtilis has developed a highly controlled system for the utilization of a diverse array of low-molecular-weight compounds as a nitrogen source when the preferred nitrogen sources, e.g., glutamate plus ammonia, are exhausted. We have identified such a system for the utilization of purines as nitrogen source in B. subtilis. Based on growth studies of strains with knockout mutations in genes, complemented with enzyme analysis, we could ascribe functions to 14 genes encoding enzymes or proteins of the purine degradation pathway. A functional xanthine dehydrogenase requires expression of five genes (pucA, pucB, pucC, pucD, and pucE). Uricase activity is encoded by the pucL and pucM genes, and a uric acid transport system is encoded by pucJ and pucK. Allantoinase is encoded by the pucH gene, and allantoin permease is encoded by the pucI gene. Allantoate amidohydrolase is encoded by pucF. In a pucR mutant, the level of expression was low for all genes tested, indicating that PucR is a positive regulator of puc gene expression. All 14 genes except pucI are located in a gene cluster at 284 to 285 degrees on the chromosome and are contained in six transcription units, which are expressed when cells are grown with glutamate as the nitrogen source (limiting conditions), but not when grown on glutamate plus ammonia (excess conditions). Our data suggest that the 14 genes and the gde gene, encoding guanine deaminase, constitute a regulon controlled by the pucR gene product. Allantoic acid, allantoin, and uric acid were all found to function as effector molecules for PucR-dependent regulation of puc gene expression. When cells were grown in the presence of glutamate plus allantoin, a 3- to 10-fold increase in expression was seen for most of the genes. However, expression of the pucABCDE unit was decreased 16-fold, while expression of pucR was decreased 4-fold in the presence of allantoin. We have identified genes of the purine degradation pathway in B

  17. Identification and mechanism of ABA receptor antagonism

    SciTech Connect

    Melcher, Karsten; Xu, Yong; Ng, Ley-Moy; Zhou, X. Edward; Soon, Fen-Fen; Chinnusamy, Viswanathan; Suino-Powell, Kelly M; Kovach, Amanda; Tham, Fook S.; Cutler, Sean R.; Li, Jun; Yong, Eu-Leong; Zhu, Jian-Kang; Xu, H. Eric

    2010-11-11

    The phytohormone abscisic acid (ABA) functions through a family of fourteen PYR/PYL receptors, which were identified by resistance to pyrabactin, a synthetic inhibitor of seed germination. ABA activates these receptors to inhibit type 2C protein phosphatases, such as ABI1, yet it remains unclear whether these receptors can be antagonized. Here we demonstrate that pyrabactin is an agonist of PYR1 and PYL1 but is unexpectedly an antagonist of PYL2. Crystal structures of the PYL2-pyrabactin and PYL1-pyrabactin-ABI1 complexes reveal the mechanism responsible for receptor-selective activation and inhibition, which enables us to design mutations that convert PYL1 to a pyrabactin-inhibited receptor and PYL2 to a pyrabactin-activated receptor and to identify new pyrabactin-based ABA receptor agonists. Together, our results establish a new concept of ABA receptor antagonism, illustrate its underlying mechanisms and provide a rational framework for discovering novel ABA receptor ligands.

  18. The NF-YC–RGL2 module integrates GA and ABA signalling to regulate seed germination in Arabidopsis

    PubMed Central

    Liu, Xu; Hu, Pengwei; Huang, Mingkun; Tang, Yang; Li, Yuge; Li, Ling; Hou, Xingliang

    2016-01-01

    The antagonistic crosstalk between gibberellic acid (GA) and abscisic acid (ABA) plays a pivotal role in the modulation of seed germination. However, the molecular mechanism of such phytohormone interaction remains largely elusive. Here we show that three Arabidopsis NUCLEAR FACTOR-Y C (NF-YC) homologues NF-YC3, NF-YC4 and NF-YC9 redundantly modulate GA- and ABA-mediated seed germination. These NF-YCs interact with the DELLA protein RGL2, a key repressor of GA signalling. The NF-YC–RGL2 module targets ABI5, a gene encoding a core component of ABA signalling, via specific CCAAT elements and collectively regulates a set of GA- and ABA-responsive genes, thus controlling germination. These results suggest that the NF-YC–RGL2–ABI5 module integrates GA and ABA signalling pathways during seed germination. PMID:27624486

  19. The NF-YC-RGL2 module integrates GA and ABA signalling to regulate seed germination in Arabidopsis.

    PubMed

    Liu, Xu; Hu, Pengwei; Huang, Mingkun; Tang, Yang; Li, Yuge; Li, Ling; Hou, Xingliang

    2016-01-01

    The antagonistic crosstalk between gibberellic acid (GA) and abscisic acid (ABA) plays a pivotal role in the modulation of seed germination. However, the molecular mechanism of such phytohormone interaction remains largely elusive. Here we show that three Arabidopsis NUCLEAR FACTOR-Y C (NF-YC) homologues NF-YC3, NF-YC4 and NF-YC9 redundantly modulate GA- and ABA-mediated seed germination. These NF-YCs interact with the DELLA protein RGL2, a key repressor of GA signalling. The NF-YC-RGL2 module targets ABI5, a gene encoding a core component of ABA signalling, via specific CCAAT elements and collectively regulates a set of GA- and ABA-responsive genes, thus controlling germination. These results suggest that the NF-YC-RGL2-ABI5 module integrates GA and ABA signalling pathways during seed germination.

  20. The NF-YC-RGL2 module integrates GA and ABA signalling to regulate seed germination in Arabidopsis.

    PubMed

    Liu, Xu; Hu, Pengwei; Huang, Mingkun; Tang, Yang; Li, Yuge; Li, Ling; Hou, Xingliang

    2016-01-01

    The antagonistic crosstalk between gibberellic acid (GA) and abscisic acid (ABA) plays a pivotal role in the modulation of seed germination. However, the molecular mechanism of such phytohormone interaction remains largely elusive. Here we show that three Arabidopsis NUCLEAR FACTOR-Y C (NF-YC) homologues NF-YC3, NF-YC4 and NF-YC9 redundantly modulate GA- and ABA-mediated seed germination. These NF-YCs interact with the DELLA protein RGL2, a key repressor of GA signalling. The NF-YC-RGL2 module targets ABI5, a gene encoding a core component of ABA signalling, via specific CCAAT elements and collectively regulates a set of GA- and ABA-responsive genes, thus controlling germination. These results suggest that the NF-YC-RGL2-ABI5 module integrates GA and ABA signalling pathways during seed germination. PMID:27624486

  1. Cholesterol catabolism as a therapeutic target in Mycobacterium tuberculosis

    PubMed Central

    Ouellet, Hugues; Johnston, Jonathan B.; Ortiz de Montellano, Paul R.

    2011-01-01

    Mycobacterium tuberculosis (Mtb) is an intracellular pathogen that infects 10 million worldwide and kills 2 million people every year. The uptake and utilization of nutrients by Mtb within the host cell is still poorly understood, although lipids play an important role in Mtb persistence. The recent identification of a large regulon of cholesterol catabolic genes suggests that Mtb can use host sterol for infection and persistence. In this review, we report on recent progress in elucidation of the Mtb cholesterol catabolic reactions and their potential utility as targets for tuberculosis therapeutic agents. PMID:21924910

  2. Small-molecule inhibition of choline catabolism in Pseudomonas aeruginosa and other aerobic choline-catabolizing bacteria.

    PubMed

    Fitzsimmons, Liam F; Flemer, Stevenson; Wurthmann, A Sandy; Deker, P Bruce; Sarkar, Indra Neil; Wargo, Matthew J

    2011-07-01

    Choline is abundant in association with eukaryotes and plays roles in osmoprotection, thermoprotection, and membrane biosynthesis in many bacteria. Aerobic catabolism of choline is widespread among soil proteobacteria, particularly those associated with eukaryotes. Catabolism of choline as a carbon, nitrogen, and/or energy source may play important roles in association with eukaryotes, including pathogenesis, symbioses, and nutrient cycling. We sought to generate choline analogues to study bacterial choline catabolism in vitro and in situ. Here we report the characterization of a choline analogue, propargylcholine, which inhibits choline catabolism at the level of Dgc enzyme-catalyzed dimethylglycine demethylation in Pseudomonas aeruginosa. We used genetic analyses and 13C nuclear magnetic resonance to demonstrate that propargylcholine is catabolized to its inhibitory form, propargylmethylglycine. Chemically synthesized propargylmethylglycine was also an inhibitor of growth on choline. Bioinformatic analysis suggests that there are genes encoding DgcA homologues in a variety of proteobacteria. We examined the broader utility of propargylcholine and propargylmethylglycine by assessing growth of other members of the proteobacteria that are known to grow on choline and possess putative DgcA homologues. Propargylcholine showed utility as a growth inhibitor in P. aeruginosa but did not inhibit growth in other proteobacteria tested. In contrast, propargylmethylglycine was able to inhibit choline-dependent growth in all tested proteobacteria, including Pseudomonas mendocina, Pseudomonas fluorescens, Pseudomonas putida, Burkholderia cepacia, Burkholderia ambifaria, and Sinorhizobium meliloti. We predict that chemical inhibitors of choline catabolism will be useful for studying this pathway in clinical and environmental isolates and could be a useful tool to study proteobacterial choline catabolism in situ.

  3. Nitric oxide modulates sensitivity to ABA.

    PubMed

    Lozano-Juste, Jorge; León, José

    2010-03-01

    Nitric oxide (NO) is a gas with crucial signaling functions in plant defense and development. As demonstrated by generating a triple nia1nia2noa1-2 mutant with extremely low levels of NO (February 2010 issue of Plant Physiology), NO is synthesized in plants through mainly two different pathways involving nitrate reductase (NR/NIA) and NO Associated 1 (AtNOA1) proteins. Depletion of basal NO levels leads to a priming of ABA-triggered responses that causes hypersensitivity to this hormone and results in enhanced seed dormancy and decreased seed germination and seedling establishment in the triple mutant. NO produced under non-stressed conditions represses inhibition of seed developmental transitions by ABA. Moreover, NO plays a positive role in post-germinative vegetative development and also exerts a critical control of ABA-related functions on stomata closure. The triple nia1nia2noa1-2 mutant is hypersensitive to ABA in stomatal closure thus resulting in a extreme phenotype of resistance to drought. In the light of the recent discovery of PYR/PYL/RCAR as a family of potential ABA receptors, regulation of ABA sensitivity by NO may be exerted either directly on ABA receptors or on downstream signaling components; both two aspects that deserve our present and future attention.

  4. Catabolism and nitrogen control in Escherichia coli.

    PubMed

    Berberich, M A

    1985-01-01

    It would appear from these studies that nitrogen control reflects the catabolic capacity of the cell and that utilizable nitrogen sources and some carbon sources are, to some extent, in competition for this capacity. The series of catabolic events initiated by addition of D-amino acids or by growth on aldol sugars, in the presence of ammonia nitrogen in the growth medium, provide an opportunity for study of the positive aspect of nitrogen control under conditions where negative control predominates. This approach may eventually clarify the apparent interactions between the modification cascade components, PII and UT/UR, with the nitrogen regulatory gene, glnG. The utilization of nutrients by E. coli seems less a matter of energy than of expeditious use of whatever is offered in the diet. A comparison of the rate of increase of GS on cultural downshift with the rate of increase following D-glutamate addition would suggest that control by nitrogen limitation is about eight times more effective than positive activation by D-glutamate in the presence of ammonia nitrogen. This observation is consistent with the finding of an additive effect for the D-amino acids which can function as positive activators in GS regulation. It has been demonstrated for the wild-type organism that the increase in GS level generated by a mixture of D-glutamate, D-lysine, D-threonine, and glycine approximates the increase in GS level observed during step-down of the culture from an ammonia-sufficient to an ammonia-limited condition. This observation further supports the physiologic relevance of the effect of D-amino acids in nitrogen control and suggests that the apparent derepression of GS observed upon exhaustion of the ammonia nitrogen supply represents a composite of positive activation generated as alternative catabolic functions assume a greater importance. As might be expected, addition of D-glutamate to cells at the point of ammonia exhaustion had no additional positive effect

  5. Isolation and characterization of an osmotic stress and ABA induced histone deacetylase in Arachis hygogaea

    PubMed Central

    Su, Liang-Chen; Deng, Bin; Liu, Shuai; Li, Li-Mei; Hu, Bo; Zhong, Yu-Ting; Li, Ling

    2015-01-01

    Histone acetylation, which together with histone methylation regulates gene activity in response to stress, is an important epigenetic modification. There is an increasing research focus on histone acetylation in crops, but there is no information to date in peanut (Arachis hypogaea). We showed that osmotic stress and ABA affect the acetylation of histone H3 loci in peanut seedlings by immunoblotting experiments. Using RNA-seq data for peanut, we found a RPD3/HDA1-like superfamily histone deacetylase (HDAC), termed AhHDA1, whose gene is up-regulated by PEG-induced water limitation and ABA signaling. We isolated and characterized AhHDA1 from A. hypogaea, showing that AhHDA1 is very similar to an Arabidopsis HDAC (AtHDA6) and, in recombinant form, possesses HDAC activity. To understand whether and how osmotic stress and ABA mediate the peanut stress response by epigenetics, the expression of AhHDA1 and stress-responsive genes following treatment with PEG, ABA, and the specific HDAC inhibitor trichostatin A (TSA) were analyzed. AhHDA1 transcript levels were enhanced by all three treatments, as was expression of peanut transcription factor genes, indicating that AhHDA1 might be involved in the epigenetic regulation of stress resistance genes that comprise the responses to osmotic stress and ABA. PMID:26217363

  6. The Ferredoxin ThnA3 Negatively Regulates Tetralin Biodegradation Gene Expression via ThnY, a Ferredoxin Reductase That Functions as a Regulator of the Catabolic Pathway

    PubMed Central

    Ledesma-García, Laura; Reyes-Ramírez, Francisca; Santero, Eduardo

    2013-01-01

    The genes for tetralin (thn) utilization in Sphingomonasmacrogolitabida strain TFA are regulated at the transcriptional level by ThnR, ThnY and ThnA3. ThnR, a LysR-type transcriptional activator activates transcription specifically in response to tetralin, and ThnY is an iron-sulfur flavoprotein that may activate ThnR by protein-protein interaction. ThnA3, a Rieske-type ferredoxin that transfers electrons to the tetralin dioxygenase, prevents transcription of thn genes when the inducer molecule of the pathway is a poor substrate for the dioxygenase. The mechanism by which ThnA3 transduces this signal to the regulatory system is a major question concerning thn gene regulation. Here, we have confirmed the discriminatory function of ThnA3 and the negative role of its reduced form. We have generated ThnY variants with amino acid exchanges in the [2Fe-2S], FAD and NAD(P) H binding domains and their regulatory properties have been analyzed. Two variants, ThnY-C40S and ThnY-N201G,S206P have completely lost the discriminatory function of the regulatory system because they induced thn gene expression with different molecules such us cis-decalin, cyclohexane, trans-decalin, or benzene, which are not real inducers of the pathway. These results support a model in which ThnA3 exerts its negative modulation via the regulator ThnY. PMID:24069247

  7. Transcriptomic Analysis Reveals Possible Influences of ABA on Secondary Metabolism of Pigments, Flavonoids and Antioxidants in Tomato Fruit during Ripening

    PubMed Central

    Mou, Wangshu; Li, Dongdong; Luo, Zisheng; Mao, Linchun; Ying, Tiejin

    2015-01-01

    Abscisic acid (ABA) has been proven to be involved in the regulation of climacteric fruit ripening, but a comprehensive investigation of its influence on ripening related processes is still lacking. By applying the next generation sequencing technology, we conducted a comparative analysis of the effects of exogenous ABA and NDGA (Nordihydroguaiaretic acid, an inhibitor of ABA biosynthesis) on tomato fruit ripening. The high throughput sequencing results showed that out of the 25728 genes expressed across all three samples, 10388 were identified as significantly differently expressed genes. Exogenous ABA was found to enhance the transcription of genes involved in pigments metabolism, including carotenoids biosynthesis and chlorophyll degradation, whereas NDGA treatment inhibited these processes. The results also revealed the crucial role of ABA in flavonoids synthesis and regulation of antioxidant system. Intriguingly, we also found that an inhibition of endogenous ABA significantly enhanced the transcriptional abundance of genes involved in photosynthesis. Our results highlighted the significance of ABA in regulating tomato ripening, which provided insight into the regulatory mechanism of fruit maturation and senescence process. PMID:26053166

  8. Transcriptomic Analysis Reveals Possible Influences of ABA on Secondary Metabolism of Pigments, Flavonoids and Antioxidants in Tomato Fruit during Ripening.

    PubMed

    Mou, Wangshu; Li, Dongdong; Luo, Zisheng; Mao, Linchun; Ying, Tiejin

    2015-01-01

    Abscisic acid (ABA) has been proven to be involved in the regulation of climacteric fruit ripening, but a comprehensive investigation of its influence on ripening related processes is still lacking. By applying the next generation sequencing technology, we conducted a comparative analysis of the effects of exogenous ABA and NDGA (Nordihydroguaiaretic acid, an inhibitor of ABA biosynthesis) on tomato fruit ripening. The high throughput sequencing results showed that out of the 25728 genes expressed across all three samples, 10388 were identified as significantly differently expressed genes. Exogenous ABA was found to enhance the transcription of genes involved in pigments metabolism, including carotenoids biosynthesis and chlorophyll degradation, whereas NDGA treatment inhibited these processes. The results also revealed the crucial role of ABA in flavonoids synthesis and regulation of antioxidant system. Intriguingly, we also found that an inhibition of endogenous ABA significantly enhanced the transcriptional abundance of genes involved in photosynthesis. Our results highlighted the significance of ABA in regulating tomato ripening, which provided insight into the regulatory mechanism of fruit maturation and senescence process.

  9. Loss of heterophylly in aquatic plants: not ABA-mediated stress but exogenous ABA treatment induces stomatal leaves in Potamogeton perfoliatus.

    PubMed

    Iida, Satoko; Ikeda, Miyuki; Amano, Momoe; Sakayama, Hidetoshi; Kadono, Yasuro; Kosuge, Keiko

    2016-09-01

    Heterophyllous aquatic plants produce aerial (i.e., floating and terrestrial) and submerged leaves-the latter lack stomata-while homophyllous plants contain only submerged leaves, and cannot survive on land. To identify whether differences in morphogenetic potential and/or physiological stress responses are responsible for variation in phenotypic plasticity between two plants types, responses to abscisic acid (ABA) and salinity stress were compared between the closely related, but ecologically diverse pondweeds, Potamogeton wrightii (heterophyllous) and P. perfoliatus (homophyllous). The ABA-treated (1 or 10 μM) P. wrightii plants exhibited heterophylly and produced leaves with stomata. The obligate submerged P. perfoliatus plants were able to produce stomata on their leaves, but there were no changes to leaf shape, and stomatal production occurred only at a high ABA concentration (10 μM). Under salinity stress conditions, only P. wrightii leaves formed stomata. Additionally, the expression of stress-responsive NCED genes, which encode a key enzyme in ABA biosynthesis, was consistently up-regulated in P. wrightii, but only temporarily in P. perfoliatus. The observed species-specific gene expression patterns may be responsible for the induction or suppression of stomatal production during exposure to salinity stress. These results suggest that the two Potamogeton species have an innate morphogenetic ability to form stomata, but the actual production of stomata depends on ABA-mediated stress responses specific to each species and habitat. PMID:27324202

  10. Glutamine alimentation in catabolic state.

    PubMed

    Boelens, P G; Nijveldt, R J; Houdijk, A P; Meijer, S; van Leeuwen, P A

    2001-09-01

    Glutamine should be reclassified as a conditionally essential amino acid in the catabolic state because the body's glutamine expenditures exceed synthesis and low glutamine levels in plasma are associated with poor clinical outcome. After severe stress, several amino acids are mobilized from muscle tissue to supply energy and substrate to the host. Glutamine is one of the most important amino acids that provide this function. Glutamine acts as the preferred respiratory fuel for lymphocytes, hepatocytes and intestinal mucosal cells and is metabolized in the gut to citrulline, ammonium and other amino acids. Low concentrations of glutamine in plasma reflect reduced stores in muscle and this reduced availability of glutamine in the catabolic state seems to correlate with increased morbidity and mortality. Adding glutamine to the nutrition of clinical patients, enterally or parenterally, may reduce morbidity. Several excellent clinical trials have been performed to prove efficacy and feasibility of the use of glutamine supplementation in parenteral and enteral nutrition. The increased intake of glutamine has resulted in lower septic morbidity in certain critically ill patient populations. This review will focus on the efficacy and the importance of glutamine supplementation in diverse catabolic states.

  11. Ureide Catabolism of Soybeans 1

    PubMed Central

    Winkler, Rodney G.; Blevins, Dale G.; Polacco, Joseph C.; Randall, Douglas D.

    1987-01-01

    Allantoin catabolism studies have been extended to intact leaf tissue of soybean (Glycine max L. Merr.). Phenyl phosphordiamidate, one of the most potent urease inhibitors known, does not inhibit 14CO2 release from [2,7-14C]allantoin (urea labeled), but inhibits urea dependent CO2 release ≥99.9% under similar conditions. Furthermore, 14CO2 and [14C] allantoate are the only detectable products of [2,7-14C]allantoin catabolism. Neither urea nor any other product were detected by analysis on HPLC organic acid or organic base columns although urea and all commercially available metabolites that have been implicated in allantoin and glyoxylate metabolism can be resolved by a combination of these two columns. In contrast, when allantoin was labeled in the two central, nonureido carbons ([4,5-14C]allantoin), its catabolism to [14C]allantoate, 14CO2, [14C]glyoxylate, [14C]glycine, and [14C]serine in leaf discs could be detected. These data are fully consistent with the metabolism of allantoate by two amidohydrolase reactions (neither of which is urease) that occur at similar rates to release glyoxylate, which in turn is metabolized via the photorespiratory pathway. This is the first evidence that allantoate is metabolized without urease action to NH4+ and CO2 and that carbons 4 and 5 enter the photorespiratory pathway. PMID:16665292

  12. A transcriptional approach to unravel the connection between phospholipases A₂ and D and ABA signal in citrus under water stress.

    PubMed

    Romero, Paco; Lafuente, M Teresa; Alférez, Fernando

    2014-07-01

    The effect of water stress on the interplay between phospholipases (PL) A2 and D and ABA signalling was investigated in fruit and leaves from the sweet orange Navelate and its fruit-specific ABA-deficient mutant Pinalate by studying simultaneously expression of 5 PLD and 3 PLA2-encoding genes. In general, expression levels of PLD-encoding genes were higher at harvest in the flavedo (coloured outer part of the peel) from Pinalate. Moreover, a higher and transient increase in expression of CsPLDα, CsPLDβ, CsPLDδ and CsPLDζ was observed in the mutant as compared to Navelate fruit under water stress, which may reflect a mechanism of acclimation to water stress influenced by ABA deficiency. An early induction in CsPLDγ gene expression, when increase in peel damage during fruit storage was most evident, suggested a role for this gene in membrane degradation processes during water stress. Exogenous ABA on mutant fruit modified the expression of all PLD genes and reduced the expression of CsPLDα and CsPLDβ by 1 week to levels similar to those of Navelate, suggesting a repressor role of ABA on these genes. In general, CssPLA2α and β transcript levels were lower in flavedo from Pinalate than from Navelate fruit during the first 3 weeks of storage, suggesting that expression of these genes also depends at least partially on ABA levels. Patterns of expression of PLD and PLA2-encoding genes were very similar in Navelate and Pinalate leaves, which have similar ABA levels, when comparing both RH conditions. Results comparison with other from previous works in the same experimental systems helped to decipher the effect of the stress severity on the differential response of some of these genes under dehydration conditions and pointed out the interplay between PLA2 and PLD families and their connection with ABA signalling in citrus. PMID:24713122

  13. A transcriptional approach to unravel the connection between phospholipases A₂ and D and ABA signal in citrus under water stress.

    PubMed

    Romero, Paco; Lafuente, M Teresa; Alférez, Fernando

    2014-07-01

    The effect of water stress on the interplay between phospholipases (PL) A2 and D and ABA signalling was investigated in fruit and leaves from the sweet orange Navelate and its fruit-specific ABA-deficient mutant Pinalate by studying simultaneously expression of 5 PLD and 3 PLA2-encoding genes. In general, expression levels of PLD-encoding genes were higher at harvest in the flavedo (coloured outer part of the peel) from Pinalate. Moreover, a higher and transient increase in expression of CsPLDα, CsPLDβ, CsPLDδ and CsPLDζ was observed in the mutant as compared to Navelate fruit under water stress, which may reflect a mechanism of acclimation to water stress influenced by ABA deficiency. An early induction in CsPLDγ gene expression, when increase in peel damage during fruit storage was most evident, suggested a role for this gene in membrane degradation processes during water stress. Exogenous ABA on mutant fruit modified the expression of all PLD genes and reduced the expression of CsPLDα and CsPLDβ by 1 week to levels similar to those of Navelate, suggesting a repressor role of ABA on these genes. In general, CssPLA2α and β transcript levels were lower in flavedo from Pinalate than from Navelate fruit during the first 3 weeks of storage, suggesting that expression of these genes also depends at least partially on ABA levels. Patterns of expression of PLD and PLA2-encoding genes were very similar in Navelate and Pinalate leaves, which have similar ABA levels, when comparing both RH conditions. Results comparison with other from previous works in the same experimental systems helped to decipher the effect of the stress severity on the differential response of some of these genes under dehydration conditions and pointed out the interplay between PLA2 and PLD families and their connection with ABA signalling in citrus.

  14. Identification and Functional Characterization of Sphingomonas macrogolitabida Strain TFA Genes Involved in the First Two Steps of the Tetralin Catabolic Pathway

    PubMed Central

    Moreno-Ruiz, Emilia; Hernáez, María José; Martínez-Pérez, Olga; Santero, Eduardo

    2003-01-01

    Five genes involved in the two initial steps of the tetralin biodegradation pathway of Sphingomonas macrogolitabida strain TFA have been characterized. ThnA1A2 and ThnA3A4, components of the ring-hydroxylating dioxygenase, were encoded in divergently transcribed operons. ThnA1, ThnA2, and ThnA3 were essential for tetralin ring-hydroxylating dioxygenase activity. ThnB was identified as a dehydrogenase required for tetralin biodegradation. PMID:12618469

  15. Pathway and enzyme redundancy in putrescine catabolism in Escherichia coli.

    PubMed

    Schneider, Barbara L; Reitzer, Larry

    2012-08-01

    Putrescine as the sole carbon source requires a novel catabolic pathway with glutamylated intermediates. Nitrogen limitation does not induce genes of this glutamylated putrescine (GP) pathway but instead induces genes for a putrescine catabolic pathway that starts with a transaminase-dependent deamination. We determined pathway utilization with putrescine as the sole nitrogen source by examining mutants with defects in both pathways. Blocks in both the GP and transaminase pathways were required to prevent growth with putrescine as the sole nitrogen source. Genetic and biochemical analyses showed redundant enzymes for γ-aminobutyraldehyde dehydrogenase (PatD/YdcW and PuuC), γ-aminobutyrate transaminase (GabT and PuuE), and succinic semialdehyde dehydrogenase (GabD and PuuC). PuuC is a nonspecific aldehyde dehydrogenase that oxidizes all the aldehydes in putrescine catabolism. A puuP mutant failed to use putrescine as the nitrogen source, which implies one major transporter for putrescine as the sole nitrogen source. Analysis of regulation of the GP pathway shows induction by putrescine and not by a product of putrescine catabolism and shows that putrescine accumulates in puuA, puuB, and puuC mutants but not in any other mutant. We conclude that two independent sets of enzymes can completely degrade putrescine to succinate and that their relative importance depends on the environment.

  16. Pathway and Enzyme Redundancy in Putrescine Catabolism in Escherichia coli

    PubMed Central

    Schneider, Barbara L.

    2012-01-01

    Putrescine as the sole carbon source requires a novel catabolic pathway with glutamylated intermediates. Nitrogen limitation does not induce genes of this glutamylated putrescine (GP) pathway but instead induces genes for a putrescine catabolic pathway that starts with a transaminase-dependent deamination. We determined pathway utilization with putrescine as the sole nitrogen source by examining mutants with defects in both pathways. Blocks in both the GP and transaminase pathways were required to prevent growth with putrescine as the sole nitrogen source. Genetic and biochemical analyses showed redundant enzymes for γ-aminobutyraldehyde dehydrogenase (PatD/YdcW and PuuC), γ-aminobutyrate transaminase (GabT and PuuE), and succinic semialdehyde dehydrogenase (GabD and PuuC). PuuC is a nonspecific aldehyde dehydrogenase that oxidizes all the aldehydes in putrescine catabolism. A puuP mutant failed to use putrescine as the nitrogen source, which implies one major transporter for putrescine as the sole nitrogen source. Analysis of regulation of the GP pathway shows induction by putrescine and not by a product of putrescine catabolism and shows that putrescine accumulates in puuA, puuB, and puuC mutants but not in any other mutant. We conclude that two independent sets of enzymes can completely degrade putrescine to succinate and that their relative importance depends on the environment. PMID:22636776

  17. The Arabidopsis MIEL1 E3 ligase negatively regulates ABA signalling by promoting protein turnover of MYB96.

    PubMed

    Lee, Hong Gil; Seo, Pil Joon

    2016-01-01

    The phytohormone abscisic acid (ABA) regulates plant responses to various environmental challenges. Controlled protein turnover is an important component of ABA signalling. Here we show that the RING-type E3 ligase MYB30-INTERACTING E3 LIGASE 1 (MIEL1) regulates ABA sensitivity by promoting MYB96 turnover in Arabidopsis. Germination of MIEL1-deficient mutant seeds is hypersensitive to ABA, whereas MIEL1-overexpressing transgenic seeds are less sensitive. MIEL1 can interact with MYB96, a regulator of ABA signalling, and stimulate its ubiquitination and degradation. Genetic analysis shows that MYB96 is epistatic to MIEL1 in the control of ABA sensitivity in seeds. While MIEL1 acts primarily via MYB96 in seed germination, MIEL1 regulates protein turnover of both MYB96 and MYB30 in vegetative tissues. We find that ABA regulates the expression of MYB30-responsive genes during pathogen infection and this regulation is partly dependent on MIEL1. These results suggest that MIEL1 may facilitate crosstalk between ABA and biotic stress signalling. PMID:27615387

  18. The Arabidopsis MIEL1 E3 ligase negatively regulates ABA signalling by promoting protein turnover of MYB96

    PubMed Central

    Lee, Hong Gil; Seo, Pil Joon

    2016-01-01

    The phytohormone abscisic acid (ABA) regulates plant responses to various environmental challenges. Controlled protein turnover is an important component of ABA signalling. Here we show that the RING-type E3 ligase MYB30-INTERACTING E3 LIGASE 1 (MIEL1) regulates ABA sensitivity by promoting MYB96 turnover in Arabidopsis. Germination of MIEL1-deficient mutant seeds is hypersensitive to ABA, whereas MIEL1-overexpressing transgenic seeds are less sensitive. MIEL1 can interact with MYB96, a regulator of ABA signalling, and stimulate its ubiquitination and degradation. Genetic analysis shows that MYB96 is epistatic to MIEL1 in the control of ABA sensitivity in seeds. While MIEL1 acts primarily via MYB96 in seed germination, MIEL1 regulates protein turnover of both MYB96 and MYB30 in vegetative tissues. We find that ABA regulates the expression of MYB30-responsive genes during pathogen infection and this regulation is partly dependent on MIEL1. These results suggest that MIEL1 may facilitate crosstalk between ABA and biotic stress signalling. PMID:27615387

  19. The ABA receptor PYL9 together with PYL8 plays an important role in regulating lateral root growth.

    PubMed

    Xing, Lu; Zhao, Yang; Gao, Jinghui; Xiang, Chengbin; Zhu, Jian-Kang

    2016-01-01

    Abscisic acid is a phytohormone regulating plant growth, development and stress responses. PYR1/PYL/RCAR proteins are ABA receptors that function by inhibiting PP2Cs to activate SnRK2s, resulting in phosphorylation of ABFs and other effectors of ABA response pathways. Exogenous ABA induces growth quiescence of lateral roots, which is prolonged by knockout of the ABA receptor PYL8. Among the 14 members of PYR1/PYL/RCAR protein family, PYL9 is a close relative of PYL8. Here we show that knockout of both PYL9 and PYL8 resulted in a longer ABA-induced quiescence on lateral root growth and a reduced sensitivity to ABA on primary root growth and lateral root formation compared to knockout of PYL8 alone. Induced overexpression of PYL9 promoted the lateral root elongation in the presence of ABA. The prolonged quiescent phase of the pyl8-1pyl9 double mutant was reversed by exogenous IAA. PYL9 may regulate auxin-responsive genes in vivo through direct interaction with MYB77 and MYB44. Thus, PYL9 and PYL8 are both responsible for recovery of lateral root from ABA inhibition via MYB transcription factors. PMID:27256015

  20. The ABA receptor PYL9 together with PYL8 plays an important role in regulating lateral root growth

    PubMed Central

    Xing, Lu; Zhao, Yang; Gao, Jinghui; Xiang, Chengbin; Zhu, Jian-Kang

    2016-01-01

    Abscisic acid is a phytohormone regulating plant growth, development and stress responses. PYR1/PYL/RCAR proteins are ABA receptors that function by inhibiting PP2Cs to activate SnRK2s, resulting in phosphorylation of ABFs and other effectors of ABA response pathways. Exogenous ABA induces growth quiescence of lateral roots, which is prolonged by knockout of the ABA receptor PYL8. Among the 14 members of PYR1/PYL/RCAR protein family, PYL9 is a close relative of PYL8. Here we show that knockout of both PYL9 and PYL8 resulted in a longer ABA-induced quiescence on lateral root growth and a reduced sensitivity to ABA on primary root growth and lateral root formation compared to knockout of PYL8 alone. Induced overexpression of PYL9 promoted the lateral root elongation in the presence of ABA. The prolonged quiescent phase of the pyl8-1pyl9 double mutant was reversed by exogenous IAA. PYL9 may regulate auxin-responsive genes in vivo through direct interaction with MYB77 and MYB44. Thus, PYL9 and PYL8 are both responsible for recovery of lateral root from ABA inhibition via MYB transcription factors. PMID:27256015

  1. Genetic analysis of the agrocinopine catabolic region of Agrobacterium tumefaciens Ti plasmid pTiC58, which encodes genes required for opine and agrocin 84 transport.

    PubMed Central

    Hayman, G T; Beck von Bodman, S; Kim, H; Jiang, P; Farrand, S K

    1993-01-01

    The acc region, subcloned from pTiC58 of classical nopaline and agrocinopine A and B Agrobacterium tumefaciens C58, allowed agrobacteria to grow using agrocinopine B as the sole source of carbon and energy. acc is approximately 6 kb in size. It consists of at least five genes, accA through accE, as defined by complementation analysis using subcloned fragments and transposon insertion mutations of acc carried on different plasmids within the same cell. All five regions are required for agrocin 84 sensitivity, and at least four are required for agrocinopine and agrocin 84 uptake. The complementation results are consistent with the hypothesis that each of the five regions is separately transcribed. Maxicell experiments showed that the first of these genes, accA, encodes a 60-kDa protein. Analysis of osmotic shock fractions showed this protein to be located in the periplasm. The DNA sequence of the accA region revealed an open reading frame encoding a predicted polypeptide of 59,147 Da. The amino acid sequence encoded by this open reading frame is similar to the periplasmic binding proteins OppA and DppA of Escherichia coli and Salmonella typhimurium and OppA of Bacillus subtilis. Images PMID:8366042

  2. A second 5-carboxyvanillate decarboxylase gene, ligW2, is important for lignin-related biphenyl catabolism in Sphingomonas paucimobilis SYK-6.

    PubMed

    Peng, Xue; Masai, Eiji; Kasai, Daisuke; Miyauchi, Keisuke; Katayama, Yoshihiro; Fukuda, Masao

    2005-09-01

    A lignin-related biphenyl compound, 5,5'-dehydrodivanillate (DDVA), is degraded to 5-carboxyvanillate (5CVA) by the enzyme reactions catalyzed by DDVA O-demethylase (LigX), meta-cleavage oxygenase (LigZ), and meta-cleavage compound hydrolase (LigY) in Sphingomonas paucimobilis SYK-6. 5CVA is then transformed to vanillate by a nonoxidative 5CVA decarboxylase and is further degraded through the protocatechuate 4,5-cleavage pathway. A 5CVA decarboxylase gene, ligW, was isolated from SYK-6 (X. Peng, E. Masai, H. Kitayama, K. Harada, Y, Katayama, and M. Fukuda, Appl. Environ. Microbiol. 68:4407-4415, 2002). However, disruption of ligW slightly affected the 5CVA decarboxylase activity and the growth rate on DDVA of the mutant, suggesting the presence of an alternative 5CVA decarboxylase gene. Here we isolated a second 5CVA decarboxylase gene, ligW2, which consists of a 1,050-bp open reading frame encoding a polypeptide with a molecular mass of 39,379 Da. The deduced amino acid sequence encoded by ligW2 exhibits 37% identity with the sequence encoded by ligW. Based on a gas chromatography-mass spectrometry analysis of the reaction product from 5CVA catalyzed by LigW2 in the presence of deuterium oxide, LigW2 was indicated to be a nonoxidative decarboxylase of 5CVA, like LigW. After disruption of ligW2, both the growth rate on DDVA and the 5CVA decarboxylase activity of the mutant were decreased to approximately 30% of the wild-type levels. The ligW ligW2 double mutant lost both the ability to grow on DDVA and the 5CVA decarboxylase activity. These results indicate that both ligW and ligW2 contribute to 5CVA degradation, although ligW2 plays the more important role in the growth of SYK-6 cells on DDVA.

  3. Cross-talk modulation between ABA and ethylene by transcription factor SlZFP2 during fruit development and ripening in tomato.

    PubMed

    Weng, Lin; Zhao, Fangfang; Li, Rong; Xiao, Han

    2015-01-01

    The stress hormone ABA not only regulates stress response, but is also required for plant development and growth. Some evidences indicate that ABA plays a pivotal role in the ripening process of non climacteric as well as climacteric fruits. In a recent study, we showed that the tomato (Solanum lycopersicum) transcription factor SlZFP2 fine tunes ABA biosynthesis during fruit development through direct suppression of ABA biosynthetic genes and it also regulates fruit ripening through transcriptional suppression of the ripening regulator CNR. This indicates that SlZFP2 likely modulates the cross-talk between ABA and ethylene in regulation of fruit development and ripening in tomato. Gene expression analysis using ABA deficient mutants sit and flc as well as the SlZFP2 RNAi lines of high fruit ABA production showed that ethylene biosynthetic genes LeACS1A, LeACS1 and LeACO1 were positively regulated by ABA during early fruit growth. We reason that ABA promotes basal ethylene biosynthesis in system 1 during fruit growth and likely plays a minor role in ripening regulation after the onset of ripening process.

  4. Neanderthal ancestry drives evolution of lipid catabolism in contemporary Europeans

    PubMed Central

    Khrameeva, Ekaterina E.; Bozek, Katarzyna; He, Liu; Yan, Zheng; Jiang, Xi; Wei, Yuning; Tang, Kun; Gelfand, Mikhail S.; Prufer, Kay; Kelso, Janet; Paabo, Svante; Giavalisco, Patrick; Lachmann, Michael; Khaitovich, Philipp

    2014-01-01

    Although Neanderthals are extinct, fragments of their genomes persist in contemporary humans. Here we show that while the genome-wide frequency of Neanderthal-like sites is approximately constant across all contemporary out-of-Africa populations, genes involved in lipid catabolism contain more than threefold excess of such sites in contemporary humans of European descent. Evolutionally, these genes show significant association with signatures of recent positive selection in the contemporary European, but not Asian or African populations. Functionally, the excess of Neanderthal-like sites in lipid catabolism genes can be linked with a greater divergence of lipid concentrations and enzyme expression levels within this pathway, seen in contemporary Europeans, but not in the other populations. We conclude that sequence variants that evolved in Neanderthals may have given a selective advantage to anatomically modern humans that settled in the same geographical areas. PMID:24690587

  5. The Arabidopsis F-box E3 ligase RIFP1 plays a negative role in abscisic acid signalling by facilitating ABA receptor RCAR3 degradation.

    PubMed

    Li, Ying; Zhang, Liang; Li, Dekuan; Liu, Zhibin; Wang, Jianmei; Li, Xufeng; Yang, Yi

    2016-03-01

    The phytohormone abscisic acid (ABA) plays a vital role in plant growth and development. The function of ABA is mediated by a group of newly discovered ABA receptors, named PYRABACTIN RESISTANCE 1/PYR-LIKE/REGULATORY COMPONENTS OF ABA RECEPTORs (PYR1/PYLs/RCARs). Here, we report that an Arabidopsis thaliana F-box protein RCAR3 INTERACTING F-BOX PROTEIN 1 (RIFP1) interacts with ABA receptor (RCAR3) and SCF E3 ligase complex subunits Arabidopsis SKP1-LIKE PROTEINs (ASKs) in vitro and in vivo. The rifp1 mutant plants displayed increased ABA-mediated inhibition of seed germination and water loss of detached leaves, while the overexpression of RIFP1 in Arabidopsis led to plants being insensitive to ABA. Meanwhile, the rifp1 mutant plants showed greater tolerance to water deficit. In addition, the RCAR3 protein level was more stable in the rifp1 mutant plants than in the wild-type plants, indicating that RIFP1 facilitates the proteasome degradation of RCAR3. Accordingly, the loss of RIFP1 increased the transcript levels of several ABA-responsive genes. Taken together, these data indicate that RIFP1 plays a negative role in the RCAR3-mediated ABA signalling pathway and likely functions as an adaptor subunit of the SCF ubiquitin ligase complex to regulate ABA receptor RCAR3 stability. PMID:26386272

  6. Genetic characterization of 4-cresol catabolism in Corynebacterium glutamicum.

    PubMed

    Li, Tang; Chen, Xi; Chaudhry, Muhammad Tausif; Zhang, Bo; Jiang, Cheng-Ying; Liu, Shuang-Jiang

    2014-12-20

    Corynebacterium glutamicum uses 4-cresol as sole carbon source for growth. Protocatechuate 3,4-dioxygenase activity had been detected when C. glutamicum was grown with 4-cresol. In this work, we found that 4-cresol was catabolized via 4-hydroxybenzoate and protocatechuate as intermediate metabolites, and a genetic cluster called cre (designated for 4-cresol, creABCDEFGHIR, tagged as ncgl0521-ncgl0531 in NCBI) was identified. The cre gene cluster comprises of 11 genes, and six of them were experimentally confirmed to be involving in 4-cresol catabolism. The genes creD, creE, and creJ were involved in oxidation of 4-cresol into 4-hydroxybenzyl alcohol. The creD encoded a protein showing Mg(2+)-dependent phosphohydrolase activity. The genes creE, creF, creJ encoded a putative P450 system. The creG encoded a NAD(+)-dependent dehydrogenase and catalyzed 4-hydroxybenzyl alcohol to 4-hydroxybenzaldehyde. Two other genes creH and creI were involved in conversion of 4-hydroxybenzyl alcohol to 4-hydroxybenzoate, but their catalytic function is still unknown. Similar genetic clusters with high DNA sequence identity were identified in Arthrobacter and additional Corynebacterium species, suggesting that this genetic organization for 4-cresol catabolism might be more widely distributed in Gram-positive bacteria.

  7. Characterization of the 3-O-methylgallate dioxygenase gene and evidence of multiple 3-O-methylgallate catabolic pathways in Sphingomonas paucimobilis SYK-6.

    PubMed

    Kasai, Daisuke; Masai, Eiji; Miyauchi, Keisuke; Katayama, Yoshihiro; Fukuda, Masao

    2004-08-01

    Sphingomonas paucimobilis SYK-6 is able to grow on various lignin-derived biaryls as the sole source of carbon and energy. These compounds are degraded to vanillate and syringate by the unique and specific enzymes in this strain. Vanillate and syringate are converted to protocatechuate (PCA) and 3-O-methylgallate (3MGA), respectively, by the tetrahydrofolate-dependent O-demethylases. Previous studies have suggested that these compounds are further degraded via the PCA 4,5-cleavage pathway. However, our subsequent analysis of the ligB insertion mutant, which encodes the beta subunit of PCA 4,5-dioxygenase, suggested that at least one alternative route is involved in 3MGA degradation. In the present study, we isolated the desZ gene, which confers 3MGA degradation activity on Escherichia coli. The deduced amino acid sequence of desZ showed ca. 20 to 43% identity with the type II extradiol dioxygenases. Gas chromatography-mass spectrometry analysis suggested that DesZ catalyzes the 3,4-cleavage of 3MGA. Disruption of both desZ and ligB in SYK-6 resulted in loss of the dioxygen-dependent 3MGA transformation activity, but the resulting mutant retained the ability to grow on syringate. We found that the cell extract of the desZ ligB double mutant was able to convert 3MGA to gallate when tetrahydrofolate was added to the reaction mixture, and the cell extract of this mutant degraded gallate to the same degree as the wild type did. All these results suggest that syringate is degraded through multiple 3MGA degradation pathways in which ligAB, desZ, 3MGA O-demethylase, and gallate dioxygenase are participants.

  8. Sucrose and ABA regulate starch biosynthesis in maize through a novel transcription factor, ZmEREB156.

    PubMed

    Huang, Huanhuan; Xie, Sidi; Xiao, Qianlin; Wei, Bin; Zheng, Lanjie; Wang, Yongbin; Cao, Yao; Zhang, Xiangge; Long, Tiandan; Li, Yangping; Hu, Yufeng; Yu, Guowu; Liu, Hanmei; Liu, Yinghong; Huang, Zhi; Zhang, Junjie; Huang, Yubi

    2016-01-01

    Sucrose is not only the carbon source for starch synthesis, but also a signal molecule. Alone or in coordination with ABA, it can regulate the expression of genes involved in starch synthesis. To investigate the molecular mechanisms underlying this effect, maize endosperms were collected from Zea mays L. B73 inbred line 10 d after pollination and treated with sucrose, ABA, or sucrose plus ABA at 28 °C in the dark for 24 h. RNA-sequence analysis of the maize endosperm transcriptome revealed 47 candidate transcription factors among the differentially expressed genes. We therefore speculate that starch synthetic gene expression is regulated by transcription factors induced by the combination of sucrose and ABA. ZmEREB156, a candidate transcription factor, is induced by sucrose plus ABA and is involved in starch biosynthesis. The ZmEREB156-GFP-fused protein was localized in the nuclei of onion epidermal cells, and ZmEREB156 protein possessed strong transcriptional activation activity. Promoter activity of the starch-related genes Zmsh2 and ZmSSIIIa increased after overexpression of ZmEREB156 in maize endosperm. ZmEREB156 could bind to the ZmSSIIIa promoter but not the Zmsh2 promoter in a yeast one-hybrid system. Thus, ZmEREB156 positively modulates starch biosynthetic gene ZmSSIIIa via the synergistic effect of sucrose and ABA.

  9. Sucrose and ABA regulate starch biosynthesis in maize through a novel transcription factor, ZmEREB156

    PubMed Central

    Huang, Huanhuan; Xie, Sidi; Xiao, Qianlin; Wei, Bin; Zheng, Lanjie; Wang, Yongbin; Cao, Yao; Zhang, Xiangge; Long, Tiandan; Li, Yangping; Hu, Yufeng; Yu, Guowu; Liu, Hanmei; Liu, Yinghong; Huang, Zhi; Zhang, Junjie; Huang, Yubi

    2016-01-01

    Sucrose is not only the carbon source for starch synthesis, but also a signal molecule. Alone or in coordination with ABA, it can regulate the expression of genes involved in starch synthesis. To investigate the molecular mechanisms underlying this effect, maize endosperms were collected from Zea mays L. B73 inbred line 10 d after pollination and treated with sucrose, ABA, or sucrose plus ABA at 28 °C in the dark for 24 h. RNA-sequence analysis of the maize endosperm transcriptome revealed 47 candidate transcription factors among the differentially expressed genes. We therefore speculate that starch synthetic gene expression is regulated by transcription factors induced by the combination of sucrose and ABA. ZmEREB156, a candidate transcription factor, is induced by sucrose plus ABA and is involved in starch biosynthesis. The ZmEREB156-GFP-fused protein was localized in the nuclei of onion epidermal cells, and ZmEREB156 protein possessed strong transcriptional activation activity. Promoter activity of the starch-related genes Zmsh2 and ZmSSIIIa increased after overexpression of ZmEREB156 in maize endosperm. ZmEREB156 could bind to the ZmSSIIIa promoter but not the Zmsh2 promoter in a yeast one-hybrid system. Thus, ZmEREB156 positively modulates starch biosynthetic gene ZmSSIIIa via the synergistic effect of sucrose and ABA. PMID:27282997

  10. Sucrose and ABA regulate starch biosynthesis in maize through a novel transcription factor, ZmEREB156.

    PubMed

    Huang, Huanhuan; Xie, Sidi; Xiao, Qianlin; Wei, Bin; Zheng, Lanjie; Wang, Yongbin; Cao, Yao; Zhang, Xiangge; Long, Tiandan; Li, Yangping; Hu, Yufeng; Yu, Guowu; Liu, Hanmei; Liu, Yinghong; Huang, Zhi; Zhang, Junjie; Huang, Yubi

    2016-01-01

    Sucrose is not only the carbon source for starch synthesis, but also a signal molecule. Alone or in coordination with ABA, it can regulate the expression of genes involved in starch synthesis. To investigate the molecular mechanisms underlying this effect, maize endosperms were collected from Zea mays L. B73 inbred line 10 d after pollination and treated with sucrose, ABA, or sucrose plus ABA at 28 °C in the dark for 24 h. RNA-sequence analysis of the maize endosperm transcriptome revealed 47 candidate transcription factors among the differentially expressed genes. We therefore speculate that starch synthetic gene expression is regulated by transcription factors induced by the combination of sucrose and ABA. ZmEREB156, a candidate transcription factor, is induced by sucrose plus ABA and is involved in starch biosynthesis. The ZmEREB156-GFP-fused protein was localized in the nuclei of onion epidermal cells, and ZmEREB156 protein possessed strong transcriptional activation activity. Promoter activity of the starch-related genes Zmsh2 and ZmSSIIIa increased after overexpression of ZmEREB156 in maize endosperm. ZmEREB156 could bind to the ZmSSIIIa promoter but not the Zmsh2 promoter in a yeast one-hybrid system. Thus, ZmEREB156 positively modulates starch biosynthetic gene ZmSSIIIa via the synergistic effect of sucrose and ABA. PMID:27282997

  11. HDL biogenesis, remodeling, and catabolism.

    PubMed

    Zannis, Vassilis I; Fotakis, Panagiotis; Koukos, Georgios; Kardassis, Dimitris; Ehnholm, Christian; Jauhiainen, Matti; Chroni, Angeliki

    2015-01-01

    In this chapter, we review how HDL is generated, remodeled, and catabolized in plasma. We describe key features of the proteins that participate in these processes, emphasizing how mutations in apolipoprotein A-I (apoA-I) and the other proteins affect HDL metabolism. The biogenesis of HDL initially requires functional interaction of apoA-I with the ATP-binding cassette transporter A1 (ABCA1) and subsequently interactions of the lipidated apoA-I forms with lecithin/cholesterol acyltransferase (LCAT). Mutations in these proteins either prevent or impair the formation and possibly the functionality of HDL. Remodeling and catabolism of HDL is the result of interactions of HDL with cell receptors and other membrane and plasma proteins including hepatic lipase (HL), endothelial lipase (EL), phospholipid transfer protein (PLTP), cholesteryl ester transfer protein (CETP), apolipoprotein M (apoM), scavenger receptor class B type I (SR-BI), ATP-binding cassette transporter G1 (ABCG1), the F1 subunit of ATPase (Ecto F1-ATPase), and the cubulin/megalin receptor. Similarly to apoA-I, apolipoprotein E and apolipoprotein A-IV were shown to form discrete HDL particles containing these apolipoproteins which may have important but still unexplored functions. Furthermore, several plasma proteins were found associated with HDL and may modulate its biological functions. The effect of these proteins on the functionality of HDL is the topic of ongoing research. PMID:25522986

  12. Genetic analysis of Physcomitrella patens identifies ABSCISIC ACID NON-RESPONSIVE, a regulator of ABA responses unique to basal land plants and required for desiccation tolerance

    DOE PAGES

    Stevenson, Sean Ross; Kamisugi, Yasuko; Trinh, Chi H.; Schmutz, Jeremy; Jenkins, Jerry W.; Grimwood, Jane; Muchero, Wellington; Tuskan, Gerald A.; Rensing, Stefan A.; Lang, Daniel; et al

    2016-05-18

    The anatomically simple plants that first colonized land must have acquired molecular and biochemical adaptations to drought stress. Abscisic acid (ABA) coordinates responses leading to desiccation tolerance in all land plants. We identified ABA nonresponsive mutants in the model bryophyte Physcomitrella patens and genotyped a segregating population to map and identify the ABA NON-RESPONSIVE (ANR) gene encoding a modular protein kinase comprising an N-terminal PAS domain, a central EDR domain, and a C-terminal MAPKKK-like domain. anr mutants fail to accumulate dehydration tolerance-associated gene products in response to drought, ABA, or osmotic stress and do not acquire ABA-dependent desiccation tolerance. Themore » crystal structure of the PAS domain, determined to 1.7-Å resolution, shows a conserved PAS-fold that dimerizes through a weak dimerization interface. Targeted mutagenesis of a conserved tryptophan residue within the PAS domain generates plants with ABA nonresponsive growth and strongly attenuated ABA-responsive gene expression, whereas deleting this domain retains a fully ABA-responsive phenotype. ANR orthologs are found in early-diverging land plant lineages and aquatic algae but are absent from more recently diverged vascular plants. Lastly, we propose that ANR genes represent an ancestral adaptation that enabled drought stress survival of the first terrestrial colonizers but were lost during land plant evolution.« less

  13. Genetic Analysis of Physcomitrella patens Identifies ABSCISIC ACID NON-RESPONSIVE, a Regulator of ABA Responses Unique to Basal Land Plants and Required for Desiccation Tolerance.

    PubMed

    Stevenson, Sean R; Kamisugi, Yasuko; Trinh, Chi H; Schmutz, Jeremy; Jenkins, Jerry W; Grimwood, Jane; Muchero, Wellington; Tuskan, Gerald A; Rensing, Stefan A; Lang, Daniel; Reski, Ralf; Melkonian, Michael; Rothfels, Carl J; Li, Fay-Wei; Larsson, Anders; Wong, Gane K-S; Edwards, Thomas A; Cuming, Andrew C

    2016-06-01

    The anatomically simple plants that first colonized land must have acquired molecular and biochemical adaptations to drought stress. Abscisic acid (ABA) coordinates responses leading to desiccation tolerance in all land plants. We identified ABA nonresponsive mutants in the model bryophyte Physcomitrella patens and genotyped a segregating population to map and identify the ABA NON-RESPONSIVE (ANR) gene encoding a modular protein kinase comprising an N-terminal PAS domain, a central EDR domain, and a C-terminal MAPKKK-like domain. anr mutants fail to accumulate dehydration tolerance-associated gene products in response to drought, ABA, or osmotic stress and do not acquire ABA-dependent desiccation tolerance. The crystal structure of the PAS domain, determined to 1.7-Å resolution, shows a conserved PAS-fold that dimerizes through a weak dimerization interface. Targeted mutagenesis of a conserved tryptophan residue within the PAS domain generates plants with ABA nonresponsive growth and strongly attenuated ABA-responsive gene expression, whereas deleting this domain retains a fully ABA-responsive phenotype. ANR orthologs are found in early-diverging land plant lineages and aquatic algae but are absent from more recently diverged vascular plants. We propose that ANR genes represent an ancestral adaptation that enabled drought stress survival of the first terrestrial colonizers but were lost during land plant evolution. PMID:27194706

  14. A G-Protein β Subunit, AGB1, Negatively Regulates the ABA Response and Drought Tolerance by Down-Regulating AtMPK6-Related Pathway in Arabidopsis

    PubMed Central

    Xu, Dong-bei; Chen, Ming; Ma, Ya-nan; Xu, Zhao-shi; Li, Lian-cheng; Chen, Yao-feng; Ma, You-zhi

    2015-01-01

    Heterotrimeric G-proteins are versatile regulators involved in diverse cellular processes in eukaryotes. In plants, the function of G-proteins is primarily associated with ABA signaling. However, the downstream effectors and the molecular mechanisms in the ABA pathway remain largely unknown. In this study, an AGB1 mutant (agb1-2) was found to show enhanced drought tolerance, indicating that AGB1 might negatively regulate drought tolerance in Arabidopsis. Data showed that AGB1 interacted with protein kinase AtMPK6 that was previously shown to phosphorylate AtVIP1, a transcription factor responding to ABA signaling. Our study found that transcript levels of three ABA responsive genes, AtMPK6, AtVIP1 and AtMYB44 (downstream gene of AtVIP1), were significantly up-regulated in agb1-2 lines after ABA or drought treatments. Other ABA-responsive and drought-inducible genes, such as RD29A (downstream gene of AtMYB44), were also up-regulated in agb1-2 lines. Furthermore, overexpression of AtVIP1 resulted in hypersensitivity to ABA at seed germination and seedling stages, and significantly enhanced drought tolerance in transgenic plants. These results suggest that AGB1 was involved in the ABA signaling pathway and drought tolerance in Arabidopsis through down-regulating the AtMPK6, AtVIP1 and AtMYB44 cascade. PMID:25635681

  15. Genetic Analysis of Physcomitrella patens Identifies ABSCISIC ACID NON-RESPONSIVE, a Regulator of ABA Responses Unique to Basal Land Plants and Required for Desiccation Tolerance[OPEN

    PubMed Central

    Kamisugi, Yasuko; Trinh, Chi H.; Schmutz, Jeremy; Muchero, Wellington; Melkonian, Michael; Rothfels, Carl J.; Li, Fay-Wei; Larsson, Anders; Edwards, Thomas A.

    2016-01-01

    The anatomically simple plants that first colonized land must have acquired molecular and biochemical adaptations to drought stress. Abscisic acid (ABA) coordinates responses leading to desiccation tolerance in all land plants. We identified ABA nonresponsive mutants in the model bryophyte Physcomitrella patens and genotyped a segregating population to map and identify the ABA NON-RESPONSIVE (ANR) gene encoding a modular protein kinase comprising an N-terminal PAS domain, a central EDR domain, and a C-terminal MAPKKK-like domain. anr mutants fail to accumulate dehydration tolerance-associated gene products in response to drought, ABA, or osmotic stress and do not acquire ABA-dependent desiccation tolerance. The crystal structure of the PAS domain, determined to 1.7-Å resolution, shows a conserved PAS-fold that dimerizes through a weak dimerization interface. Targeted mutagenesis of a conserved tryptophan residue within the PAS domain generates plants with ABA nonresponsive growth and strongly attenuated ABA-responsive gene expression, whereas deleting this domain retains a fully ABA-responsive phenotype. ANR orthologs are found in early-diverging land plant lineages and aquatic algae but are absent from more recently diverged vascular plants. We propose that ANR genes represent an ancestral adaptation that enabled drought stress survival of the first terrestrial colonizers but were lost during land plant evolution. PMID:27194706

  16. Genetic Analysis of Physcomitrella patens Identifies ABSCISIC ACID NON-RESPONSIVE, a Regulator of ABA Responses Unique to Basal Land Plants and Required for Desiccation Tolerance.

    PubMed

    Stevenson, Sean R; Kamisugi, Yasuko; Trinh, Chi H; Schmutz, Jeremy; Jenkins, Jerry W; Grimwood, Jane; Muchero, Wellington; Tuskan, Gerald A; Rensing, Stefan A; Lang, Daniel; Reski, Ralf; Melkonian, Michael; Rothfels, Carl J; Li, Fay-Wei; Larsson, Anders; Wong, Gane K-S; Edwards, Thomas A; Cuming, Andrew C

    2016-06-01

    The anatomically simple plants that first colonized land must have acquired molecular and biochemical adaptations to drought stress. Abscisic acid (ABA) coordinates responses leading to desiccation tolerance in all land plants. We identified ABA nonresponsive mutants in the model bryophyte Physcomitrella patens and genotyped a segregating population to map and identify the ABA NON-RESPONSIVE (ANR) gene encoding a modular protein kinase comprising an N-terminal PAS domain, a central EDR domain, and a C-terminal MAPKKK-like domain. anr mutants fail to accumulate dehydration tolerance-associated gene products in response to drought, ABA, or osmotic stress and do not acquire ABA-dependent desiccation tolerance. The crystal structure of the PAS domain, determined to 1.7-Å resolution, shows a conserved PAS-fold that dimerizes through a weak dimerization interface. Targeted mutagenesis of a conserved tryptophan residue within the PAS domain generates plants with ABA nonresponsive growth and strongly attenuated ABA-responsive gene expression, whereas deleting this domain retains a fully ABA-responsive phenotype. ANR orthologs are found in early-diverging land plant lineages and aquatic algae but are absent from more recently diverged vascular plants. We propose that ANR genes represent an ancestral adaptation that enabled drought stress survival of the first terrestrial colonizers but were lost during land plant evolution.

  17. GsAPK, an ABA-activated and calcium-independent SnRK2-type kinase from G. soja, mediates the regulation of plant tolerance to salinity and ABA stress.

    PubMed

    Yang, Liang; Ji, Wei; Gao, Peng; Li, Yong; Cai, Hua; Bai, Xi; Chen, Qin; Zhu, Yanming

    2012-01-01

    Plant Snf1 (sucrose non-fermenting-1) related protein kinase (SnRK), a subfamily of serine/threonine kinases, has been implicated as a crucial upstream regulator of ABA and osmotic signaling as in many other signaling cascades. In this paper, we have isolated a novel plant specific ABA activated calcium independent protein kinase (GsAPK) from a highly salt tolerant plant, Glycine soja (50109), which is a member of the SnRK2 family. Subcellular localization studies using GFP fusion protein indicated that GsAPK is localized in the plasma membrane. We found that autophosphorylation and Myelin Basis Protein phosphorylation activity of GsAPK is only activated by ABA and the kinase activity also was observed when calcium was replaced by EGTA, suggesting its independence of calcium in enzyme activity. We also found that cold, salinity, drought, and ABA stress alter GsAPK gene transcripts and heterogonous overexpression of GsAPK in Arabidopsis alters plant tolerance to high salinity and ABA stress. In summary, we demonstrated that GsAPK is a Glycine soja ABA activated calcium independent SnRK-type kinase presumably involved in ABA mediated stress signal transduction.

  18. An ABA-increased interaction of the PYL6 ABA receptor with MYC2 Transcription Factor: A putative link of ABA and JA signaling

    PubMed Central

    Aleman, Fernando; Yazaki, Junshi; Lee, Melissa; Takahashi, Yohei; Kim, Alice Y.; Li, Zixing; Kinoshita, Toshinori; Ecker, Joseph R.; Schroeder, Julian I.

    2016-01-01

    Abscisic acid (ABA) is a plant hormone that mediates abiotic stress tolerance and regulates growth and development. ABA binds to members of the PYL/RCAR ABA receptor family that initiate signal transduction inhibiting type 2C protein phosphatases. Although crosstalk between ABA and the hormone Jasmonic Acid (JA) has been shown, the molecular entities that mediate this interaction have yet to be fully elucidated. We report a link between ABA and JA signaling through a direct interaction of the ABA receptor PYL6 (RCAR9) with the basic helix-loop-helix transcription factor MYC2. PYL6 and MYC2 interact in yeast two hybrid assays and the interaction is enhanced in the presence of ABA. PYL6 and MYC2 interact in planta based on bimolecular fluorescence complementation and co-immunoprecipitation of the proteins. Furthermore, PYL6 was able to modify transcription driven by MYC2 using JAZ6 and JAZ8 DNA promoter elements in yeast one hybrid assays. Finally, pyl6 T-DNA mutant plants show an increased sensitivity to the addition of JA along with ABA in cotyledon expansion experiments. Overall, the present study identifies a direct mechanism for transcriptional modulation mediated by an ABA receptor different from the core ABA signaling pathway, and a putative mechanistic link connecting ABA and JA signaling pathways. PMID:27357749

  19. Elevated CO2-Induced Responses in Stomata Require ABA and ABA Signaling.

    PubMed

    Chater, Caspar; Peng, Kai; Movahedi, Mahsa; Dunn, Jessica A; Walker, Heather J; Liang, Yun-Kuan; McLachlan, Deirdre H; Casson, Stuart; Isner, Jean Charles; Wilson, Ian; Neill, Steven J; Hedrich, Rainer; Gray, Julie E; Hetherington, Alistair M

    2015-10-19

    An integral part of global environment change is an increase in the atmospheric concentration of CO2 ([CO2]) [1]. Increased [CO2] reduces leaf stomatal apertures and density of stomata that plays out as reductions in evapotranspiration [2-4]. Surprisingly, given the importance of transpiration to the control of terrestrial water fluxes [5] and plant nutrient acquisition [6], we know comparatively little about the molecular components involved in the intracellular signaling pathways by which [CO2] controls stomatal development and function [7]. Here, we report that elevated [CO2]-induced closure and reductions in stomatal density require the generation of reactive oxygen species (ROS), thereby adding a new common element to these signaling pathways. We also show that the PYR/RCAR family of ABA receptors [8, 9] and ABA itself are required in both responses. Using genetic approaches, we show that ABA in guard cells or their precursors is sufficient to mediate the [CO2]-induced stomatal density response. Taken together, our results suggest that stomatal responses to increased [CO2] operate through the intermediacy of ABA. In the case of [CO2]-induced reductions in stomatal aperture, this occurs by accessing the guard cell ABA signaling pathway. In both [CO2]-mediated responses, our data are consistent with a mechanism in which ABA increases the sensitivity of the system to [CO2] but could also be explained by requirement for a CO2-induced increase in ABA biosynthesis specifically in the guard cell lineage. Furthermore, the dependency of stomatal [CO2] signaling on ABA suggests that the ABA pathway is, in evolutionary terms, likely to be ancestral.

  20. Elevated CO2-Induced Responses in Stomata Require ABA and ABA Signaling.

    PubMed

    Chater, Caspar; Peng, Kai; Movahedi, Mahsa; Dunn, Jessica A; Walker, Heather J; Liang, Yun-Kuan; McLachlan, Deirdre H; Casson, Stuart; Isner, Jean Charles; Wilson, Ian; Neill, Steven J; Hedrich, Rainer; Gray, Julie E; Hetherington, Alistair M

    2015-10-19

    An integral part of global environment change is an increase in the atmospheric concentration of CO2 ([CO2]) [1]. Increased [CO2] reduces leaf stomatal apertures and density of stomata that plays out as reductions in evapotranspiration [2-4]. Surprisingly, given the importance of transpiration to the control of terrestrial water fluxes [5] and plant nutrient acquisition [6], we know comparatively little about the molecular components involved in the intracellular signaling pathways by which [CO2] controls stomatal development and function [7]. Here, we report that elevated [CO2]-induced closure and reductions in stomatal density require the generation of reactive oxygen species (ROS), thereby adding a new common element to these signaling pathways. We also show that the PYR/RCAR family of ABA receptors [8, 9] and ABA itself are required in both responses. Using genetic approaches, we show that ABA in guard cells or their precursors is sufficient to mediate the [CO2]-induced stomatal density response. Taken together, our results suggest that stomatal responses to increased [CO2] operate through the intermediacy of ABA. In the case of [CO2]-induced reductions in stomatal aperture, this occurs by accessing the guard cell ABA signaling pathway. In both [CO2]-mediated responses, our data are consistent with a mechanism in which ABA increases the sensitivity of the system to [CO2] but could also be explained by requirement for a CO2-induced increase in ABA biosynthesis specifically in the guard cell lineage. Furthermore, the dependency of stomatal [CO2] signaling on ABA suggests that the ABA pathway is, in evolutionary terms, likely to be ancestral. PMID:26455301

  1. A Dual-Function Transcription Factor, AtYY1, Is a Novel Negative Regulator of the Arabidopsis ABA Response Network.

    PubMed

    Li, Tian; Wu, Xiu-Yun; Li, Hui; Song, Jian-Hui; Liu, Jin-Yuan

    2016-05-01

    Abscisic acid (ABA) plays crucial roles in plant growth and development, as well as in response to various environmental stresses. To date, many regulatory genes involved in the ABA response network have been identified; however, their roles have remained to be fully elucidated. In this study, we identified AtYY1, an Arabidopsis homolog of the mammalian C2H2 zinc-finger transcription factor Yin Yang 1 (YY1), as a novel negative regulator of the ABA response. AtYY1 is a dual-function transcription factor with both repression and activation domains. The expression of AtYY1 was induced by ABA and stress conditions including high salt and dehydration. The yy1 mutant was more sensitive to ABA and NaCl than the wild-type, while overexpressing AtYY1 plants were less sensitive. AtYY1 loss also enhanced ABA-induced stomatal closing and drought resistance. Moreover, AtYY1 can bind the ABA REPRESSOR1 (ABR1) promoter and directly upregulate ABR1 expression, as well as negatively regulate ABA- and salt-responsive gene expression. Additional analysis indicated that ABA INSENSITIVE4 (ABI4) might positively regulate AtYY1 expression and that ABR1 can antagonize this regulation. Our findings provide direct evidence that AtYY1 is a novel negative regulator of the ABA response network and that the ABI4-AtYY1-ABR1 regulatory pathway may fine-tune ABA-responsive gene expression in Arabidopsis. PMID:26961720

  2. A Role for Arabidopsis miR399f in Salt, Drought, and ABA Signaling

    PubMed Central

    Baek, Dongwon; Chun, Hyun Jin; Kang, Songhwa; Shin, Gilok; Park, Su Jung; Hong, Hyewon; Kim, Chanmin; Kim, Doh Hoon; Lee, Sang Yeol; Kim, Min Chul; Yun, Dae-Jin

    2016-01-01

    MiR399f plays a crucial role in maintaining phosphate homeostasis in Arabidopsis thaliana. Under phosphate starvation conditions, AtMYB2, which plays a role in plant salt and drought stress responses, directly regulates the expression of miR399f. In this study, we found that miR399f also participates in plant responses to abscisic acid (ABA), and to abiotic stresses including salt and drought. Salt and ABA treatment induced the expression of miR399f, as confirmed by histochemical analysis of promoter-GUS fusions. Transgenic Arabidopsis plants overexpressing miR399f (miR399f-OE) exhibited enhanced tolerance to salt stress and exogenous ABA, but hypersensitivity to drought. Our in silico analysis identified ABF3 and CSP41b as putative target genes of miR399f, and expression analysis revealed that mRNA levels of ABF3 and CSP41b decreased remarkably in miR399f-OE plants under salt stress and in response to treatment with ABA. Moreover, we showed that activation of stress-responsive gene expression in response to salt stress and ABA treatment was impaired in miR399f-OE plants. Thus, these results suggested that in addition to phosphate starvation signaling, miR399f might also modulates plant responses to salt, ABA, and drought, by regulating the expression of newly discovered target genes such as ABF3 and CSP41b. PMID:26674968

  3. Bacterial Cytochrome P450 System Catabolizing the Fusarium Toxin Deoxynivalenol

    PubMed Central

    Ito, Michihiro; Sato, Ikuo; Ishizaka, Masumi; Yoshida, Shin-ichiro; Koitabashi, Motoo; Yoshida, Shigenobu

    2013-01-01

    Deoxynivalenol (DON) is a natural toxin of fungi that cause Fusarium head blight disease of wheat and other small-grain cereals. DON accumulates in infected grains and promotes the spread of the infection on wheat, posing serious problems to grain production. The elucidation of DON-catabolic genes and enzymes in DON-degrading microbes will provide new approaches to decrease DON contamination. Here, we report a cytochrome P450 system capable of catabolizing DON in Sphingomonas sp. strain KSM1, a DON-utilizing bacterium newly isolated from lake water. The P450 gene ddnA was cloned through an activity-based screening of a KSM1 genomic library. The genes of its redox partner candidates (flavin adenine dinucleotide [FAD]-dependent ferredoxin reductase and mitochondrial-type [2Fe-2S] ferredoxin) were not found adjacent to ddnA; the redox partner candidates were further cloned separately based on conserved motifs. The DON-catabolic activity was reconstituted in vitro in an electron transfer chain comprising the three enzymes and NADH, with a catalytic efficiency (kcat/Km) of 6.4 mM−1 s−1. The reaction product was identified as 16-hydroxy-deoxynivalenol. A bioassay using wheat seedlings revealed that the hydroxylation dramatically reduced the toxicity of DON to wheat. The enzyme system showed similar catalytic efficiencies toward nivalenol and 3-acetyl deoxynivalenol, toxins that frequently cooccur with DON. These findings identify an enzyme system that catabolizes DON, leading to reduced phytotoxicity to wheat. PMID:23275503

  4. Pyrabactin, an ABA agonist, induced stomatal closure and changes in signalling components of guard cells in abaxial epidermis of Pisum sativum.

    PubMed

    Puli, Mallikarjuna Rao; Raghavendra, Agepati S

    2012-02-01

    Pyrabactin, a synthetic agonist of abscisic acid (ABA), inhibits seed germination and hypocotyl growth and stimulates gene expression in a very similar way to ABA, implying the possible modulation of stomatal function by pyrabactin as well. The effect of pyrabactin on stomatal closure and secondary messengers was therefore studied in guard cells of Pisum sativum abaxial epidermis. Pyrabactin caused marked stomatal closure in a pattern similar to ABA. In addition, pyrabactin elevated the levels of reactive oxygen species (ROS), nitric oxide (NO), and cytoplasmic pH levels in guard cells, as indicated by the respective fluorophores. However, apyrabactin, an inactive analogue of ABA, did not affect either stomatal closure or the signalling components of guard cells. The effects of pyrabactin-induced changes were reversed by pharmalogical compounds that modulate ROS, NO or cytoplasmic pH levels, quite similar to ABA effects. Fusicoccin, a fungal toxin, could reverse the stomatal closure caused by pyrabactin, as well as that caused by ABA. Experiments on stomatal closure by varying concentrations of ABA, in the presence of fixed concentration of pyrabactin, and vice versa, revealed that the actions of ABA and pyrabactin were additive. Further kinetic analysis of data revealed that the apparent K(D) of ABA was increased almost 4-fold in the presence of ABA, suggesting that pyrabactin and ABA were competing with each other either at the same site or close to the active site. It is proposed that pyrabactin could be used to examine the ABA-related signal-transduction components in stomatal guard cells as well as in other plant tissues. It is also suggested that pyrabactin can be used as an antitranspirant or as a priming agent for improving the drought tolerance of crop plants.

  5. MhNCED3 in Malus hupehensis Rehd. induces NO generation under osmotic stress by regulating ABA accumulation.

    PubMed

    Zhang, Wei-wei; Yang, Hong-qiang; You, Shu-zhen; Ran, Kun

    2015-11-01

    Abscisic acid (ABA) biosynthesis has been widely characterized in plants, whereas the effects of ABA biosynthesis on nitric oxide (NO) generation in osmotic stress are less well understood. In this study, Malus hupehensis Rehd. 9-cis-epoxycarotenoid dioxygenase gene (MhNCED3) which is the key gene in ABA biosynthesis was transformed into wild type (WT) and 129B08/nced3 mutant (AtNCED3 deficient), respectively, and two transgenic Arabidopsis lines were obtained. The transgenic Arabidopsis lines displayed higher endogenous ABA content, NO generation rate, AtNIA1 transcript level and nitrate reductase (NR) activity than WT and 129B08/nced3 mutant. Ectopic expression of MhNCED3 reduced the electrolyte leakage and relieved Arabidopsis damage caused by 20% PEG on the growth and development. The ABA content, NO generation rate, AtNIA1 expression and NR activity increased after 20% PEG treatment, importantly, their increases amplitude relative to that in control were higher in two transgenic lines. Additionally, during the treatment for the four genotype Arabidopsis, the time of ABA contents reaching the highest peak was earlier than the time of NO generation, AtNIA1 expression and NR activity reaching their highest peak. These results show that NCED gene indirectly induced endogenous NO generation in osmotic-stressed Arabidopsis partially contributing to the up-regulation of AtNIA1 expression and NR activity.

  6. Grafting cucumber onto luffa improves drought tolerance by increasing ABA biosynthesis and sensitivity.

    PubMed

    Liu, Shanshan; Li, Hao; Lv, Xiangzhang; Ahammed, Golam Jalal; Xia, Xiaojian; Zhou, Jie; Shi, Kai; Asami, Tadao; Yu, Jingquan; Zhou, Yanhong

    2016-01-01

    Balancing stomata-dependent CO2 assimilation and transpiration is a key challenge for increasing crop productivity and water use efficiency under drought stress for sustainable crop production worldwide. Here, we show that cucumber and luffa plants with luffa as rootstock have intrinsically increased water use efficiency, decreased transpiration rate and less affected CO2 assimilation capacity following drought stress over those with cucumber as rootstock. Drought accelerated abscisic acid (ABA) accumulation in roots, xylem sap and leaves, and induced the transcript of ABA signaling genes, leading to a decreased stomatal aperture and transpiration in the plants grafted onto luffa roots as compared to plants grafted onto cucumber roots. Furthermore, stomatal movement in the plants grafted onto luffa roots had an increased sensitivity to ABA. Inhibition of ABA biosynthesis in luffa roots decreased the drought tolerance in cucumber and luffa plants. Our study demonstrates that the roots of luffa have developed an enhanced ability to sense the changes in root-zone moisture and could eventually deliver modest level of ABA from roots to shoots that enhances water use efficiency under drought stress. Such a mechanism could be greatly exploited to benefit the agricultural production especially in arid and semi-arid areas. PMID:26832070

  7. Grafting cucumber onto luffa improves drought tolerance by increasing ABA biosynthesis and sensitivity

    PubMed Central

    Liu, Shanshan; Li, Hao; Lv, Xiangzhang; Ahammed, Golam Jalal; Xia, Xiaojian; Zhou, Jie; Shi, Kai; Asami, Tadao; Yu, Jingquan; Zhou, Yanhong

    2016-01-01

    Balancing stomata-dependent CO2 assimilation and transpiration is a key challenge for increasing crop productivity and water use efficiency under drought stress for sustainable crop production worldwide. Here, we show that cucumber and luffa plants with luffa as rootstock have intrinsically increased water use efficiency, decreased transpiration rate and less affected CO2 assimilation capacity following drought stress over those with cucumber as rootstock. Drought accelerated abscisic acid (ABA) accumulation in roots, xylem sap and leaves, and induced the transcript of ABA signaling genes, leading to a decreased stomatal aperture and transpiration in the plants grafted onto luffa roots as compared to plants grafted onto cucumber roots. Furthermore, stomatal movement in the plants grafted onto luffa roots had an increased sensitivity to ABA. Inhibition of ABA biosynthesis in luffa roots decreased the drought tolerance in cucumber and luffa plants. Our study demonstrates that the roots of luffa have developed an enhanced ability to sense the changes in root-zone moisture and could eventually deliver modest level of ABA from roots to shoots that enhances water use efficiency under drought stress. Such a mechanism could be greatly exploited to benefit the agricultural production especially in arid and semi-arid areas. PMID:26832070

  8. Interplay between ABA and phospholipases A(2) and D in the response of citrus fruit to postharvest dehydration.

    PubMed

    Romero, Paco; Gandía, Mónica; Alférez, Fernando

    2013-09-01

    The interplay between abscisic acid (ABA) and phospholipases A2 and D (PLA2 and PLD) in the response of citrus fruit to water stress was investigated during postharvest by using an ABA-deficient mutant from 'Navelate' orange named 'Pinalate'. Fruit from both varieties harvested at two different maturation stages (mature-green and full-mature) were subjected to prolonged water loss inducing stem-end rind breakdown (SERB) in full-mature fruit. Treatment with PLA2 inhibitor aristolochic acid (AT) and PLD inhibitor lysophosphatidylethanolamine (LPE) reduced the disorder in both varieties, suggesting that phospholipid metabolism is involved in citrus peel quality. Expression of CsPLDα and CsPLDβ, and CssPLA2α and CssPLA2β was studied by real-time RT-PCR during water stress and in response to ABA. CsPLDα expression increased in mature-green fruit from 'Navelate' but not in 'Pinalate' and ABA did not counteract this effect. ABA enhanced repression of CsPLDα in full-mature fruit. CsPLDβ gene expression decreased in mature-green 'Pinalate', remained unchanged in 'Navelate' and was induced in full-mature fruit from both varieties. CssPLA2α expression increased in mature-green fruit from both varieties whereas in full-mature fruit only increased in 'Navelate'. CssPLA2β expression increased in mature-green flavedo from both varieties, but in full-mature fruit remained steady in 'Navelate' and barely increased in 'Pinalate' fruit. ABA reduced expression in both after prolonged storage. Responsiveness to ABA increased with maturation. Our results show interplay between PLA2 and PLD and suggest that ABA action is upstream phospholipase activation. Response to ABA during water stress in citrus is regulated during fruit maturation and involves membrane phospholipid degradation.

  9. The plant-specific SR45 protein negatively regulates glucose and ABA signaling during early seedling development in Arabidopsis.

    PubMed

    Carvalho, Raquel Fonseca; Carvalho, Sofia Domingues; Duque, Paula

    2010-10-01

    The plant-specific SR45 belongs to the highly conserved family of serine/arginine-rich (SR) proteins, which play key roles in precursor-mRNA splicing and other aspects of RNA metabolism. An Arabidopsis (Arabidopsis thaliana) loss-of-function mutant, sr45-1, displays pleiotropic phenotypes, such as defects in flower and leaf morphology, root growth, and flowering time. Here, we show that the sr45-1 mutation confers hypersensitivity to glucose (Glc) during early seedling growth in Arabidopsis. Unlike wild-type plants, the sr45-1 mutant displays impaired cotyledon greening and expansion as well as reduced hypocotyl elongation of dark-grown seedlings when grown in the presence of low (3%) Glc concentrations. In addition, SR45 is involved in the control of Glc-responsive gene expression, as the mutant displays enhanced repression of photosynthetic and nitrogen metabolism genes and overinduction of starch and anthocyanin biosynthesis genes. Like many other sugar response mutants, sr45-1 also shows hypersensitivity to abscisic acid (ABA) but appears to be unaffected in ethylene signaling. Importantly, the sr45-1 mutant shows enhanced ability to accumulate ABA in response to Glc, and the ABA biosynthesis inhibitor fluridone partially rescues the sugar-mediated growth arrest. Moreover, three ABA biosynthesis genes and two key ABA signaling genes, ABI3 and ABI5, are markedly overinduced by Glc in sr45-1. These results provide evidence that the SR45 protein defines a novel player in plant sugar response that negatively regulates Glc signaling during early seedling development by down-regulating both Glc-specific ABA accumulation and ABA biosynthesis and signaling gene expression. PMID:20699397

  10. Isolation and characterization of novel mutant loci suppressing the ABA hypersensitivity of the Arabidopsis coronatine insensitive 1-16 (coi1-16) mutant during germination and seedling growth.

    PubMed

    Fernández-Arbaizar, Alejandro; Regalado, José J; Lorenzo, Oscar

    2012-01-01

    The phytohormone ABA regulates seed germination and stress responses. The identification of clade A protein phosphatase type 2C (PP2C)-interacting proteins PYRABACTIN RESISTANCE 1 (PYR1)/RCAR (REGULATORY COMPONENT OF ABA RECEPTOR) and PYR1-LIKEs (PYLs) as ABA receptors has been a major advance in understanding this process. Here, our aim was to identify additional ABA response loci by suppressor screening of the jasmonate (JA)-insensitive coronatine insensitive 1-16 (coi1-16) mutant using its ABA-hypersensitive phenotype. The identification and genetic characterization of Coi1-16 Resistant to ABA (CRA) loci revealed several unknown and three previously known abi mutants (abi1, abi3 and abi4), thus providing proof-of-concept evidence for this study. The synergistic effect of ABA and JA on seed germination and cotyledon expansion was analyzed in depth and the roles of cra5 coi1-16, cra6 coi1-16, cra7 coi1-16 and cra8 coi1-16 in ABA signaling during seed germination and stress responses were functionally characterized. The cra5 coi1-16 mutant showed resistance to ABA, paclobutrazol, and abiotic stresses during germination and early developmental stages. Furthermore, the cra5 coi1-16 mutation was mapped to the short arm of chromosome V and mutants exhibited differential expression of ABA-responsive genes, suggesting that CRA5 may function as a positive regulator of ABA signaling. Interestingly, cra6 coi1-16, cra7 coi1-16 and cra8 coi1-16 mutants display similar ABA- and abiotic stress-insensitive phenotypes during seed germination and seedling establishment. Taken together, our results demonstrate a key role for CRA genes in regulating the onset of seed germination by ABA, and highlight how cra mutants can be used as powerful tools to analyze novel molecular components of ABA signaling in seeds. PMID:22156383

  11. Ureide Catabolism in Soybeans 1

    PubMed Central

    Winkler, Rodney G.; Blevins, Dale G.; Randall, Douglas D.

    1988-01-01

    We demonstrate that allantoate is catabolized in soybean seedcoat extracts by an enzyme complex that has allantoate amidohydrolase and ureidoglycolate amidohydrolase activities. Soybean seedcoat extracts released 14CO2 from [ureido-14C]ureidoglycolate under conditions in which urease is not detectable. CO2 and glyoxylate are enzymically released in a one to one ratio indicating that ureidoglycolate amidohydrolase is the responsible activity. Ureidoglycolate amidohydrolase has a Km of 85 micromolar for ureidoglycolate. Glyoxylate and CO2 are enzymically released from allantoate at linear rates in a one to 2.3 ratio from 5 to 30 min. This ratio is consistent with the degradation of allantoate to two CO2 and one glyoxylate with approximately 23% of the allantoate degraded reacting with 2-mercaptoethanol to yield 2-hydroxyethylthio, 2′-ureido, acetate (RG Winkler, JC Polacco, DG Blevins, DD Randall 1985 Plant Physiol 79: 787-793). That [14C]urea production from [2,7-14C]allantoate is not detectable indicates that allantoate-dependent glyoxylate production is enzymic and not a result of nonenzymic hydrolysis of a ureido intermediate (nonenzymic hydrolysis releases urea). These results and those from intact tissue studies (RG Winkler DG Blevins, JC Polacco, DD Randall 1987 Plant Physiol 83: 585-591) suggest that soybeans have a second amidohydrolase reaction (ureidoglycolate amidohydrolase) that follows allantoate amidohydrolase in allantoate catabolism. The rate of 14CO2 release from [2,7-14C]allantoate is not reduced when the volume of the reaction mixture is increased, suggesting that the release of 14CO2 is not dependent on the accumulation of free intermediates. That [2,7-14C]allantoate dependent 14CO2 release is not proportionally diluted by unlabeled ureidoglycolate indicates that the reaction is carried out by an enzyme complex. This is the first report of ureidoglycolate amidohydrolase activity in any organism and the first in vitro demonstration in plants

  12. Phenylacetic acid catabolism and its transcriptional regulation in Corynebacterium glutamicum.

    PubMed

    Chen, Xi; Kohl, Thomas A; Rückert, Christian; Rodionov, Dmitry A; Li, Ling-Hao; Ding, Jiu-Yuan; Kalinowski, Jörn; Liu, Shuang-Jiang

    2012-08-01

    The industrially important organism Corynebacterium glutamicum has been characterized in recent years for its robust ability to assimilate aromatic compounds. In this study, C. glutamicum strain AS 1.542 was investigated for its ability to catabolize phenylacetic acid (PAA). The paa genes were identified; they are organized as a continuous paa gene cluster. The type strain of C. glutamicum, ATCC 13032, is not able to catabolize PAA, but the recombinant strain ATCC 13032/pEC-K18mob2::paa gained the ability to grow on PAA. The paaR gene, encoding a TetR family transcription regulator, was studied in detail. Disruption of paaR in strain AS 1.542 resulted in transcriptional increases of all paa genes. Transcription start sites and putative promoter regions were determined. An imperfect palindromic motif (5'-ACTNACCGNNCGNNCGGTNAGT-3'; 22 bp) was identified in the upstream regions of paa genes. Electrophoretic mobility shift assays (EMSA) demonstrated specific binding of PaaR to this motif, and phenylacetyl coenzyme A (PA-CoA) blocked binding. It was concluded that PaaR is the negative regulator of PAA degradation and that PA-CoA is the PaaR effector. In addition, GlxR binding sites were found, and binding to GlxR was confirmed. Therefore, PAA catabolism in C. glutamicum is regulated by the pathway-specific repressor PaaR, and also likely by the global transcription regulator GlxR. By comparative genomic analysis, we reconstructed orthologous PaaR regulons in 57 species, including species of Actinobacteria, Proteobacteria, and Flavobacteria, that carry PAA utilization genes and operate by conserved binding motifs, suggesting that PaaR-like regulation might commonly exist in these bacteria.

  13. Identification and Characterization of ABA-Responsive MicroRNAs in Rice.

    PubMed

    Tian, Caijuan; Zuo, Zhangli; Qiu, Jin-Long

    2015-07-20

    MicroRNAs (miRNAs) are endogenous non-coding small RNAs that silence genes through mRNA degradation or translational inhibition. The phytohormone abscisic acid (ABA) is essential for plant development and adaptation to abiotic and biotic stresses. In Arabidopsis, miRNAs are implicated in ABA functions. However, ABA-responsive miRNAs have not been systematically studied in rice. Here high throughput sequencing of small RNAs revealed that 107 miRNAs were differentially expressed in the rice ABA deficient mutant, Osaba1. Of these, 13 were confirmed by stem-loop RT-PCR. Among them, miR1425-5P, miR169a, miR169n, miR390-5P, miR397a and miR397b were up-regulated, but miR162b reduced in expression in Osaba1. The targets of these 13 miRNAs were predicted and validated by gene expression profiling. Interestingly, the expression levels of these miRNAs and their targets were regulated by ABA. Cleavage sites were detected on 7 of the miRNA targets by 5'-Rapid Amplification of cDNA Ends (5'-RACE). Finally, miR162b and its target OsTRE1 were shown to affect rice resistance to drought stress, suggesting that miR162b increases resistance to drought by targeting OsTRE1. Our work provides important information for further characterization and functional analysis of ABA-responsive miRNAs in rice. PMID:26233894

  14. Characterization of p-Hydroxycinnamate Catabolism in a Soil Actinobacterium

    PubMed Central

    Otani, Hiroshi; Lee, Young-Eun; Casabon, Israël

    2014-01-01

    p-Hydroxycinnamates, such as ferulate and p-coumarate, are components of plant cell walls and have a number of commercial applications. Rhodococcus jostii RHA1 (RHA1) catabolizes ferulate via vanillate and the β-ketoadipate pathway. Here, we used transcriptomics to identify genes in RHA1 that are upregulated during growth on ferulate versus benzoate. The upregulated genes included three transcriptional units predicted to encode the uptake and β-oxidative deacetylation of p-hydroxycinnamates: couHTL, couNOM, and couR. Neither ΔcouL mutants nor ΔcouO mutants grew on p-hydroxycinnamates, but they did grow on vanillate. Among several p-hydroxycinnamates, CouL catalyzed the thioesterification of p-coumarate and caffeate most efficiently (kcat/Km = ∼400 mM−1 s−1). p-Coumarate was also RHA1's preferred growth substrate, suggesting that CouL is a determinant of the pathway's specificity. CouL did not catalyze the activation of sinapate, in similarity to two p-coumaric acid:coenzyme A (CoA) ligases from plants, and contains the same bulged loop that helps determine substrate specificity in the plant homologues. The couO mutant accumulated 4-hydroxy-3-methoxyphenyl-β-ketopropionate in the culture supernatant when incubated with ferulate, supporting β-oxidative deacetylation. This phenotype was not complemented with a D257N variant of CouO, consistent with the predicted role of Asp257 as a metal ligand in this amidohydrolase superfamily member. These data suggest that CouO functionally replaces the β-ketothiolase and acyl-CoA thioesterase that occur in canonical β-oxidative pathways. Finally, the transcriptomics data suggest the involvement of two distinct formaldehyde detoxification pathways in vanillate catabolism and identify a eugenol catabolic pathway. The results of this study augment our understanding of the bacterial catabolism of aromatics from renewable feedstocks. PMID:25266382

  15. Characterization of p-hydroxycinnamate catabolism in a soil Actinobacterium.

    PubMed

    Otani, Hiroshi; Lee, Young-Eun; Casabon, Israël; Eltis, Lindsay D

    2014-12-01

    p-Hydroxycinnamates, such as ferulate and p-coumarate, are components of plant cell walls and have a number of commercial applications. Rhodococcus jostii RHA1 (RHA1) catabolizes ferulate via vanillate and the β-ketoadipate pathway. Here, we used transcriptomics to identify genes in RHA1 that are upregulated during growth on ferulate versus benzoate. The upregulated genes included three transcriptional units predicted to encode the uptake and β-oxidative deacetylation of p-hydroxycinnamates: couHTL, couNOM, and couR. Neither ΔcouL mutants nor ΔcouO mutants grew on p-hydroxycinnamates, but they did grow on vanillate. Among several p-hydroxycinnamates, CouL catalyzed the thioesterification of p-coumarate and caffeate most efficiently (k(cat)/K(m) = ∼ 400 mM(-1) s(-1)). p-Coumarate was also RHA1's preferred growth substrate, suggesting that CouL is a determinant of the pathway's specificity. CouL did not catalyze the activation of sinapate, in similarity to two p-coumaric acid:coenzyme A (CoA) ligases from plants, and contains the same bulged loop that helps determine substrate specificity in the plant homologues. The couO mutant accumulated 4-hydroxy-3-methoxyphenyl-β-ketopropionate in the culture supernatant when incubated with ferulate, supporting β-oxidative deacetylation. This phenotype was not complemented with a D257N variant of CouO, consistent with the predicted role of Asp257 as a metal ligand in this amidohydrolase superfamily member. These data suggest that CouO functionally replaces the β-ketothiolase and acyl-CoA thioesterase that occur in canonical β-oxidative pathways. Finally, the transcriptomics data suggest the involvement of two distinct formaldehyde detoxification pathways in vanillate catabolism and identify a eugenol catabolic pathway. The results of this study augment our understanding of the bacterial catabolism of aromatics from renewable feedstocks.

  16. The RING finger ubiquitin E3 ligase SDIR1 targets SDIR1-INTERACTING PROTEIN1 for degradation to modulate the salt stress response and ABA signaling in Arabidopsis.

    PubMed

    Zhang, Huawei; Cui, Feng; Wu, Yaorong; Lou, Lijuan; Liu, Lijing; Tian, Miaomiao; Ning, Yuese; Shu, Kai; Tang, Sanyuan; Xie, Qi

    2015-01-01

    The plant hormone abscisic acid (ABA) regulates many aspects of plant development and the stress response. The intracellular E3 ligase SDIR1 (SALT- AND DROUGHT-INDUCED REALLY INTERESTING NEW GENE FINGER1) plays a key role in ABA signaling, regulating ABA-related seed germination and the stress response. In this study, we found that SDIR1 is localized on the endoplasmic reticulum membrane in Arabidopsis thaliana. Using cell biology, molecular biology, and biochemistry approaches, we demonstrated that SDIR1 interacts with and ubiquitinates its substrate, SDIRIP1 (SDIR1-INTERACTING PROTEIN1), to modulate SDIRIP1 stability through the 26S proteasome pathway. SDIRIP1 acts genetically downstream of SDIR1 in ABA and salt stress signaling. In detail, SDIRIP1 selectively regulates the expression of the downstream basic region/leucine zipper motif transcription factor gene ABA-INSENSITIVE5, rather than ABA-RESPONSIVE ELEMENTS BINDING FACTOR3 (ABF3) or ABF4, to regulate ABA-mediated seed germination and the plant salt response. Overall, the SDIR1/SDIRIP1 complex plays a vital role in ABA signaling through the ubiquitination pathway. PMID:25616872

  17. The RING Finger Ubiquitin E3 Ligase SDIR1 Targets SDIR1-INTERACTING PROTEIN1 for Degradation to Modulate the Salt Stress Response and ABA Signaling in Arabidopsis

    PubMed Central

    Zhang, Huawei; Cui, Feng; Wu, Yaorong; Lou, Lijuan; Liu, Lijing; Tian, Miaomiao; Ning, Yuese; Shu, Kai; Tang, Sanyuan; Xie, Qi

    2015-01-01

    The plant hormone abscisic acid (ABA) regulates many aspects of plant development and the stress response. The intracellular E3 ligase SDIR1 (SALT- AND DROUGHT-INDUCED REALLY INTERESTING NEW GENE FINGER1) plays a key role in ABA signaling, regulating ABA-related seed germination and the stress response. In this study, we found that SDIR1 is localized on the endoplasmic reticulum membrane in Arabidopsis thaliana. Using cell biology, molecular biology, and biochemistry approaches, we demonstrated that SDIR1 interacts with and ubiquitinates its substrate, SDIRIP1 (SDIR1-INTERACTING PROTEIN1), to modulate SDIRIP1 stability through the 26S proteasome pathway. SDIRIP1 acts genetically downstream of SDIR1 in ABA and salt stress signaling. In detail, SDIRIP1 selectively regulates the expression of the downstream basic region/leucine zipper motif transcription factor gene ABA-INSENSITIVE5, rather than ABA-RESPONSIVE ELEMENTS BINDING FACTOR3 (ABF3) or ABF4, to regulate ABA-mediated seed germination and the plant salt response. Overall, the SDIR1/SDIRIP1 complex plays a vital role in ABA signaling through the ubiquitination pathway. PMID:25616872

  18. Tryptophan-Catabolizing Enzymes – Party of Three

    PubMed Central

    Ball, Helen J.; Jusof, Felicita F.; Bakmiwewa, Supun M.; Hunt, Nicholas H.; Yuasa, Hajime J.

    2014-01-01

    Indoleamine 2,3-dioxygenase (IDO) and tryptophan 2,3-dioxygenase (TDO) are tryptophan-degrading enzymes that have independently evolved to catalyze the first step in tryptophan catabolism via the kynurenine pathway (KP). The depletion of tryptophan and formation of KP metabolites modulates the activity of the mammalian immune, reproductive, and central nervous systems. IDO and TDO enzymes can have overlapping or distinct functions depending on their expression patterns. The expression of TDO and IDO enzymes in mammals differs not only by tissue/cellular localization but also by their induction by distinct stimuli. To add to the complexity, these genes also have undergone duplications in some organisms leading to multiple isoforms of IDO or TDO. For example, many vertebrates, including all mammals, have acquired two IDO genes via gene duplication, although the IDO1-like gene has been lost in some lower vertebrate lineages. Gene duplications can allow the homologs to diverge and acquire different properties to the original gene. There is evidence for IDO enzymes having differing enzymatic characteristics, signaling properties, and biological functions. This review analyzes the evolutionary convergence of IDO and TDO enzymes as tryptophan-catabolizing enzymes and the divergent evolution of IDO homologs to generate an enzyme family with diverse characteristics not possessed by TDO enzymes, with an emphasis on the immune system. PMID:25346733

  19. Tryptophan catabolism in Bacillus megaterium.

    PubMed Central

    Bouknight, R R; Sadoff, H L

    1975-01-01

    Bacillus megaterium grows in a medium containing L-tryptophan as the sole carbon, nitrogen, and energy source. Kynurenine, anthranilic acid, and catechol are metabolic intermediates, suggesting that this organism used the anthranilic acid pathway for tryptophan degradation. Cells that grow on L-tryptophan oxidize kynurenine, alanine, and anthranilic acid and the presence of tryptophan oxygenase (EC 1.13.1.12), kynureninase (EC 3.7.1.3), and catechol oxygenase (EC 1.13.1.1) in cell extracts provide additional evidence for the degradative pathway in B. megaterium. Tryptophan oxygenase is inhibited by sodium azide, potassium cyanide, and hydroxylamine, indicating that the enzyme has a functional heme group. D-Tryptophan is not a substrate for tryptophan oxygenase, and the D-isomer does not inhibit this enzyme. Formamidase (EC 3.5.1.9) and anthranilate hydroxylase are not detectable in extracts. Tryptophan catabolism is inducible in B megaterium and is subject to catabolite repression by glucose and glutamate. Arginine does not cause repression, and kynurenine induces both tryptophan oxygenase and kynureninase. PMID:803956

  20. Catabolic flexibility of mammalian-associated lactobacilli

    PubMed Central

    2013-01-01

    Metabolic flexibility may be generally defined as “the capacity for the organism to adapt fuel oxidation to fuel availability”. The metabolic diversification strategies used by individual bacteria vary greatly from the use of novel or acquired enzymes to the use of plasmid-localised genes and transporters. In this review, we describe the ability of lactobacilli to utilise a variety of carbon sources from their current or new environments in order to grow and survive. The genus Lactobacillus now includes more than 150 species, many with adaptive capabilities, broad metabolic capacity and species/strain variance. They are therefore, an informative example of a cell factory capable of adapting to new niches with differing nutritional landscapes. Indeed, lactobacilli naturally colonise and grow in a wide variety of environmental niches which include the roots and foliage of plants, silage, various fermented foods and beverages, the human vagina and the mammalian gastrointestinal tract (GIT; including the mouth, stomach, small intestine and large intestine). Here we primarily describe the metabolic flexibility of some lactobacilli isolated from the mammalian gastrointestinal tract, and we also describe some of the food-associated species with a proven ability to adapt to the GIT. As examples this review concentrates on the following species - Lb. plantarum, Lb. acidophilus, Lb. ruminis, Lb. salivarius, Lb. reuteri and Lb. sakei, to highlight the diversity and inter-relationships between the catabolic nature of species within the genus. PMID:23680304

  1. Expression analysis of β-glucosidase genes that regulate abscisic acid homeostasis during watermelon (Citrullus lanatus) development and under stress conditions.

    PubMed

    Li, Qian; Li, Ping; Sun, Liang; Wang, Yanping; Ji, Kai; Sun, Yufei; Dai, Shengjie; Chen, Pei; Duan, Chaorui; Leng, Ping

    2012-01-01

    The aim of this study was to obtain new insights into the mechanisms that regulate endogenous abscisic acid (ABA) levels by β-glucosidase genes during the development of watermelons (Citrullus lanatus) and under drought stress conditions. In total, five cDNAs from watermelons were cloned by using reverse transcription-PCR (RT-PCR). They included three cDNAs (ClBG1, ClBG2 and ClBG3) homologous to those that encode β-glucosidase l that hydrolyzes the ABA glucose ester (ABA-GE) to release active ABA, ClNCED4, which encodes 9-cis-epoxycarotenoid dioxygenase (NCED), a key enzyme in ABA biosynthesis, and ClCYP707A1, encoding ABA 8'-hydroxylase. A BLAST homology search revealed that the sequences of cDNAs and the deduced amino acids of these genes showed a high degree of homology to comparable molecules of other plant species. During fruit development and ripening, the expressions of ClBG1, ClNCED4 and ClCYP707A1 were relatively low at an early stage, increased rapidly along with fruit ripening, and reached the highest levels at 27 days after full bloom (DAFB) at the harvest stage. This trend was consistent with the accumulation of ABA. The ClBG2 gene on the other hand was highly expressed at 5 DAFB, and then decreased gradually with fruit development. Unlike ClBG1 and ClBG2, the expression of ClBG3 was low at an early stage; its expression peak occurred at 15 DAFB and then declined to the lowest point. When watermelon seedlings were subjected to drought stress, expressions of ClBG1 and ClCYP707A1 were significantly down-regulated, while expressions of ClBG2 and ClNCED4 were up-regulated in the roots, stems and leaves. The expression of ClBG3 was down-regulated in root tissue, but was up-regulated in stems and leaves. In conclusion, endogenous ABA content was modulated by a dynamic balance between biosynthesis and catabolism regulated by ClNCED4, ClCYP707A1 and ClBGs during development and under drought stress condition. It seems likely that β-glucosidase genes are

  2. Transcriptome profiling identifies ABA mediated regulatory changes towards storage filling in developing seeds of castor bean (Ricinus communis L.)

    PubMed Central

    2014-01-01

    Background The potential biodiesel plant castor bean (Ricinus communis) has been in the limelight for bioenergy research due to the availability of its genome which raises the bar for genome-wide studies claiming advances that impact the “genome-phenome challenge”. Here we report the application of phytohormone ABA as an exogenous factor for the improvement of storage reserve accumulation with a focus on the complex interaction of pathways associated with seed filling. Results After the application of exogenous ABA treatments, we measured an increased ABA levels in the developing seeds cultured in vitro using the ELISA technique and quantified the content of major biomolecules (including total lipids, sugars and protein) in treated seeds. Exogenous ABA (10 μM) enhanced the accumulation of soluble sugar content (6.3%) followed by deposition of total lipid content (4.9 %). To elucidate the possible ABA signal transduction pathways towards overall seed filling, we studied the differential gene expression analysis using Illumina RNA-Sequencing technology, resulting in 2568 (1507-up/1061-down regulated) differentially expressed genes were identified. These genes were involved in sugar metabolism (such as glucose-6-phosphate, fructose 1,6 bis-phosphate, glycerol-3-phosphate, pyruvate kinase), lipid biosynthesis (such as ACS, ACBP, GPAT2, GPAT3, FAD2, FAD3, SAD1 and DGAT1), storage proteins synthesis (such as SGP1, zinc finger protein, RING H2 protein, nodulin 55 and cytochrome P450), and ABA biosynthesis (such as NCED1, NCED3 and beta carotene). Further, we confirmed the validation of RNA-Sequencing data by Semi-quantitative RT-PCR analysis. Conclusions Taken together, metabolite measurements supported by genes and pathway expression results indicated in this study provide new insights to understand the ABA signaling mechanism towards seed storage filling and also contribute useful information for facilitating oilseed crop functional genomics on an aim for utilizing

  3. Regulation and evolution of malonate and propionate catabolism in proteobacteria.

    PubMed

    Suvorova, I A; Ravcheev, D A; Gelfand, M S

    2012-06-01

    Bacteria catabolize malonate via two pathways, encoded by the mdc and mat genes. In various bacteria, transcription of these genes is controlled by the GntR family transcription factors (TFs) MatR/MdcY and/or the LysR family transcription factor MdcR. Propionate is metabolized via the methylcitrate pathway, comprising enzymes encoded by the prp and acn genes. PrpR, the Fis family sigma 54-dependent transcription factor, is known to be a transcriptional activator of the prp genes. Here, we report a detailed comparative genomic analysis of malonate and propionate metabolism and its regulation in proteobacteria. We characterize genomic loci and gene regulation and identify binding motifs for four new TFs and also new regulon members, in particular, tripartite ATP-independent periplasmic (TRAP) transporters. We describe restructuring of the genomic loci and regulatory interactions during the evolution of proteobacteria.

  4. Rapid Phosphoproteomic Effects of Abscisic Acid (ABA) on Wild-Type and ABA Receptor-Deficient A. thaliana Mutants*

    PubMed Central

    Minkoff, Benjamin B.; Stecker, Kelly E.; Sussman, Michael R.

    2015-01-01

    Abscisic acid (ABA)1 is a plant hormone that controls many aspects of plant growth, including seed germination, stomatal aperture size, and cellular drought response. ABA interacts with a unique family of 14 receptor proteins. This interaction leads to the activation of a family of protein kinases, SnRK2s, which in turn phosphorylate substrates involved in many cellular processes. The family of receptors appears functionally redundant. To observe a measurable phenotype, four of the fourteen receptors have to be mutated to create a multilocus loss-of-function quadruple receptor (QR) mutant, which is much less sensitive to ABA than wild-type (WT) plants. Given these phenotypes, we asked whether or not a difference in ABA response between the WT and QR backgrounds would manifest on a phosphorylation level as well. We tested WT and QR mutant ABA response using isotope-assisted quantitative phosphoproteomics to determine what ABA-induced phosphorylation changes occur in WT plants within 5 min of ABA treatment and how that phosphorylation pattern is altered in the QR mutant. We found multiple ABA-induced phosphorylation changes that occur within 5 min of treatment, including three SnRK2 autophosphorylation events and phosphorylation on SnRK2 substrates. The majority of robust ABA-dependent phosphorylation changes observed were partially diminished in the QR mutant, whereas many smaller ABA-dependent phosphorylation changes observed in the WT were not responsive to ABA in the mutant. A single phosphorylation event was increased in response to ABA treatment in both the WT and QR mutant. A portion of the discovery data was validated using selected reaction monitoring-based targeted measurements on a triple quadrupole mass spectrometer. These data suggest that different subsets of phosphorylation events depend upon different subsets of the ABA receptor family to occur. Altogether, these data expand our understanding of the model by which the family of ABA receptors directs

  5. Rapid Phosphoproteomic Effects of Abscisic Acid (ABA) on Wild-Type and ABA Receptor-Deficient A. thaliana Mutants.

    PubMed

    Minkoff, Benjamin B; Stecker, Kelly E; Sussman, Michael R

    2015-05-01

    Abscisic acid (ABA)¹ is a plant hormone that controls many aspects of plant growth, including seed germination, stomatal aperture size, and cellular drought response. ABA interacts with a unique family of 14 receptor proteins. This interaction leads to the activation of a family of protein kinases, SnRK2s, which in turn phosphorylate substrates involved in many cellular processes. The family of receptors appears functionally redundant. To observe a measurable phenotype, four of the fourteen receptors have to be mutated to create a multilocus loss-of-function quadruple receptor (QR) mutant, which is much less sensitive to ABA than wild-type (WT) plants. Given these phenotypes, we asked whether or not a difference in ABA response between the WT and QR backgrounds would manifest on a phosphorylation level as well. We tested WT and QR mutant ABA response using isotope-assisted quantitative phosphoproteomics to determine what ABA-induced phosphorylation changes occur in WT plants within 5 min of ABA treatment and how that phosphorylation pattern is altered in the QR mutant. We found multiple ABA-induced phosphorylation changes that occur within 5 min of treatment, including three SnRK2 autophosphorylation events and phosphorylation on SnRK2 substrates. The majority of robust ABA-dependent phosphorylation changes observed were partially diminished in the QR mutant, whereas many smaller ABA-dependent phosphorylation changes observed in the WT were not responsive to ABA in the mutant. A single phosphorylation event was increased in response to ABA treatment in both the WT and QR mutant. A portion of the discovery data was validated using selected reaction monitoring-based targeted measurements on a triple quadrupole mass spectrometer. These data suggest that different subsets of phosphorylation events depend upon different subsets of the ABA receptor family to occur. Altogether, these data expand our understanding of the model by which the family of ABA receptors directs

  6. Gladiolus hybridus ABSCISIC ACID INSENSITIVE 5 (GhABI5) is an important transcription factor in ABA signaling that can enhance Gladiolus corm dormancy and Arabidopsis seed dormancy

    PubMed Central

    Wu, Jian; Seng, Shanshan; Sui, Juanjuan; Vonapartis, Eliana; Luo, Xian; Gong, Benhe; Liu, Chen; Wu, Chenyu; Liu, Chao; Zhang, Fengqin; He, Junna; Yi, Mingfang

    2015-01-01

    The phytohormone abscisic acid (ABA) regulates plant development and is crucial for abiotic stress response. In this study, cold storage contributes to reducing endogenous ABA content, resulting in dormancy breaking of Gladiolus. The ABA inhibitor fluridone also promotes germination, suggesting that ABA is an important hormone that regulates corm dormancy. Here, we report the identification and functional characterization of the Gladiolus ABI5 homolog (GhABI5), which is a basic leucine zipper motif transcriptional factor (TF). GhABI5 is expressed in dormant vegetative organs (corm, cormel, and stolon) as well as in reproductive organs (stamen), and it is up-regulated by ABA or drought. Complementation analysis reveals that GhABI5 rescues the ABA insensitivity of abi5-3 during seed germination and induces the expression of downstream ABA response genes in Arabidopsis thaliana (EM1, EM6, and RD29B). Down-regulation of GhABI5 in dormant cormels via virus induced gene silence promotes sprouting and reduces the expression of downstream genes (GhLEA and GhRD29B). The results of this study reveal that GhABI5 regulates bud dormancy (vegetative organ) in Gladiolus in addition to its well-studied function in Arabidopsis seeds (reproductive organ). PMID:26579187

  7. Mechanisms independent of abscisic acid (ABA) or proline feedback have a predominant role in transcriptional regulation of proline metabolism during low water potential and stress recovery.

    PubMed

    Sharma, Sandeep; Verslues, Paul E

    2010-11-01

    Proline accumulation in response to abiotic stress is controlled partially by transcriptional regulation of key enzymes including Δ¹-pyrroline-carboxylate synthetase1 (P5CS1), proline dehydrogenase (ProDH), ornithine amino transferase (OAT) and Δ¹-pyrroline-carboxylate dehydrogenase (P5CDH). For these genes, the role of abscisic acid (ABA), role of feedback regulation by high proline and the mechanisms of gene regulation upon stress release remain unclear. An ABA-deficient (aba2-1) mutant, mutants deficient in proline accumulation (p5cs1), as well as double mutants deficient in both, were used to determine the importance of these factors in transcriptional regulation of proline metabolism. Upregulation of P5CS1 by low water potential was less dependent on ABA than that of stress-marker genes used for comparison. ProDH downregulation by low water potential and upregulation by stress release was not impaired in aba2-1, p5cs1 or p5cs1/aba2-1 compared with wild type despite differing ABA and proline levels in these mutants. Thus, ProDH is a model for characterization of novel regulatory mechanisms associated with low water potential and stress recovery. Both OAT and P5CDH were upregulated during low water potential. This contrasts with previous salt stress experiments and raises questions about the flux of metabolites through proline metabolism under low water potential when high levels of proline accumulate.

  8. Root ABA Accumulation Enhances Rice Seedling Drought Tolerance under Ammonium Supply: Interaction with Aquaporins

    PubMed Central

    Ding, Lei; Li, Yingrui; Wang, Ying; Gao, Limin; Wang, Min; Chaumont, François; Shen, Qirong; Guo, Shiwei

    2016-01-01

    In previous studies, we demonstrated that ammonium nutrition enhances the drought tolerance of rice seedlings compared to nitrate nutrition and contributes to a higher root water uptake ability. It remains unclear why rice seedlings maintain a higher water uptake ability when supplied with ammonium under drought stress. Here, we focused on the effects of nitrogen form and drought stress on root abscisic acid (ABA) concentration and aquaporin expression using hydroponics experiments and stimulating drought stress with 10% PEG6000. Drought stress decreased the leaf photosynthetic rate and stomatal conductivity and increased the leaf temperature of plants supplied with either ammonium or nitrate, but especially under nitrate supply. After 4 h of PEG treatment, the root protoplast water permeability and the expression of root PIP and TIP genes decreased in plants supplied with ammonium or nitrate. After 24 h of PEG treatment, the root hydraulic conductivity, the protoplast water permeability, and the expression of some aquaporin genes increased in plants supplied with ammonium compared to those under non-PEG treatment. Root ABA accumulation was induced by 24 h of PEG treatment, especially in plants supplied with ammonium. The addition of exogenous ABA decreased the expression of PIP and TIP genes under non-PEG treatment but increased the expression of some of them under PEG treatment. We concluded that drought stress induced a down-regulation of aquaporin expression, which appeared earlier than did root ABA accumulation. With continued drought stress, aquaporin expression and activity increased due to root ABA accumulation in plants supplied with ammonium. PMID:27559341

  9. Root ABA Accumulation Enhances Rice Seedling Drought Tolerance under Ammonium Supply: Interaction with Aquaporins.

    PubMed

    Ding, Lei; Li, Yingrui; Wang, Ying; Gao, Limin; Wang, Min; Chaumont, François; Shen, Qirong; Guo, Shiwei

    2016-01-01

    In previous studies, we demonstrated that ammonium nutrition enhances the drought tolerance of rice seedlings compared to nitrate nutrition and contributes to a higher root water uptake ability. It remains unclear why rice seedlings maintain a higher water uptake ability when supplied with ammonium under drought stress. Here, we focused on the effects of nitrogen form and drought stress on root abscisic acid (ABA) concentration and aquaporin expression using hydroponics experiments and stimulating drought stress with 10% PEG6000. Drought stress decreased the leaf photosynthetic rate and stomatal conductivity and increased the leaf temperature of plants supplied with either ammonium or nitrate, but especially under nitrate supply. After 4 h of PEG treatment, the root protoplast water permeability and the expression of root PIP and TIP genes decreased in plants supplied with ammonium or nitrate. After 24 h of PEG treatment, the root hydraulic conductivity, the protoplast water permeability, and the expression of some aquaporin genes increased in plants supplied with ammonium compared to those under non-PEG treatment. Root ABA accumulation was induced by 24 h of PEG treatment, especially in plants supplied with ammonium. The addition of exogenous ABA decreased the expression of PIP and TIP genes under non-PEG treatment but increased the expression of some of them under PEG treatment. We concluded that drought stress induced a down-regulation of aquaporin expression, which appeared earlier than did root ABA accumulation. With continued drought stress, aquaporin expression and activity increased due to root ABA accumulation in plants supplied with ammonium. PMID:27559341

  10. Carbon dioxide enrichment alleviates heat stress by improving cellular redox homeostasis through an ABA-independent process in tomato plants.

    PubMed

    Li, X; Ahammed, G J; Zhang, Y Q; Zhang, G Q; Sun, Z H; Zhou, J; Zhou, Y H; Xia, X J; Yu, J Q; Shi, K

    2015-01-01

    Plant responses to elevated CO₂ and high temperature are critically regulated through a complex network of phytohormones and redox homeostasis. However, the involvement of abscisic acid (ABA) in plant adaptation to heat stress under elevated CO₂ conditions has not been thoroughly studied. This study investigated the interactive effects of elevated CO₂ (800 μmol·mol(-1) ) and heat stress (42 °C for 24 h) on the endogenous level of ABA and the cellular redox state of two genotypes of tomato with different ABA biosynthesis capacities. Heat stress significantly decreased maximum photochemical efficiency of PSII (Fv/Fm) and leaf water potential, but also increased levels of malondialdehyde (MDA) and electrolyte leakage (EL) in both genotypes. Heat-induced damage was more severe in the ABA-deficient mutant notabilis (not) than in its parental cultivar Ailsa Craig (Ailsa), suggesting that a certain level of endogenous ABA is required to minimise the heat-induced oxidative damage to the photosynthetic apparatus. Irrespective of genotype, the enrichment of CO₂ remarkably stimulated Fv/Fm, MDA and EL in heat-stressed plants towards enhanced tolerance. In addition, elevated CO₂ significantly strengthened the antioxidant capacity of heat-stressed tomato seedlings towards a reduced cellular redox state for a prolonged period, thereby mitigating oxidative stress. However, elevated CO₂ and heat stress did not alter the endogenous level of ABA or the expression of its biosynthetic gene NCED2 in either genotype, indicating that ABA is not involved in elevated CO₂ -induced heat stress alleviation. The results of this study suggest that elevated CO₂ alleviated heat stress through efficient regulation of the cellular redox poise in an ABA-independent manner in tomato plants.

  11. RhHB1 mediates the antagonism of gibberellins to ABA and ethylene during rose (Rosa hybrida) petal senescence.

    PubMed

    Lü, Peitao; Zhang, Changqing; Liu, Jitao; Liu, Xiaowei; Jiang, Guimei; Jiang, Xinqiang; Khan, Muhammad Ali; Wang, Liangsheng; Hong, Bo; Gao, Junping

    2014-05-01

    Rose (Rosa hybrida) is one of the most important ornamental plants worldwide; however, senescence of its petals terminates the ornamental value of the flower, resulting in major economic loss. It is known that the hormones abscisic acid (ABA) and ethylene promote petal senescence, while gibberellins (GAs) delay the process. However, the molecular mechanisms underlying the antagonistic effects amongst plant hormones during petal senescence are still unclear. Here we isolated RhHB1, a homeodomain-leucine zipper I transcription factor gene, from rose flowers. Quantitative RT-PCR and GUS reporter analyses showed that RhHB1 was strongly expressed in senescing petals, and its expression was induced by ABA or ethylene in petals. ABA or ethylene treatment clearly accelerated rose petal senescence, while application of the gibberellin GA3 delayed the process. However, silencing of RhHB1 delayed the ABA- or ethylene-mediated senescence, and resulted in higher petal anthocyanin levels and lower expression of RhSAG12. Moreover, treatment with paclobutrazol, an inhibitor of GA biosynthesis, repressed these delays. In addition, silencing of RhHB1 blocked the ABA- or ethylene-induced reduction in expression of the GA20 oxidase encoded by RhGA20ox1, a gene in the GA biosynthetic pathway. Furthermore, RhHB1 directly binds to the RhGA20ox1 promoter, and silencing of RhGA20ox1 promoted petal senescence. Eight senescence-related genes showed substantial differences in expression in petals after treatment with GA3 or paclobutrazol. These results suggest that RhHB1 mediates the antagonistic effect of GAs on ABA and ethylene during rose petal senescence, and that the promotion of petal senescence by ABA or ethylene operates through an RhHB1-RhGA20ox1 regulatory checkpoint.

  12. Abscisic acid (ABA) regulates grape bud dormancy, and dormancy release stimuli may act through modification of ABA metabolism

    PubMed Central

    Zheng, Chuanlin; Halaly, Tamar; Acheampong, Atiako Kwame; Takebayashi, Yumiko; Jikumaru, Yusuke; Kamiya, Yuji; Or, Etti

    2015-01-01

    In warm-winter regions, induction of dormancy release by hydrogen cyanamide (HC) is mandatory for commercial table grape production. Induction of respiratory stress by HC leads to dormancy release via an uncharacterized biochemical cascade that could reveal the mechanism underlying this phenomenon. Previous studies proposed a central role for abscisic acid (ABA) in the repression of bud meristem activity, and suggested its removal as a critical step in the HC-induced cascade. In the current study, support for these assumptions was sought. The data show that ABA indeed inhibits dormancy release in grape (Vitis vinifera) buds and attenuates the advancing effect of HC. However, HC-dependent recovery was detected, and was affected by dormancy status. HC reduced VvXERICO and VvNCED transcript levels and induced levels of VvABA8’OH homologues. Regulation of these central players in ABA metabolism correlated with decreased ABA and increased ABA catabolite levels in HC-treated buds. Interestingly, an inhibitor of ethylene signalling attenuated these effects of HC on ABA metabolism. HC also modulated the expression of ABA signalling regulators, in a manner that supports a decreased ABA level and response. Taken together, the data support HC-induced removal of ABA-mediated repression via regulation of ABA metabolism and signalling. Expression profiling during the natural dormancy cycle revealed that at maximal dormancy, the HC-regulated VvNCED1 transcript level starts to drop. In parallel, levels of VvA8H-CYP707A4 transcript and ABA catabolites increase sharply. This may provide initial support for the involvement of ABA metabolism also in the execution of natural dormancy. PMID:25560179

  13. Abscisic acid (ABA) regulates grape bud dormancy, and dormancy release stimuli may act through modification of ABA metabolism.

    PubMed

    Zheng, Chuanlin; Halaly, Tamar; Acheampong, Atiako Kwame; Takebayashi, Yumiko; Jikumaru, Yusuke; Kamiya, Yuji; Or, Etti

    2015-03-01

    In warm-winter regions, induction of dormancy release by hydrogen cyanamide (HC) is mandatory for commercial table grape production. Induction of respiratory stress by HC leads to dormancy release via an uncharacterized biochemical cascade that could reveal the mechanism underlying this phenomenon. Previous studies proposed a central role for abscisic acid (ABA) in the repression of bud meristem activity, and suggested its removal as a critical step in the HC-induced cascade. In the current study, support for these assumptions was sought. The data show that ABA indeed inhibits dormancy release in grape (Vitis vinifera) buds and attenuates the advancing effect of HC. However, HC-dependent recovery was detected, and was affected by dormancy status. HC reduced VvXERICO and VvNCED transcript levels and induced levels of VvABA8'OH homologues. Regulation of these central players in ABA metabolism correlated with decreased ABA and increased ABA catabolite levels in HC-treated buds. Interestingly, an inhibitor of ethylene signalling attenuated these effects of HC on ABA metabolism. HC also modulated the expression of ABA signalling regulators, in a manner that supports a decreased ABA level and response. Taken together, the data support HC-induced removal of ABA-mediated repression via regulation of ABA metabolism and signalling. Expression profiling during the natural dormancy cycle revealed that at maximal dormancy, the HC-regulated VvNCED1 transcript level starts to drop. In parallel, levels of VvA8H-CYP707A4 transcript and ABA catabolites increase sharply. This may provide initial support for the involvement of ABA metabolism also in the execution of natural dormancy.

  14. The Heat Stress Factor HSFA6b Connects ABA Signaling and ABA-Mediated Heat Responses1[OPEN

    PubMed Central

    Yang, Chen-Ru

    2016-01-01

    Heat stress response (HSR) is a conserved mechanism developed to increase the expression of heat shock proteins (HSPs) via a heat shock factor (HSF)-dependent mechanism. Signaling by the stress phytohormone abscisic acid (ABA) is involved in acquired thermotolerance as well. Analysis of Arabidopsis (Arabidopsis thaliana) microarray databases revealed that the expression of HSFA6b, a class A HSF, extensively increased with salinity, osmotic, and cold stresses, but not heat. Here, we show that HSFA6b plays a pivotal role in the response to ABA and in thermotolerance. Salt-inducible HSFA6b expression was down-regulated in ABA-insensitive and -deficient mutants; however, exogenous ABA application restored expression in ABA-deficient, but not -insensitive plants. Thus, ABA signaling is required for proper HSFA6b expression. A transcriptional activation assay of protoplasts revealed that ABA treatment and coexpression of an ABA signaling master effector, ABA-RESPONSIVE ELEMENT-BINDING PROTEIN1, could activate the HSFA6b promoter. In addition, HSFA6b directly bound to the promoter of DEHYDRATION-RESPONSIVE ELEMENT-BINDING PROTEIN2A and enhanced its expression. Analysis of ABA responses in seed germination, cotyledon greening, and root growth as well as salt and drought tolerance in HSFA6b-null, overexpression, and dominant negative mutants revealed that HSFA6b is a positive regulator participating in ABA-mediated salt and drought resistance. Thermoprotection tests showed that HSFA6b was required for thermotolerance acquisition. Our study reveals a network in which HSFA6b operates as a downstream regulator of the ABA-mediated stress response and is required for heat stress resistance. This new ABA-signaling pathway is integrated into the complex HSR network in planta. PMID:27493213

  15. The genomes of the South American opossum (Monodelphis domestica) and platypus (Ornithorhynchus anatinus) encode a more complete purine catabolic pathway than placental mammals

    PubMed Central

    Keebaugh, Alaine C.; Thomas, James W.

    2009-01-01

    The end product of purine catabolism varies amongst vertebrates and is a consequence of independent gene inactivation events that have truncated the purine catabolic pathway. Mammals have traditionally been grouped into two classes based on their end product of purine catabolism: most mammals, whose end product is allantoin due to an ancient loss of allantoinase (ALLN), and the hominoids, whose end product is uric acid due to recent inactivations of urate oxidase (UOX). However little is known about purine catabolism in marsupials and monotremes. Here we report the results of a comparative genomics study designed to characterize the purine catabolic pathway in a marsupial, the South American opossum (Monodelphis domestica), and a monotreme, the platypus (Ornithorhynchus anatinus). We found that both genomes encode a more complete set of genes for purine catabolism than do eutherians and conclude that a near complete purine catabolic pathway was present in the common ancestor of all mammals, and that the loss of ALLN is specific to placental mammals. Our results therefore provide a revised history for gene loss in the purine catabolic pathway and suggest that marsupials and monotremes represent a third class of mammals with respect to their end products of purine catabolism. PMID:20161190

  16. Unity in organisation and regulation of catabolic operons in Lactobacillus plantarum, Lactococcus lactis and Listeria monocytogenes.

    PubMed

    Andersson, Ulrika; Molenaar, Douwe; Rådström, Peter; de Vos, Willem M

    2005-04-01

    Global regulatory circuits together with more specific local regulators play a notable role when cells are adapting to environmental changes. Lactococcus lactis is a lactic acid bacterium abundant in nature fermenting most mono- and disaccharides. Comparative genomics analysis of the operons encoding the proteins and enzymes crucial for catabolism of lactose, maltose and threhalose revealed an obvious unity in operon organisation . The local regulator of each operon was located in a divergent transcriptional direction to the rest of the operon including the transport protein-encoding genes. Furthermore, in all three operons a catabolite responsive element (CRE) site was detected inbetween the gene encoding the local regulator and one of the genes encoding a sugar transport protein. It is evident that regardless of type of transport system and catabolic enzymes acting upon lactose, maltose and trehalose, respectively, Lc. lactis shows unity in both operon organisation and regulation of these catabolic operons. This knowledge was further extended to other catabolic operons in Lc. lactis and the two related bacteria Lactobacillus plantarum and Listeria monocytogenes. Thirty-nine catabolic operons responsible for degradation of sugars and sugar alcohols in Lc. lactis, Lb. plantarum and L. monocytogenes were investigated and the majority of those possessed the same organisation as the lactose, maltose and trehalose operons of Lc. lactis. Though, the frequency of CRE sites and their location varied among the bacteria. Both Lc. lactis and Lb. plantarum showed CRE sites in direct proximity to genes coding for proteins responsible for sugar uptake. However, in L. monocytogenes CRE sites were not frequently found and not in the vicinity of genes encoding transport proteins, suggesting a more local mode of regulation of the catabolic operons found and/or the use of inducer control in this bacterium. PMID:15900965

  17. NRGA1, a putative mitochondrial pyruvate carrier, mediates ABA regulation of guard cell ion channels and drought stress responses in Arabidopsis.

    PubMed

    Li, Chun-Long; Wang, Mei; Ma, Xiao-Yan; Zhang, Wei

    2014-10-01

    Abscisic acid (ABA) regulates ion channel activity and stomatal movements in response to drought and other stresses. Here, we show that the Arabidopsis thaliana gene NRGA1 is a putative mitochondrial pyruvate carrier which negatively regulates ABA-induced guard cell signaling. NRGA1 transcript was abundant in the A. thaliana leaf and particularly in the guard cells, and its product was directed to the mitochondria. The heterologous co-expression of NRGA1 and AtMPC1 in yeast complemented a loss-of-function mitochondrial pyruvate carrier (MPC) mutant. The nrga1 loss-of-function mutant was very sensitive to the presence of ABA in the context of stomatal movements, and exhibited a heightened tolerance to drought stress. Disruption of NRGA1 gene resulted in increased ABA inhibition of inward K(+) currents and ABA activation of slow anion currents in guard cells. The nrga1/NRGA1 functional complementation lines restored the mutant's phenotypes. Furthermore, transgenic lines of constitutively overexpressing NRGA1 showed opposite stomatal responses, reduced drought tolerance, and ABA sensitivity of guard cell inward K(+) channel inhibition and anion channel activation. Our findings highlight a putative role for the mitochondrial pyruvate carrier in guard cell ABA signaling in response to drought.

  18. A 14-3-3 Family Protein from Wild Soybean (Glycine Soja) Regulates ABA Sensitivity in Arabidopsis

    PubMed Central

    Sun, Xiaoli; Sun, Mingzhe; Jia, Bowei; Chen, Chao; Qin, Zhiwei; Yang, Kejun; Shen, Yang; Meiping, Zhang; Mingyang, Cong; Zhu, Yanming

    2015-01-01

    It is widely accepted that the 14-3-3 family proteins are key regulators of multiple stress signal transduction cascades. By conducting genome-wide analysis, researchers have identified the soybean 14-3-3 family proteins; however, until now, there is still no direct genetic evidence showing the involvement of soybean 14-3-3s in ABA responses. Hence, in this study, based on the latest Glycine max genome on Phytozome v10.3, we initially analyzed the evolutionary relationship, genome organization, gene structure and duplication, and three-dimensional structure of soybean 14-3-3 family proteins systematically. Our results suggested that soybean 14-3-3 family was highly evolutionary conserved and possessed segmental duplication in evolution. Then, based on our previous functional characterization of a Glycine soja 14-3-3 protein GsGF14o in drought stress responses, we further investigated the expression characteristics of GsGF14o in detail, and demonstrated its positive roles in ABA sensitivity. Quantitative real-time PCR analyses in Glycine soja seedlings and GUS activity assays in PGsGF14O:GUS transgenic Arabidopsis showed that GsGF14o expression was moderately and rapidly induced by ABA treatment. As expected, GsGF14o overexpression in Arabidopsis augmented the ABA inhibition of seed germination and seedling growth, promoted the ABA induced stomata closure, and up-regulated the expression levels of ABA induced genes. Moreover, through yeast two hybrid analyses, we further demonstrated that GsGF14o physically interacted with the AREB/ABF transcription factors in yeast cells. Taken together, results presented in this study strongly suggested that GsGF14o played an important role in regulation of ABA sensitivity in Arabidopsis. PMID:26717241

  19. A 14-3-3 Family Protein from Wild Soybean (Glycine Soja) Regulates ABA Sensitivity in Arabidopsis.

    PubMed

    Sun, Xiaoli; Sun, Mingzhe; Jia, Bowei; Chen, Chao; Qin, Zhiwei; Yang, Kejun; Shen, Yang; Meiping, Zhang; Mingyang, Cong; Zhu, Yanming

    2015-01-01

    It is widely accepted that the 14-3-3 family proteins are key regulators of multiple stress signal transduction cascades. By conducting genome-wide analysis, researchers have identified the soybean 14-3-3 family proteins; however, until now, there is still no direct genetic evidence showing the involvement of soybean 14-3-3s in ABA responses. Hence, in this study, based on the latest Glycine max genome on Phytozome v10.3, we initially analyzed the evolutionary relationship, genome organization, gene structure and duplication, and three-dimensional structure of soybean 14-3-3 family proteins systematically. Our results suggested that soybean 14-3-3 family was highly evolutionary conserved and possessed segmental duplication in evolution. Then, based on our previous functional characterization of a Glycine soja 14-3-3 protein GsGF14o in drought stress responses, we further investigated the expression characteristics of GsGF14o in detail, and demonstrated its positive roles in ABA sensitivity. Quantitative real-time PCR analyses in Glycine soja seedlings and GUS activity assays in PGsGF14O:GUS transgenic Arabidopsis showed that GsGF14o expression was moderately and rapidly induced by ABA treatment. As expected, GsGF14o overexpression in Arabidopsis augmented the ABA inhibition of seed germination and seedling growth, promoted the ABA induced stomata closure, and up-regulated the expression levels of ABA induced genes. Moreover, through yeast two hybrid analyses, we further demonstrated that GsGF14o physically interacted with the AREB/ABF transcription factors in yeast cells. Taken together, results presented in this study strongly suggested that GsGF14o played an important role in regulation of ABA sensitivity in Arabidopsis. PMID:26717241

  20. A 14-3-3 Family Protein from Wild Soybean (Glycine Soja) Regulates ABA Sensitivity in Arabidopsis.

    PubMed

    Sun, Xiaoli; Sun, Mingzhe; Jia, Bowei; Chen, Chao; Qin, Zhiwei; Yang, Kejun; Shen, Yang; Meiping, Zhang; Mingyang, Cong; Zhu, Yanming

    2015-01-01

    It is widely accepted that the 14-3-3 family proteins are key regulators of multiple stress signal transduction cascades. By conducting genome-wide analysis, researchers have identified the soybean 14-3-3 family proteins; however, until now, there is still no direct genetic evidence showing the involvement of soybean 14-3-3s in ABA responses. Hence, in this study, based on the latest Glycine max genome on Phytozome v10.3, we initially analyzed the evolutionary relationship, genome organization, gene structure and duplication, and three-dimensional structure of soybean 14-3-3 family proteins systematically. Our results suggested that soybean 14-3-3 family was highly evolutionary conserved and possessed segmental duplication in evolution. Then, based on our previous functional characterization of a Glycine soja 14-3-3 protein GsGF14o in drought stress responses, we further investigated the expression characteristics of GsGF14o in detail, and demonstrated its positive roles in ABA sensitivity. Quantitative real-time PCR analyses in Glycine soja seedlings and GUS activity assays in PGsGF14O:GUS transgenic Arabidopsis showed that GsGF14o expression was moderately and rapidly induced by ABA treatment. As expected, GsGF14o overexpression in Arabidopsis augmented the ABA inhibition of seed germination and seedling growth, promoted the ABA induced stomata closure, and up-regulated the expression levels of ABA induced genes. Moreover, through yeast two hybrid analyses, we further demonstrated that GsGF14o physically interacted with the AREB/ABF transcription factors in yeast cells. Taken together, results presented in this study strongly suggested that GsGF14o played an important role in regulation of ABA sensitivity in Arabidopsis.

  1. Isohydric and anisohydric strategies of wheat genotypes under osmotic stress: biosynthesis and function of ABA in stress responses.

    PubMed

    Gallé, Ágnes; Csiszár, Jolán; Benyó, Dániel; Laskay, Gábor; Leviczky, Tünde; Erdei, László; Tari, Irma

    2013-11-01

    Changes in water potential (ψw), stomatal conductance, abscisic acid (ABA) accumulation, expression of the major genes involved in ABA biosynthesis, activities of abscisic aldehyde oxidase (AO, EC 1.2.3.1) and antioxidant enzymes were studied in two wheat cultivars with contrasting acclimation strategies subjected to medium strength osmotic stress (-0.976MPa) induced by polyethylene glycol (PEG 6000). Because the biosynthetic pathway of ABA involves multiple gene products, the aim of this study was to unravel how these genes are regulated in isohydric and anisohydric wheat genotypes. In the root tissues of the isohydric cultivar, Triticum aestivum cv. Kobomugi, osmotic stress increased the transcript levels of 9-cis-epoxycarotenoid dioxygenase (NCED) gene, controlling the rate limiting step of ABA biosynthesis. Moreover, this cultivar exhibited a higher basal activity and a higher induction of aldehyde oxidase isoenzymes (AAO2-AAO3), responsible for converting ABAldehyde to ABA. It was found that the fast activation of the ABA biosynthesis in the roots generated an enhanced ABA pool in the shoot, which brought about a faster closure of the stomata upon increasing osmotic stress and, as a result, the plants could maintain ψw in the tissues close to the control level. In contrast, the anisohydric genotype, cv. GK Öthalom, exhibited a moderate induction of ABA biosynthesis in the roots, leading to the maintenance but no increase in the concentration of ABA on the basis of tissue water content in the leaves. Due to the slower response of their stomata to water deficit, the tissues of cv. GK Öthalom have to acclimate to much more negative water potentials during increasing osmotic stress. A decreased activity of superoxide dismutase (SOD) was found in the leaves and roots of both cultivars exposed to osmotic stress, but in the roots elevated activities of catalase (CAT), peroxidase (POX), glutathione reductase (GR) and glutathione transferase (GST) were detected in

  2. Understanding Sugar Catabolism in Unicellular Cyanobacteria Toward the Application in Biofuel and Biomaterial Production.

    PubMed

    Osanai, Takashi; Iijima, Hiroko; Hirai, Masami Yokota

    2016-01-01

    Synechocystis sp. PCC 6803 is a model species of the cyanobacteria that undergo oxygenic photosynthesis, and has garnered much attention for its potential biotechnological applications. The regulatory mechanism of sugar metabolism in this cyanobacterium has been intensively studied and recent omics approaches have revealed the changes in transcripts, proteins, and metabolites of sugar catabolism under different light and nutrient conditions. Several transcriptional regulators that control the gene expression of enzymes related to sugar catabolism have been identified in the past 10 years, including a sigma factor, transcription factors, and histidine kinases. The modification of these genes can lead to alterations in the primary metabolism as well as the levels of high-value products such as bioplastics and hydrogen. This review summarizes recent studies on sugar catabolism in Synechocystis sp. PCC 6803, emphasizing the importance of elucidating the molecular mechanisms of cyanobacterial metabolism for biotechnological applications. PMID:27023248

  3. Phenylalanine induces Burkholderia cenocepacia phenylacetic acid catabolism through degradation to phenylacetyl-CoA in synthetic cystic fibrosis sputum medium.

    PubMed

    Yudistira, Harry; McClarty, Leigh; Bloodworth, Ruhi A M; Hammond, Sydney A; Butcher, Haley; Mark, Brian L; Cardona, Silvia T

    2011-09-01

    Synthetic cystic fibrosis sputum medium (SCFM) is rich in amino acids and supports robust growth of Burkholderia cenocepacia, a member of the Burkholderia cepacia complex (Bcc). Previous work demonstrated that B. cenocepacia phenylacetic acid (PA) catabolic genes are up-regulated during growth in SCFM and are required for full virulence in a Caenorhabditis elegans host model. In this work, we investigated the role of phenylalanine, one of the aromatic amino acids present in SCFM, as an inducer of the PA catabolic pathway. Phenylalanine degradation intermediates were used as sole carbon sources for growth and gene reporter experiments. In addition to phenylalanine and PA, phenylethylamine, phenylpyruvate, and 2-phenylacetamide were usable as sole carbon sources by wild type B. cenocepacia K56-2, but not by a PA catabolism-defective mutant. EMSA analysis showed that the binding of PaaR, the negative regulator protein of B. cenocepacia PA catabolism, to PA regulatory DNA could only be relieved by phenylacetyl-Coenzyme A (PA-CoA), but not by any of the putative phenylalanine degradation intermediates. Taken together, our results show that in B. cenocepacia, phenylalanine is catabolized to PA and induces PA catabolism through PA activation to PA-CoA. Thus, PaaR shares the same inducer with PaaX, the regulator of PA catabolism in Escherichia coli, despite belonging to a different protein family.

  4. Laboratory evolution of catabolic enzymes and pathways.

    PubMed

    Parales, Rebecca E; Ditty, Jayna L

    2005-06-01

    The laboratory evolution of environmentally relevant enzymes and proteins has resulted in the generation of optimized and stabilized enzymes, as well as enzymes with activity against new substrates. Numerous methods, including random mutagenesis, site-directed mutagenesis and DNA shuffling, have been widely used to generate variants of existing enzymes. These evolved catabolic enzymes have application for improving biodegradation pathways, generating engineered pathways for the degradation of particularly recalcitrant compounds, and for the development of biocatalytic processes to produce useful compounds. Regulatory proteins associated with catabolic pathways have been utilized to generate biosensors for the detection of bioavailable concentrations of environmentally relevant chemicals.

  5. Intracellular Growth Is Dependent on Tyrosine Catabolism in the Dimorphic Fungal Pathogen Penicillium marneffei

    PubMed Central

    Boyce, Kylie J.; McLauchlan, Alisha; Schreider, Lena; Andrianopoulos, Alex

    2015-01-01

    During infection, pathogens must utilise the available nutrient sources in order to grow while simultaneously evading or tolerating the host’s defence systems. Amino acids are an important nutritional source for pathogenic fungi and can be assimilated from host proteins to provide both carbon and nitrogen. The hpdA gene of the dimorphic fungus Penicillium marneffei, which encodes an enzyme which catalyses the second step of tyrosine catabolism, was identified as up-regulated in pathogenic yeast cells. As well as enabling the fungus to acquire carbon and nitrogen, tyrosine is also a precursor in the formation of two types of protective melanin; DOPA melanin and pyomelanin. Chemical inhibition of HpdA in P. marneffei inhibits ex vivo yeast cell production suggesting that tyrosine is a key nutrient source during infectious growth. The genes required for tyrosine catabolism, including hpdA, are located in a gene cluster and the expression of these genes is induced in the presence of tyrosine. A gene (hmgR) encoding a Zn(II)2-Cys6 binuclear cluster transcription factor is present within the cluster and is required for tyrosine induced expression and repression in the presence of a preferred nitrogen source. AreA, the GATA-type transcription factor which regulates the global response to limiting nitrogen conditions negatively regulates expression of cluster genes in the absence of tyrosine and is required for nitrogen metabolite repression. Deletion of the tyrosine catabolic genes in the cluster affects growth on tyrosine as either a nitrogen or carbon source and affects pyomelanin, but not DOPA melanin, production. In contrast to other genes of the tyrosine catabolic cluster, deletion of hpdA results in no growth within macrophages. This suggests that the ability to catabolise tyrosine is not required for macrophage infection and that HpdA has an additional novel role to that of tyrosine catabolism and pyomelanin production during growth in host cells. PMID:25812137

  6. A balanced JA/ABA status may correlate with adaptation to osmotic stress in Vitis cells.

    PubMed

    Ismail, Ahmed; Seo, Mitsunori; Takebayashi, Yumiko; Kamiya, Yuji; Nick, Peter

    2015-08-01

    Water-related stress is considered a major type of plant stress. Osmotic stress, in particular, represents the common part of all water-related stresses. Therefore, plants have evolved different adaptive mechanisms to cope with osmotic-related disturbances. In the current work, two grapevine cell lines that differ in their osmotic adaptability, Vitis rupestris and Vitis riparia, were investigated under mannitol-induced osmotic stress. To dissect signals that lead to adaptability from those related to sensitivity, osmotic-triggered responses with respect to jasmonic acid (JA) and its active form JA-Ile, abscisic acid (ABA), and stilbene compounds, as well as the expression of their related genes were observed. In addition, the transcript levels of the cellular homeostasis gene NHX1 were examined. The data are discussed with a hypothesis suggesting that a balance of JA and ABA status might correlate with cellular responses, either guiding cells to sensitivity or to progress toward adaptation. PMID:26277753

  7. Molecular Characterization of the Genes pcaG and pcaH, Encoding Protocatechuate 3,4-Dioxygenase, Which Are Essential for Vanillin Catabolism in Pseudomonas sp. Strain HR199

    PubMed Central

    Overhage, Jörg; Kresse, Andreas U.; Priefert, Horst; Sommer, Horst; Krammer, Gerhard; Rabenhorst, Jürgen; Steinbüchel, Alexander

    1999-01-01

    Pseudomonas sp. strain HR199 is able to utilize eugenol (4-allyl-2-methoxyphenol), vanillin (4-hydroxy-3-methoxybenzaldehyde), or protocatechuate as the sole carbon source for growth. Mutants of this strain which were impaired in the catabolism of vanillin but retained the ability to utilize eugenol or protocatechuate were obtained after nitrosoguanidine mutagenesis. One mutant (SK6169) was used as recipient of a Pseudomonas sp. strain HR199 genomic library in cosmid pVK100, and phenotypic complementation was achieved with a 5.8-kbp EcoRI fragment (E58). The amino acid sequences deduced from two corresponding open reading frames (ORF) identified on E58 revealed high degrees of homology to pcaG and pcaH, encoding the two subunits of protocatechuate 3,4-dioxygenase. Three additional ORF most probably encoded a 4-hydroxybenzoate 3-hydroxylase (PobA) and two putative regulatory proteins, which exhibited homology to PcaQ of Agrobacterium tumefaciens and PobR of Pseudomonas aeruginosa, respectively. Since mutant SK6169 was also complemented by a subfragment of E58 that harbored only pcaH, this mutant was most probably lacking a functional β subunit of the protocatechuate 3,4-dioxygenase. Since this mutant was still able to grow on protocatechuate and lacked protocatechuate 4,5-dioxygenase and protocatechuate 2,3-dioxygenase, the degradation had to be catalyzed by different enzymes. Two other mutants (SK6184 and SK6190), which were also impaired in the catabolism of vanillin, were not complemented by fragment E58. Since these mutants accumulated 3-carboxy muconolactone during cultivation on eugenol, they most probably exhibited a defect in a step of the catabolic pathway following the ortho cleavage. Moreover, in these mutants cyclization of 3-carboxymuconic acid seems to occur by a syn absolute stereochemical course, which is normally only observed for cis,cis-muconate lactonization in pseudomonads. In conclusion, vanillin is degraded through the ortho-cleavage pathway

  8. A plasmid of Rhizobium meliloti 41 encodes catabolism of two compounds from root exudate of Calystegium sepium.

    PubMed Central

    Tepfer, D; Goldmann, A; Pamboukdjian, N; Maille, M; Lepingle, A; Chevalier, D; Dénarié, J; Rosenberg, C

    1988-01-01

    Our objectives were to identify substances produced by plant roots that might act as nutritional mediators of specific plant-bacterium relationships and to delineate the bacterial genes responsible for catabolizing these substances. We discovered new compounds, which we call calystegins, that have the characteristics of nutritional mediators. They were detected in only 3 of 105 species of higher plants examined: Calystegia sepium, Convolvulus arvensis (both of the Convolvulaceae family), and Atropa belladonna. Calystegins are abundant in organs in contact with the rhizosphere and are not found, or are observed only in small quantities, in aerial plant parts. Just as the synthesis of calystegins is infrequent in the plant kingdom, their catabolism is rare among rhizosphere bacteria that associate with plants and influence their growth. Of 42 such bacteria tested, only one (Rhizobium meliloti 41) was able to catabolize calystegins and use them as a sole source of carbon and nitrogen. The calystegin catabolism gene(s) (cac) in this strain is located on a self-transmissible plasmid (pRme41a), which is not essential to nitrogen-fixing symbiosis with legumes. We suggest that under natural conditions calystegins provide an exclusive carbon and nitrogen source to rhizosphere bacteria which are able to catabolize these compounds. Calystegins (and the corresponding microbial catabolic genes) might be used to analyze and possibly modify rhizosphere ecology. Images PMID:2981046

  9. Catabolism of Benzoate and Phthalate in Rhodococcus sp. Strain RHA1: Redundancies and Convergence

    PubMed Central

    Patrauchan, Marianna A.; Florizone, Christine; Dosanjh, Manisha; Mohn, William W.; Davies, Julian; Eltis, Lindsay D.

    2005-01-01

    Genomic and proteomic approaches were used to investigate phthalate and benzoate catabolism in Rhodococcus sp. strain RHA1, a polychlorinated biphenyl-degrading actinomycete. Sequence analyses identified genes involved in the catabolism of benzoate (ben) and phthalate (pad), the uptake of phthalate (pat), and two branches of the β-ketoadipate pathway (catRABC and pcaJIHGBLFR). The regulatory and structural ben genes are separated by genes encoding a cytochrome P450. The pad and pat genes are contained on a catabolic island that is duplicated on plasmids pRHL1 and pRHL2 and includes predicted terephthalate catabolic genes (tpa). Proteomic analyses demonstrated that the β-ketoadipate pathway is functionally convergent. Specifically, the pad and pat gene products were only detected in phthalate-grown cells. Similarly, the ben and cat gene products were only detected in benzoate-grown cells. However, pca-encoded enzymes were present under both growth conditions. Activity assays for key enzymes confirmed these results. Disruption of pcaL, which encodes a fusion enzyme, abolished growth on phthalate. In contrast, after a lag phase, growth of the mutant on benzoate was similar to that of the wild type. Proteomic analyses revealed 20 proteins in the mutant that were not detected in wild-type cells during growth on benzoate, including a CatD homolog that apparently compensated for loss of PcaL. Analysis of completed bacterial genomes indicates that the convergent β-ketoadipate pathway and some aspects of its genetic organization are characteristic of rhodococci and related actinomycetes. In contrast, the high redundancy of catabolic pathways and enzymes appears to be unique to RHA1 and may increase its potential to adapt to new carbon sources. PMID:15937168

  10. Induction of the oxidative catabolism of retinoid acid in MCF-7 cells.

    PubMed Central

    Krekels, M. D.; Verhoeven, A.; van Dun, J.; Cools, W.; Van Hove, C.; Dillen, L.; Coene, M. C.; Wouters, W.

    1997-01-01

    Cytochrome P450-dependent oxidation is a pathway for all-trans-retinoic acid (all-trans-RA) catabolism. Induction of this catabolic pathway was studied in MCF-7 breast cancer cells. MCF-7 cells showed low constitutive all-trans-RA catabolism. Concentration-dependent induction was obtained by preincubation of the cells with all-trans-RA (10(-9) to 10(-6) M). Onset of induction was fast, being detectable within 60 min, with maximal induction (45-fold) obtained after 16 h. Enzymatic characterization of induced all-trans-RA catabolism showed an estimated Km value (Michaelis-Menten constant) of 0.33 microM and a Vmax value (maximal velocity of an enzyme-catalysed reaction) of 54.5 fmol polar all-trans-RA metabolites 10(6) cells(-1) h(-1). These kinetic parameters represent the overall formation of polar metabolites from all-trans-RA. Induction of all-trans-RA catabolism was also obtained with other retinoids, CH55 >> 13-cis-RA = all-trans-RA > 9-cis-RA > 4-keto-all-trans-RA > 4-keto-13-cis-RA > retinol. The potency of the retinoids to induce all-trans-RA catabolism was correlated to their retinoic acid receptor affinity (Crettaz et al, 1990; Repa et al, 1990; Sani et al, 1990). Induction of all-trans-RA catabolism was inhibited by actinomycin D. Furthermore, all-trans-RA did not increase cytosolic retinoic acid-binding protein (CRABP) mRNA levels. These data suggest that induction of all-trans-RA catabolism in MCF-7 cells is a retinoic acid receptor-mediated gene transcriptional event. Induced all-trans-RA catabolism was inhibited by various retinoids with decreasing potency in the order: all-trans-RA > 4-keto-all-trans-RA > 13-cis-RA > 9-cis-RA > 4-keto-13-cis-RA > retinol > CH55. The antitumoral compound liarozole-fumarate inhibited all-trans-RA catabolism with a potency similar to that of all-trans-RA. Images Figure 4 PMID:9099955

  11. Comparative genomics and functional analysis of rhamnose catabolic pathways and regulons in bacteria

    PubMed Central

    Rodionova, Irina A.; Li, Xiaoqing; Thiel, Vera; Stolyar, Sergey; Stanton, Krista; Fredrickson, James K.; Bryant, Donald A.; Osterman, Andrei L.; Best, Aaron A.; Rodionov, Dmitry A.

    2013-01-01

    L-rhamnose (L-Rha) is a deoxy-hexose sugar commonly found in nature. L-Rha catabolic pathways were previously characterized in various bacteria including Escherichia coli. Nevertheless, homology searches failed to recognize all the genes for the complete L-Rha utilization pathways in diverse microbial species involved in biomass decomposition. Moreover, the regulatory mechanisms of L-Rha catabolism have remained unclear in most species. A comparative genomics approach was used to reconstruct the L-Rha catabolic pathways and transcriptional regulons in the phyla Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Proteobacteria, and Thermotogae. The reconstructed pathways include multiple novel enzymes and transporters involved in the utilization of L-Rha and L-Rha-containing polymers. Large-scale regulon inference using bioinformatics revealed remarkable variations in transcriptional regulators for L-Rha utilization genes among bacteria. A novel bifunctional enzyme, L-rhamnulose-phosphate aldolase (RhaE) fused to L-lactaldehyde dehydrogenase (RhaW), which is not homologous to previously characterized L-Rha catabolic enzymes, was identified in diverse bacteria including Chloroflexi, Bacilli, and Alphaproteobacteria. By using in vitro biochemical assays we validated both enzymatic activities of the purified recombinant RhaEW proteins from Chloroflexus aurantiacus and Bacillus subtilis. Another novel enzyme of the L-Rha catabolism, L-lactaldehyde reductase (RhaZ), was identified in Gammaproteobacteria and experimentally validated by in vitro enzymatic assays using the recombinant protein from Salmonella typhimurium. C. aurantiacus induced transcription of the predicted L-Rha utilization genes when L-Rha was present in the growth medium and consumed L-Rha from the medium. This study provided comprehensive insights to L-Rha catabolism and its regulation in diverse Bacteria. PMID:24391637

  12. The Arabidopsis a zinc finger domain protein ARS1 is essential for seed germination and ROS homeostasis in response to ABA and oxidative stress

    PubMed Central

    Baek, Dongwon; Cha, Joon-Yung; Kang, Songhwa; Park, Bokyung; Lee, Hyo-Jung; Hong, Hyewon; Chun, Hyun Jin; Kim, Doh Hoon; Kim, Min Chul; Lee, Sang Yeol; Yun, Dae-Jin

    2015-01-01

    The phytohormone abscisic acid (ABA) induces accumulation of reactive oxygen species (ROS), which can disrupt seed dormancy and plant development. Here, we report the isolation and characterization of an Arabidopsis thaliana mutant called ars1 (aba and ros sensitive 1) that showed hypersensitivity to ABA during seed germination and to methyl viologen (MV) at the seedling stage. ARS1 encodes a nuclear protein with one zinc finger domain, two nuclear localization signal (NLS) domains, and one nuclear export signal (NES). The ars1 mutants showed reduced expression of a gene for superoxide dismutase (CSD3) and enhanced accumulation of ROS after ABA treatment. Transient expression of ARS1 in Arabidopsis protoplasts strongly suppressed ABA-mediated ROS production. Interestingly, nuclear-localized ARS1 translocated to the cytoplasm in response to treatment with ABA, H2O2, or MV. Taken together, these results suggest that ARS1 modulates seed germination and ROS homeostasis in response to ABA and oxidative stress in plants. PMID:26583028

  13. CLONING AND CHARACTERIZATION OF THE PHTHALATE CATABOLISM REGION OF PRE1 OF ARTHROBACTER KEYSERI 12B

    EPA Science Inventory

    o-Phthalate (benzene-1,2-dicarboxylate) is a central intermediate in the bacterial degradation of phthalate ester plasticizers as well as of a number of fused-ring polycyclic aromatic hydrocarbons found in fossil fuels. In Arthrobacter keyseri 12B, the genes encoding catabolism o...

  14. A NAP-AAO3 Regulatory Module Promotes Chlorophyll Degradation via ABA Biosynthesis in Arabidopsis Leaves[W][OPEN

    PubMed Central

    Yang, Jiading; Worley, Eric

    2014-01-01

    Chlorophyll degradation is an important part of leaf senescence, but the underlying regulatory mechanisms are largely unknown. Excised leaves of an Arabidopsis thaliana NAC-LIKE, ACTIVATED BY AP3/PI (NAP) transcription factor mutant (nap) exhibited lower transcript levels of known chlorophyll degradation genes, STAY-GREEN1 (SGR1), NON-YELLOW COLORING1 (NYC1), PHEOPHYTINASE (PPH), and PHEIDE a OXYGENASE (PaO), and higher chlorophyll retention than the wild type during dark-induced senescence. Transcriptome coexpression analysis revealed that abscisic acid (ABA) metabolism/signaling genes were disproportionately represented among those positively correlated with NAP expression. ABA levels were abnormally low in nap leaves during extended darkness. The ABA biosynthetic genes 9-CIS-EPOXYCAROTENOID DIOXYGENASE2, ABA DEFICIENT3, and ABSCISIC ALDEHYDE OXIDASE3 (AAO3) exhibited abnormally low transcript levels in dark-treated nap leaves. NAP transactivated the promoter of AAO3 in mesophyll cell protoplasts, and electrophoretic mobility shift assays showed that NAP can bind directly to a segment (−196 to −162 relative to the ATG start codon) of the AAO3 promoter. Exogenous application of ABA increased the transcript levels of SGR1, NYC1, PPH, and PaO and suppressed the stay-green phenotype of nap leaves during extended darkness. Overexpression of AAO3 in nap leaves also suppressed the stay-green phenotype under extended darkness. Collectively, the results show that NAP promotes chlorophyll degradation by enhancing transcription of AAO3, which leads to increased levels of the senescence-inducing hormone ABA. PMID:25516602

  15. ABA says NO to UV-B: a universal response?

    PubMed

    Tossi, Vanesa; Cassia, Raul; Bruzzone, Santina; Zocchi, Elena; Lamattina, Lorenzo

    2012-09-01

    Abscisic acid (ABA) signaling pathways have been widely characterized in plants, whereas the function of ABA in animals is less well understood. However, recent advances show ABA production by a wide range of lower animals and higher mammals. This enables a new evaluation of ABA signaling pathways in different organisms in response to common environmental stress, such as ultraviolet (UV)-B. In this opinion article, we propose that the induction of common signaling components, such as ABA, nitric oxide (NO) and Ca(2+), in plant and animal cells in response to high doses of UV-B, suggests that the evolution of a general mechanism activated by UV-B is conserved in divergent multicellular organisms challenged by a changing common environment.

  16. AsHSP17, a creeping bentgrass small heat shock protein modulates plant photosynthesis and ABA-dependent and independent signalling to attenuate plant response to abiotic stress.

    PubMed

    Sun, Xinbo; Sun, Chunyu; Li, Zhigang; Hu, Qian; Han, Liebao; Luo, Hong

    2016-06-01

    Heat shock proteins (HSPs) are molecular chaperones that accumulate in response to heat and other abiotic stressors. Small HSPs (sHSPs) belong to the most ubiquitous HSP subgroup with molecular weights ranging from 12 to 42 kDa. We have cloned a new sHSP gene, AsHSP17 from creeping bentgrass (Agrostis stolonifera) and studied its role in plant response to environmental stress. AsHSP17 encodes a protein of 17 kDa. Its expression was strongly induced by heat in both leaf and root tissues, and by salt and abscisic acid (ABA) in roots. Transgenic Arabidopsis plants constitutively expressing AsHSP17 exhibited enhanced sensitivity to heat and salt stress accompanied by reduced leaf chlorophyll content and decreased photosynthesis under both normal and stressed conditions compared to wild type. Overexpression of AsHSP17 also led to hypersensitivity to exogenous ABA and salinity during germination and post-germinative growth. Gene expression analysis indicated that AsHSP17 modulates expression of photosynthesis-related genes and regulates ABA biosynthesis, metabolism and ABA signalling as well as ABA-independent stress signalling. Our results suggest that AsHSP17 may function as a protein chaperone to negatively regulate plant responses to adverse environmental stresses through modulating photosynthesis and ABA-dependent and independent signalling pathways. PMID:26610288

  17. Regulation of phenolic catabolism in Rhizobium leguminosarum biovar trifolii

    SciTech Connect

    Parke, D. ); Rynne, F.; Glenn, A. )

    1991-09-01

    In members of the family Rhizobiaceae, many phenolic compounds are degraded by the protocatechuate branch of the {beta}-ketoadipate pathway, In this paper the authors describe a novel pattern of induction of protocatechuate (pca) genes in Rhizobium leguminosarum biovar trifolii. Isolation of pca mutant strains revealed that 4-hydroxybenzoate, quinate, and 4-coumarate are degraded via the protocatechuate pathway. At least three inducers govern catabolism of 4-hydroxybenzoate to succinyl coenzyme A and acetyl coenzyme A. The enzyme that catalyzes the initial step is induced by its substrate, whereas the catabolite {beta}-carboxy-cis, cis-muconate induces enzymes for the upper protocatechuate pathway, and {beta}-ketoadipate elicits expression of the enzyme for a subsequent step, {beta}-ketoadipate succinyl-coenzyme A transferase. Elucidation of the induction pattern relied in part on complementation of mutant Rhizobium strains by known subclones of Acinetobacter genes expressed off the lac promoter in a broad-host-range vector.

  18. A hub for ABA signaling to the nucleus: significance of a cytosolic and nuclear dual-localized PPR protein SOAR1 acting downstream of Mg-chelatase H subunit.

    PubMed

    Jiang, Shang-Chuan; Mei, Chao; Wang, Xiao-Fang; Zhang, Da-Peng

    2014-01-01

    SOAR1 is a cytosol-nucleus dual-localized pentatricopeptide repeat (PPR) protein, which we indentified recently as a crucial regulator in the CHLH/ABAR (Mg-chelatase H subunit /putative ABA receptor)-mediated signaling pathway, acting downstream of CHLH/ABAR and upstream of a nuclear ABA-responsive bZIP transcription factor ABI5. Downregulation and upregulation of SOAR1 expression alter dramatically both ABA sensitivity and expression of a subset of key, nuclear ABA-responsive genes, suggesting that SOAR1 is a hub for ABA signaling to the nucleus, and CHLH/ABAR mediates a central signaling pathway to regulate downstream gene expression through SOAR1.

  19. A novel role of PR2 in abscisic acid (ABA) mediated, pathogen-induced callose deposition in Arabidopsis thaliana.

    PubMed

    Oide, Shinichi; Bejai, Sarosh; Staal, Jens; Guan, Na; Kaliff, Maria; Dixelius, Christina

    2013-12-01

    Pathogenesis-related protein 2 (PR2) is known to play a major role in plant defense and general stress responses. Resistance against the fungal pathogen Leptosphaeria maculans in Arabidopsis requires abscisic acid (ABA), which promotes the deposition of callose, a β-1,3-glucan polymer. Here, we examined the role of PR2 in callose deposition in relation to ABA treatment and challenge with L. maculans and Pseudomonas syringae. Characterization of PR2-overexpressing plants and the knockout line indicated that PR2 negatively affects callose deposition. Recombinant PR2 purified from Pichia pastoris showed callose-degrading activity, and a considerable reduction in the callose-degrading activity was observed in the leaf extract of the PR2 knockout line compared with the wild-type. ABA pretreatment before challenge with L. maculans concomitantly repressed PR2 and enhanced callose accumulation. Likewise, overexpression of an ABA biosynthesis gene NCED3 resulted in reduced PR2 expression and increased callose deposition. We propose that ABA promotes callose deposition through the transcriptional repression of PR2 in Arabidopsis challenged by L. maculans and P. syringae. Callose by itself is likely to act antagonistically on salicylic acid (SA) defense signaling, suggesting that PR2 may function as a modulator of callose- and SA-dependent defense responses.

  20. An l-glucose Catabolic Pathway in Paracoccus Species 43P*

    PubMed Central

    Shimizu, Tetsu; Takaya, Naoki; Nakamura, Akira

    2012-01-01

    An l-glucose-utilizing bacterium, Paracoccus sp. 43P, was isolated from soil by enrichment cultivation in a minimal medium containing l-glucose as the sole carbon source. In cell-free extracts from this bacterium, NAD+-dependent l-glucose dehydrogenase was detected as having sole activity toward l-glucose. This enzyme, LgdA, was purified, and the lgdA gene was found to be located in a cluster of putative inositol catabolic genes. LgdA showed similar dehydrogenase activity toward scyllo- and myo-inositols. l-Gluconate dehydrogenase activity was also detected in cell-free extracts, which represents the reaction product of LgdA activity toward l-glucose. Enzyme purification and gene cloning revealed that the corresponding gene resides in a nine-gene cluster, the lgn cluster, which may participate in aldonate incorporation and assimilation. Kinetic and reaction product analysis of each gene product in the cluster indicated that they sequentially metabolize l-gluconate to glycolytic intermediates, d-glyceraldehyde-3-phosphate, and pyruvate through reactions of C-5 epimerization by dehydrogenase/reductase, dehydration, phosphorylation, and aldolase reaction, using a pathway similar to l-galactonate catabolism in Escherichia coli. Gene disruption studies indicated that the identified genes are responsible for l-glucose catabolism. PMID:23038265

  1. The Plant-Specific SR45 Protein Negatively Regulates Glucose and ABA Signaling during Early Seedling Development in Arabidopsis1[W

    PubMed Central

    Carvalho, Raquel Fonseca; Carvalho, Sofia Domingues; Duque, Paula

    2010-01-01

    The plant-specific SR45 belongs to the highly conserved family of serine/arginine-rich (SR) proteins, which play key roles in precursor-mRNA splicing and other aspects of RNA metabolism. An Arabidopsis (Arabidopsis thaliana) loss-of-function mutant, sr45-1, displays pleiotropic phenotypes, such as defects in flower and leaf morphology, root growth, and flowering time. Here, we show that the sr45-1 mutation confers hypersensitivity to glucose (Glc) during early seedling growth in Arabidopsis. Unlike wild-type plants, the sr45-1 mutant displays impaired cotyledon greening and expansion as well as reduced hypocotyl elongation of dark-grown seedlings when grown in the presence of low (3%) Glc concentrations. In addition, SR45 is involved in the control of Glc-responsive gene expression, as the mutant displays enhanced repression of photosynthetic and nitrogen metabolism genes and overinduction of starch and anthocyanin biosynthesis genes. Like many other sugar response mutants, sr45-1 also shows hypersensitivity to abscisic acid (ABA) but appears to be unaffected in ethylene signaling. Importantly, the sr45-1 mutant shows enhanced ability to accumulate ABA in response to Glc, and the ABA biosynthesis inhibitor fluridone partially rescues the sugar-mediated growth arrest. Moreover, three ABA biosynthesis genes and two key ABA signaling genes, ABI3 and ABI5, are markedly overinduced by Glc in sr45-1. These results provide evidence that the SR45 protein defines a novel player in plant sugar response that negatively regulates Glc signaling during early seedling development by down-regulating both Glc-specific ABA accumulation and ABA biosynthesis and signaling gene expression. PMID:20699397

  2. Arabidopsis suppressor mutant of abh1 shows a new face of the already known players: ABH1 (CBP80) and ABI4-in response to ABA and abiotic stresses during seed germination.

    PubMed

    Daszkowska-Golec, Agata; Wojnar, Weronika; Rosikiewicz, Marta; Szarejko, Iwona; Maluszynski, Miroslaw; Szweykowska-Kulinska, Zofia; Jarmolowski, Artur

    2013-01-01

    Although the importance of abscisic acid (ABA) in plant development and response to abiotic and biotic stresses is well recognized, the molecular basis of the signaling pathway has not been fully elucidated. Mutants in genes related to ABA are widely used as a tool for gaining insight into the mechanisms of ABA signal transduction and ABA-dependent stress response. We used a genetic approach of a suppressor screening in order to decipher the interaction between ABH1 (CBP80) and other components of ABA signaling. ABH1 (CBP80) encodes a large subunit of CBC (CAP BINDING COMPLEX) and the abh1 mutant is drought-tolerant and hypersensitive to ABA during seed germination. The suppressor mutants of abh1 were generated after chemical mutagenesis. The mutant named soa1 (suppressor of abh1 hypersensitivity to ABA 1) displayed an ABA-insensitive phenotype during seed germination. The genetic analysis showed that the soa1 phenotype is dominant in relation to abh1 and segregates as a single locus. Based on soa1's response to a wide spectrum of physiological assays during different stages of development, we used the candidate-genes approach in order to identify a suppressor gene. The molecular analysis revealed that mutation causing the phenotype of soa1 occurred in the ABI4 (ABA insensitive 4) gene. Analysis of pre-miR159 expression, whose processing depends on CBC, as well as targets of miR159: MYB33 and MYB101, which are positive regulators of ABA signaling, revealed a possible link between CBP80 (ABH1) and ABI4 presented here.

  3. Graphene oxide modulates root growth of Brassica napus L. and regulates ABA and IAA concentration.

    PubMed

    Cheng, Fan; Liu, Yu-Feng; Lu, Guang-Yuan; Zhang, Xue-Kun; Xie, Ling-Li; Yuan, Cheng-Fei; Xu, Ben-Bo

    2016-04-01

    Researchers have proven that nanomaterials have a significant effect on plant growth and development. To better understand the effects of nanomaterials on plants, Zhongshuang 11 was treated with different concentrations of graphene oxide. The results indicated that 25-100mg/l graphene oxide treatment resulted in shorter seminal root length compared with the control samples. The fresh root weight decreased when treated with 50-100mg/l graphene oxide. The graphene oxide treatment had no significant effect on the Malondialdehyde (MDA) content. Treatment with 50mg/l graphene oxide increased the transcript abundance of genes involved in ABA biosynthesis (NCED, AAO, and ZEP) and some genes involved in IAA biosynthesis (ARF2, ARF8, IAA2, and IAA3), but inhibited the transcript levels of IAA4 and IAA7. The graphene oxide treatment also resulted in a higher ABA content, but a lower IAA content compared with the control samples. The results indicated that graphene oxide modulated the root growth of Brassica napus L. and affected ABA and IAA biosynthesis and concentration. PMID:26945480

  4. Glycosidases: inborn errors of glycosphingolipid catabolism.

    PubMed

    Ashida, Hisashi; Li, Yu-Teh

    2014-01-01

    Glycosphingolipids (GSLs) are information-rich glycoconjugates that occur in nature mainly as constituents of biomembranes. Each GSL contains a complex carbohydrate chain linked to a ceramide moiety that anchors the molecule to biomembranes. In higher animals, catabolism of GSLs takes place in lysosomes where sugar chains in GSLs are hydrolyzed by exo-glycosidases to cleave a sugar residue from the non-reducing end of a sugar chain. Inborn errors of GSL-catabolism, collectively called sphingolipidoses or GSL-storage diseases, are caused by the deficiency of exo-glycosidases responsible for the degradation of the specific sugar residues at the non-reducing termini in GSLs. This chapter briefly discusses glycone, anomeric, linkage, and aglycone specificities of exo-glycosidases and some of the historical landmarks on their associations with the chemical pathology of the five best known sphingolipidoses: GM1 gangliosidosis, GM2 gangliosidosis (Tay-Sachs disease), Fabry disease, Gaucher disease, and Krabbe disease. PMID:25151392

  5. The ABA-deficiency suppressor locus HAS2 encodes the PPR protein LOI1/MEF11 involved in mitochondrial RNA editing.

    PubMed

    Sechet, Julien; Roux, Camille; Plessis, Anne; Effroy, Delphine; Frey, Anne; Perreau, François; Biniek, Catherine; Krieger-Liszkay, Anja; Macherel, David; North, Helen M; Mireau, Hakim; Marion-Poll, Annie

    2015-04-01

    The hot ABA-deficiency suppressor2 (has2) mutation increases drought tolerance and the ABA sensitivity of stomata closure and seed germination. Here we report that the HAS2 locus encodes the mitochondrial editing factor11 (MEF11), also known as lovastatin insensitive1. has2/mef11 mutants exhibited phenotypes very similar to the ABA-hypersensitive mutant, hai1-1 pp2ca-1 hab1-1 abi1-2, which is impaired in four genes encoding type 2C protein phosphatases (PP2C) that act as upstream negative regulators of the ABA signaling cascade. Like pp2c, mef11 plants were more resistant to progressive water stress and seed germination was more sensitive to paclobutrazol (a gibberellin biosynthesis inhibitor) as well as mannitol and NaCl, compared with the wild-type plants. Phenotypic alterations in mef11 were associated with the lack of editing of transcripts for the mitochondrial cytochrome c maturation FN2 (ccmFN2) gene, which encodes a cytochrome c-heme lyase subunit involved in cytochrome c biogenesis. Although the abundance of electron transfer chain complexes was not affected, their dysfunction could be deduced from increased respiration and altered production of hydrogen peroxide and nitric oxide in mef11 seeds. As minor defects in mitochondrial respiration affect ABA signaling, this suggests an essential role for ABA in mitochondrial retrograde regulation.

  6. Transfer of a Catabolic Pathway for Chloromethane in Methylobacterium Strains Highlights Different Limitations for Growth with Chloromethane or with Dichloromethane

    DOE PAGES

    Michener, Joshua K.; Vuilleumier, Stéphane; Bringel, Françoise; Marx, Christopher J.

    2016-07-19

    Chloromethane is an ozone-depleting gas, produced predominantly from natural sources, that provides an important environmental niche for microbes capable of consuming it. Chloromethane catabolism has been difficult to study owing to the challenging genetics of its native microbial hosts. Since the pathways for chloromethane catabolism show evidence of horizontal gene transfer, we reproduced this transfer process in the laboratory to generate new chloromethane-catabolizing strains in tractable hosts. Here, we demonstrate that six putative accessory genes improve chloromethane catabolism, though heterologous expression of only one of the six is strictly necessary for growth on chloromethane. In contrast to growth of Methylobacteriummore » strains with the closely-related compound dichloromethane, we find that chloride export does not limit growth on chloromethane and, in general, that the ability of a strain to grow on dichloromethane is uncorrelated with its ability to grow on chloromethane. Finally, this heterologous expression system allows us to investigate the components required for effective chloromethane catabolism and the factors that limit effective catabolism after horizontal transfer.« less

  7. Transfer of a Catabolic Pathway for Chloromethane in Methylobacterium Strains Highlights Different Limitations for Growth with Chloromethane or with Dichloromethane

    PubMed Central

    Michener, Joshua K.; Vuilleumier, Stéphane; Bringel, Françoise; Marx, Christopher J.

    2016-01-01

    Chloromethane (CM) is an ozone-depleting gas, produced predominantly from natural sources, that provides an important carbon source for microbes capable of consuming it. CM catabolism has been difficult to study owing to the challenging genetics of its native microbial hosts. Since the pathways for CM catabolism show evidence of horizontal gene transfer, we reproduced this transfer process in the laboratory to generate new CM-catabolizing strains in tractable hosts. We demonstrate that six putative accessory genes improve CM catabolism, though heterologous expression of only one of the six is strictly necessary for growth on CM. In contrast to growth of Methylobacterium strains with the closely related compound dichloromethane (DCM), we find that chloride export does not limit growth on CM and, in general that the ability of a strain to grow on DCM is uncorrelated with its ability to grow on CM. This heterologous expression system allows us to investigate the components required for effective CM catabolism and the factors that limit effective catabolism after horizontal transfer. PMID:27486448

  8. Transfer of a Catabolic Pathway for Chloromethane in Methylobacterium Strains Highlights Different Limitations for Growth with Chloromethane or with Dichloromethane.

    PubMed

    Michener, Joshua K; Vuilleumier, Stéphane; Bringel, Françoise; Marx, Christopher J

    2016-01-01

    Chloromethane (CM) is an ozone-depleting gas, produced predominantly from natural sources, that provides an important carbon source for microbes capable of consuming it. CM catabolism has been difficult to study owing to the challenging genetics of its native microbial hosts. Since the pathways for CM catabolism show evidence of horizontal gene transfer, we reproduced this transfer process in the laboratory to generate new CM-catabolizing strains in tractable hosts. We demonstrate that six putative accessory genes improve CM catabolism, though heterologous expression of only one of the six is strictly necessary for growth on CM. In contrast to growth of Methylobacterium strains with the closely related compound dichloromethane (DCM), we find that chloride export does not limit growth on CM and, in general that the ability of a strain to grow on DCM is uncorrelated with its ability to grow on CM. This heterologous expression system allows us to investigate the components required for effective CM catabolism and the factors that limit effective catabolism after horizontal transfer. PMID:27486448

  9. Negative regulation of ABA signaling by WRKY33 is critical for Arabidopsis immunity towards Botrytis cinerea 2100.

    PubMed

    Liu, Shouan; Kracher, Barbara; Ziegler, Jörg; Birkenbihl, Rainer P; Somssich, Imre E

    2015-06-15

    The Arabidopsis mutant wrky33 is highly susceptible to Botrytis cinerea. We identified >1680 Botrytis-induced WRKY33 binding sites associated with 1576 Arabidopsis genes. Transcriptional profiling defined 318 functional direct target genes at 14 hr post inoculation. Comparative analyses revealed that WRKY33 possesses dual functionality acting either as a repressor or as an activator in a promoter-context dependent manner. We confirmed known WRKY33 targets involved in hormone signaling and phytoalexin biosynthesis, but also uncovered a novel negative role of abscisic acid (ABA) in resistance towards B. cinerea 2100. The ABA biosynthesis genes NCED3 and NCED5 were identified as direct targets required for WRKY33-mediated resistance. Loss-of-WRKY33 function resulted in elevated ABA levels and genetic studies confirmed that WRKY33 acts upstream of NCED3/NCED5 to negatively regulate ABA biosynthesis. This study provides the first detailed view of the genome-wide contribution of a specific plant transcription factor in modulating the transcriptional network associated with plant immunity.

  10. Negative regulation of ABA signaling by WRKY33 is critical for Arabidopsis immunity towards Botrytis cinerea 2100

    PubMed Central

    Liu, Shouan; Kracher, Barbara; Ziegler, Jörg; Birkenbihl, Rainer P; Somssich, Imre E

    2015-01-01

    The Arabidopsis mutant wrky33 is highly susceptible to Botrytis cinerea. We identified >1680 Botrytis-induced WRKY33 binding sites associated with 1576 Arabidopsis genes. Transcriptional profiling defined 318 functional direct target genes at 14 hr post inoculation. Comparative analyses revealed that WRKY33 possesses dual functionality acting either as a repressor or as an activator in a promoter-context dependent manner. We confirmed known WRKY33 targets involved in hormone signaling and phytoalexin biosynthesis, but also uncovered a novel negative role of abscisic acid (ABA) in resistance towards B. cinerea 2100. The ABA biosynthesis genes NCED3 and NCED5 were identified as direct targets required for WRKY33-mediated resistance. Loss-of-WRKY33 function resulted in elevated ABA levels and genetic studies confirmed that WRKY33 acts upstream of NCED3/NCED5 to negatively regulate ABA biosynthesis. This study provides the first detailed view of the genome-wide contribution of a specific plant transcription factor in modulating the transcriptional network associated with plant immunity. DOI: http://dx.doi.org/10.7554/eLife.07295.001 PMID:26076231

  11. Glucose Catabolism in Micrococcus sodonensis1

    PubMed Central

    Perry, Jerome J.; Evans, James B.

    1967-01-01

    The inability of Micrococcus sodonensis to grow on glucose as the sole source of carbon and energy was investigated. Estimation of pathways of glucose catabolism indicated that both the glycolytic and hexose monophosphate pathways are present in this organism. Comparative studies with Escherichia coli demonstrated that key enzymes for glucose catabolism were present in M. sodonensis in quantities equivalent to those of E. coli. The glucose-6-phosphate and 6-phosphogluconate dehydrogenases of M. sodonensis were nicotinamide adenine dinucleotide phosphate (NADP) specific, and glyceraldehyde-3-phosphate dehydrogenase was nicotinamide adenine dinucleotide specific. Transhydrogenase and reduced NADP oxidase were absent. Growth of the organism in the presence of glucose did not result in a repressed ability to oxidize tricarboxylic acid cycle intermediates, but these cells did have a decreased capacity for glucose degradation. The addition of substrates rich in growth-promoting substances, e.g., yeast extract, did not provide requisite nutrients for growth on glucose. Studies with 32P suggest that M. sodonensis is incapable of synthesizing energy-rich phosphate compounds during the catabolism of glucose. PMID:4381630

  12. Catabolism of caffeine in plants and microorganisms.

    PubMed

    Mazzafera, Paulo

    2004-05-01

    Caffeine has been found in tissues of several plants. Because of its stimulating effect on the central nervous system, a great number of reports have been published on its content in beverages and foodstuffs. However, a much more restricted number of reports have dealt specifically with caffeine metabolism in plants. This review presents, in chronological manner, the contribution of these reports to the vast knowledge accumulated on caffeine catabolism in plants and microorganisms over the last 40 years. In plants, the accumulated data indicate the operation of a main catabolic pathway: caffeine --> theophylline --> 3-methylxantine --> xanthine --> uric acid --> allantoin --> allantoic acid --> glyoxylic acid + urea --> NH3 + CO2. Some studies have shown that, depending on the plant species, other minor routes may operate with the formation of theobromine and 7-methylxantine, which are salvaged for caffeine formation since they also appear in the biosynthetic pathway. A specific group of coffee known as liberio-excelsioides has the ability to convert caffeine to the corresponding methyluric acid, which is methylated to other uric acid derivatives. In bacteria caffeine is either degraded to theobromine or paraxanthine. Both dimethylxanthines are demethylated to 7-methylxantine which in turn is demethylated to xanthine and then enters the catabolic pathway of purines. In bacteria, theobromine, paraxanthine and 7-methylxantine may also be oxidized to their corresponding methyluric acids.

  13. A role for PacMYBA in ABA-regulated anthocyanin biosynthesis in red-colored sweet cherry cv. Hong Deng (Prunus avium L.).

    PubMed

    Shen, Xinjie; Zhao, Kai; Liu, Linlin; Zhang, Kaichun; Yuan, Huazhao; Liao, Xiong; Wang, Qi; Guo, Xinwei; Li, Fang; Li, Tianhong

    2014-05-01

    The MYB transcription factors and plant hormone ABA have been suggested to play a role in fruit anthocyanin biosynthesis, but supporting genetic evidence has been lacking in sweet cherry. The present study describes the first functional characterization of an R2R3-MYB transcription factor, PacMYBA, from red-colored sweet cherry cv. Hong Deng (Prunus avium L.). Transient promoter assays demonstrated that PacMYBA physically interacted with several anthocyanin-related basic helix-loop-helix (bHLH) transcription factors to activate the promoters of PacDFR, PacANS and PacUFGT, which are thought to be involved in anthocyanin biosynthesis. Furthermore, the immature seeds of transgenic Arabidopsis plants overexpressing PacMYBA exhibited ectopic pigmentation. Silencing of PacMYBA, using a Tobacco rattle virus (TRV)-induced gene silencing technique, resulted in sweet cherry fruit that lacked red pigment. ABA treatment significantly induced anthocyanin accumulation, while treatment with the ABA biosynthesis inhibitor nordihydroguaiaretic acid (NDGA) blocked anthocyanin production. PacMYBA expression peaked after 2 h of pre-incubation in ABA and was 15.2-fold higher than that of sweet cherries treated with NDGA. The colorless phenotype was also observed in the fruits silenced in PacNCED1, which encodes a key enzyme in the ABA biosynthesis pathway. The endogenous ABA content as well as the transcript levels of six structural genes and PacMYBA in PacNCED1-RNAi (RNA interference) fruit were significantly lower than in the TRV vector control fruit. These results suggest that PacMYBA plays an important role in ABA-regulated anthocyanin biosynthesis and ABA is a signal molecule that promotes red-colored sweet cherry fruit accumulating anthocyanin. PMID:24443499

  14. A role for PacMYBA in ABA-regulated anthocyanin biosynthesis in red-colored sweet cherry cv. Hong Deng (Prunus avium L.).

    PubMed

    Shen, Xinjie; Zhao, Kai; Liu, Linlin; Zhang, Kaichun; Yuan, Huazhao; Liao, Xiong; Wang, Qi; Guo, Xinwei; Li, Fang; Li, Tianhong

    2014-05-01

    The MYB transcription factors and plant hormone ABA have been suggested to play a role in fruit anthocyanin biosynthesis, but supporting genetic evidence has been lacking in sweet cherry. The present study describes the first functional characterization of an R2R3-MYB transcription factor, PacMYBA, from red-colored sweet cherry cv. Hong Deng (Prunus avium L.). Transient promoter assays demonstrated that PacMYBA physically interacted with several anthocyanin-related basic helix-loop-helix (bHLH) transcription factors to activate the promoters of PacDFR, PacANS and PacUFGT, which are thought to be involved in anthocyanin biosynthesis. Furthermore, the immature seeds of transgenic Arabidopsis plants overexpressing PacMYBA exhibited ectopic pigmentation. Silencing of PacMYBA, using a Tobacco rattle virus (TRV)-induced gene silencing technique, resulted in sweet cherry fruit that lacked red pigment. ABA treatment significantly induced anthocyanin accumulation, while treatment with the ABA biosynthesis inhibitor nordihydroguaiaretic acid (NDGA) blocked anthocyanin production. PacMYBA expression peaked after 2 h of pre-incubation in ABA and was 15.2-fold higher than that of sweet cherries treated with NDGA. The colorless phenotype was also observed in the fruits silenced in PacNCED1, which encodes a key enzyme in the ABA biosynthesis pathway. The endogenous ABA content as well as the transcript levels of six structural genes and PacMYBA in PacNCED1-RNAi (RNA interference) fruit were significantly lower than in the TRV vector control fruit. These results suggest that PacMYBA plays an important role in ABA-regulated anthocyanin biosynthesis and ABA is a signal molecule that promotes red-colored sweet cherry fruit accumulating anthocyanin.

  15. The induction of free proline accumulation by endogenous ABA in Arabidopsis thaliana during drought

    SciTech Connect

    Gottlieb, M.L.; Bray, E.A. )

    1991-05-01

    Endogenous levels of abscisic acid (ABA) and free proline increase in response to drought stress. Exogenous ABA has been shown to induce proline accumulation, suggesting that ABA triggers the amino acid response. To determine if endogenous ABA induces free proline accumulation, increases in ABA and proline during drought stress were compared between wild type (WT), ABA-insensitive (abi) and ABA-deficient (aba) mutants of Arabidopsis thaliana. If elevated levels of endogenous ABA signal the proline response, then the mutants would not be expected to accumulate proline during stress. abi should be unable to respond to increased levels of endogenous ABA, while aba should be unable to accumulate sufficient ABA to elicit a proline response. Drought-stressed three week old shoots of WT, abi, and aba exhibited different patterns of endogenous ABA accumulation, but similar patterns of proline accumulation over 24 hours. Although the patterns of endogenous ABA accumulation differed, maximum levels were similar in WT and abi, but aba produced approximately 25% less. However, free proline accumulated in all three plant lines. abi exhibited a greater, more rapid increase in free proline over that in either WT or aba. aba, however, showed the same pattern and levels of accumulation as that in WT. Since free proline accumulated to at least similar levels in both WT and mutants, regardless of the levels of ABA accumulation, it may be that only a small endogenous ABA accumulation is required for proline accumulation. Alternatively, endogenous ABA may not be the direct signal for the proline response during drought stress.

  16. The RpiR-Like Repressor IolR Regulates Inositol Catabolism in Sinorhizobium meliloti▿†

    PubMed Central

    Kohler, Petra R. A.; Choong, Ee-Leng; Rossbach, Silvia

    2011-01-01

    Sinorhizobium meliloti, the nitrogen-fixing symbiont of alfalfa, has the ability to catabolize myo-, scyllo-, and d-chiro-inositol. Functional inositol catabolism (iol) genes are required for growth on these inositol isomers, and they play a role during plant-bacterium interactions. The inositol catabolism genes comprise the chromosomally encoded iolA (mmsA) and the iolY(smc01163)RCDEB genes, as well as the idhA gene located on the pSymB plasmid. Reverse transcriptase assays showed that the iolYRCDEB genes are transcribed as one operon. The iol genes were weakly expressed without induction, but their expression was strongly induced by myo-inositol. The putative transcriptional regulator of the iol genes, IolR, belongs to the RpiR-like repressor family. Electrophoretic mobility shift assays demonstrated that IolR recognized a conserved palindromic sequence (5′-GGAA-N6-TTCC-3′) in the upstream regions of the idhA, iolY, iolR, and iolC genes. Complementation assays found IolR to be required for the repression of its own gene and for the downregulation of the idhA-encoded myo-inositol dehydrogenase activity in the presence and absence of inositol. Further expression studies indicated that the late pathway intermediate 2-keto-5-deoxy-d-gluconic acid 6-phosphate (KDGP) functions as the true inducer of the iol genes. The iolA (mmsA) gene encoding methylmalonate semialdehyde dehydrogenase was not regulated by IolR. The S. meliloti iolA (mmsA) gene product seems to be involved in more than only the inositol catabolic pathway, since it was also found to be essential for valine catabolism, supporting its more recent annotation as mmsA. PMID:21784930

  17. Regulation of myo-inositol catabolism by a GntR-type repressor SCO6974 in Streptomyces coelicolor.

    PubMed

    Yu, Lingjun; Li, Shuxian; Gao, Wenyan; Pan, Yuanyuan; Tan, Huarong; Liu, Gang

    2015-04-01

    Myo-inositol is important for Streptomyces growth and morphological differentiation. Genomic sequence analysis revealed a myo-inositol catabolic gene cluster in Streptomyces coelicolor. Disruption of the corresponding genes in this cluster abolished the bacterial growth on myo-inositol as a single carbon source. The transcriptions of these genes were remarkably enhanced by addition of myo-inositol in minimal medium. A putative regulatory gene SCO6974, encoding a GntR family protein, is situated in the cluster. Disruption of SCO6974 significantly enhanced the transcription of myo-inositol catabolic genes. SCO6974 was shown to interact with the promoter regions of myo-inositol catabolic genes using electrophoretic mobility shift assays. DNase I footprinting assays demonstrated that SCO6974 recognized a conserved palindromic sequence (A/T)TGT(A/C)N(G/T)(G/T)ACA(A/T). Base substitution of the conserved sequence completely abolished the binding of SCO6974 to the targets demonstrating that SCO6974 directly represses the transcriptions of myo-inositol catabolic genes. Furthermore, the disruption of SCO6974 was correlated with a reduced sporulation of S. coelicolor in mannitol soya flour medium and with the overproduction of actinorhodin and calcium-dependent antibiotic. The addition of myo-inositol suppressed the sporulation deficiency of the mutant, indicating that the effect could be related to a shortage in myo-inositol due to its enhanced catabolism in this strain. This enhanced myo-inositol catabolism likely yields dihydroxyacetone phosphate and acetyl-CoA that are indirect or direct precursors of the overproduced antibiotics.

  18. Mg-chelatase H subunit affects ABA signaling in stomatal guard cells, but is not an ABA receptor in Arabidopsis thaliana.

    PubMed

    Tsuzuki, Tomo; Takahashi, Koji; Inoue, Shin-ichiro; Okigaki, Yukiko; Tomiyama, Masakazu; Hossain, Mohammad Anowar; Shimazaki, Ken-ichiro; Murata, Yoshiyuki; Kinoshita, Toshinori

    2011-07-01

    Mg-chelatase H subunit (CHLH) is a multifunctional protein involved in chlorophyll synthesis, plastid-to-nucleus retrograde signaling, and ABA perception. However, whether CHLH acts as an actual ABA receptor remains controversial. Here we present evidence that CHLH affects ABA signaling in stomatal guard cells but is not itself an ABA receptor. We screened ethyl methanesulfonate-treated Arabidopsis thaliana plants with a focus on stomatal aperture-dependent water loss in detached leaves and isolated a rapid transpiration in detached leaves 1 (rtl1) mutant that we identified as a novel missense mutant of CHLH. The rtl1 and CHLH RNAi plants showed phenotypes in which stomatal movements were insensitive to ABA, while the rtl1 phenotype showed normal sensitivity to ABA with respect to seed germination and root growth. ABA-binding analyses using (3)H-labeled ABA revealed that recombinant CHLH did not bind ABA, but recombinant pyrabactin resistance 1, a reliable ABA receptor used as a control, showed specific binding. Moreover, we found that the rtl1 mutant showed ABA-induced stomatal closure when a high concentration of extracellular Ca(2+) was present and that a knockout mutant of Mg-chelatase I subunit (chli1) showed the same ABA-insensitive phenotype as rtl1. These results suggest that the Mg-chelatase complex as a whole affects the ABA-signaling pathway for stomatal movements.

  19. Complete Genome Sequence of the d-Amino Acid Catabolism Bacterium Phaeobacter sp. Strain JL2886, Isolated from Deep Seawater of the South China Sea.

    PubMed

    Fu, Yingnan; Wang, Rui; Zhang, Zilian; Jiao, Nianzhi

    2016-01-01

    Phaeobacter sp. strain JL2886, isolated from deep seawater of the South China Sea, can catabolize d-amino acids. Here, we report the complete genome sequence of Phaeobacter sp. JL2886. It comprises ~4.06 Mbp, with a G+C content of 61.52%. A total of 3,913 protein-coding genes and 10 genes related to d-amino acid catabolism were obtained. PMID:27587825

  20. Complete Genome Sequence of the d-Amino Acid Catabolism Bacterium Phaeobacter sp. Strain JL2886, Isolated from Deep Seawater of the South China Sea

    PubMed Central

    Fu, Yingnan; Wang, Rui

    2016-01-01

    Phaeobacter sp. strain JL2886, isolated from deep seawater of the South China Sea, can catabolize d-amino acids. Here, we report the complete genome sequence of Phaeobacter sp. JL2886. It comprises ~4.06 Mbp, with a G+C content of 61.52%. A total of 3,913 protein-coding genes and 10 genes related to d-amino acid catabolism were obtained. PMID:27587825

  1. Complete Genome Sequence of the d-Amino Acid Catabolism Bacterium Phaeobacter sp. Strain JL2886, Isolated from Deep Seawater of the South China Sea.

    PubMed

    Fu, Yingnan; Wang, Rui; Zhang, Zilian; Jiao, Nianzhi

    2016-01-01

    Phaeobacter sp. strain JL2886, isolated from deep seawater of the South China Sea, can catabolize d-amino acids. Here, we report the complete genome sequence of Phaeobacter sp. JL2886. It comprises ~4.06 Mbp, with a G+C content of 61.52%. A total of 3,913 protein-coding genes and 10 genes related to d-amino acid catabolism were obtained.

  2. ASG2 is a farnesylated DWD protein that acts as ABA negative regulator in Arabidopsis.

    PubMed

    Dutilleul, Christelle; Ribeiro, Iliana; Blanc, Nathalie; Nezames, Cynthia D; Deng, Xing Wang; Zglobicki, Piotr; Palacio Barrera, Ana María; Atehortùa, Lucia; Courtois, Martine; Labas, Valérie; Giglioli-Guivarc'h, Nathalie; Ducos, Eric

    2016-01-01

    The tagging-via-substrate approach designed for the capture of mammal prenylated proteins was adapted to Arabidopsis cell culture. In this way, proteins are in vivo tagged with an azide-modified farnesyl moiety and captured thanks to biotin alkyne Click-iT® chemistry with further streptavidin-affinity chromatography. Mass spectrometry analyses identified four small GTPases and ASG2 (ALTERED SEED GERMINATION 2), a protein previously associated to the seed germination gene network. ASG2 is a conserved protein in plants and displays a unique feature that associates WD40 domains and tetratricopeptide repeats. Additionally, we show that ASG2 has a C-terminal CaaX-box that is farnesylated in vitro. Protoplast transfections using CaaX prenyltransferase mutants show that farnesylation provokes ASG2 nucleus exclusion. Moreover, ASG2 interacts with DDB1 (DAMAGE DNA BINDING protein 1), and the subcellular localization of this complex depends on ASG2 farnesylation status. Finally, germination and root elongation experiments reveal that asg2 and the farnesyltransferase mutant era1 (ENHANCED RESPONSE TO ABSCISIC ACID (ABA) 1) behave in similar manners when exposed to ABA or salt stress. To our knowledge, ASG2 is the first farnesylated DWD (DDB1 binding WD40) protein related to ABA response in Arabidopsis that may be linked to era1 phenotypes. PMID:26147561

  3. Isolation of a mutation resulting in constitutive synthesis of L-fucose catabolic enzymes.

    PubMed Central

    Bartkus, J M; Mortlock, R P

    1986-01-01

    A ribitol-positive transductant of Escherichia coli K-12, JM2112, was used to facilitate the isolation and identification of mutations affecting the L-fucose catabolic pathway. Analysis of L-fucose-negative mutants of JM2112 enabled us to confirm that L-fucose-1-phosphate is the apparent inducer of the fucose catabolic enzymes. Plating of an L-fuculokinase-negative mutant of JM2112 on D-arabinose yielded an isolate containing a second fucose mutation which resulted in the constitutive synthesis of L-fucose permease, isomerase, and kinase. This constitutive mutation differs from the constitutive mutation described by Chen et al. (J. Bacteriol. 159:725-729, 1984) in that it is tightly linked to the fucose genes and appears to be located in the gene believed to code for the positive activator of the L-fucose genes. PMID:3005235

  4. A locus necessary for the transport and catabolism of erythritol in Sinorhizobium meliloti.

    PubMed

    Geddes, Barney A; Pickering, Brad S; Poysti, Nathan J; Collins, Heather; Yudistira, Harry; Oresnik, Ivan J

    2010-10-01

    In this work we have genetically defined an erythritol utilization locus in Sinorhizobium meliloti. A cosmid containing the locus was isolated by complementation of a transposon mutant and was subsequently mutagenized using Tn5 : : B20. The locus was found to consist of five transcriptional units, each of which was necessary for the utilization of erythritol. Genetic complementation experiments using genes putatively annotated as erythritol catabolic genes clearly showed that, of the 17 genes at this locus, six genes are not necessary for the utilization of erythritol as a sole carbon source. The remaining genes encode EryA, EryB, EryC and TpiB as well as an uncharacterized ABC-type transporter. Transport experiments using labelled erythritol showed that components of the ABC transporter are necessary for the uptake of erythritol. The locus also contains two regulators: EryD, a SorC class regulator, and SMc01615, a DeoR class regulator. Quantitative RT-PCR experiments showed that each of these regulators negatively regulates its own transcription. In addition, induction of the erythritol locus was dependent upon EryD and a product of erythritol catabolism. Further characterization of polar mutations revealed that in addition to erythritol, the locus contains determinants for adonitol and l-arabitol utilization. The context of the mutations suggests that the locus is important for both the transport and catabolism of adonitol and l-arabitol.

  5. Expression analysis of abscisic acid (ABA) and metabolic signalling factors in developing endosperm and embryo of barley☆

    PubMed Central

    Chen, Zhiwei; Huang, Jianhua; Muttucumaru, Nira; Powers, Stephen J.; Halford, Nigel G.

    2013-01-01

    The expression of genes encoding components of ABA and metabolic signalling pathways in developing barley endosperm and embryo was investigated. The genes included HvRCAR35_47387 and HvRCAR35_2538 (encoding ABA receptors), HvABI1d (protein phosphatase 2C), HvSnRK2.4, HvSnRK2.6 and HvPKABA1 (SnRK2-type protein kinases) and HvABI5 (ABA response element binding protein; AREBP), as well as two genes encoding SnRK1-type protein kinases. Both SnRK1 and SnRK2 phosphorylate AREBPs, but SnRK2 is activated by ABA whereas SnRK1 may be broken down. Multiple cereal AREBPs with two conserved SnRK1/2 target sites and another class of BZIP transcription factors with SnRK1/2 binding sites, including HvBLZ1, were identified. Barley grain (cv. Triumph) was sampled at 15, 20, 25 and 30 days post-anthesis (dpa). HvRCAR35_47387, HvABI1d, HvSnRK2.4 and HvABI5 were expressed highly in the endosperm but at much lower levels in the embryo. Conversely, HvPKABA1 and HvRCAR35_2538 were expressed at higher levels in the embryo than the endosperm, while HvSnRK2.6 was expressed at similar levels in both. HvRCAR35_47387, HvABI1d, HvSnRK2.4 and HvABI5 all peaked in expression in the endosperm at 20 dpa. A model is proposed in which ABA brings about a transition from a SnRK1-dominated state in the endosperm during grain filling to a SnRK2-dominated state during maturation. PMID:24748715

  6. Characterization of the mannitol catabolic operon of Corynebacterium glutamicum.

    PubMed

    Peng, Xue; Okai, Naoko; Vertès, Alain A; Inatomi, Ken-Ichi; Inui, Masayuki; Yukawa, Hideaki

    2011-09-01

    Corynebacterium glutamicum encodes a mannitol catabolic operon, which comprises three genes: the DeoR-type repressor coding gene mtlR (sucR), an MFS transporter gene (mtlT), and a mannitol 2-dehydrogenase gene (mtlD). The mtlR gene is located upstream of the mtlTD genes in the opposite orientation. In spite of this, wild-type C. glutamicum lacks the ability to utilize mannitol. This wild-type phenotype results from the genetic regulation of the genes coding for mannitol transport and catalytic proteins mediated by the autoregulated MtlR protein since mtlR mutants grow on mannitol as the sole carbon source. MtlR binds to sites near the mtlR (two sites) and mtlTD promoters (one site downstream of the promoter), with the consensus sequence 5'-TCTAACA-3' being required for its binding. The newly discovered operon comprises the three basic functional elements required for mannitol utilization: regulation, transport, and metabolism to fructose, further processed to the common intermediate of glycolysis fructose-6-phosphate. When relieved from MtlR repression, C. glutamicum, which lacks a functional fructokinase, excretes the fructose derived from mannitol and imports it by the fructose-specific PTS. In order to use mannitol from seaweed biomass hydrolysates as a carbon source for the production of useful commodity chemicals and materials, an overexpression system using the tac promoter was developed. For congruence with the operon, we propose to rename sucR as the mtlR gene. PMID:21655984

  7. Glutamate racemization and catabolism in Fusobacterium varium.

    PubMed

    Ramezani, Mohammad; Resmer, Kelly L; White, Robert L

    2011-07-01

    The pathways of glutamate catabolism in the anaerobic bacterium Fusobacterium varium, grown on complex, undefined medium and chemically defined, minimal medium, were investigated using specifically labelled (13)C-glutamate. The metabolic end-products acetate and butyrate were isolated from culture fluids and derivatized for analysis by nuclear magnetic resonance and mass spectrometry. On complex medium, labels from L-[1-(13)C]glutamate and L-[4-(13)C]glutamate were incorporated into C1 of acetate and equally into C1/C3 of butyrate, while label derived from L-[5-(13)C]glutamate was not incorporated. The isotopic incorporation results and the detection of glutamate mutase and 3-methylaspartate ammonia lyase in cell extracts are most consistent with the methylaspartate pathway, the best known route of glutamate catabolism in Clostridium species. When F. varium was grown on defined medium, label from L-[4-(13)C]glutamate was incorporated mainly into C4 of butyrate, demonstrating a major role for the hydroxyglutarate pathway. Upon addition of coenzyme B(12) or cobalt ion to the defined medium in replicate experiments, isotope was located equally at C1/C3 of butyrate in accord with the methylaspartate pathway. Racemization of D-glutamate and subsequent degradation of L-glutamate via the methylaspartate pathway are supported by incorporation of label into C2 of acetate and equally into C2/C4 of butyrate from D-[3-(13)C]glutamate and the detection of a cofactor-independent glutamate racemase in cell extracts. Together the results demonstrate a major role for the methylaspartate pathway of glutamate catabolism in F. varium and substantial participation of the hydroxyglutarate pathway when coenzyme B(12) is not available.

  8. The chlorocatechol-catabolic transposon Tn5707 of Alcaligenes eutrophus NH9, carrying a gene cluster highly homologous to that in the 1,2,4-trichlorobenzene-degrading bacterium Pseudomonas sp. strain P51, confers the ability to grow on 3-chlorobenzoate

    SciTech Connect

    Ogawa, Naoto; Miyashita, Kiyotaka

    1999-02-01

    Alcaligenes eutrophus (Ralstonia eutropha) NH9, isolated in Japan, utilizes 3-chlorobenzoate as its sole source of carbon and energy. Sequencing of the relevant region of plasmid pENH91 from strain NH9 revealed that the genes for the catabolic enzymes were homologous to the genes of the modified ortho-cleavage pathway. The genes from strain NH9 (cbnR-ABCD) showed the highest homology to the tcbR-CDEF genes on plasmid pP51 of the 1,2,4-trichlorobenzene-degrading bacterium Pseudomonas sp. strain P51, which was isolated in The Netherlands. The structure of the operon, including the lengths of open reading frames and intervening sequences, was completely conserved between the cbn and tcb genes. Most nucleotide substitutions were localized within and proximal to the cbnB (tcbD) gene. The difference in the chloroaromatics that the two strains could use as growth substrates seemed to be due to differences in enzymes that convert substrates to chlorocatechols. The restriction map of plasmid pENH91 was clearly different from that of pP51 except in the regions that contained the cbnR-ABCD and tcbR-CDEF genes, respectively, suggesting that the chlorocatechol gene clusters might have been transferred as units. Two homologous sequences, present as direct repeats in both flanking regions of the cbnR-ABCD genes on pENH91, were found to be identical insertion sequences (ISs), designated IS1600, which formed a composite transposon designated Tn5707. Although the tcbR-CDEF genes were not associated with similar ISs, a DNA fragment homologous to IS/1600 was cloned from the chromosome of strain P51. The sequence of the fragment suggested that it might be a remnant of an IS. The two sequences, together with IS1326 and nmoT, formed a distinct cluster on a phylogenetic tree of the IS21 family. The diversity of the sources of these IS or IS-like elements suggests the prevalence of ISs of this type.

  9. Catabolism of volatile organic compounds influences plant survival.

    PubMed

    Oikawa, Patricia Y; Lerdau, Manuel T

    2013-12-01

    Plants emit a diverse array of phytogenic volatile organic compounds (VOCs). The production and emission of VOCs has been an important area of research for decades. However, recent research has revealed the importance of VOC catabolism by plants and VOC degradation in the atmosphere for plant growth and survival. Specifically, VOC catabolism and degradation have implications for plant C balance, tolerance to environmental stress, plant signaling, and plant-atmosphere interactions. Here we review recent advances in our understanding of VOC catabolism and degradation, propose experiments for investigating VOC catabolism, and suggest ways to incorporate catabolism into VOC emission models. Improving our knowledge of VOC catabolism and degradation is crucial for understanding plant metabolism and predicting plant survival in polluted environments.

  10. cGMP-dependent ABA-induced stomatal closure in the ABA-insensitive Arabidopsis mutant abi1-1.

    PubMed

    Dubovskaya, Lyudmila V; Bakakina, Yulia S; Kolesneva, Ekaterina V; Sodel, Dmitry L; McAinsh, Martin R; Hetherington, Alistair M; Volotovski, Igor D

    2011-07-01

    • The drought hormone abscisic acid (ABA) is widely known to produce reductions in stomatal aperture in guard cells. The second messenger cyclic guanosine 3', 5'-monophosphate (cGMP) is thought to form part of the signalling pathway by which ABA induces stomatal closure. • We have examined the signalling events during cGMP-dependent ABA-induced stomatal closure in wild-type Arabidopsis plants and plants of the ABA-insensitive Arabidopsis mutant abi1-1. • We show that cGMP acts downstream of hydrogen peroxide (H(2) O(2) ) and nitric oxide (NO) in the signalling pathway by which ABA induces stomatal closure. H(2) O(2) - and NO-induced increases in the cytosolic free calcium concentration ([Ca(2+) ](cyt) ) were cGMP-dependent, positioning cGMP upstream of [Ca(2+) ](cyt) , and involved the action of the type 2C protein phosphatase ABI1. Increases in cGMP were mediated through the stimulation of guanylyl cyclase by H(2) O(2) and NO. We identify nucleoside diphosphate kinase as a new cGMP target protein in Arabidopsis. • This study positions cGMP downstream of ABA-induced changes in H(2) O(2) and NO, and upstream of increases in [Ca(2+) ](cyt) in the signalling pathway leading to stomatal closure.

  11. Application of p-toluidine in chromogenic detection of catechol and protocatechuate, diphenolic intermediates in catabolism of aromatic compounds

    SciTech Connect

    Parke, D. )

    1992-08-01

    In the presence of p-toluidine and iron, protocatechuate and catechols yield color. Inclusion of p-toluidine in media facilities the screening of microbial strains for alterations affecting aromatic catabolism. Such strains include mutants affected in the expression of oxygenases and Escherichia coli colonies carrying cloned or subcloned aromatic catabolic genes which encode enzymes giving rise to protocatechuate or catechol. The diphenolic detection system can also be applied to the creation of vectors relying on insertion of cloned DNA into one of the latter marker genes.

  12. Involvement of rice histone deacetylase HDA705 in seed germination and in response to ABA and abiotic stresses.

    PubMed

    Zhao, Jinhui; Li, Mingzhi; Gu, Dachuan; Liu, Xuncheng; Zhang, Jianxia; Wu, Kunlin; Zhang, Xinhua; Teixeira da Silva, Jaime A; Duan, Jun

    2016-02-01

    Histone acetylation and deacetylation play crucial roles in the modification of chromatin structure and regulation of gene expression in eukaryotes. Histone acetyltransferases (HATs) and histone deacetylases (HDACs) assist to maintain the balance of chromatin acetylation status. Previous studies showed that plant HDACs are key regulators involved in response to development and stresses. In this study, we examined the expression pattern and function of HDA705, a member of the RPD3/HDA1-type HDAC in rice. Overexpression of HDA705 in rice decreased ABA and salt stress resistance during seed germination. Delayed seed germination of HDA705 overexpression lines was associated with down-regulated expression of GA biosynthetic genes and up-regulation of ABA biosynthetic genes. Moreover, overexpression of HDA705 in rice enhanced osmotic stress resistance during the seedling stage. Our findings demonstrate that HDA705 may play a role in regulating seed germination and the response to abiotic stresses in rice.

  13. GsSKP21, a Glycine soja S-phase kinase-associated protein, mediates the regulation of plant alkaline tolerance and ABA sensitivity.

    PubMed

    Liu, Ailin; Yu, Yang; Duan, Xiangbo; Sun, Xiaoli; Duanmu, Huizi; Zhu, Yanming

    2015-01-01

    Plant SKP1-like family proteins, components of the SCF complex E3 ligases, are involved in the regulation of plant development and stress responses. Little is known about the precise function of SKP genes in plant responses to environmental stresses. GsSKP21 was initially identified as a potential stress-responsive gene based on the transcriptome sequencing of Glycine soja. In this study, we found that GsSKP21 protein contains highly conserved SKP domains in its N terminus and an extra unidentified domain in its C terminus. The transcript abundance of GsSKP21, detected by quantitative real-time PCR, was induced under the treatment of alkali and salt stresses. Overexpression of GsSKP21 in Arabidopsis dramatically increased plant tolerance to alkali stress. Furthermore, we found that overexpression of GsSKP21 resulted in decreased ABA sensitivity during both the seed germination and early seedling growth stages. GsSKP21 mediated ABA signaling by altering the expression levels of the ABA signaling-related and ABA-induced genes. We also investigated the tissue expression specificity and subcellular localization of GsSKP21. These results suggest that GsSKP21 is important for plant tolerance to alkali stress and plays a critical regulatory role in the ABA-mediated stress response.

  14. Putrescine Catabolism is a Metabolic Response to Several Stresses in Escherichia coli

    PubMed Central

    Schneider, Barbara L.; Hernandez, V. James; Reitzer, Larry

    2013-01-01

    Summary Genes whose products degrade arginine and ornithine, precursors of putrescine synthesis, are activated by either regulators of the nitrogen-regulated (Ntr) response or σS-RNA polymerase. To determine if dual control regulates a complete putrescine catabolic pathway, we examined expression of patA and patD, which specify the first two enzymes of one putrescine catabolic pathway. Assays of PatA (putrescine transaminase) activity and β-galactosidase from cells with patA-lacZ transcriptional and translational fusions indicate dual control of patA transcription and putrescine-stimulated patA translation. Similar assays for PatD indicate that patD transcription required σS-RNA polymerase, and Nac, an Ntr regulator, enhanced the σS-dependent transcription. Since Nac activation via σS-RNA polymerase is without precedent, transcription with purified components was examined and the results confirmed this conclusion. This result indicates that the Ntr regulon can intrude into the σS regulon. Strains lacking both polyamine catabolic pathways have defective responses to oxidative stress, high temperature, and a sublethal concentration of an antibiotic. These defects and the σS-dependent expression indicates that polyamine catabolism is a core metabolic response to stress. PMID:23531166

  15. Catabolism and safety of supplemental L-arginine in animals.

    PubMed

    Wu, Zhenlong; Hou, Yongqing; Hu, Shengdi; Bazer, Fuller W; Meininger, Cynthia J; McNeal, Catherine J; Wu, Guoyao

    2016-07-01

    L-arginine (Arg) is utilized via multiple pathways to synthesize protein and low-molecular-weight bioactive substances (e.g., nitric oxide, creatine, and polyamines) with enormous physiological importance. Furthermore, Arg regulates cell signaling pathways and gene expression to improve cardiovascular function, augment insulin sensitivity, enhance lean tissue mass, and reduce obesity in humans. Despite its versatile roles, the use of Arg as a dietary supplement is limited due to the lack of data to address concerns over its safety in humans. Data from animal studies are reviewed to assess arginine catabolism and the safety of long-term Arg supplementation. The arginase pathway was responsible for catabolism of 76-85 and 81-96 % Arg in extraintestinal tissues of pigs and rats, respectively. Dietary supplementation with Arg-HCl or the Arg base [315- and 630-mg Arg/(kg BW d) for 91 d] had no adverse effects on male or female pigs. Similarly, no safety issues were observed for male or female rats receiving supplementation with 1.8- and 3.6-g Arg/(kg BW d) for at least 91 d. Intravenous administration of Arg-HCl to gestating sheep at 81 and 180 mg Arg/(kg BW d) is safe for at least 82 and 40 d, respectively. Animals fed conventional diets can well tolerate large amounts of supplemental Arg [up to 630-mg Arg/(kg BW d) in pigs or 3.6-g Arg/(kg BW d) in rats] for 91 d, which are equivalent to 573-mg Arg/(kg BW d) for humans. Collectively, these results can help guide studies to determine the safety of long-term oral administration of Arg in humans. PMID:27156062

  16. Pepper protein phosphatase type 2C, CaADIP1 and its interacting partner CaRLP1 antagonistically regulate ABA signalling and drought response.

    PubMed

    Lim, Chae Woo; Lee, Sung Chul

    2016-07-01

    Abscisic acid (ABA) is a key phytohormone that regulates plant growth and developmental processes, including seed germination and stomatal closing. Here, we report the identification and functional characterization of a novel type 2C protein phosphatase, CaADIP1 (Capsicum annuum ABA and Drought-Induced Protein phosphatase 1). The expression of CaADIP1 was induced in pepper leaves by ABA, drought and NaCl treatments. Arabidopsis plants overexpressing CaADIP1 (CaADIP1-OX) exhibited an ABA-hyposensitive and drought-susceptible phenotype. We used a yeast two-hybrid screening assay to identify CaRLP1 (Capsicum annuum RCAR-Like Protein 1), which interacts with CaADIP1 in the cytoplasm and nucleus. In contrast to CaADIP1-OX plants, CaRLP1-OX plants displayed an ABA-hypersensitive and drought-tolerant phenotype, which was characterized by low levels of transpirational water loss and increased expression of stress-responsive genes relative to those of wild-type plants. In CaADIP1-OX/CaRLP1-OX double transgenic plants, ectopic expression of the CaRLP1 gene led to strong suppression of CaADIP1-induced ABA hyposensitivity during the germinative and post-germinative stages, indicating that CaADIP1 and CaRLP1 act in the same signalling pathway and CaADIP1 functions downstream of CaRLP1. Our results indicate that CaADIP1 and its interacting partner CaRLP1 antagonistically regulate the ABA-dependent defense signalling response to drought stress. PMID:26825039

  17. ABA flow modelling in Ricinus communis exposed to salt stress and variable nutrition

    PubMed Central

    Peuke, Andreas D.

    2016-01-01

    In a series of experiments with Ricinus communis, abscisic acid (ABA) concentrations in tissues and transport saps, its de novo biosynthesis, long-distance transport, and metabolism (degradation) were affected by nutritional conditions, nitrogen (N) source, and nutrient limitation, or salt stress. In the present study these data were statistically re-evaluated, and new correlations presented that underpin the importance of this universal phytohormone. The biggest differences in ABA concentration were observed in xylem sap. N source had the strongest effect; however, nutrient limitation (particularly phosphorus limitation) and salt also had significant effects. ABA was found in greater concentration in phloem sap compared with xylem sap; however, the effect of treatment on ABA concentration in phloem was lower. In the leaves, ABA concentration was most variable compared with the other tissues. This variation was only affected by the N source. In roots, ABA was significantly decreased by nutrient limitation. Of the compartments in which ABA was quantified, xylem sap ABA concentration was most significantly correlated with leaf stomatal conductance and leaf growth. Additionally, ABA concentration in xylem was significantly correlated to that in phloem, indicating a 6-fold concentration increase from xylem to phloem. The ABA flow model showed that biosynthesis of ABA in roots affected the xylem flow of ABA. Moreover, ABA concentration in xylem affected the degradation of the phytohormone in shoots and also its export from shoots via phloem. The role of phloem transport is discussed since it stimulates ABA metabolism in roots. PMID:27440939

  18. The catabolism of 2,4-xylenol and p-cresol share the enzymes for the oxidation of para-methyl group in Pseudomonas putida NCIMB 9866.

    PubMed

    Chen, Yan-Fei; Chao, Hongjun; Zhou, Ning-Yi

    2014-02-01

    Pseudomonas putida NCIMB 9866 utilizes p-cresol or 2,4-xylenol as a sole carbon and energy source. Enzymes catalyzing the oxidation of the para-methyl group of p-cresol have been studied in detail. However, those responsible for the oxidation of the para-methyl group in 2,4-xylenol catabolism are still not reported. In this study, real-time quantitative PCR analysis indicated pchC- and pchF-encoded p-cresol methylhydroxylase (PCMH) and pchA-encoded p-hydroxybenzaldehyde dehydrogenase (PHBDD) in p-cresol catabolism were also likely involved in the catabolism of 2,4-xylenol. Enzyme activity assays and intermediate identification indicated that the PCMH and PHBDD catalyzed the oxidations of 2,4-xylenol to 4-hydroxy-3-methylbenzaldehyde and 4-hydroxy-3-methylbenzaldehyde to 4-hydroxy-3-methylbenzoic acid, respectively. Furthermore, the PCMH-encoding gene pchF was found to be necessary for the catabolism of 2,4-xylenol, whereas the PHBDD-encoding gene pchA was not essential for the catabolism by gene knockout and complementation. Analyses of the maximum specific growth rate (μ m) and specific activity of the gene-knockout strain to different intermediates revealed the presence of other enzyme(s) with PHBDD activity in strain 9866. However, PHBDD played a major role in the catabolism of 2,4-xylenol in contrast to the other enzyme(s).

  19. Opine catabolism and conjugal transfer of the nopaline Ti plasmid pTiC58 are coordinately regulated by a single repressor.

    PubMed

    Beck von Bodman, S; Hayman, G T; Farrand, S K

    1992-01-15

    The Ti plasmids of Agrobacterium tumefaciens are conjugal elements whose transfer is strongly repressed. Transfer is induced by the conjugal opines, a group of unique carbon compounds synthesized in crown gall tumors. The opines also induce Ti plasmid-encoded genes required by the bacteria for opine catabolism. We have cloned and sequenced a gene from the Ti plasmid pTiC58, whose product mediates the opine-dependent regulation of conjugal transfer and catabolism of the conjugal opines, agrocinopines A and B. The gene, accR, is closely linked to the agrocinopine catabolic locus. A spontaneous mutant Ti plasmid, pTiC58Trac, which constitutively expresses conjugal transfer and opine catabolism, was complemented in trans by a clone of wild-type accR. Comparative sequence analysis identified a 5-base-pair deletion close to the 5' end of the mutant accR allele from pTiC58Trac. Analysis of lacZ fusions in conjugal transfer and opine catabolic structural genes demonstrated that the accR-encoded function is a transcriptional repressor. accR can encode a 28-kDa protein. This protein is related to a class of repressor proteins that includes LacR, GutR, DeoR, FucR, and GlpR that regulate sugar catabolic systems in several bacterial genera. PMID:1731335

  20. Unravelling molecular responses to moderate dehydration in harvested fruit of sweet orange (Citrus sinensis L. Osbeck) using a fruit-specific ABA-deficient mutant.

    PubMed

    Romero, Paco; Rodrigo, María J; Alférez, Fernando; Ballester, Ana-Rosa; González-Candelas, Luis; Zacarías, Lorenzo; Lafuente, María T

    2012-04-01

    Water stress affects many agronomic traits that may be regulated by the phytohormone abscisic acid (ABA). Within these traits, loss of fruit quality becomes important in many citrus cultivars that develop peel damage in response to dehydration. To study peel dehydration transcriptional responsiveness in harvested citrus fruit and the putative role of ABA in this process, this study performed a comparative large-scale transcriptional analysis of water-stressed fruits of the wild-type Navelate orange (Citrus sinesis L. Osbeck) and its spontaneous ABA-deficient mutant Pinalate, which is more prone to dehydration and to developing peel damage. Major changes in gene expression occurring in the wild-type line were impaired in the mutant fruit. Gene ontology analysis revealed the ability of Navelate fruits to induce the response to water deprivation and di-, tri-valent inorganic cation transport biological processes, as well as repression of the carbohydrate biosynthesis process in the mutant. Exogenous ABA triggered relevant transcriptional changes and repressed the protein ubiquitination process, although it could not fully rescue the physiological behaviour of the mutant. Overall, the results indicated that dehydration responsiveness requires ABA-dependent and -independent signals, and highlight that the ability of citrus fruits to trigger molecular responses against dehydration is an important factor in reducing their susceptibility to developing peel damage.

  1. Integrated Response to Inducers by Communication between a Catabolic Pathway and Its Regulatory System▿

    PubMed Central

    Martínez-Pérez, Olga; López-Sánchez, Aroa; Reyes-Ramírez, Francisca; Floriano, Belén; Santero, Eduardo

    2007-01-01

    Efficient gene regulation of metabolic pathways implies that the profile of molecules inducing the pathway matches that of the molecules that are metabolized. Gratuitous induction, a well-known phenomenon in catabolic pathways, is the consequence of differences in the substrate and inducer profiles. This phenomenon is particularly evident in pathways for biodegradation of organic contaminants that can be induced by a variety of molecules similar to the real substrates. Analysis of the regulation of tetralin biodegradation genes in mutant strains with mutations that affect each component of the initial dioxygenase enzymatic complex indicated that the response of the regulatory system to potential inducers is altered differently depending on the mutated component. Based on the expression phenotypes of a number of single or double mutants, we propose a model that represents an unprecedented way of communication between a catabolic pathway and its regulatory system to prevent efficient induction by a molecule that is not a real substrate. This communication allows a better fit of the substrate and inducer profiles, thus minimizing gratuitous induction, without a requirement for optimal coevolution to match the specificity of catabolic enzymes and their regulatory systems. Modulation of the regulatory system in this way not only provides a more appropriate response to potential inducers recognized by the regulatory system but also may properly adjust the levels of gene expression to the substrate availability. PMID:17351041

  2. A role for TNFα in intervertebral disc degeneration: A non-recoverable catabolic shift

    SciTech Connect

    Purmessur, D.; Walter, B.A.; Roughley, P.J.; Laudier, D.M.; Hecht, A.C.; Iatridis, James

    2013-03-29

    Highlights: ► TNFα induced catabolic changes similar to human intervertebral disc degeneration. ► The metabolic shift induced by TNFα was sustained following removal. ► TNFα induced changes suggestive of cell senescence without affecting cell viability. ► Interventions are required to stimulate anabolism and increase cell proliferation. -- Abstract: This study examines the effect of TNFα on whole bovine intervertebral discs in organ culture and its association with changes characteristic of intervertebral disc degeneration (IDD) in order to inform future treatments to mitigate the chronic inflammatory state commonly found with painful IDD. Pro-inflammatory cytokines such as TNFα contribute to disc pathology and are implicated in the catabolic phenotype associated with painful IDD. Whole bovine discs were cultured to examine cellular (anabolic/catabolic gene expression, cell viability and senescence using β-galactosidase) and structural (histology and aggrecan degradation) changes in response to TNFα treatment. Control or TNFα cultures were assessed at 7 and 21 days; the 21 day group also included a recovery group with 7 days TNFα followed by 14 days in basal media. TNFα induced catabolic and anti-anabolic shifts in the nucleus pulposus (NP) and annulus fibrosus (AF) at 7 days and this persisted until 21 days however cell viability was not affected. Data indicates that TNFα increased aggrecan degradation products and suggests increased β-galactosidase staining at 21 days without any recovery. TNFα treatment of whole bovine discs for 7 days induced changes similar to the degeneration processes that occur in human IDD: aggrecan degradation, increased catabolism, pro-inflammatory cytokines and nerve growth factor expression. TNFα significantly reduced anabolism in cultured IVDs and a possible mechanism may be associated with cell senescence. Results therefore suggest that successful treatments must promote anabolism and cell proliferation in

  3. Bone marrow: its contribution to heme catabolism.

    PubMed

    Mähönen, Y; Anttinen, M; Vuopio, P; Tenhunen, R

    1976-01-01

    Heme oxygenase (HO) and biliverdin reductase (BR), the two NADPH-dependent enzymes involved in the degradation of hemoglobin and its derivatives, were measured in bone marrow aspirates from 5 hematologically normal persons, 4 patients with chronic leucemia (CL), 11 patients with acute leucemia (AL), 8 patients with refractory sideroblastic anemia (RA), 7 patients with iron-deficiency anemia (IA), 5 patients with hemolytic anemia (HA), and 7 patients with secondary anemia (SA) to determine the enzymatic capacity of the bone marrow in different hematologic disorders for heme catabolism. HO activity in the bone marrow of normal persons was 0.42 +/- 0.28 (SD) nmoles bilirubin/10 mg protein/min; in CL, 2.15 +/- 1.34; in AL, 0.39 +/- 0.25; in RA, 0.58 +/- 0.37; in IA, 0.41 +/- 0.28; in HA, 2.56 +/- 1.40; and in SA, 1.72 +/- 1.06. BR activity, respectively, was in normal persons 8.7 +/- 2.4 (SD) nmoles bilirubin/10 mg protein/min; in CL, 13.6 +/- 9.1; in AL, 3.8 +/- 3.1 in RA, 5.1 +/- 2.7; in IA, 5.5 +/- 3.7; in HA, 17.0 +/- 7.2; and in SA, 10.5 +/- 4.2. On the basis of these findings it seems evident that both oxygenase and biliverdin reductase activities of the bone marrow are capable of adaptive regulation. The physiologic role of bone marrow in heme catabolism seems to be of significant importance.

  4. Structural basis for selective activation of ABA receptors

    SciTech Connect

    Peterson, Francis C.; Burgie, E. Sethe; Park, Sang-Youl; Jensen, Davin R.; Weiner, Joshua J.; Bingman, Craig A.; Chang, Chia-En A.; Cutler, Sean R.; Phillips, Jr., George N.; Volkman, Brian F.

    2010-11-01

    Changing environmental conditions and lessening fresh water supplies have sparked intense interest in understanding and manipulating abscisic acid (ABA) signaling, which controls adaptive responses to drought and other abiotic stressors. We recently discovered a selective ABA agonist, pyrabactin, and used it to discover its primary target PYR1, the founding member of the PYR/PYL family of soluble ABA receptors. To understand pyrabactin's selectivity, we have taken a combined structural, chemical and genetic approach. We show that subtle differences between receptor binding pockets control ligand orientation between productive and nonproductive modes. Nonproductive binding occurs without gate closure and prevents receptor activation. Observations in solution show that these orientations are in rapid equilibrium that can be shifted by mutations to control maximal agonist activity. Our results provide a robust framework for the design of new agonists and reveal a new mechanism for agonist selectivity.

  5. Local root abscisic acid (ABA) accumulation depends on the spatial distribution of soil moisture in potato: implications for ABA signalling under heterogeneous soil drying.

    PubMed

    Puértolas, Jaime; Conesa, María R; Ballester, Carlos; Dodd, Ian C

    2015-04-01

    Patterns of root abscisic acid (ABA) accumulation ([ABA]root), root water potential (Ψroot), and root water uptake (RWU), and their impact on xylem sap ABA concentration ([X-ABA]) were measured under vertical partial root-zone drying (VPRD, upper compartment dry, lower compartment wet) and horizontal partial root-zone drying (HPRD, two lateral compartments: one dry, the other wet) of potato (Solanum tuberosum L.). When water was withheld from the dry compartment for 0-10 d, RWU and Ψroot were similarly lower in the dry compartment when soil volumetric water content dropped below 0.22cm(3) cm(-3) for both spatial distributions of soil moisture. However, [ABA]root increased in response to decreasing Ψroot in the dry compartment only for HPRD, resulting in much higher ABA accumulation than in VPRD. The position of the sampled roots (~4cm closer to the surface in the dry compartment of VPRD than in HPRD) might account for this difference, since older (upper) roots may accumulate less ABA in response to decreased Ψroot than younger (deeper) roots. This would explain differences in root ABA accumulation patterns under vertical and horizontal soil moisture gradients reported in the literature. In our experiment, these differences in root ABA accumulation did not influence [X-ABA], since the RWU fraction (and thus ABA export to shoots) from the dry compartment dramatically decreased simultaneously with any increase in [ABA]root. Thus, HPRD might better trigger a long-distance ABA signal than VPRD under conditions allowing simultaneous high [ABA]root and relatively high RWU fraction. PMID:25547916

  6. Local root abscisic acid (ABA) accumulation depends on the spatial distribution of soil moisture in potato: implications for ABA signalling under heterogeneous soil drying

    PubMed Central

    Puértolas, Jaime; Conesa, María R.; Ballester, Carlos; Dodd, Ian C.

    2015-01-01

    Patterns of root abscisic acid (ABA) accumulation ([ABA]root), root water potential (Ψroot), and root water uptake (RWU), and their impact on xylem sap ABA concentration ([X-ABA]) were measured under vertical partial root-zone drying (VPRD, upper compartment dry, lower compartment wet) and horizontal partial root-zone drying (HPRD, two lateral compartments: one dry, the other wet) of potato (Solanum tuberosum L.). When water was withheld from the dry compartment for 0–10 d, RWU and Ψroot were similarly lower in the dry compartment when soil volumetric water content dropped below 0.22cm3 cm–3 for both spatial distributions of soil moisture. However, [ABA]root increased in response to decreasing Ψroot in the dry compartment only for HPRD, resulting in much higher ABA accumulation than in VPRD. The position of the sampled roots (~4cm closer to the surface in the dry compartment of VPRD than in HPRD) might account for this difference, since older (upper) roots may accumulate less ABA in response to decreased Ψroot than younger (deeper) roots. This would explain differences in root ABA accumulation patterns under vertical and horizontal soil moisture gradients reported in the literature. In our experiment, these differences in root ABA accumulation did not influence [X-ABA], since the RWU fraction (and thus ABA export to shoots) from the dry compartment dramatically decreased simultaneously with any increase in [ABA]root. Thus, HPRD might better trigger a long-distance ABA signal than VPRD under conditions allowing simultaneous high [ABA]root and relatively high RWU fraction. PMID:25547916

  7. Local root abscisic acid (ABA) accumulation depends on the spatial distribution of soil moisture in potato: implications for ABA signalling under heterogeneous soil drying.

    PubMed

    Puértolas, Jaime; Conesa, María R; Ballester, Carlos; Dodd, Ian C

    2015-04-01

    Patterns of root abscisic acid (ABA) accumulation ([ABA]root), root water potential (Ψroot), and root water uptake (RWU), and their impact on xylem sap ABA concentration ([X-ABA]) were measured under vertical partial root-zone drying (VPRD, upper compartment dry, lower compartment wet) and horizontal partial root-zone drying (HPRD, two lateral compartments: one dry, the other wet) of potato (Solanum tuberosum L.). When water was withheld from the dry compartment for 0-10 d, RWU and Ψroot were similarly lower in the dry compartment when soil volumetric water content dropped below 0.22cm(3) cm(-3) for both spatial distributions of soil moisture. However, [ABA]root increased in response to decreasing Ψroot in the dry compartment only for HPRD, resulting in much higher ABA accumulation than in VPRD. The position of the sampled roots (~4cm closer to the surface in the dry compartment of VPRD than in HPRD) might account for this difference, since older (upper) roots may accumulate less ABA in response to decreased Ψroot than younger (deeper) roots. This would explain differences in root ABA accumulation patterns under vertical and horizontal soil moisture gradients reported in the literature. In our experiment, these differences in root ABA accumulation did not influence [X-ABA], since the RWU fraction (and thus ABA export to shoots) from the dry compartment dramatically decreased simultaneously with any increase in [ABA]root. Thus, HPRD might better trigger a long-distance ABA signal than VPRD under conditions allowing simultaneous high [ABA]root and relatively high RWU fraction.

  8. The Top 10 Reasons Children With Autism Deserve ABA

    PubMed Central

    Walsh, Mary Beth

    2011-01-01

    We who advocate for applied behavior analysis (ABA) for children with autism spectrum disorders often construct our arguments based on the scientific evidence. However, the audience that most needs to hear this argument, that is, the parents of children, especially very young children, diagnosed with autism, may not be convinced by the science alone. This essay attempts to make the case for the multiple benefits of ABA intervention through the use of humor and anecdotes couched in a “Top Ten List,” and illustrating most points with stories of an engaging child with autism (my son, Ben). PMID:22532906

  9. Efficient tryptophan-catabolizing activity is consistently conserved through evolution of TDO enzymes, but not IDO enzymes.

    PubMed

    Yuasa, Hajime J; Ball, Helen J

    2015-03-01

    Indoleamine 2,3-dioxygenase (IDO) and tryptophan 2,3-dioxygenase (TDO) enzymes have independently evolved to catalyze the first step in the catabolism of tryptophan (L-Trp) through the kynurenine pathway. TDO is found in almost all metazoan and many bacterial species, but not in fungi. We show that TDO enzymes have high catalytic-efficiency for L-Trp catabolism, regardless of their biological origin, suggesting that TDO has been an L-Trp-specific degrading enzyme throughout its evolution. Meanwhile, IDO was initially discovered in mammals, and subsequently has been found in lower vertebrates, several invertebrates, fungi and a number of bacterial species. Some lineages have independently generated multiple IDO paralogues through gene duplications. Interestingly, only mammalian IDO1s and fungal "typical" IDOs have high affinity and catalytic efficiency for L-Trp catabolism, comparable to TDOs. We show that invertebrate IDO enzymes have low affinity and catalytic efficiency for L-Trp catabolism. We suggest that the phylogenetic distribution of "low catalytic-efficiency IDOs" indicates the ancestral IDO also had low affinity and catalytic efficiency for L-Trp catabolism. IDOs with high catalytic-efficiency for L-Trp-catabolism may have evolved in certain lineages to fulfill particular biological roles. The low catalytic-efficiency IDOs have been well conserved in a number of lineages throughout their evolution, although it is not clear that the enzymes contribute significantly to L-Trp catabolism in these species. Investigation of other substrates and functions of the ancestral IDO and low catalytic efficiency IDOs may identify additional biological roles for these enzymes.

  10. The ABI4-induced Arabidopsis ANAC060 transcription factor attenuates ABA signaling and renders seedlings sugar insensitive when present in the nucleus.

    PubMed

    Li, Ping; Zhou, Hua; Shi, Xiaoliang; Yu, Bo; Zhou, Yan; Chen, Suli; Wang, Yufeng; Peng, Yu; Meyer, Rhonda C; Smeekens, Sjef C; Teng, Sheng

    2014-03-01

    Seedling establishment is inhibited on media containing high levels (∼ 6%) of glucose or fructose. Genetic loci that overcome the inhibition of seedling growth on high sugar have been identified using natural variation analysis and mutant selection, providing insight into sugar signaling pathways. In this study, a quantitative trait locus (QTL) analysis was performed for seedling sensitivity to high sugar in a Col/C24 F2 population of Arabidopsis thaliana. A glucose and fructose-sensing QTL, GSQ11, was mapped through selective genotyping and confirmed in near-isogenic lines in both Col and C24 backgrounds. Allelism tests and transgenic complementation showed that GSQ11 lies within the ANAC060 gene. The Col ANAC060 allele confers sugar insensitivity and was dominant over the sugar-sensitive C24 allele. Genomic and mRNA analyses showed that a single-nucleotide polymorphism (SNP) in Col ANAC060 affects the splicing patterns of ANAC060 such that 20 additional nucleotides are present in the mRNA. The insertion created a stop codon, resulting in a truncated ANAC60 protein lacking the transmembrane domain (TMD) that is present in the C24 ANAC060 protein. The absence of the TMD results in the nuclear localization of ANAC060. The short version of the ANAC060 protein is found in ∼ 12% of natural Arabidopsis accessions. Glucose induces GSQ11/ANAC060 expression in a process that requires abscisic acid (ABA) signaling. Chromatin immunoprecipitation-qPCR and transient expression analysis showed that ABI4 directly binds to the GSQ11/ANAC060 promoter to activate transcription. Interestingly, Col ANAC060 reduced ABA sensitivity and Glc-induced ABA accumulation, and ABI4 expression was also reduced in Col ANAC060 lines. Thus, the sugar-ABA signaling cascade induces ANAC060 expression, but the truncated Col ANAC060 protein attenuates ABA induction and ABA signaling. This negative feedback from nuclear ANAC060 on ABA signaling results in sugar insensitivity.

  11. Biochemical and genetic analyses of acetoin catabolism in Alcaligenes eutrophus.

    PubMed Central

    Fründ, C; Priefert, H; Steinbüchel, A; Schlegel, H G

    1989-01-01

    In genetic studies on the catabolism of acetoin in Alcaligenes eutrophus, we used Tn5::mob-induced mutants which were impaired in the utilization of acetoin as the sole carbon source for growth. The transposon-harboring EcoRI restriction fragments from 17 acetoin-negative and slow-growing mutants (class 2a) and from six pleiotropic mutants of A. eutorphus, which were acetoin-negative and did not grow chemolithoautotrophically (class 2b), were cloned from pHC79 gene banks. The insertions of Tn5 were mapped on four different chromosomal EcoRI restriction fragments (A, C, D, and E) in class 2a mutants. The native DNA fragments were cloned from a lambda L47 or from a cosmid gene bank. Evidence is provided that fragments A (21 kilobase pairs [kb]) and C (7.7 kb) are closely linked in the genome; the insertions of Tn5 covered a region of approximately 5 kb. Physiological experiments revealed that this region encodes for acetoin:dichlorophenol-indophenol oxidoreductase, a fast-migrating protein, and probably for one additional protein that is as yet unknown. In mutants which were not completely impaired in growth on acetoin but which grew much slower and after a prolonged lag phase, fragments D (7.2 kb) and E (8.1 kb) were inactivated by insertion of Tn5::mob. No structural gene could be assigned to the D or E fragments. In class 2b mutants, insertions of Tn5 were mapped on fragment B (11.3 kb). This fragment complemented pleiotropic hno mutants in trans; these mutants were impaired in the formation of a rpoN-like protein. The expression of the gene cluster on fragments A and C seemed to be rpoN dependent. PMID:2556366

  12. Cell-free conversion of 1 prime -deoxy- sup 2 H-ABA to sup 2 H-ABA in extracts from Cercospora rosicola

    SciTech Connect

    Al-Nimri, L.; Coolbaugh, R.C. )

    1990-05-01

    The characteristics of the enzyme converting 1{prime}-deoxy-ABA into ABA have been studied in the fungus C. rosicola. Enzyme extracts were prepared from cold-pressed mycelia of C. rosicola. The suspension was a high speed supernatant and a microsomal fraction. A cell-free system was developed to convert 1{prime}-deoxy-{sup 2}H-ABA into {sup 2}H-ABA using a reaction mixture containing 300 {mu}l enzyme extract, 10 {mu}m 1{prime}-deoxy-{sup 2}H-ABA. The reaction products were chromatographed by reverse phase HPLC. The presumptive ABA fractions were collected and {sup 2}H-ABA was quantified by GC-MS using a {sup 2}H-(2Z, 4E)-ABA standard curve. 1{prime}-deoxy-{sup 2}H-ABA was converted to an average of 1.47 pmole {sup 2}H-ABA/mg protein per min. Most of the enzymic activity was found in the microsomal fraction. The reaction required NADPH and was enhanced by FAD. The reaction was not inhibited by triarimol.

  13. ABA Regulates Subcellular Redistribution of OsABI-LIKE2, a Negative Regulator in ABA Signaling, to Control Root Architecture and Drought Resistance in Oryza sativa.

    PubMed

    Li, Chengxiang; Shen, Hongyun; Wang, Tao; Wang, Xuelu

    2015-12-01

    The phytohormone ABA is a key stress signal in plants. Although the identification of ABA receptors led to significant progress in understanding the Arabidopsis ABA signaling pathway, there are still many unsolved mysteries regarding ABA signaling in monocots, such as rice. Here, we report that a rice ortholog of AtABI1 and AtABI2, named OsABI-LIKE2 (OsABIL2), plays a negative role in rice ABA signaling. Overexpression of OsABIL2 not only led to ABA insensitivity, but also significantly altered plant developmental phenotypes, including stomatal density and root architecture, which probably caused the hypersensitivity to drought stress. OsABIL2 interacts with OsPYL1, SAPK8 and SAPK10 both in vitro and in vivo, and the phosphatase activity of OsABIL2 was repressed by ABA-bound OsPYL1. However, unlike many other solely nuclear-localized clade A type 2C protein phosphatases (PP2Cs), OsABIL2 is localized in both the nucleus and cytosol. Furthermore, OsABIL2 interacts with and co-localized with OsPYL1 mainly in the cytosol, and ABA treatment regulates the nucleus-cytosol distribution of OsABIL2, suggesting a different mechanism for the activation of ABA signaling. Taken together, this study provides significant insights into rice ABA signaling and indicates the important role of OsABIL2 in regulating root development. PMID:26491145

  14. Functional analysis in Arabidopsis of FsPTP1, a tyrosine phosphatase from beechnuts, reveals its role as a negative regulator of ABA signaling and seed dormancy and suggests its involvement in ethylene signaling modulation.

    PubMed

    Alonso-Ramírez, Ana; Rodríguez, Dolores; Reyes, David; Jiménez, Jesús A; Nicolás, Gregorio; Nicolás, Carlos

    2011-09-01

    By means of an RT-PCR approach we isolated a specific tyrosine phosphatase (FsPTP1) induced by abscisic acid (ABA) and correlated with seed dormancy in Fagus sylvatica seeds. To provide genetic evidence of FsPTP1 function in seed dormancy and ABA signal transduction pathway, we overexpressed this gene in Cape Verde Island ecotype of Arabidopsis thaliana, which shows the deepest degree of seed dormancy among Arabidopsis accessions. As a result, 35S:FsPTP1 transgenic seeds showed a reduced dormancy and insensitivity to ABA and osmotic stress conditions accompanied by a reduction in the level of expression of RAB18 and RD29, well-known ABA-responsive genes. Taken together, all these data are consistent with a role of this tyrosine phosphatase as a negative regulator of ABA signaling. In addition, phenotypes of FsPTP1 transgenic plants resemble those observed in ethylene constitutive mutants, accompanied by an increase in the level of expression of a key gene involved in ethylene signaling such as EIN2. All the data presented along the paper suggest that the effect of tyrosine phosphatases in ABA action during the transition from seed dormancy to germination may be through modulation of ethylene signaling.

  15. SKN-1 and Nrf2 couples proline catabolism with lipid metabolism during nutrient deprivation.

    PubMed

    Pang, Shanshan; Lynn, Dana A; Lo, Jacqueline Y; Paek, Jennifer; Curran, Sean P

    2014-10-06

    Mechanisms that coordinate different metabolic pathways, such as glucose and lipid, have been recognized. However, a potential interaction between amino acid and lipid metabolism remains largely elusive. Here we show that during starvation of Caenorhabditis elegans, proline catabolism is coupled with lipid metabolism by SKN-1. Mutation of alh-6, a conserved proline catabolic enzyme, accelerates fat mobilization, enhances the expression of genes involved in fatty acid oxidation and reduces survival in response to fasting. This metabolic coordination is mediated by the activation of the transcription factor SKN-1/Nrf2, possibly due to the accumulation of the alh-6 substrate P5C, and also requires the transcriptional co-regulator MDT-15. Constitutive activation of SKN-1 induces a similar transcriptional response, which protects animals from fat accumulation when fed a high carbohydrate diet. In human cells, an orthologous alh-6 enzyme, ALDH4A1, is also linked to the activity of Nrf2, the human orthologue of SKN-1, and regulates the expression of lipid metabolic genes. Our findings identify a link between proline catabolism and lipid metabolism, and uncover a physiological role for SKN-1 in metabolism.

  16. Purine catabolic pathway revealed by transcriptomics in the model marine bacterium Ruegeria pomeroyi DSS-3.

    PubMed

    Cunliffe, Michael

    2016-01-01

    Purines are nitrogen-rich compounds that are widely distributed in the marine environment and are an important component of the dissolved organic nitrogen (DON) pool. Even though purines have been shown to be degraded by bacterioplankton, the identities of marine bacteria capable of purine degradation and their underlying catabolic mechanisms are currently unknown. This study shows that Ruegeria pomeroyi, a model marine bacterium and Marine Roseobacter Clade (MRC) representative, utilizes xanthine as a source of carbon and nitrogen. The R. pomeroyi genome contains putative genes that encode xanthine dehydrogenase (XDH), which is expressed during growth with xanthine. RNAseq-based analysis of the R. pomeroyi transcriptome revealed that the transcription of an XDH-initiated catabolic pathway is up-regulated during growth with xanthine, with transcription greatest when xanthine was the only available carbon source. The RNAseq-deduced pathway indicates that glyoxylate and ammonia are the key intermediates from xanthine degradation. Utilising a laboratory model, this study has identified the potential genes and catabolic pathway active during xanthine degradation. The ability of R. pomeroyi to utilize xanthine provides novel insights into the capabilities of the MRC that may contribute to their success in marine ecosystems and the potential biogeochemical importance of the group in processing DON.

  17. Dissociations among ABA, ABC, and AAB Recovery Effects

    ERIC Educational Resources Information Center

    Ungor, Metin; Lachnit, Harald

    2008-01-01

    In a human predictive learning experiment, the strengths of ABA, ABC, and AAB recovery effects after discrimination reversal learning were compared. Initially, a discrimination between two stimuli (X+, Y-) was trained in Context A. During Phase 2, participants received discrimination reversal training (X-, Y+) either in Context A (Group AAB) or in…

  18. Personality Traits Associated with Occupational "Burnout" in ABA Therapists

    ERIC Educational Resources Information Center

    Hurt, Amy A.; Grist, Cathy Lann; Malesky, Lann A., Jr.; McCord, David M.

    2013-01-01

    Background: Applied behaviour analysis (ABA) therapists typically work one-to-one with children with autism for extended periods of time, which often leads to high levels of job-related stress, lower levels of job satisfaction, increased frequency of occupational "burnout" and higher than average job turnover (Journal of Autism…

  19. ABA, AAB and ABC Renewal in Taste Aversion Learning

    ERIC Educational Resources Information Center

    Bernal-Gamboa, Rodolfo; Juarez, Yectivani; Gonzalez-Martin, Gabriela; Carranza, Rodrigo; Sanchez-Carrasco, Livia; Nieto, Javier

    2012-01-01

    Context renewal is identified when the conditioned response (CR) elicited by an extinguished conditioned stimulus (CS) reappears as a result of changing the contextual cues during the test. Two experiments were designed for testing contextual renewal in a conditioned taste aversion preparation. Experiment 1 assessed ABA and AAB context renewal,…

  20. ABA and Diverse Cultural and Linguistic Environments: A Welsh Perspective

    ERIC Educational Resources Information Center

    Jones, E. W.; Hoerger, M.; Hughes, J. C.; Williams, B. M.; Jones, B.; Moseley, Y.; Hughes, D. R.; Prys, D.

    2011-01-01

    Gwynedd Local Education Authority (LEA) in North West Wales, UK, is funding a small-scale autism-specific specialist education service using ABA methodology. The program is available through the medium of Welsh, English or bilingually, depending on the individual needs of the child (Jones and Hoerger in Eur J Behav Anal 10:249-253, "2009").…

  1. Adaptive Behaviour Assessment System: Indigenous Australian Adaptation Model (ABAS: IAAM)

    ERIC Educational Resources Information Center

    du Plessis, Santie

    2015-01-01

    The study objectives were to develop, trial and evaluate a cross-cultural adaptation of the Adaptive Behavior Assessment System-Second Edition Teacher Form (ABAS-II TF) ages 5-21 for use with Indigenous Australian students ages 5-14. This study introduced a multiphase mixed-method design with semi-structured and informal interviews, school…

  2. Quorum-dependent mannopine-inducible conjugative transfer of an Agrobacterium opine-catabolic plasmid.

    PubMed

    Wetzel, Margaret E; Kim, Kun-Soo; Miller, Marilyn; Olsen, Gary J; Farrand, Stephen K

    2014-03-01

    The Ti plasmid in Agrobacterium tumefaciens strain 15955 carries two alleles of traR that regulate conjugative transfer. The first is a functional allele, called traR, that is transcriptionally induced by the opine octopine. The second, trlR, is a nonfunctional, dominant-negative mutant located in an operon that is inducible by the opine mannopine (MOP). Based on these findings, we predicted that there exist wild-type agrobacterial strains harboring plasmids in which MOP induces a functional traR and, hence, conjugation. We analyzed 11 MOP-utilizing field isolates and found five where MOP induced transfer of the MOP-catabolic element and increased production of the acyl-homoserine lactone (acyl-HSL) quormone. The transmissible elements in these five strains represent a set of highly related plasmids. Sequence analysis of one such plasmid, pAoF64/95, revealed that the 176-kb element is not a Ti plasmid but carries genes for catabolism of MOP, mannopinic acid (MOA), agropinic acid (AGA), and the agrocinopines. The plasmid additionally carries all of the genes required for conjugative transfer, including the regulatory genes traR, traI, and traM. The traR gene, however, is not located in the MOP catabolism region. The gene, instead, is monocistronic and located within the tra-trb-rep gene cluster. A traR mutant failed to transfer the plasmid and produced little to no quormone even when grown with MOP, indicating that TraRpAoF64/95 is the activator of the tra regulon. A traM mutant was constitutive for transfer and acyl-HSL production, indicating that the anti-activator function of TraM is conserved. PMID:24363349

  3. Quorum-Dependent Mannopine-Inducible Conjugative Transfer of an Agrobacterium Opine-Catabolic Plasmid

    PubMed Central

    Wetzel, Margaret E.; Kim, Kun-Soo; Miller, Marilyn; Olsen, Gary J.

    2014-01-01

    The Ti plasmid in Agrobacterium tumefaciens strain 15955 carries two alleles of traR that regulate conjugative transfer. The first is a functional allele, called traR, that is transcriptionally induced by the opine octopine. The second, trlR, is a nonfunctional, dominant-negative mutant located in an operon that is inducible by the opine mannopine (MOP). Based on these findings, we predicted that there exist wild-type agrobacterial strains harboring plasmids in which MOP induces a functional traR and, hence, conjugation. We analyzed 11 MOP-utilizing field isolates and found five where MOP induced transfer of the MOP-catabolic element and increased production of the acyl-homoserine lactone (acyl-HSL) quormone. The transmissible elements in these five strains represent a set of highly related plasmids. Sequence analysis of one such plasmid, pAoF64/95, revealed that the 176-kb element is not a Ti plasmid but carries genes for catabolism of MOP, mannopinic acid (MOA), agropinic acid (AGA), and the agrocinopines. The plasmid additionally carries all of the genes required for conjugative transfer, including the regulatory genes traR, traI, and traM. The traR gene, however, is not located in the MOP catabolism region. The gene, instead, is monocistronic and located within the tra-trb-rep gene cluster. A traR mutant failed to transfer the plasmid and produced little to no quormone even when grown with MOP, indicating that TraRpAoF64/95 is the activator of the tra regulon. A traM mutant was constitutive for transfer and acyl-HSL production, indicating that the anti-activator function of TraM is conserved. PMID:24363349

  4. Coping as a Predictor of Burnout and General Health in Therapists Working in ABA Schools

    ERIC Educational Resources Information Center

    Griffith, G. M.; Barbakou, A.; Hastings, R. P.

    2014-01-01

    Background: Little is known about the work-related well-being of applied behaviour analysis (ABA) therapists who work in school-based contexts and deliver ABA interventions to children with autism. Methods: A questionnaire on work-related stress (burnout), general distress, perceived supervisor support and coping was completed by 45 ABA therapists…

  5. Catabolism of host-derived compounds during extracellular bacterial infections.

    PubMed

    Meadows, Jamie A; Wargo, Matthew J

    2014-02-01

    Efficient catabolism of host-derived compounds is essential for bacterial survival and virulence. While these links in intracellular bacteria are well studied, such studies in extracellular bacteria lag behind, mostly for technical reasons. The field has identified important metabolic pathways, but the mechanisms by which they impact infection and in particular, establishing the importance of a compound's catabolism versus alternate metabolic roles has been difficult. In this review we will examine evidence for catabolism during extracellular bacterial infections in animals and known or potential roles in virulence. In the process, we point out key gaps in the field that will require new or newly adapted techniques.

  6. The expression of a rab-related gene, rab18, is induced by abscisic acid during the cold acclimation process of Arabidopsis thaliana (L.) Heynh.

    PubMed

    Lång, V; Palva, E T

    1992-12-01

    We have isolated a rab-related (responsive to ABA) gene, rab18 from Arabidopsis thaliana. The gene encodes a hydrophilic, glycine-rich protein (18.5 kDa), which contains the conserved serine- and lysine-rich domains characteristic of similar RAB proteins in other plant species. The rab18 mRNA accumulates in plants exposed to low temperature, water stress or exogenous ABA but not in plants subjected to heat shock. This stress-related accumulation of the rab18 mRNA is markedly decreased in the ABA-synthesis mutant aba-1, the ABA-response mutant abi-1 or in wild-type plants treated with the carotenoid synthesis inhibitor, fluridone. Exogenous ABA treatment can induce the rab18 mRNA in the aba-1 mutant but not in the abi-1 mutant. These results provide direct genetic evidence for the ABA-dependent regulation of the rab18 gene in A. thaliana.

  7. Arginine transport in catabolic disease states.

    PubMed

    Pan, Ming; Choudry, Haroon A; Epler, Mark J; Meng, Qinghe; Karinch, Anne; Lin, Chengmao; Souba, Wiley

    2004-10-01

    Arginine appears to be a semiessential amino acid in humans during critical illness. Catabolic disease states such as sepsis, injury, and cancer cause an increase in arginine utilization, which exceeds body production, leading to arginine depletion. This is aggravated by the reduced nutrient intake that is associated with critical illness. Arginine depletion may have negative consequences on tissue function under these circumstances. Nutritional regimens containing arginine have been shown to improve nitrogen balance and lymphocyte function, and stimulate arginine transport in the liver. We have studied the effects of stress mediators on arginine transport in vascular endothelium, liver, and gut epithelium. In vascular endothelium, endotoxin stimulates arginine uptake, an effect that is mediated by the cytokine tumor necrosis factor-alpha (TNF-alpha) and by the cyclo-oxygenase pathway. This TNF-alpha stimulation involves the activation of intracellular protein kinase C (PKC). A significant increase in hepatic arginine transport activity also occurs following burn injury and in rats with progressive malignant disease. Surgical removal of the growing tumor results in a normalization of the accelerated hepatic arginine transport within days. Chronic metabolic acidosis and sepsis individually augment intestinal arginine transport in rats and Caco-2 cell culture. PKC and mitogen-activated protein kinases are involved in mediating the sepsis/acidosis stimulation of arginine transport. Understanding the regulation of plasma membrane arginine transport will enhance our knowledge of nutrition and metabolism in seriously ill patients and may lead to the design of improved nutritional support formulas. PMID:15465794

  8. Thyroid hormone stimulates hepatic lipid catabolism via activation of autophagy.

    PubMed

    Sinha, Rohit Anthony; You, Seo-Hee; Zhou, Jin; Siddique, Mobin M; Bay, Boon-Huat; Zhu, Xuguang; Privalsky, Martin L; Cheng, Sheue-Yann; Stevens, Robert D; Summers, Scott A; Newgard, Christopher B; Lazar, Mitchell A; Yen, Paul M

    2012-07-01

    For more than a century, thyroid hormones (THs) have been known to exert powerful catabolic effects, leading to weight loss. Although much has been learned about the molecular mechanisms used by TH receptors (TRs) to regulate gene expression, little is known about the mechanisms by which THs increase oxidative metabolism. Here, we report that TH stimulation of fatty acid β-oxidation is coupled with induction of hepatic autophagy to deliver fatty acids to mitochondria in cell culture and in vivo. Furthermore, blockade of autophagy by autophagy-related 5 (ATG5) siRNA markedly decreased TH-mediated fatty acid β-oxidation in cell culture and in vivo. Consistent with this model, autophagy was altered in livers of mice expressing a mutant TR that causes resistance to the actions of TH as well as in mice with mutant nuclear receptor corepressor (NCoR). These results demonstrate that THs can regulate lipid homeostasis via autophagy and help to explain how THs increase oxidative metabolism.

  9. Genetic dissection of methylcrotonyl CoA carboxylase indicates a complex role for mitochondrial leucine catabolism during seed development and germination.

    PubMed

    Ding, Geng; Che, Ping; Ilarslan, Hilal; Wurtele, Eve S; Nikolau, Basil J

    2012-05-01

    3-methylcrotonyl CoA carboxylase (MCCase) is a nuclear-encoded, mitochondrial-localized biotin-containing enzyme. The reaction catalyzed by this enzyme is required for leucine (Leu) catabolism, and it may also play a role in the catabolism of isoprenoids and the mevalonate shunt. In Arabidopsis, two MCCase subunits (the biotinylated MCCA subunit and the non-biotinylated MCCB subunit) are each encoded by single genes (At1g03090 and At4g34030, respectively). A reverse genetic approach was used to assess the physiological role of MCCase in plants. We recovered and characterized T-DNA and transposon-tagged knockout alleles of the MCCA and MCCB genes. Metabolite profiling studies indicate that mutations in either MCCA or MCCB block mitochondrial Leu catabolism, as inferred from the increased accumulation of Leu. Under light deprivation conditions, the hyper-accumulation of Leu, 3-methylcrotonyl CoA and isovaleryl CoA indicates that mitochondrial and peroxisomal Leu catabolism pathways are independently regulated. This biochemical block in mitochondrial Leu catabolism is associated with an impaired reproductive growth phenotype, which includes aberrant flower and silique development and decreased seed germination. The decreased seed germination phenotype is only observed for homozygous mutant seeds collected from a parent plant that is itself homozygous, but not from a parent plant that is heterozygous. These characterizations may shed light on the role of catabolic processes in growth and development, an area of plant biology that is poorly understood.

  10. The biochemistry of nitrogen mobilization: purine ring catabolism.

    PubMed

    Werner, Andrea K; Witte, Claus-Peter

    2011-07-01

    The enzymatic route of purine ring catabolism has recently been completed by the discovery of several novel enzymes identified through comparative genome analyses. Here, we review these recent discoveries and present an overview of purine ring catabolism in plants. Xanthine is oxidized to urate in the cytosol, followed by three enzymatic steps taking place in the peroxisome and four reactions in the endoplasmic reticulum releasing the four ring nitrogen as ammonia. Although the main physiological function of purine degradation might lie in the remobilization of nitrogen resources, it has also emerged that catabolic intermediates, the ureides allantoin and allantoate, are likely to be involved in protecting plants against abiotic stress. Conserved alternative splicing mediating the peroxisomal as well as cytosolic localization of allantoin synthase potentially links purine ring catabolism to brassinosteroid signaling.

  11. ABA signaling in stomatal guard cells: lessons from Commelina and Vicia.

    PubMed

    Mori, Izumi C; Murata, Yoshiyuki

    2011-07-01

    Abscisic acid (ABA) signaling mechanisms have been studied in a broad variety of plant species using complementary analyses, taking advantage of different methodologies suitable for each plant species. Early studies on ABA biosynthesis using Solanum lycopersicum mutants suggested an importance of ABA synthesis in stomatal closure. To understand ABA signaling in guard cells, cellular, biochemical and electrophysiological studies in Vicia faba and Commelina communis have been conducted, providing fundamental knowledge that was further reconfirmed by molecular genetic studies of Arabidopsis. In this article, examples of stomatal studies in several plants and prospects in ABA research are discussed.

  12. Rice salT promoter is activated in Papaver somniferum and Nicotiana tabacum transgenic cells in the absence of exogenous ABA.

    PubMed

    Elleuch; Belbahri; Boetti; David; Thomassetb; David

    2001-01-01

    With the aim of modifying secondary metabolism in Opium poppy (Papaver somniferum) and tobacco (Nicotiana tabacum) cells, gene transfer was performed using the sam1 gene from Arabidopsis thaliana under the control of the salT promoter. This promoter is induced by ABA in rice and in tobacco and we have shown that it is also induced in poppy cells (gus gene). Putatively transformed poppy and tobacco cell lines with the sam1 gene were obtained. In the absence of exogenous inducer we noticed the expression of the transgene resulting in a significant increase of SAM-S activity in all tested transformants of poppy and in half the transgenic tobacco cell lines tested. Addition of ABA to the culture medium failed to enhance the expression of the transgene in both species and resulted in a decrease of the sam1 gene expression in some cell lines. Since the salT promoter is induced by exogenous ABA in both species (gus reporter gene), we suggest a partial sam1 transgene inactivation in certain cell lines. These results show that the efficiency of a regulatory sequence may be different when fused with a reporter gene (gus) compared to fusion with a gene belonging to the housekeeping family (sam1).

  13. Glycogen catabolism, but not its biosynthesis, affects virulence of Fusarium oxysporum on the plant host.

    PubMed

    Corral-Ramos, Cristina; Roncero, M Isabel G

    2015-04-01

    The role of glycogen metabolism was investigated in the fungal pathogen Fusarium oxysporum. Targeted inactivation was performed of genes responsible for glycogen biosynthesis: gnn1 encoding glycogenin, gls1 encoding glycogen synthase, and gbe1 encoding glycogen branching enzyme. Moreover genes involved in glycogen catabolism were deleted: gph1 encoding glycogen phosphorylase and gdb1 encoding glycogen de-branching enzyme. Glycogen reserves increased steadily during growth of the wild type strain in axenic cultures, to reach up to 1500μg glucose equivalents mg(-1) protein after 14 days. Glycogen accumulation was abolished in mutants lacking biosynthesis genes, whereas it increased by 20-40% or 80%, respectively, in the single and double mutants affected in catabolic genes. Transcript levels of glycogen metabolism genes during tomato plant infection peaked at four days post inoculation, similar to the results observed during axenic culture. Significant differences were observed between gdb mutants and the wild type strain for vegetative hyphal fusion ability. The single mutants defective in glycogen metabolism showed similar levels of virulence in the invertebrate animal model Galleria mellonella. Interestingly, the deletion of gdb1 reduced virulence on the plant host up to 40% compared to the wild type in single and in double mutant backgrounds, whereas the other mutants showed the virulence at the wild-type level.

  14. Protein catabolism and requirements in severe illness.

    PubMed

    Genton, L; Pichard, C

    2011-03-01

    Reduced total body protein mass is a marker of protein-energy malnutrition and has been associated with numerous complications. Severe illness is characterized by a loss of total body protein mass, mainly from the skeletal muscle. Studies on protein turnover describe an increased protein breakdown and, to a lesser extent, an increased whole-body protein synthesis, as well as an increased flux of amino acids from the periphery to the liver. Appropriate nutrition could limit protein catabolism. Nutritional support limits but does not stop the loss of total body protein mass occurring in acute severe illness. Its impact on protein kinetics is so far controversial, probably due to the various methodologies and characteristics of nutritional support used in the studies. Maintaining calorie balance alone the days after an insult does not clearly lead to an improved clinical outcome. In contrast, protein intakes between 1.2 and 1.5 g/kg body weight/day with neutral energy balance minimize total body protein mass loss. Glutamine and possibly leucine may improve clinical outcome, but it is unclear whether these benefits occur through an impact on total body protein mass and its turnover, or through other mechanisms. Present recommendations suggest providing 20 - 25 kcal/kg/day over the first 72 - 96 hours and increasing energy intake to target thereafter. Simultaneously, protein intake should be between 1.2 and 1.5 g/kg/day. Enteral immunonutrition enriched with arginine, nucleotides, and omega-3 fatty acids is indicated in patients with trauma, acute respiratory distress syndrome (ARDS), and mild sepsis. Glutamine (0.2 - 0.4 g/kg/day of L-glutamine) should be added to enteral nutrition in burn and trauma patients (ESPEN guidelines 2006) and to parenteral nutrition, in the form of dipeptides, in intensive care unit (ICU) patients in general (ESPEN guidelines 2009). PMID:22139565

  15. Protein catabolism and requirements in severe illness.

    PubMed

    Genton, L; Pichard, C

    2011-03-01

    Reduced total body protein mass is a marker of protein-energy malnutrition and has been associated with numerous complications. Severe illness is characterized by a loss of total body protein mass, mainly from the skeletal muscle. Studies on protein turnover describe an increased protein breakdown and, to a lesser extent, an increased whole-body protein synthesis, as well as an increased flux of amino acids from the periphery to the liver. Appropriate nutrition could limit protein catabolism. Nutritional support limits but does not stop the loss of total body protein mass occurring in acute severe illness. Its impact on protein kinetics is so far controversial, probably due to the various methodologies and characteristics of nutritional support used in the studies. Maintaining calorie balance alone the days after an insult does not clearly lead to an improved clinical outcome. In contrast, protein intakes between 1.2 and 1.5 g/kg body weight/day with neutral energy balance minimize total body protein mass loss. Glutamine and possibly leucine may improve clinical outcome, but it is unclear whether these benefits occur through an impact on total body protein mass and its turnover, or through other mechanisms. Present recommendations suggest providing 20 - 25 kcal/kg/day over the first 72 - 96 hours and increasing energy intake to target thereafter. Simultaneously, protein intake should be between 1.2 and 1.5 g/kg/day. Enteral immunonutrition enriched with arginine, nucleotides, and omega-3 fatty acids is indicated in patients with trauma, acute respiratory distress syndrome (ARDS), and mild sepsis. Glutamine (0.2 - 0.4 g/kg/day of L-glutamine) should be added to enteral nutrition in burn and trauma patients (ESPEN guidelines 2006) and to parenteral nutrition, in the form of dipeptides, in intensive care unit (ICU) patients in general (ESPEN guidelines 2009).

  16. CsPAO4 of Citrus sinensis functions in polyamine terminal catabolism and inhibits plant growth under salt stress

    PubMed Central

    Wang, Wei; Liu, Ji-Hong

    2016-01-01

    Polyamine oxidase (PAO) is a key enzyme catalyzing polyamine catabolism leading to H2O2 production. We previously demonstrated that Citrus sinensis contains six putative PAO genes, but their functions are not well understood. In this work, we reported functional elucidation of CsPAO4 in polyamine catabolism and salt stress response. CsPAO4 was localized to the apoplast and used both spermidine (Spd) and spermine (Spm) as substrates for terminal catabolism. Transgenic plants overexpressing CsPAO4 displayed prominent increase in PAO activity, concurrent with marked decrease of Spm and Spd and elevation of H2O2. Seeds of transgenic lines displayed better germination when compared with wild type (WT) under salt stress. However, both vegetative growth and root elongation of the transgenic lines were prominently inhibited under salt stress, accompanied by higher level of H2O2 and more conspicuous programmed cell death (PCD). Exogenous supply of catalase (CAT), a H2O2 scavenger, partially recovered the vegetative growth and root elongation. In addition, spermine inhibited root growth of transgenic plants. Taken together, these data demonstrated that CsPAO4 accounts for production of H2O2 causing oxidative damages under salt stress and that down-regulation of a PAO gene involved in polyamine terminal catabolism may be an alternative approach for improving salt stress tolerance. PMID:27535697

  17. CsPAO4 of Citrus sinensis functions in polyamine terminal catabolism and inhibits plant growth under salt stress.

    PubMed

    Wang, Wei; Liu, Ji-Hong

    2016-01-01

    Polyamine oxidase (PAO) is a key enzyme catalyzing polyamine catabolism leading to H2O2 production. We previously demonstrated that Citrus sinensis contains six putative PAO genes, but their functions are not well understood. In this work, we reported functional elucidation of CsPAO4 in polyamine catabolism and salt stress response. CsPAO4 was localized to the apoplast and used both spermidine (Spd) and spermine (Spm) as substrates for terminal catabolism. Transgenic plants overexpressing CsPAO4 displayed prominent increase in PAO activity, concurrent with marked decrease of Spm and Spd and elevation of H2O2. Seeds of transgenic lines displayed better germination when compared with wild type (WT) under salt stress. However, both vegetative growth and root elongation of the transgenic lines were prominently inhibited under salt stress, accompanied by higher level of H2O2 and more conspicuous programmed cell death (PCD). Exogenous supply of catalase (CAT), a H2O2 scavenger, partially recovered the vegetative growth and root elongation. In addition, spermine inhibited root growth of transgenic plants. Taken together, these data demonstrated that CsPAO4 accounts for production of H2O2 causing oxidative damages under salt stress and that down-regulation of a PAO gene involved in polyamine terminal catabolism may be an alternative approach for improving salt stress tolerance.

  18. CsPAO4 of Citrus sinensis functions in polyamine terminal catabolism and inhibits plant growth under salt stress.

    PubMed

    Wang, Wei; Liu, Ji-Hong

    2016-01-01

    Polyamine oxidase (PAO) is a key enzyme catalyzing polyamine catabolism leading to H2O2 production. We previously demonstrated that Citrus sinensis contains six putative PAO genes, but their functions are not well understood. In this work, we reported functional elucidation of CsPAO4 in polyamine catabolism and salt stress response. CsPAO4 was localized to the apoplast and used both spermidine (Spd) and spermine (Spm) as substrates for terminal catabolism. Transgenic plants overexpressing CsPAO4 displayed prominent increase in PAO activity, concurrent with marked decrease of Spm and Spd and elevation of H2O2. Seeds of transgenic lines displayed better germination when compared with wild type (WT) under salt stress. However, both vegetative growth and root elongation of the transgenic lines were prominently inhibited under salt stress, accompanied by higher level of H2O2 and more conspicuous programmed cell death (PCD). Exogenous supply of catalase (CAT), a H2O2 scavenger, partially recovered the vegetative growth and root elongation. In addition, spermine inhibited root growth of transgenic plants. Taken together, these data demonstrated that CsPAO4 accounts for production of H2O2 causing oxidative damages under salt stress and that down-regulation of a PAO gene involved in polyamine terminal catabolism may be an alternative approach for improving salt stress tolerance. PMID:27535697

  19. RNA Interference Mediated Interleukin-1β Silencing in Inflamed Chondrocytes Decreases Target and Downstream Catabolic Responses.

    PubMed

    Ortved, Kyla F; Austin, Bethany S; Scimeca, Michael S; Nixon, Alan J

    2016-01-01

    Posttraumatic activation of the catabolic cascade plays a major role in degradation of cartilage. Interleukin-1β (IL-1β), a primary instigator in the catabolic axis, is upregulated in chondrocytes following injury. IL-1β activates key degradative enzymes, including MMPs and aggrecanases, and other proinflammatory mediators such as PGE2 which contribute to ECM breakdown. Posttranscriptional silencing of IL-1β by RNA interference (RNAi) may drive a reduction in IL-1β. We hypothesized that transduction of chondrocytes using rAAV2 expressing a short hairpin RNAi motif targeting IL-1β (shIL-1β) would significantly decrease IL-1β expression and, in turn, decrease expression of other catabolic enzymes. Chondrocyte cultures were transduced with rAAV2-tdT-shIL-1β in serum-free media. The fluorescent protein, tdTomato, was used to determine transduction efficiency via flow cytometry and fluorescent microscopy. Cells were stimulated with lipopolysaccharide (LPS) 48 hours following transduction. After 24-hour stimulation, supernatants were collected for cytokine analysis, and cells lysed for gene expression analysis. IL-1β knockdown led to significantly decreased expression of IL-1β, TNF-α, and ADAMTS5. PGE2 synthesis was also significantly downregulated. Overall, effective silencing of IL-1β using rAAV2 vector expressing a short hairpin IL-1β knockdown sequence was shown. Additionally, significant downstream effects were evident, including decreased expression of TNF-α and ADAMTS5. Targeted silencing of catabolic cytokines may provide a promising treatment avenue for osteoarthritic (OA) joints. PMID:27073697

  20. Abscisic acid: biosynthesis, inactivation, homoeostasis and signalling.

    PubMed

    Dong, Ting; Park, Youngmin; Hwang, Inhwan

    2015-01-01

    The phytohormone abscisic acid (ABA) plays crucial roles in numerous physiological processes during plant growth and abiotic stress responses. The endogenous ABA level is controlled by complex regulatory mechanisms involving biosynthesis, catabolism, transport and signal transduction pathways. This complex regulatory network may target multiple levels, including transcription, translation and post-translational regulation of genes involved in ABA responses. Most of the genes involved in ABA biosynthesis, catabolism and transport have been characterized. The local ABA concentration is critical for initiating ABA-mediated signalling during plant development and in response to environmental changes. In this chapter we discuss the mechanisms that regulate ABA biosynthesis, catabolism, transport and homoeostasis. We also present the findings of recent research on ABA perception by cellular receptors, and ABA signalling in response to cellular and environmental conditions.

  1. Characterization of the catabolic pathway for a phenylcoumaran-type lignin-derived biaryl in Sphingobium sp. strain SYK-6.

    PubMed

    Takahashi, Kenji; Kamimura, Naofumi; Hishiyama, Shojiro; Hara, Hirofumi; Kasai, Daisuke; Katayama, Yoshihiro; Fukuda, Masao; Kajita, Shinya; Masai, Eiji

    2014-09-01

    Sphingobium sp. strain SYK-6 is capable of degrading various lignin-derived biaryls. We determined the catabolic pathway of a phenylcoumaran-type compound, dehydrodiconiferyl alcohol (DCA) in SYK-6, and identified some of the DCA catabolism genes. In SYK-6 cells, the alcohol group of DCA was oxidized to the carboxyl group, first at the B-ring side chain and then at the A-ring side chain. The resultant metabolite was degraded to 5-formylferulate and vanillin through the decarboxylation and the Cα-Cβ cleavage of the A-ring side chain. Based on the DCA catabolic pathway, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) genes are thought to be involved in the conversion of DCA into an aldehyde intermediate (DCA-L) and the conversion of DCA-L into a carboxylic acid intermediate (DCA-C), respectively. SLG_05620 and SLG_24930, which belong to quinohemoprotein ADH and aryl ADH, respectively, were isolated as the genes responsible for the oxidation of DCA. In addition to these genes, multiple genes similar to SLG_05620 and SLG_24930 were found to confer DCA oxidation activities on Escherichia coli cells. In order to identify the DCA-L dehydrogenase genes, the DCA-L oxidation activities of the SYK-6 gene products of putative twenty-one ALDH genes were examined. Significant activities were observed in the four ALDH gene products, including the SLG_27910 product, which showed the highest activity. The disruption of SLG_27910 caused a decreased conversion of DCA-L, suggesting that SLG_27910 plays an important role in the DCA-L oxidation. In conclusion, no specific gene seems to be solely responsible for the conversion of DCA and DCA-L, however, the multiple genes encoding quinohemoprotein ADH and aryl ADH genes, and four ALDH genes are probably involved in the conversion processes. PMID:24916011

  2. ABA-Cloud: support for collaborative breath research.

    PubMed

    Elsayed, Ibrahim; Ludescher, Thomas; King, Julian; Ager, Clemens; Trosin, Michael; Senocak, Uygar; Brezany, Peter; Feilhauer, Thomas; Amann, Anton

    2013-06-01

    This paper introduces the advanced breath analysis (ABA) platform, an innovative scientific research platform for the entire breath research domain. Within the ABA project, we are investigating novel data management concepts and semantic web technologies to document breath analysis studies for the long run as well as to enable their full automatic reproducibility. We propose several concept taxonomies (a hierarchical order of terms from a glossary of terms), which can be seen as a first step toward the definition of conceptualized terms commonly used by the international community of breath researchers. They build the basis for the development of an ontology (a concept from computer science used for communication between machines and/or humans and representation and reuse of knowledge) dedicated to breath research. PMID:23619467

  3. Rheology and Relaxation Timescales of ABA Triblock Polymer Gels

    NASA Astrophysics Data System (ADS)

    Peters, Andrew; Lodge, Timothy

    When dissolved in a midblock selective solvent, ABA polymers form gels composed of aggregated end block micelles bridged by the midblocks. While much effort has been devoted to the study of the structure of these systems, the dynamics of these systems has received less attention. We examine the underlying mechanism of shear relaxation of ABA triblock polymer gels, especially as a function of chain length, composition, and concentration. Recent work using time-resolved small-angle neutron scattering of polystyrene (PS)-block-poly(ethylene-alt-propylene) (PEP) in squalane has elucidated many aspects of the dynamics of diblock chain exchange. By using rheology to study bulk relaxation phenomena of the triblock equivalent, PS-PEP-PS, we apply the knowledge gained from the chain exchange studies to bridge the gap between the molecular and macroscopic relaxation phenomena in PS-PEP-PS triblock gels.

  4. ABA-Cloud: support for collaborative breath research.

    PubMed

    Elsayed, Ibrahim; Ludescher, Thomas; King, Julian; Ager, Clemens; Trosin, Michael; Senocak, Uygar; Brezany, Peter; Feilhauer, Thomas; Amann, Anton

    2013-06-01

    This paper introduces the advanced breath analysis (ABA) platform, an innovative scientific research platform for the entire breath research domain. Within the ABA project, we are investigating novel data management concepts and semantic web technologies to document breath analysis studies for the long run as well as to enable their full automatic reproducibility. We propose several concept taxonomies (a hierarchical order of terms from a glossary of terms), which can be seen as a first step toward the definition of conceptualized terms commonly used by the international community of breath researchers. They build the basis for the development of an ontology (a concept from computer science used for communication between machines and/or humans and representation and reuse of knowledge) dedicated to breath research.

  5. Sarcosine Catabolism in Pseudomonas aeruginosa Is Transcriptionally Regulated by SouR

    PubMed Central

    Willsey, Graham G.

    2015-01-01

    ABSTRACT Sarcosine (N-methylglycine) is present in many environments inhabited by pseudomonads and is likely most often encountered as an intermediate in the metabolism of choline, carnitine, creatine, and glyphosate. While the enzymology of sarcosine metabolism has been relatively well studied in bacteria, the regulatory mechanisms governing catabolism have remained largely unknown. We previously determined that the sarcosine-catabolic (sox) operon of Pseudomonas aeruginosa is induced by the AraC family regulator GbdR in response to glycine betaine and dimethylglycine. However, induction of these genes was still observed in response to sarcosine in a gbdR deletion mutant, indicating that an independent sarcosine-responsive transcription factor also acted at this locus. Our goal in this study was to identify and characterize this regulator. Using a transposon-based genetic screen, we identified PA4184, or SouR (sarcosine oxidation and utilization regulator), as the sarcosine-responsive regulator of the sox operon, with tight induction specificity for sarcosine. The souR gene is required for appreciable growth on sarcosine as a carbon and nitrogen source. We also characterized the transcriptome response to sarcosine governed by SouR using microarray analyses and performed electrophoretic mobility shift assays to identify promoters directly regulated by the transcription factor. Finally, we characterized PA3630, or GfnR (glutathione-dependent formaldehyde neutralization regulator), as the regulator of the glutathione-dependent formaldehyde detoxification system in P. aeruginosa that is expressed in response to formaldehyde released during the catabolism of sarcosine. This study expands our understanding of sarcosine metabolic regulation in bacteria through the identification and characterization of the first known sarcosine-responsive transcriptional regulator. IMPORTANCE The Pseudomonas aeruginosa genome encodes many diverse metabolic pathways, yet the specific

  6. Vanillin catabolism in Rhodococcus jostii RHA1.

    PubMed

    Chen, Hao-Ping; Chow, Mindy; Liu, Chi-Chun; Lau, Alice; Liu, Jie; Eltis, Lindsay D

    2012-01-01

    Genes encoding vanillin dehydrogenase (vdh) and vanillate O-demethylase (vanAB) were identified in Rhodococcus jostii RHA1 using gene disruption and enzyme activities. During growth on vanillin or vanillate, vanA was highly upregulated while vdh was not. This study contributes to our understanding of lignin degradation by RHA1 and other actinomycetes.

  7. [Biochemical methods for the determination of a clinical protein catabolism].

    PubMed

    Roth, E; Funovics, J; Schulz, F; Karner, J

    1980-12-01

    1. 20 patients before surgery received enteral nutrition for three days (12 g nitrogen, 1800 Kcal). Nitrogen and urea excretions in urine during the second and third day were determined. Eleven patients had a negative nitrogen balance (-2,7 and -2,4 g/day). In these patients urea production rates were 21,1 and 20,1 g/day. An urea production rate exceeding 15 g urea/day is probable an indication for a protein catabolism. The reason for this catabolic state seems to be a decreased protein utilisation (49 and 47 percent) as the result of a metabolic stress situation. This metabolic stress was determined according the stress index (Bistrian). The patients were in a stress situation comparable to postoperative stress (+3,7 and +3,9). The determination of urea production rate and catabolic index seems a suitable tool for defining a catabolic state. 2. 3-met-histidine excretion in urine were measured in seven patients postoperatively. In different periods saline or aminoacids solutions (5% alanine) were infused. During alanine administration protein (+49%)--and 3-met-histidine excretions (+50%) increased. It is not possible to state a catabolic situation out of the 3-met-histidine excretion, because an increased excretion may result from a stimulated protein synthesis in muscle tissue or from an increased muscleprotein wasting. 3. Free amino acid pools in plasma and muscle tissue were analysed in patients with severe illness of liver and pancreas. The free amino acid pattern differed from healthy volunteers. In patients with liver disease significantly increased concentrations of phenylalanine, tyrosine and methionine were found. In patients with acute pancreatitis highly abnormal pattern of intracellular amino acids occurred with decreased concentrations of glutamine, cysteine, histidine, lysine, arginine and ornithine. The highly significant decreased concentrations of glutamine (p less than 0,01) indicate a catabolic situation of these patients. A quantification of the

  8. Overexpression of soybean miR172c confers tolerance to water deficit and salt stress, but increases ABA sensitivity in transgenic Arabidopsis thaliana.

    PubMed

    Li, Wenbin; Wang, Tao; Zhang, Yuhang; Li, Yongguang

    2016-01-01

    MiRNAs play crucial roles in many aspects of plant development and the response to the environment. The miR172 family has been shown to participate in the control of flowering time and the response to abiotic stress. This family regulates the expression of APETALA2 (AP2)-like transcription factors in Arabidopsis. In the present study, soybean (Glycine max L. Merr.) miR172c, a member of the miR172 family, and its target gene were investigated for abiotic stress responses in transgenic Arabidopsis. gma-miR172c was induced by abscisic acid (ABA) treatments and abiotic stresses, including salt and water deficit. 5'-RACE (5'-rapid amplification of cDNA ends) assays indicated that miR172c directed Glyma01g39520 mRNA cleavage in soybeans. Overexpression of gma-miR172c in Arabidopsis resulted in reduced leaf water loss and increased survival rate under stress conditions. Meanwhile, the root length, germination rate, and cotyledon greening of transgenic plants were improved during both high salt and water deficit conditions. In addition, transgenic plants exhibited hypersensitivity to ABA during both the seed germination and post-germination seedling growth stages. Stress-related physiological indicators and the expression of stress/ABA-responsive genes were affected by abiotic treatments. The overexpression of gma-miR172c in Arabidopsis promoted earlier flowering compared with the wild type through modulation of the expression of flowering genes, such as FT and LFY during long days, especially under drought conditions. Glyma01g39520 weakened ABA sensitivity and reduced the tolerance to drought stress in the snz mutant of Arabidopsis by reducing the expression of ABI3 and ABI5. Overall, the present results demonstrate that gma-miR172c confers water deficit and salt tolerance but increased ABA sensitivity by regulating Glyma01g39520, which also accelerates flowering under abiotic stresses.

  9. RING Type E3 Ligase CaAIR1 in Pepper Acts in the Regulation of ABA Signaling and Drought Stress Response.

    PubMed

    Park, Chanmi; Lim, Chae Woo; Baek, Woonhee; Lee, Sung Chul

    2015-09-01

    Several E3 ubiquitin ligases have been associated with the response to abiotic and biotic stresses in higher plants. Here, we report that the hot pepper (Capsicum annuum) ABA-Insensitive RING protein 1 gene (CaAIR1) is essential for a hypersensitive response to drought stress. CaAIR1 contains a C3HC4-type RING finger motif, which plays a role for attachment of ubiquitins to the target protein, and a putative transmembrane domain. The expression levels of CaAIR1 are up-regulated in pepper leaves by ABA treatments, drought and NaCl, suggesting its role in the response to abiotic stress. Our analysis showed that CaAIR1 displays self-ubiquitination and is localized in the nucleus. We generated CaAIR1-silenced peppers via virus-induced gene silencing (VIGS) and CaAIR1-overexpressing (OX) transgenic Arabidopsis plants to evaluate their responses to ABA and drought. VIGS of CaAIR1 in pepper plants conferred an enhanced tolerance to drought stress, which was accompanied by low levels of transpirational water loss in the drought-treated leaves. CaAIR1-OX plants displayed an impaired sensitivity to ABA during seed germination, seedling and adult stages. Moreover, these plants showed enhanced sensitivity to drought stress because of reduced stomatal closure and decreased expression of stress-responsive genes. Thus, our data indicate that CaAIR1 is a negative regulator of the ABA-mediated drought stress tolerance mechanism.

  10. Developmental and hormonal regulation of gibberellin biosynthesis and catabolism in pea fruit.

    PubMed

    Ozga, Jocelyn A; Reinecke, Dennis M; Ayele, Belay T; Ngo, Phuong; Nadeau, Courtney; Wickramarathna, Aruna D

    2009-05-01

    In pea (Pisum sativum), normal fruit growth requires the presence of the seeds. The coordination of growth between the seed and ovary tissues involves phytohormones; however, the specific mechanisms remain speculative. This study further explores the roles of the gibberellin (GA) biosynthesis and catabolism genes during pollination and fruit development and in seed and auxin regulation of pericarp growth. Pollination and fertilization events not only increase pericarp PsGA3ox1 message levels (codes for GA 3-oxidase that converts GA(20) to bioactive GA(1)) but also reduce pericarp PsGA2ox1 mRNA levels (codes for GA 2-oxidase that mainly catabolizes GA(20) to GA(29)), suggesting a concerted regulation to increase levels of bioactive GA(1) following these events. 4-Chloroindole-3-acetic acid (4-Cl-IAA) was found to mimic the seeds in the stimulation of PsGA3ox1 and the repression of PsGA2ox1 mRNA levels as well as the stimulation of PsGA2ox2 mRNA levels (codes for GA 2-oxidase that mainly catabolizes GA(1) to GA(8)) in pericarp at 2 to 3 d after anthesis, while the other endogenous pea auxin, IAA, did not. This GA gene expression profile suggests that both seeds and 4-Cl-IAA can stimulate the production, as well as modulate the half-life, of bioactive GA(1), leading to initial fruit set and subsequent growth and development of the ovary. Consistent with these gene expression profiles, deseeded pericarps converted [(14)C]GA(12) to [(14)C]GA(1) only if treated with 4-Cl-IAA. These data further support the hypothesis that 4-Cl-IAA produced in the seeds is transported to the pericarp, where it differentially regulates the expression of pericarp GA biosynthesis and catabolism genes to modulate the level of bioactive GA(1) required for initial fruit set and growth. PMID:19297588

  11. Proteomic analyses reveal the key roles of BrlA and AbaA in biogenesis of gliotoxin in Aspergillus fumigatus

    SciTech Connect

    Shin, Kwang-Soo; Kim, Young Hwan; Yu, Jae-Hyuk

    2015-07-31

    The opportunistic human pathogenic fungus Aspergillus fumigatus primarily reproduces by forming a large number of asexual spores (conidia). Sequential activation of the central regulators BrlA, AbaA and WetA is necessary for the fungus to undergo asexual development. In this study, to address the presumed roles of these key developmental regulators during proliferation of the fungus, we analyzed and compared the proteomes of vegetative cells of wild type (WT) and individual mutant strains. Approximately 1300 protein spots were detectable from 2-D electrophoresis gels. Among these, 13 proteins exhibiting significantly altered accumulation levels were further identified by ESI-MS/MS. Markedly, we found that the GliM and GliT proteins associated with gliotoxin (GT) biosynthesis and self-protection of the fungus from GT were significantly down-regulated in the ΔabaA and ΔbrlA mutants. Moreover, mRNA levels of other GT biosynthetic genes including gliM, gliP, gliT, and gliZ were significantly reduced in both mutant strains, and no and low levels of GT were detectable in the ΔbrlA and ΔabaA mutant strains, respectively. As GliT is required for the protection of the fungus from GT, growth of the ΔbrlA mutant with reduced levels of GliT was severely impaired by exogenous GT. Our studies demonstrate that AbaA and BrlA positively regulate expression of the GT biosynthetic gene cluster in actively growing vegetative cells, and likely bridge morphological and chemical development during the life-cycle of A. fumigatus. - Highlights: • Proteome analyses of WT and mutants reveal 13 differentially expressed proteins. • The GliT and GliM proteins are significantly down-regulated by ΔabaA and ΔbrlA. • Expression of other gliotoxin biosynthetic genes is lowered by ΔabaA and ΔbrlA. • Growth of ΔbrlA strain lacking GliT is completely inhibited by exogenous gliotoxin. • BrlA and AbaA play key roles in biogenesis of gliotoxin in Aspergillus fumigatus.

  12. Molecular cloning, functional expression and characterisation of RCC reductase involved in chlorophyll catabolism.

    PubMed

    Wüthrich, K L; Bovet, L; Hunziker, P E; Donnison, I S; Hörtensteiner, S

    2000-01-01

    Red chlorophyll catabolite (RCC) reductase (RCCR) and pheophorbide (Pheide) a oxygenase (PaO) catalyse the key reaction of chlorophyll catabolism, porphyrin macrocycle cleavage of Pheide a to a primary fluorescent catabolite (pFCC). RCCR was purified from barley and a partial gene sequence was cloned (pHvRCCR). The gene was expressed at all stages of leaf development and in roots. By comparison with different databases, genomic sequences and expressed sequence tags similar to RCCR were found in phylogenetically diverse species, and activity of RCCR was demonstrated in two of them, Arabidopsis thaliana and Marchantia polymorpha. The gene of A. thaliana (AtRCCR) was employed for molecular cloning, heterologous expression and the production of polyclonal antibodies. With recombinant RCCR, the major product of RCC reduction was pFCC-1, but small quantities of its C1 epimer, pFCC-2, also accumulated. The reaction required reduced ferredoxin and was sensitive to oxygen. AtRCCR encoded a 35 kDa protein which was used for chloroplast import experiments. Upon transport, it was processed to a mature form of 31 kDa. The significance of cloning of RCCR is discussed in respect to the evolution of chlorophyll catabolism and to the cloning of PaO.

  13. ABA and GA3 increase carbon allocation in different organs of grapevine plants by inducing accumulation of non-structural carbohydrates in leaves, enhancement of phloem area and expression of sugar transporters.

    PubMed

    Murcia, Germán; Pontin, Mariela; Reinoso, Herminda; Baraldi, Rita; Bertazza, Gianpaolo; Gómez-Talquenca, Sebastián; Bottini, Rubén; Piccoli, Patricia N

    2016-03-01

    Grape quality for winemaking depends on sugar accumulation and metabolism in berries. Abscisic acid (ABA) and gibberellins (GAs) have been reported to control sugar allocation in economically important crops, although the mechanisms involved are still unknown. The present study tested if ABA and gibberellin A3 (GA3) enhance carbon allocation in fruits of grapevines by modifying phloem loading, phloem area and expression of sugar transporters in leaves and berries. Pot-grown Vitis vinifera cv. Malbec plants were sprayed with ABA and GA3 solutions. The amount of soluble sugars in leaves and berries related to photosynthesis were examined at three points of berry growth: pre-veraison, full veraison and post-veraison. Starch levels and amylase activity in leaves, gene expression of sugar transporters in leaves and berries and phloem anatomy were examined at full veraison. Accumulation of glucose and fructose in berries was hastened in ABA-treated plants at the stage of full veraison, which was correlated with enhancement of Vitis vinifera HEXOSE TRANSPORTER 2 (VvHT2) and Vitis vinifera HEXOSE TRANSPORTER 6 (VvHT6) gene expression, increases of phloem area and sucrose content in leaves. On the other hand, GA3 increased the quantity of photoassimilates delivered to the stem thus increasing xylem growth. In conclusion, stimulation of sugar transport by ABA and GA3 to berries and stems, respectively, was due to build-up of non-structural carbohydrates in leaves, modifications in phloem tissue and modulation in gene expression of sugar transporters.

  14. Molecular Mimicry Regulates ABA Signaling by SnRK2 Kinases and PP2C Phosphatases

    SciTech Connect

    Soon, Fen-Fen; Ng, Ley-Moy; Zhou, X. Edward; West, Graham M.; Kovach, Amanda; Tan, M.H. Eileen; Suino-Powell, Kelly M.; He, Yuanzheng; Xu, Yong; Chalmers, Michael J.; Brunzelle, Joseph S.; Zhang, Huiming; Yang, Huaiyu; Jiang, Hualiang; Li, Jun; Yong, Eu-Leong; Cutler, Sean; Zhu, Jian-Kang; Griffin, Patrick R.; Melcher, Karsten; Xu, H. Eric

    2014-10-02

    Abscisic acid (ABA) is an essential hormone for plants to survive environmental stresses. At the center of the ABA signaling network is a subfamily of type 2C protein phosphatases (PP2Cs), which form exclusive interactions with ABA receptors and subfamily 2 Snfl-related kinase (SnRK2s). Here, we report a SnRK2-PP2C complex structure, which reveals marked similarity in PP2C recognition by SnRK2 and ABA receptors. In the complex, the kinase activation loop docks into the active site of PP2C, while the conserved ABA-sensing tryptophan of PP2C inserts into the kinase catalytic cleft, thus mimicking receptor-PP2C interactions. These structural results provide a simple mechanism that directly couples ABA binding to SnRK2 kinase activation and highlight a new paradigm of kinase-phosphatase regulation through mutual packing of their catalytic sites.

  15. Molecular Mimicry Regulates ABA Signaling by SnRK2 Kinases and PP2C Phosphatases

    PubMed Central

    Soon, Fen-Fen; Ng, Ley-Moy; Zhou, X. Edward; West, Graham M.; Kovach, Amanda; Tan, M. H. Eileen; Suino-Powell, Kelly M.; He, Yuanzheng; Xu, Yong; Chalmers, Michael J.; Brunzelle, Joseph S.; Zhang, Huiming; Yang, Huaiyu; Jiang, Hualiang; Li, Jun; Yong, Eu-Leong; Cutler, Sean; Zhu, Jian-Kang; Griffin, Patrick R.; Melcher, Karsten; Xu, H. Eric

    2013-01-01

    Abscisic acid (ABA) is an essential hormone for plants to survive environmental stresses. At the center of the ABA signaling network is a subfamily of type 2C protein phosphatases (PP2Cs), which form exclusive interactions with ABA receptors and subfamily 2 Snfl-related kinase (SnRK2s). Here, we report a SnRK2-PP2C complex structure, which reveals marked similarity in PP2C recognition by SnRK2 and ABA receptors. In the complex, the kinase activation loop docks into the active site of PP2C, while the conserved ABA-sensing tryptophan of PP2C inserts into the kinase catalytic cleft, thus mimicking receptor-PP2C interactions. These structural results provide a simple mechanism that directly couples ABA binding to SnRK2 kinase activation and highlight a new paradigm of kinase-phosphatase regulation through mutual packing of their catalytic sites. PMID:22116026

  16. Alkaline-stress response in Glycine soja leaf identifies specific transcription factors and ABA-mediated signaling factors.

    PubMed

    Ge, Ying; Li, Yong; Lv, De-Kang; Bai, Xi; Ji, Wei; Cai, Hua; Wang, Ao-Xue; Zhu, Yan-Ming

    2011-06-01

    Transcriptome of Glycine soja leaf tissue during a detailed time course formed a foundation for examining transcriptional processes during NaHCO(3) stress treatment. Of a total of 2,310 detected differentially expressed genes, 1,664 genes were upregulated and 1,704 genes were downregulated at various time points. The number of stress-regulated genes increased dramatically after a 6-h stress treatment. GO category gene enrichment analysis revealed that most of the differentially expressed genes were involved in cell structure, protein synthesis, energy, and secondary metabolism. Another enrichment test revealed that the response of G. soja to NaHCO(3) highlights specific transcription factors, such as the C2C2-CO-like, MYB-related, WRKY, GARP-G2-like, and ZIM families. Co-expressed genes were clustered into ten classes (P < 0.001). Intriguingly, one cluster of 188 genes displayed a unique expression pattern that increases at an early stage (0.5 and 3 h), followed by a decrease from 6 to 12 h. This group was enriched in regulation of transcription components, including AP2-EREBP, bHLH, MYB/MYB-related, C2C2-CO-like, C2C2-DOF, C2C2, C3H, and GARP-G2-like transcription factors. Analysis of the 1-kb upstream regions of transcripts displaying similar changes in abundance identified 19 conserved motifs, potential binding sites for transcription factors. The appearance of ABA-responsive elements in the upstream of co-expression genes reveals that ABA-mediated signaling participates in the signal transduction in alkaline response.

  17. Root ABA Accumulation in Long-Term Water-Stressed Plants is Sustained by Hormone Transport from Aerial Organs.

    PubMed

    Manzi, Matías; Lado, Joanna; Rodrigo, María Jesús; Zacarías, Lorenzo; Arbona, Vicent; Gómez-Cadenas, Aurelio

    2015-12-01

    The reduced pool of the ABA precursors, β,β-carotenoids, in roots does not account for the substantial increase in ABA content in response to water stress (WS) conditions, suggesting that ABA could be transported from other organs. Basipetal transport was interrupted by stem-girdling, and ABA levels were determined in roots after two cycles of WS induced by transplanting plants to dry perlite. Leaf applications of isotope-labeled ABA and reciprocal grafting of ABA-deficient tomato mutants were used to confirm the involvement of aerial organs on root ABA accumulation. Disruption of basipetal transport reduced ABA accumulation in roots, and this decrease was more severe after two consecutive WS periods. This effect was linked to a sharp decrease in the β,β-carotenoid pool in roots in response to water deficit. Significant levels of isotope-labeled ABA were transported from leaves to roots, mainly in plants subjected to water dehydration. Furthermore, the use of different ABA-deficient tomato mutants in reciprocal grafting combinations with wild-type genotypes confirmed the involvement of aerial organs in the ABA accumulation in roots. In conclusion, accumulation of ABA in roots after long-term WS periods largely relies on the aerial organs, suggesting a reduced ability of the roots to synthesize ABA from carotenoids. Furthermore, plants are able to transport ABA basipetally to sustain high hormone levels in roots.

  18. The site of water stress governs the pattern of ABA synthesis and transport in peanut

    PubMed Central

    Hu, Bo; Cao, Jiajia; Ge, Kui; Li, Ling

    2016-01-01

    Abscisic acid (ABA) is one of the most important phytohormones involved in stress responses in plants. However, knowledge of the effect on ABA distribution and transport of water stress at different sites on the plant is limited. In this study, water stress imposed on peanut leaves or roots by treatment with PEG 6000 is termed “leaf stress” or “root stress”, respectively. Immunoenzyme localization technolony was first used to detect ABA distribution in peanut. Under root stress, ABA biosynthesis and distribution level were all more pronounced in root than in leaf. However, ABA transport and the ability to induce stomatal closure were still better in leaf than in root during root stress; However, ABA biosynthesis initially increased in leaf, then rapidly accumulated in the vascular cambium of leaves and induced stomatal closure under leaf stress; ABA produced in root tissues was also transported to leaf tissues to maintain stomatal closure. The vascular system was involved in the coordination and integration of this complex regulatory mechanism for ABA signal accumulation. Water stress subject to root or leaf results in different of ABA biosynthesis and transport ability that trigger stoma close in peanut. PMID:27694957

  19. Genetic and metabolic analysis of the carbofuran catabolic pathway in Novosphingobium sp. KN65.2.

    PubMed

    Nguyen, Thi Phi Oanh; Helbling, Damian E; Bers, Karolien; Fida, Tekle Tafese; Wattiez, Ruddy; Kohler, Hans-Peter E; Springael, Dirk; De Mot, René

    2014-10-01

    The widespread agricultural application of carbofuran and concomitant contamination of surface and ground waters has raised health concerns due to the reported toxic effects of this insecticide and its degradation products. Most bacteria that degrade carbofuran only perform partial degradation involving carbamate hydrolysis without breakdown of the resulting phenolic metabolite. The capacity to mineralize carbofuran beyond the benzofuran ring has been reported for some bacterial strains, especially sphingomonads, and some common metabolites, including carbofuran phenol, were identified. In the current study, the catabolism of carbofuran by Novosphingobium sp. KN65.2 (LMG 28221), a strain isolated from a carbofuran-exposed Vietnamese soil and utilizing the compound as a sole carbon and nitrogen source, was studied. Several KN65.2 plasposon mutants with diminished or abolished capacity to degrade and mineralize carbofuran were generated and characterized. Metabolic profiling of representative mutants revealed new metabolic intermediates, in addition to the initial hydrolysis product carbofuran phenol. The promiscuous carbofuran-hydrolyzing enzyme Mcd, which is present in several bacteria lacking carbofuran ring mineralization capacity, is not encoded by the Novosphingobium sp. KN65.2 genome. An alternative hydrolase gene required for this step was not identified, but the constitutively expressed genes of the unique cfd operon, including the oxygenase genes cfdC and cfdE, could be linked to further degradation of the phenolic metabolite. A third involved oxygenase gene, cfdI, and the transporter gene cftA, encoding a TonB-dependent outer membrane receptor with potential regulatory function, are located outside the cfd cluster. This study has revealed the first dedicated carbofuran catabolic genes and provides insight in the early steps of benzofuran ring degradation.

  20. PP2C-like Promoter and Its Deletion Variants Are Induced by ABA but Not by MeJA and SA in Arabidopsis thaliana.

    PubMed

    Bhalothia, Purva; Sangwan, Chetna; Alok, Anshu; Mehrotra, Sandhya; Mehrotra, Rajesh

    2016-01-01

    Gene expression is mediated through interaction between cis regulatory elements and its cognate transcription factors. Cis regulatory elements are defined as non-coding DNA sequences that provide the binding sites for transcription factors and are clustered in the upstream region of genes. ACGT cis regulatory element is one of the important cis regulatory elements found to be involved in diverse biological processes like auxin response, salicylic acid (SA) response, UV light response, ABA response and jasmonic acid (JA) response. We identified through in silico analysis that the upstream region of protein phosphatase 2C (PP2C) gene has a distinct genetic architecture of ACGT elements. In the present study, the activation of the full length promoter and its deletion constructs like 900 base pair, 500 base pair, 400 base pair and NRM (Nathji Rajesh Mehrotra) were examined by stable transformation in Arabidopsis thaliana using β-glucuronidase as the reporter gene. Evaluation of deletion constructs of PP2C-like promoter was carried out in the presence of phytohormones like abscisic acid (ABA), SA and JA. Our result indicated that the full length and 900 base pair promoter-reporter constructs of PP2C-like promoter was induced in response to ABA but not to methyl jasmonate and SA. PMID:27200023

  1. Monitoring of naphthalene catabolism by bioluminescence with nah-lux transcriptional fusions.

    PubMed Central

    Burlage, R S; Sayler, G S; Larimer, F

    1990-01-01

    We have demonstrated the efficacy of a light-generating genetic construction in describing the induction of a nah operon for the catabolism of naphthalene. A fragment from plasmid NAH7, which contains the promoter for the upper pathway of degradation, was transcriptionally fused to the lux genes of Vibrio fischeri. A Pseudomonas strain containing this construction is inducible to high levels of light production in the presence of a suitable substrate and the nahR regulatory gene product. This system was used to examine catabolic activity in a unique manner under a variety of growth conditions. Induction of bioluminescence was demonstrated to coincide with naphthalene degradation in all cases through the use of mineralization assays. A significant delay in bioluminescence and biodegradation was observed when naphthalene was added to batch cultures that were growing exponentially. These results suggest that the metabolism of naphthalene by this Pseudomonas strain is optimal when the growth rate of the culture is slow and is greatly reduced during exponential growth. Images PMID:2203729

  2. Glucocorticoid receptor-PPARα axis in fetal mouse liver prepares neonates for milk lipid catabolism

    PubMed Central

    Rando, Gianpaolo; Tan, Chek Kun; Khaled, Nourhène; Montagner, Alexandra; Leuenberger, Nicolas; Bertrand-Michel, Justine; Paramalingam, Eeswari; Guillou, Hervé; Wahli, Walter

    2016-01-01

    In mammals, hepatic lipid catabolism is essential for the newborns to efficiently use milk fat as an energy source. However, it is unclear how this critical trait is acquired and regulated. We demonstrate that under the control of PPARα, the genes required for lipid catabolism are transcribed before birth so that the neonatal liver has a prompt capacity to extract energy from milk upon suckling. The mechanism involves a fetal glucocorticoid receptor (GR)-PPARα axis in which GR directly regulates the transcriptional activation of PPARα by binding to its promoter. Certain PPARα target genes such as Fgf21 remain repressed in the fetal liver and become PPARα responsive after birth following an epigenetic switch triggered by β-hydroxybutyrate-mediated inhibition of HDAC3. This study identifies an endocrine developmental axis in which fetal GR primes the activity of PPARα in anticipation of the sudden shifts in postnatal nutrient source and metabolic demands. DOI: http://dx.doi.org/10.7554/eLife.11853.001 PMID:27367842

  3. Perturbation of polyamine catabolism affects grape ripening of Vitis vinifera cv. Trincadeira.

    PubMed

    Agudelo-Romero, Patricia; Ali, Kashif; Choi, Young H; Sousa, Lisete; Verpoorte, Rob; Tiburcio, Antonio F; Fortes, Ana M

    2014-01-01

    Grapes are economically the most important fruit worldwide. However, the complexity of biological events that lead to ripening of nonclimacteric fruits is not fully understood, particularly the role of polyamines' catabolism. The transcriptional and metabolic profilings complemented with biochemical data were studied during ripening of Trincadeira grapes submitted to guazatine treatment, a potent inhibitor of polyamine oxidase activity. The mRNA expression profiles of one time point (EL 38) corresponding to harvest stage was compared between mock and guazatine treatments using Affymetrix GrapeGen(®) genome array. A total of 2113 probesets (1880 unigenes) were differentially expressed between these samples. Quantitative RT-PCR validated microarrays results being carried out for EL 35 (véraison berries), EL 36 (ripe berries) and EL 38 (harvest stage berries). Metabolic profiling using HPLC and (1)H NMR spectroscopy showed increase of putrescine, proline, threonine and 1-O-ethyl-β-glucoside in guazatine treated samples. Genes involved in amino acid, carbohydrate and water transport were down-regulated in guazatine treated samples suggesting that the strong dehydrated phenotype obtained in guazatine treated samples may be due to impaired transport mechanisms. Genes involved in terpenes' metabolism were differentially expressed between guazatine and mock treated samples. Altogether, results support an important role of polyamine catabolism in grape ripening namely in cell expansion and aroma development.

  4. Ectoine-induced proteins in Sinorhizobium meliloti include an Ectoine ABC-type transporter involved in osmoprotection and ectoine catabolism.

    PubMed

    Jebbar, Mohamed; Sohn-Bösser, Linda; Bremer, Erhard; Bernard, Théophile; Blanco, Carlos

    2005-02-01

    To understand the mechanisms of ectoine-induced osmoprotection in Sinorhizobium meliloti, a proteomic examination of S. meliloti cells grown in minimal medium supplemented with ectoine was undertaken. This revealed the induction of 10 proteins. The protein products of eight genes were identified by using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. Five of these genes, with four other genes whose products were not detected on two-dimensional gels, belong to the same gene cluster, which is localized on the pSymB megaplasmid. Four of the nine genes encode the characteristic components of an ATP-binding cassette transporter that was named ehu, for ectoine/hydroxyectoine uptake. This transporter was encoded by four genes (ehuA, ehuB, ehuC, and ehuD) that formed an operon with another gene cluster that contains five genes, named eutABCDE for ectoine utilization. On the basis of sequence homologies, eutABCDE encode enzymes with putative and hypothetical functions in ectoine catabolism. Analysis of the properties of ehuA and eutA mutants suggests that S. meliloti possesses at least one additional ectoine catabolic pathway as well as a lower-affinity transport system for ectoine and hydroxyectoine. The expression of ehuB, as determined by measurements of UidA activity, was shown to be induced by ectoine and hydroxyectoine but not by glycine betaine or by high osmolality.

  5. Branched chain amino acid catabolism fuels adipocyte differentiation and lipogenesis

    PubMed Central

    Green, Courtney R.; Wallace, Martina; Divakaruni, Ajit S.; Phillips, Susan A.; Murphy, Anne N.; Ciaraldi, Theodore P.; Metallo, Christian M.

    2015-01-01

    Adipose tissue plays important roles in regulating carbohydrate and lipid homeostasis, though less is known about the regulation of amino acid metabolism in adipocytes. Here we applied isotope tracing to pre–adipocytes and differentiated adipocytes to quantify the contributions of different substrates to tricarboxylic acid metabolism and lipogenesis. In contrast to proliferating cells that use glucose and glutamine for acetyl–coenzyme A (AcCoA) generation, differentiated adipocytes increased branched chain amino acid (BCAA) catabolic flux such that leucine and isoleucine from media and/or protein catabolism accounted for as much as 30% of lipogenic AcCoA pools. Medium cobalamin deficiency caused methylmalonic acid accumulation and odd–chain fatty acid synthesis. B12 supplementation reduced these metabolites and altered the balance of substrates entering mitochondria. Finally, inhibition of BCAA catabolism compromised adipogenesis. These results quantitatively highlight the contribution of BCAAs to adipocyte metabolism and suggest that BCAA catabolism plays a functional role in adipocyte differentiation. PMID:26571352

  6. The cotton WRKY transcription factor GhWRKY17 functions in drought and salt stress in transgenic Nicotiana benthamiana through ABA signaling and the modulation of reactive oxygen species production.

    PubMed

    Yan, Huiru; Jia, Haihong; Chen, Xiaobo; Hao, Lili; An, Hailong; Guo, Xingqi

    2014-12-01

    Drought and high salinity are two major environmental factors that significantly limit the productivity of agricultural crops worldwide. WRKY transcription factors play essential roles in the adaptation of plants to abiotic stresses. However, WRKY genes involved in drought and salt tolerance in cotton (Gossypium hirsutum) are largely unknown. Here, a group IId WRKY gene, GhWRKY17, was isolated and characterized. GhWRKY17 was found to be induced after exposure to drought, salt, H2O2 and ABA. The constitutive expression of GhWRKY17 in Nicotiana benthamiana remarkably reduced plant tolerance to drought and salt stress, as determined through physiological analyses of the germination rate, root growth, survival rate, leaf water loss and Chl content. GhWRKY17 transgenic plants were observed to be more sensitive to ABA-mediated seed germination and root growth. However, overexpressing GhWRKY17 in N. benthamiana impaired ABA-induced stomatal closure. Furthermore, we found that GhWRKY17 modulated the increased sensitivity of plants to drought by reducing the level of ABA, and transcript levels of ABA-inducible genes, including AREB, DREB, NCED, ERD and LEA, were clearly repressed under drought and salt stress conditions. Consistent with the accumulation of reactive oxygen species (ROS), reduced proline contents and enzyme activities, elevated electrolyte leakage and malondialdehyde, and lower expression of ROS-scavenging genes, including APX, CAT and SOD, the GhWRKY17 transgenic plants exhibited reduced tolerance to oxidative stress compared with wild-type plants. These results therefore indicate that GhWRKY17 responds to drought and salt stress through ABA signaling and the regulation of cellular ROS production in plants.

  7. Microemulsions of ABA Amphiphilic Block Copolymers and Surfactants

    NASA Astrophysics Data System (ADS)

    Braun-Shmueli, Liora; Netanel, Ortal; Regev, Oren; Gottlieb, Moshe

    2001-03-01

    The system composed of oil (decane), water and an ABA amphiphilic block copolymer is capable of exhibiting an extremely rich phase and rheological behavior. In this paper we describe the rheological properties of a synthetic amphiphilic block copolymer dissolved in a water-in-oil microemulsion with and without the stabilizing effect of small molecular weight surfactant molecules. The block copolymer is an ABA type copolymer composed of poly(oxyethylene) (PEO) as the hydrophilic A block and poly(dimethyl siloxane) (PDMS) as the hydrophobic center B block. The resulting copolymer is insoluble in water and hardly soluble in decane (good solvent for the PDMS). In the presence of water in oil microemulsion stabilized by the small molecular weight surfactant AOT a one-phase region is maintained when the copolymer is added. Yet, peculiar rheological behavior is observed. For constant water-microemulsion concentration (φ) addition of polymer increases the system viscosity as expected. Yet, the lower φ the higher the viscosity and at high φ the effect of polymer addition is quite low. Furthermore, the insoluble block copolymer in oil turns into a gel-like one phase system upon addition of small amounts of either water or water and surfactant solution. Experiments show that a maximum in elasticity or viscosity is attained at a droplet concentration equivalent to about 80 polymer chains per drop. Small angle x-ray and neutron scattering experiments were carried out to elucidate the system morphology.

  8. Sites of catabolism of murine monomeric IgA

    SciTech Connect

    Moldoveanu, Z.; Epps, J.M.; Thorpe, S.R.; Mestecky, J.

    1988-07-01

    The tissue sites of monomeric IgA (mIgA) catabolism were determined in a BALB/c mouse model. Mouse mIgA myeloma proteins were labeled either by direct iodination or by coupling the residualizing label, dilactitol-125I-tyramine (125I-DLT) to the proteins; catabolites from protein labeled with 125I-DLT accumulate at the site of protein degradation, allowing identification of the tissue and cellular sites involved in catabolism of the protein. The circulating half-lives of 125I- and 125I-DLT-mIgA were the same. The distribution of radioactivity in tissues was measured at 1, 3, 24, and 96 h after iv. injection of 125I-DLT-labeled mIgA, dimeric IgA (dIgA), IgG, or mouse serum albumin. The greatest uptake of 125I-DLT-mIgA was attributable to the liver. This organ accounted for more internal catabolism of mIgA than all other tissues combined. In contrast, 125I-DLT-IgG was catabolized equally in skin, muscle, and liver. These data indicate that, in mice, the liver is the major site of mIgA catabolism. To determine the cell types involved, collagenase digestion was used to isolate parenchymal and non-parenchymal cells from perfused liver of animals injected with 125I-DLT-mIgA. Most of the radioactivity was associated with the hepatocyte fraction, even though both cell types showed uptake of 125I-DLT-mIgA. Inhibition studies, with asialofetuin and mouse IgA demonstrated that the uptake of mIgA by liver cells was mediated primarily by the asialoglycoprotein receptor.

  9. Renal catabolism of /sup 125/I-glicentin

    SciTech Connect

    Lopez-Novoa, J.M.; Santos, J.C.; Villamediana, L.M.; Garrote, F.J.; Thim, L.; Moody, A.J.; Valverde, I.

    1986-05-01

    The renal catabolism of /sup 125/I-glicentin has been studied in vivo by the disappearance of this peptide from the plasma of bilaterally nephrectomized, ureteral-ligated, or normal rats and by using tubular microinfusion techniques. In addition the catabolism of glicentin by the isolated, perfused kidney has been studied. Results from in vivo studies demonstrated that half-disappearance time was lower in control (59.5 +/- 1.8 min) than in bilaterally nephrectomized rats (97.2 +/- 2.6 min), and this value was significantly higher than that of ureteral-ligated animals (83.2 +/- 1.1 min, P less than 0.005). Microinfusion experiments revealed that when /sup 125/I-glicentin was injected into the proximal tubule, no trichloroacetic-precipitable radioactivity was recovered in the urine, whereas most of inulin injected was recovered. By contrast most of the /sup 125/I-glicentin injected into the distal tubule was recovered in the urine. In isolated kidney experiments, organ clearance rate of /sup 125/I-glicentin averaged 0.88 +/- 0.10 ml/min, a value significantly higher than that of glomerular filtration rate (0.72 +/- 0.06 ml/min, P less than 0.005, paired data), and both parameters showed a close linear relationship (r = 0.90). Urinary clearance of glicentin was negligible. These results demonstrate that the kidney plays a major role in the catabolism of glicentin, mainly by glomerular filtration and tubular catabolism. The site of tubular catabolism appears to be the proximal tubule. Peritubular uptake was minimal.

  10. A Maize Jasmonate Zim-Domain Protein, ZmJAZ14, Associates with the JA, ABA, and GA Signaling Pathways in Transgenic Arabidopsis

    PubMed Central

    Li, Suzhen; Li, Jie; Xu, Miaoyun; Liu, Xiaoqing; Zhang, Shaojun; Zhao, Qianqian; Li, Ye; Fan, Yunliu; Chen, Rumei; Wang, Lei

    2015-01-01

    Jasmonate (JA) is an important signaling molecule involved in the regulation of many physiological and stress-related processes in plants. Jasmonate ZIM-domain (JAZ) proteins have been implicated in regulating JA signaling pathways and the cross talk between various phytohormones. Maize is not only an important cereal crop, but also a model plant for monocotyledon studies. Although many JAZ proteins have been characterized in Arabidopsis and rice, few reports have examined the function of JAZ proteins in maize. In this report, we examined the phylogenetic relationship and expression pattern of JAZ family genes in maize. In addition, a tassel and endosperm-specific JAZ gene, ZmJAZ14, was identified using microarray data analysis and real-time RT-PCR, and its expression was induced by polyethylene glycol (PEG), jasmonate (JA), abscisic acid (ABA), and gibberellins (GAs). ZmJAZ14 was shown to be localized in the nucleus and possessed no transcriptional activating activity, suggesting that it functions as a transcriptional regulator. We found that overexpression of ZmJAZ14 in Arabidopsis enhanced plant tolerance to JA and ABA treatment, as well as PEG stress, while it promoted growth under GA stimulus. Moreover, ZmJAZ14 interacted with a subset of transcription factors in Arabidopsis, and the accumulation of several marker genes involved in JA, ABA, and GA signaling pathways were altered in the overexpression lines. These results suggest that ZmJAZ14 may serve as a hub for the cross talk among the JA, ABA, and GA signaling pathways. Our results can be used to further characterize the function of JAZ family proteins in maize, and the gene cloned in this study may serve as a candidate for drought tolerance and growth promotion regulation in maize. PMID:25807368

  11. A Glycine soja ABA-responsive receptor-like cytoplasmic kinase, GsRLCK, positively controls plant tolerance to salt and drought stresses.

    PubMed

    Sun, XiaoLi; Sun, Mingzhe; Luo, Xiao; Ding, XiaoDong; Ji, Wei; Cai, Hua; Bai, Xi; Liu, XiaoFei; Zhu, YanMing

    2013-06-01

    Receptor such as protein kinases are proposed to work as sensors to initiate signaling cascades in higher plants. However, little is known about the precise functions of receptor such as protein kinases in abiotic stress response in plants, especially in wild soybean. Here, we focused on characterization of the biological functions of a receptor-like cytoplasmic serine/threonine protein kinase gene, GsRLCK, which was previously identified as a putative salt-alkali stress-related gene from the transcriptome profiles of Glycine soja. Bioinformatic analysis showed that GsRLCK protein contained a conserved kinase catalytic domain and two transmembrane domains at the N-terminus, but no typical extracellular domain. Consistently, GsRLCK-eGFP fusion protein was observed on the plasma membrane, but eGFP alone was distributing throughout the cytoplasm in onion epidermal cells. Quantitative real-time PCR analysis revealed the induced expression of GsRLCK by ABA, salt, alkali, and drought stresses. However, the expression levels of GsRLCK seemed to be similar in different tissues, except soybean pod. Phenotypic assays demonstrated that GsRLCK overexpression decreased ABA sensitivity and altered expression levels of ABA-responsive genes. Furthermore, we also found that GsRLCK conferred increased tolerance to salt and drought stresses and increased expression levels of a handful of stress-responsive genes, when overexpressing in Arabidopsis. In a word, we gave exact evidence that GsRLCK was a novel receptor-like cytoplasmic protein kinase and played a crucial role in plant responses to ABA, salt, and drought stresses.

  12. Differences in respiration between dormant and non-dormant buds suggest the involvement of ABA in the development of endodormancy in grapevines.

    PubMed

    Parada, Francisca; Noriega, Ximena; Dantas, Débora; Bressan-Smith, Ricardo; Pérez, Francisco J

    2016-08-20

    Grapevine buds (Vitis vinifera L) enter endodormancy (ED) after perceiving the short-day (SD) photoperiod signal and undergo metabolic changes that allow them to survive the winter temperatures. In the present study, we observed an inverse relationship between the depth of ED and the respiration rate of grapevine buds. Moreover, the respiration of dormant and non-dormant buds differed in response to temperature and glucose, two stimuli that normally increase respiration in plant tissues. While respiration in non-dormant buds rose sharply in response to both stimuli, respiration in dormant buds was only slightly affected. This suggests that a metabolic inhibitor is present. Here, we propose that the plant hormone abscisic acid (ABA) could be this inhibitor. ABA inhibits respiration in non-dormant buds and represses the expression of respiratory genes, such as ALTERNATIVE NADH DEHYDROGENASE (VaND1, VvaND2), CYTOCHROME OXIDASE (VvCOX6) and CYTOCHROME C (VvCYTC), and induces the expression of VvSnRK1, a gene encoding a member of a highly conserved family of protein kinases that act as energy sensors and regulate gene expression in response to energy depletion. In addition to inducing ED the SD-photoperiod up-regulated the expression of VvNCED, a gene that encodes a key enzyme in ABA synthesis. Taken together, these results suggest that ABA through the mediation of VvSnRK1, could play a key role in the regulation of the metabolic changes accompanying the entry into ED of grapevine buds. PMID:27448722

  13. PYD2 encodes 5,6-dihydropyrimidine amidohydrolase, which participates in a novel fungal catabolic pathway.

    PubMed

    Gojkovic, Z; Jahnke, K; Schnackerz, K D; Piskur, J

    2000-01-28

    Most fungi cannot use pyrimidines or their degradation products as the sole nitrogen source. Previously, we screened several yeasts for their ability to catabolise pyrimidines. One of them, Saccharomyces kluyveri, was able to degrade the majority of pyrimidines. Here, a series of molecular techniques have been modified to clone pyrimidine catabolic genes, study their expression and purify the corresponding enzymes from this yeast. The pyd2-1 mutant, which lacked the 5,6-dihydropyrimidine amidohydrolase (DHPase) activity, was transformed with wild-type S. kluyveri genomic library. The complementing plasmid contained the full sequence of the PYD2 gene, which exhibited a high level of homology with mammalian DHPases and bacterial hydantoinases. The organisation of PYD2 showed a couple of specific features. The 542-codons open reading frame was interrupted by a 63 bp intron, which does not contain the Saccharomyces cerevisiae branch-point sequence, and the transcripts contained a long 5' untranslated leader with five or six AUG codons. The derived amino acid sequence showed similarities with dihydroorotases, allantoinases and uricases from various organisms. Surprisingly, the URA4 gene from S. cerevisiae, which encodes dihydroorotase, shows greater similarity to PYD2 and other catabolic enzymes than to dihydroorotases from several other non-fungal organisms. The S. kluyveri DHPase was purified to homogeneity and sequencing of the N-terminal region revealed that the purified enzyme corresponds to the PYD2 gene product. The enzyme is a tetramer, likely consisting of similar if not identical subunits each with a molecular mass of 59 kDa. The S. kluyveri DHPase was capable of catalysing both dihydrouracil and dihydrothymine degradation, presumably by the same reaction mechanism as that described for mammalian DHPase. On the other hand, the regulation of the yeast PYD2 gene and DHPase seem to be different from that in other organisms. DHPase activity and Northern analysis

  14. Sustained low abscisic acid levels increase seedling vigor under cold stress in rice (Oryza sativa L.).

    PubMed

    Mega, Ryosuke; Meguro-Maoka, Ayano; Endo, Akira; Shimosaka, Etsuo; Murayama, Seiji; Nambara, Eiji; Seo, Mitsunori; Kanno, Yuri; Abrams, Suzanne R; Sato, Yutaka

    2015-01-01

    Stress-induced abscisic acid (ABA) is mainly catabolized by ABA 8'-hydroxylase (ABA8ox), which also strictly regulates endogenous ABA levels. Although three members of the ABA8ox gene family are conserved in rice, it is not clear which stressors induce expression of these genes. Here, we found that OsABA8ox1 was induced by cold stress within 24 h and that OsABA8ox2 and OsABA8ox3 were not. In contrast, OsABA8ox2 and OsABA8ox3 were ABA-inducible, but OsABA8ox1 was not. OsABA8ox1, OsABA8ox2, and OsABA8ox3 restored germination of a cyp707a1/a2/a3 triple mutant of Arabidopsis to rates comparable to those of the wild type, indicating that OsABA8ox1, OsABA8ox2, and OsABA8ox3 function as ABA-catabolic genes in vivo. Transgenic rice lines overexpressing OsABA8ox1 showed decreased levels of ABA and increased seedling vigor at 15 °C. These results indicate that sustained low levels of ABA lead to increased seedling vigor during cold stress. On the other hand, excessively low endogenous ABA levels caused reduced drought and cold tolerance, although some of the transgenic rice lines expressing OsABA8ox1 at moderate levels did not show these harmful effects. Adequate regulation of endogenous ABA levels is thought to be crucial for maintaining seedling vigor under cold stress and for cold and drought tolerance in rice.

  15. A stress-responsive caleosin-like protein, AtCLO4, acts as a negative regulator of ABA responses in Arabidopsis.

    PubMed

    Kim, Yun Young; Jung, Kwang Wook; Yoo, Kyoung Shin; Jeung, Ji Ung; Shin, Jeong Sheop

    2011-05-01

    Caleosins or related sequences have been found in a wide range of higher plants. In Arabidopsis, seed-specific caleosins are viewed as oil-body (OB)-associated proteins that possess Ca(2+)-dependent peroxygenase activity and are involved in processes of lipid degradation. Recent experimental evidence suggests that one of the Arabidopsis non-seed caleosins, AtCLO3, is involved in controlling stomatal aperture during the drought response; the roles of the other caleosin-like proteins in Arabidopsis remain largely uncharacterized. We have demonstrated that a novel stress-responsive and OB-associated Ca(2+)-binding caleosin-like protein, AtCLO4, is expressed in non-seed tissues of Arabidopsis, including guard cells, and down-regulated following exposure to exogenous ABA and salt stress. At the seed germination stage, a loss-of-function mutant (atclo4) was hypersensitive to ABA, salt and mannitol stresses, whereas AtCLO4-overexpressing (Ox) lines were more hyposensitive to those stresses than the wild type. In adult stage, atclo4 mutant and AtCLO4-Ox plants showed enhanced and decreased drought tolerance, respectively. Following exposure to exogenous ABA, the expression of key ABA-dependent regulatory genes, such as ABF3 and ABF4, was up-regulated in the atclo4 mutant, while it was down-regulated in AtCLO4-Ox lines. Based on these results, we propose that the OB-associated Ca(2+)-binding AtCLO4 protein acts as a negative regulator of ABA responses in Arabidopsis. PMID:21471120

  16. The ABI4-Induced Arabidopsis ANAC060 Transcription Factor Attenuates ABA Signaling and Renders Seedlings Sugar Insensitive when Present in the Nucleus

    PubMed Central

    Shi, Xiaoliang; Yu, Bo; Zhou, Yan; Chen, Suli; Wang, Yufeng; Peng, Yu; Meyer, Rhonda C.; Smeekens, Sjef C.; Teng, Sheng

    2014-01-01

    Seedling establishment is inhibited on media containing high levels (∼6%) of glucose or fructose. Genetic loci that overcome the inhibition of seedling growth on high sugar have been identified using natural variation analysis and mutant selection, providing insight into sugar signaling pathways. In this study, a quantitative trait locus (QTL) analysis was performed for seedling sensitivity to high sugar in a Col/C24 F2 population of Arabidopsis thaliana. A glucose and fructose-sensing QTL, GSQ11, was mapped through selective genotyping and confirmed in near-isogenic lines in both Col and C24 backgrounds. Allelism tests and transgenic complementation showed that GSQ11 lies within the ANAC060 gene. The Col ANAC060 allele confers sugar insensitivity and was dominant over the sugar-sensitive C24 allele. Genomic and mRNA analyses showed that a single-nucleotide polymorphism (SNP) in Col ANAC060 affects the splicing patterns of ANAC060 such that 20 additional nucleotides are present in the mRNA. The insertion created a stop codon, resulting in a truncated ANAC60 protein lacking the transmembrane domain (TMD) that is present in the C24 ANAC060 protein. The absence of the TMD results in the nuclear localization of ANAC060. The short version of the ANAC060 protein is found in ∼12% of natural Arabidopsis accessions. Glucose induces GSQ11/ANAC060 expression in a process that requires abscisic acid (ABA) signaling. Chromatin immunoprecipitation-qPCR and transient expression analysis showed that ABI4 directly binds to the GSQ11/ANAC060 promoter to activate transcription. Interestingly, Col ANAC060 reduced ABA sensitivity and Glc-induced ABA accumulation, and ABI4 expression was also reduced in Col ANAC060 lines. Thus, the sugar-ABA signaling cascade induces ANAC060 expression, but the truncated Col ANAC060 protein attenuates ABA induction and ABA signaling. This negative feedback from nuclear ANAC060 on ABA signaling results in sugar insensitivity. PMID:24625790

  17. The Steroid Catabolic Pathway of the Intracellular Pathogen Rhodococcus equi Is Important for Pathogenesis and a Target for Vaccine Development

    PubMed Central

    van der Geize, R.; Grommen, A. W. F.; Hessels, G. I.; Jacobs, A. A. C.; Dijkhuizen, L.

    2011-01-01

    Rhodococcus equi causes fatal pyogranulomatous pneumonia in foals and immunocompromised animals and humans. Despite its importance, there is currently no effective vaccine against the disease. The actinobacteria R. equi and the human pathogen Mycobacterium tuberculosis are related, and both cause pulmonary diseases. Recently, we have shown that essential steps in the cholesterol catabolic pathway are involved in the pathogenicity of M. tuberculosis. Bioinformatic analysis revealed the presence of a similar cholesterol catabolic gene cluster in R. equi. Orthologs of predicted M. tuberculosis virulence genes located within this cluster, i.e. ipdA (rv3551), ipdB (rv3552), fadA6 and fadE30, were identified in R. equi RE1 and inactivated. The ipdA and ipdB genes of R. equi RE1 appear to constitute the α-subunit and β-subunit, respectively, of a heterodimeric coenzyme A transferase. Mutant strains RE1ΔipdAB and RE1ΔfadE30, but not RE1ΔfadA6, were impaired in growth on the steroid catabolic pathway intermediates 4-androstene-3,17-dione (AD) and 3aα-H-4α(3′-propionic acid)-5α-hydroxy-7aβ-methylhexahydro-1-indanone (5α-hydroxy-methylhexahydro-1-indanone propionate; 5OH-HIP). Interestingly, RE1ΔipdAB and RE1ΔfadE30, but not RE1ΔfadA6, also displayed an attenuated phenotype in a macrophage infection assay. Gene products important for growth on 5OH-HIP, as part of the steroid catabolic pathway, thus appear to act as factors involved in the pathogenicity of R. equi. Challenge experiments showed that RE1ΔipdAB could be safely administered intratracheally to 2 to 5 week-old foals and oral immunization of foals even elicited a substantial protective immunity against a virulent R. equi strain. Our data show that genes involved in steroid catabolism are promising targets for the development of a live-attenuated vaccine against R. equi infections. PMID:21901092

  18. The effects of abscisic acid (ABA) addition on cadmium accumulation of two ecotypes of Solanum photeinocarpum.

    PubMed

    Wang, Jin; Lin, Lijin; Luo, Li; Liao, Ming'an; Lv, Xiulan; Wang, Zhihui; Liang, Dong; Xia, Hui; Wang, Xun; Lai, Yunsong; Tang, Yi

    2016-03-01

    The study of the effects of exogenous abscisic acid (ABA) addition on cadmium (Cd) accumulation of two ecotypes (mining and farmland) of Solanum photeinocarpum was operated through a pot experiment. The results showed that the biomass and chlorophyll content of the two ecotypes of S. photeinocarpum increased with increasing ABA concentration. Applying exogenous ABA increased Cd content in the two ecotypes of S. photeinocarpum. The maximum Cd contents in shoots of the two ecotypes of S. photeinocarpum were obtained at 20 μmol/L ABA; shoot Cd contents respectively for the mining and farmland ecotypes were 33.92 and 24.71% higher than those for the control. Applying exogenous ABA also increased Cd extraction by the two ecotypes of S. photeinocarpum, and the highest Cd extraction was obtained at 20 μmol/L ABA with 569.42 μg/plant in shoots of the mining ecotype and 520.51 μg/plant in shoots of the farmland ecotype respectively. Therefore, exogenous ABA can be used for enhancing the Cd extraction ability of S. photeinocarpum, and 20 μmol/L ABA was the optimal dose. PMID:26899030

  19. ABA in bryophytes: how a universal growth regulator in life became a plant hormone?

    PubMed

    Takezawa, Daisuke; Komatsu, Kenji; Sakata, Yoichi

    2011-07-01

    Abscisic acid (ABA) is not a plant-specific compound but one found in organisms across kingdoms from bacteria to animals, suggesting that it is a ubiquitous and versatile substance that can modulate physiological functions of various organisms. Recent studies have shown that plants developed an elegant system for ABA sensing and early signal transduction mechanisms to modulate responses to environmental stresses for survival in terrestrial conditions. ABA-induced increase in stress tolerance has been reported not only in vascular plants but also in non-vascular bryophytes. Since bryophytes are the key group of organisms in the context of plant evolution, clarification of their ABA-dependent processes is important for understanding evolutionary adaptation of land plants. Molecular approaches using Physcomitrella patens have revealed that ABA plays a role in dehydration stress tolerance in mosses, which comprise a major group of bryophytes. Furthermore, we recently reported that signaling machinery for ABA responses is also conserved in liverworts, representing the most basal members of extant land plant lineage. Conservation of the mechanism for ABA sensing and responses in angiosperms and basal land plants suggests that acquisition of this mechanism for stress tolerance in vegetative tissues was one of the critical evolutionary events for adaptation to the land. This review describes the role of ABA in basal land plants as well as non-land plant organisms and further elaborates on recent progress in molecular studies of model bryophytes by comparative and functional genomic approaches.

  20. From the Classroom to the Family Room: Using ABA for Best Behavior

    ERIC Educational Resources Information Center

    Smith, Dawn

    2010-01-01

    When it comes to supporting individuals with disabilities including Autism Spectrum Disorder (ASD), Applied Behavior Analysis (ABA) can be an invaluable tool in understanding and changing behavior. More than a technique or method, ABA is a disciplined approach rooted in science to teach specific skills and then reinforce them so individuals can…

  1. The effects of abscisic acid (ABA) addition on cadmium accumulation of two ecotypes of Solanum photeinocarpum.

    PubMed

    Wang, Jin; Lin, Lijin; Luo, Li; Liao, Ming'an; Lv, Xiulan; Wang, Zhihui; Liang, Dong; Xia, Hui; Wang, Xun; Lai, Yunsong; Tang, Yi

    2016-03-01