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Sample records for 3-acetic acid iaa

  1. Alternative mechanism for the evaluation of indole-3-acetic acid (IAA) production by Azospirillum brasilense strains and its effects on the germination and growth of maize seedlings.

    PubMed

    Masciarelli, Oscar; Urbani, Lucia; Reinoso, Herminda; Luna, Virginia

    2013-10-01

    We evaluated the production of indole-3-acetic acid (IAA) by Azospirillum brasilense strains in vitro (cell culture supernatants) and in vivo (stems and roots of maize seedlings) to clarify the role of this phytohormone as a signaling and effector molecule in the symbiotic interaction between maize and A. brasilense. The three strains all showed IAA production when cultured in NFb medium supplemented with 100 μg/ml L-tryptophan. The level of IAA production was 41.5 μg/ml for Yu62, 12.9 μg/ml for Az39, and 0.15 μg/ml for ipdC-. The release of IAA into culture medium by the bacteria appeared to be the main activator of the early growth promotion observed in the inoculated maize seedlings. The application of supernatants with different IAA contents caused significant differences in the seedling growth. This observation provides the basis for novel technological tools for effective quality control procedures on inoculants. The approach described can be incorporated into different inoculation methods, including line sowing, downspout, and foliar techniques, and increase the sustainability of symbiotic plant-bacteria systems.

  2. Oxidation of indole-3-acetic acid to oxindole-3-acetic acid by etiolated and green corn tissues

    SciTech Connect

    Reinecke, D. )

    1989-04-01

    Etiolated corn tissues oxidase indole-3-acetic acid (IAA) to oxindole-3-acetic acid (OxIAA). This oxidation results in loss of auxin activity and may plant a role in regulating IAA-stimulated growth. The enzyme has been partially purified and characterized and shown to require O{sub 2}, and a heat-stable lipid-soluble corn factor which can be replaced by linolenic or linoleic acids in the oxidation of IAA. Corn oil was tested as a cofactor in the IAA oxidation reaction. Corn oil stimulated enzyme activity by 30% while trilinolein was inactive. The capacity of green tissue to oxidize IAA was examined by incubating leaf sections from 2 week old light-grown corn seedlings with {sup 14}C-IAA. OxIAA and IAA were separated from other IAA metabolites on a 3 ml anion exchange column. Of the IAA taken up by the sections, 13% was oxidized to OxIAA. This is the first evidence that green tissue of corn may also regulate IAA levels by oxidizing IAA to OxIAA.

  3. Indole-3-acetic acid (IAA) induced changes in oil content, fatty acid profiles and expression of four fatty acid biosynthetic genes in Chlorella vulgaris at early stationary growth phase.

    PubMed

    Jusoh, Malinna; Loh, Saw Hong; Chuah, Tse Seng; Aziz, Ahmad; Cha, Thye San

    2015-03-01

    Microalgae lipids and oils are potential candidates for renewable biodiesel. Many microalgae species accumulate a substantial amount of lipids and oils under environmental stresses. However, low growth rate under these adverse conditions account for the decrease in overall biomass productivity which directly influence the oil yield. This study was undertaken to investigate the effect of exogenously added auxin (indole-3-acetic acid; IAA) on the oil content, fatty acid compositions, and the expression of fatty acid biosynthetic genes in Chlorella vulgaris (UMT-M1). Auxin has been shown to regulate growth and metabolite production of several microalgae. Results showed that oil accumulation was highest on days after treatment (DAT)-2 with enriched levels of palmitic (C16:0) and stearic (C18:0) acids, while the linoleic (C18:2) and α-linolenic (C18:3n3) acids levels were markedly reduced by IAA. The elevated levels of saturated fatty acids (C16:0 and C18:0) were consistent with high expression of the β-ketoacyl ACP synthase I (KAS I) gene, while low expression of omega-6 fatty acid desaturase (ω-6 FAD) gene was consistent with low production of C18:2. However, the increment of stearoyl-ACP desaturase (SAD) gene expression upon IAA induction did not coincide with oleic acid (C18:1) production. The expression of omega-3 fatty acid desaturase (ω-3 FAD) gene showed a positive correlation with the synthesis of PUFA and C18:3n3.

  4. Metabolic regulation of the plant hormone indole-3-acetic acid

    SciTech Connect

    Jerry D. Cohen

    2009-11-01

    The phytohormone indole-3-acetic acid (IAA, auxin) is important for many aspects of plant growth, development and responses to the environment yet the routes to is biosynthesis and mechanisms for regulation of IAA levels remain important research questions. A critical issue concerning the biosynthesis if IAA in plants is that redundant pathways for IAA biosynthesis exist in plants. We showed that these redundant pathways and their relative contribution to net IAA production are under both developmental and environmental control. We worked on three fundamental problems related to how plants get their IAA: 1) An in vitro biochemical approach was used to define the tryptophan dependent pathway to IAA using maize endosperm, where relatively large amounts of IAA are produced over a short developmental period. Both a stable isotope dilution and a protein MS approach were used to identify intermediates and enzymes in the reactions. 2) We developed an in vitro system for analysis of tryptophan-independent IAA biosynthesis in maize seedlings and we used a metabolite profiling approach to isolate intermediates in this reaction. 3) Arabidopsis contains a small family of genes that encode potential indolepyruvate decarboxylase enzymes. We cloned these genes and studied plants that are mutant in these genes and that over-express each member in the family in terms of the level and route of IAA biosynthesis. Together, these allowed further development of a comprehensive picture of the pathways and regulatory components that are involved in IAA homeostasis in higher plants.

  5. Indole-3-acetic acid: A widespread physiological code in interactions of fungi with other organisms

    PubMed Central

    Fu, Shih-Feng; Wei, Jyuan-Yu; Chen, Hung-Wei; Liu, Yen-Yu; Lu, Hsueh-Yu; Chou, Jui-Yu

    2015-01-01

    Plants as well as microorganisms, including bacteria and fungi, produce indole-3-acetic acid (IAA). IAA is the most common plant hormone of the auxin class and it regulates various aspects of plant growth and development. Thus, research is underway globally to exploit the potential for developing IAA-producing fungi for promoting plant growth and protection for sustainable agriculture. Phylogenetic evidence suggests that IAA biosynthesis evolved independently in bacteria, microalgae, fungi, and plants. Present studies show that IAA regulates the physiological response and gene expression in these microorganisms. The convergent evolution of IAA production leads to the hypothesis that natural selection might have favored IAA as a widespread physiological code in these microorganisms and their interactions. We summarize recent studies of IAA biosynthetic pathways and discuss the role of IAA in fungal ecology. PMID:26179718

  6. Determination of Endogenous Indole-3-Acetic Acid in Plagiochila arctica (Hepaticae) 1

    PubMed Central

    Law, David M.; Basile, Dominick V.; Basile, Margaret R.

    1985-01-01

    Endogenous indole-3-acetic acid (IAA) was found in axenically cultured gametophytes of the leafy liverwort, Plagiochila arctica Bryhn and Kaal., by high-performance liquid chromatography with electrochemical detection. Identification of the methylated auxin was confirmed by gas chromatography-mass spectrometry. Addition of 57 micromolar IAA to cultures increased relative production of ethylene. This is the first definitive (gas chromatography-mass spectrometry) demonstration of the natural occurrence of IAA in a bryophyte. PMID:16664164

  7. Biosynthesis of indole-3-acetic acid via the indole-3-acetamide pathway in Streptomyces spp.

    PubMed

    Manulis, S; Shafrir, H; Epstein, E; Lichter, A; Barash, I

    1994-05-01

    Various Streptomyces spp. including S. violaceus, S. scabies, S. griseus, S. exfoliatus, S. coelicolor and S. lividans secrete indole-3-acetic acid (IAA) when fed with L-tryptophan (Trp). Production of IAA was detected in Streptomyces strains causing potato scab as well as in non-pathogenic strains. The pathways for IAA synthesis from Trp were investigated in S. violaceus and S. exfoliatus. Indole-3-acetamide (IAM), indole-3-lactic acid (ILA), indole-3-ethanol (IEt) and IAA were identified by HPLC and GC-MS. Streptomyces cells were capable of catabolizing IAM, ILA, IEt and indole-3-acetaldehyde (IAAId) into IAA. Incorporation of radioactivity into IAM, IAA and ILA but not IEt was detected when cells were fed with L-[3-14C]tryptophan. Results indicate the presence of the IAM pathway (Trp-->IAM-->IAA) and the possible presence of additional pathways for IAA biosynthesis in Streptomyces. PMID:8025670

  8. Auxin Biosynthesis: Are the Indole-3-Acetic Acid and Phenylacetic Acid Biosynthesis Pathways Mirror Images?

    PubMed

    Cook, Sam D; Nichols, David S; Smith, Jason; Chourey, Prem S; McAdam, Erin L; Quittenden, Laura; Ross, John J

    2016-06-01

    The biosynthesis of the main auxin in plants (indole-3-acetic acid [IAA]) has been elucidated recently and is thought to involve the sequential conversion of Trp to indole-3-pyruvic acid to IAA However, the pathway leading to a less well studied auxin, phenylacetic acid (PAA), remains unclear. Here, we present evidence from metabolism experiments that PAA is synthesized from the amino acid Phe, via phenylpyruvate. In pea (Pisum sativum), the reverse reaction, phenylpyruvate to Phe, is also demonstrated. However, despite similarities between the pathways leading to IAA and PAA, evidence from mutants in pea and maize (Zea mays) indicate that IAA biosynthetic enzymes are not the main enzymes for PAA biosynthesis. Instead, we identified a putative aromatic aminotransferase (PsArAT) from pea that may function in the PAA synthesis pathway. PMID:27208245

  9. UGT74D1 Catalyzes the Glucosylation of 2-Oxindole-3-Acetic Acid in the Auxin Metabolic Pathway in Arabidopsis

    PubMed Central

    Tanaka, Keita; Hayashi, Ken-ichiro; Natsume, Masahiro; Kamiya, Yuji; Sakakibara, Hitoshi; Kawaide, Hiroshi; Kasahara, Hiroyuki

    2014-01-01

    IAA is a naturally occurring auxin that plays a crucial role in the regulation of plant growth and development. The endogenous concentration of IAA is spatiotemporally regulated by biosynthesis, transport and its inactivation in plants. Previous studies have shown that the metabolism of IAA to 2-oxindole-3-acetic acid (OxIAA) and OxIAA-glucoside (OxIAA-Glc) may play an important role in IAA homeostasis, but the genes involved in this metabolic pathway are still unknown. In this study, we show that UGT74D1 catalyzes the glucosylation of OxIAA in Arabidopsis. By screening yeasts transformed with Arabidopsis UDP-glycosyltransferase (UGT) genes, we found that OxIAA-Glc accumulates in the culture media of yeasts expressing UGT74D1 in the presence of OxIAA. Further, we showed that UGT74D1 expressed in Escherichia coli converts OxIAA to OxIAA-Glc. The endogenous concentration of OxIAA-Glc decreased by 85% while that of OxIAA increased 2.5-fold in ugt74d1-deficient mutants, indicating the major role of UGT74D1 in OxIAA metabolism. Moreover, the induction of UGT74D1 markedly increased the level of OxIAA-Glc and loss of root gravitropism. These results indicate that UGT74D1 catalyzes a committed step in the OxIAA-dependent IAA metabolic pathway in Arabidopsis. PMID:24285754

  10. Nutrient salts promote light-induced degradation of indole-3-acetic Acid in tissue culture media.

    PubMed

    Dunlap, J R; Robacker, K M

    1988-10-01

    The disappearance of indole-3-acetic acid (IAA) from cell-free liquid culture medium was followed in response to nutrient salts found in Murashige-Skoog salt base, light, and pH range of 4 to 7. The loss of IAA was accelerated by light or Murashige-Skoog salts. However, the combination of both light and Murashige-Skoog salts acted synergistically to catalyze the destruction of over 80% of the original IAA within 7 days of continuous incubation. Under these same conditions, the loss of IAA was decreased to approximately 50% by adjusting the initial pH of the medium to 7. Iron was identified as the single major contributor to light-catalyzed destruction of IAA. Removal of nitrates, which represented 87% of the molar salt composition, also reduced the light-catalyzed loss of IAA. Treatments that protected IAA from degradation, such as darkness or removal of iron from the medium, suppressed the growth of muskmelon (Cucumis melo. Naud., var. reticulatus) callus tissue cultured for 30 days. Treatments in the light that rapidly degraded IAA resulted in maximum growth. Consequently, the brief exposure to IAA prior to degradation was apparently sufficient to initiate physiological changes required for growth. Possible approaches to the preservation of IAA during incubation are discussed. PMID:16666312

  11. Indole-3-acetic acid in Fusarium graminearum: Identification of biosynthetic pathways and characterization of physiological effects.

    PubMed

    Luo, Kun; Rocheleau, Hélène; Qi, Peng-Fei; Zheng, You-Liang; Zhao, Hui-Yan; Ouellet, Thérèse

    2016-09-01

    Fusarium graminearum is a devastating pathogenic fungus causing fusarium head blight (FHB) of wheat. This fungus can produce indole-3-acetic acid (IAA) and a very large amount of IAA accumulates in wheat head tissues during the first few days of infection by F. graminearum. Using liquid culture conditions, we have determined that F. graminearum can use tryptamine (TAM) and indole-3-acetonitrile (IAN) as biosynthetic intermediates to produce IAA. It is the first time that F. graminearum is shown to use the l-tryptophan-dependent TAM and IAN pathways rather than the indole-3-acetamide or indole-3-pyruvic acid pathways to produce IAA. Our experiments also showed that exogenous IAA was metabolized by F. graminearum. Exogenous IAA, TAM, and IAN inhibited mycelial growth; IAA and IAN also affected the hyphae branching pattern and delayed macroconidium germination. IAA and TAM had a small positive effect on the production of the mycotoxin 15-ADON while IAN inhibited its production. Our results showed that IAA and biosynthetic intermediates had a significant effect on F. graminearum physiology and suggested a new area of exploration for fungicidal compounds. PMID:27567719

  12. Transport of the two natural auxins, indole-3-butyric acid and indole-3-acetic acid, in Arabidopsis

    NASA Technical Reports Server (NTRS)

    Rashotte, Aaron M.; Poupart, Julie; Waddell, Candace S.; Muday, Gloria K.; Brown, C. S. (Principal Investigator)

    2003-01-01

    Polar transport of the natural auxin indole-3-acetic acid (IAA) is important in a number of plant developmental processes. However, few studies have investigated the polar transport of other endogenous auxins, such as indole-3-butyric acid (IBA), in Arabidopsis. This study details the similarities and differences between IBA and IAA transport in several tissues of Arabidopsis. In the inflorescence axis, no significant IBA movement was detected, whereas IAA is transported in a basipetal direction from the meristem tip. In young seedlings, both IBA and IAA were transported only in a basipetal direction in the hypocotyl. In roots, both auxins moved in two distinct polarities and in specific tissues. The kinetics of IBA and IAA transport appear similar, with transport rates of 8 to 10 mm per hour. In addition, IBA transport, like IAA transport, is saturable at high concentrations of auxin, suggesting that IBA transport is protein mediated. Interestingly, IAA efflux inhibitors and mutations in genes encoding putative IAA transport proteins reduce IAA transport but do not alter IBA movement, suggesting that different auxin transport protein complexes are likely to mediate IBA and IAA transport. Finally, the physiological effects of IBA and IAA on hypocotyl elongation under several light conditions were examined and analyzed in the context of the differences in IBA and IAA transport. Together, these results present a detailed picture of IBA transport and provide the basis for a better understanding of the transport of these two endogenous auxins.

  13. Translocation of radiolabeled indole-3-acetic acid and indole-3-acetyl-myo-inositol from kernel to shoot of Zea mays L

    NASA Technical Reports Server (NTRS)

    Chisnell, J. R.; Bandurski, R. S.

    1988-01-01

    Either 5-[3H]indole-3-acetic acid (IAA) or 5-[3H]indole-3-acetyl-myo-inositol was applied to the endosperm of kernels of dark-grown Zea mays seedlings. The distribution of total radioactivity, radiolabeled indole-3-acetic acid, and radiolabeled ester conjugated indole-3-acetic acid, in the shoots was then determined. Differences were found in the distribution and chemical form of the radiolabeled indole-3-acetic acid in the shoot depending upon whether 5-[3H]indole-3-acetic acid or 5-[3H]indole-3-acetyl-myo-inositol was applied to the endosperm. We demonstrated that indole-3-acetyl-myo-inositol applied to the endosperm provides both free and ester conjugated indole-3-acetic acid to the mesocotyl and coleoptile. Free indole-3-acetic acid applied to the endosperm supplies some of the indole-3-acetic acid in the mesocotyl but essentially no indole-3-acetic acid to the coleoptile or primary leaves. It is concluded that free IAA from the endosperm is not a source of IAA for the coleoptile. Neither radioactive indole-3-acetyl-myo-inositol nor IAA accumulates in the tip of the coleoptile or the mesocotyl node and thus these studies do not explain how the coleoptile tip controls the amount of IAA in the shoot.

  14. Aberrant synthesis of indole-3-acetic acid in Saccharomyces cerevisiae triggers morphogenic transition, a virulence trait of pathogenic fungi.

    PubMed

    Rao, Reeta Prusty; Hunter, Ally; Kashpur, Olga; Normanly, Jennifer

    2010-05-01

    Many plant-associated microbes synthesize the auxin indole-3-acetic acid (IAA), and several IAA biosynthetic pathways have been identified in microbes and plants. Saccharomyces cerevisiae has previously been shown to respond to IAA by inducing pseudohyphal growth. We observed that IAA also induced hyphal growth in the human pathogen Candida albicans and thus may function as a secondary metabolite signal that regulates virulence traits such as hyphal transition in pathogenic fungi. Aldehyde dehydrogenase (Ald) is required for IAA synthesis from a tryptophan (Trp) precursor in Ustilago maydis. Mutant S. cerevisiae with deletions in two ALD genes are unable to convert radiolabeled Trp to IAA, yet produce IAA in the absence of exogenous Trp and at levels higher than wild type. These data suggest that yeast may have multiple pathways for IAA synthesis, one of which is not dependent on Trp. PMID:20233857

  15. The tryptophan conjugates of jasmonic and indole-3-acetic acids are endogenous auxin inhibitors.

    PubMed

    Staswick, Paul E

    2009-07-01

    Most conjugates of plant hormones are inactive, and some function to reduce the active hormone pool. This study characterized the activity of the tryptophan (Trp) conjugate of jasmonic acid (JA-Trp) in Arabidopsis (Arabidopsis thaliana). Unexpectedly, JA-Trp caused agravitropic root growth in seedlings, unlike JA or nine other JA-amino acid conjugates. The response was dose dependent from 1 to 100 microm, was independent of the COI1 jasmonate signaling locus, and unlike the jasmonate signal JA-isoleucine, JA-Trp minimally inhibited root growth. The Trp conjugate with indole-3-acetic acid (IAA-Trp) produced a similar response, while Trp alone and conjugates with benzoic and cinnamic acids did not. JA-Trp and IAA-Trp at 25 microm nearly eliminated seedling root inhibition caused by 2 microm IAA. The TIR1 auxin receptor is required for activity because roots of tir1-1 grew only approximately 60% of wild-type length on IAA plus JA-Trp, even though tir1-1 is auxin resistant. However, neither JA-Trp nor IAA-Trp interfered with IAA-dependent interaction between TIR1 and Aux/IAA7 in cell-free assays. Trp conjugates inhibited IAA-stimulated lateral root production and DR5-beta-glucuronidase gene expression. JA-deficient mutants were hypersensitive to IAA and a Trp-overaccumulating mutant was less sensitive, suggesting endogenous conjugates affect auxin sensitivity. Conjugates were present at 5.8 pmol g(-1) fresh weight or less in roots, seedlings, leaves, and flowers, and the values increased approximately 10-fold in roots incubated in 25 microm Trp and IAA or JA at 2 microm. These results show that JA-Trp and IAA-Trp constitute a previously unrecognized mechanism to regulate auxin action.

  16. Oxidation of indole-3-acetic acid to oxindole-3-acetic acid by an enzyme preparation from Zea mays

    NASA Technical Reports Server (NTRS)

    Reinecke, D. M.; Bandurski, R. S.

    1988-01-01

    Indole-3-acetic acid is oxidized to oxindole-3-acetic acid by Zea mays tissue extracts. Shoot, root, and endosperm tissues have enzyme activities of 1 to 10 picomoles per hour per milligram protein. The enzyme is heat labile, is soluble, and requires oxygen for activity. Cofactors of mixed function oxygenase, peroxidase, and intermolecular dioxygenase are not stimulatory to enzymic activity. A heat-stable, detergent-extractable component from corn enhances enzyme activity 6- to 10-fold. This is the first demonstration of the in vitro enzymic oxidation of indole-3-acetic acid to oxindole-3-acetic acid in higher plants.

  17. Production of the Phytohormone Indole-3-Acetic Acid by Estuarine Species of the Genus Vibrio▿

    PubMed Central

    Gutierrez, Casandra K.; Matsui, George Y.; Lincoln, David E.; Lovell, Charles R.

    2009-01-01

    Strains of Vibrio spp. isolated from roots of the estuarine grasses Spartina alterniflora and Juncus roemerianus produce the phytohormone indole-3-acetic acid (IAA). The colorimetric Salkowski assay was used for initial screening of IAA production. Gas chromatography-mass spectroscopy (GC-MS) was then employed to confirm and quantify IAA production. The accuracy of IAA quantification by the Salkowski assay was examined by comparison to GC-MS assay values. Indole-3-acetamide, an intermediate in IAA biosynthesis by the indole-3-acetamide pathway, was also identified by GC-MS. Multilocus sequence typing of concatenated 16S rRNA, recA, and rpoA genes was used for phylogenetic analysis of environmental isolates within the genus Vibrio. Eight Vibrio type strains and five additional species-level clades containing a total of 16 environmental isolates and representing five presumptive new species were identified as IAA-producing Vibrio species. Six additional environmental isolates similar to four of the Vibrio type strains were also IAA producers. To our knowledge, this is the first report of IAA production by species of the genus Vibrio or by bacteria isolated from an estuarine environment. PMID:19218411

  18. Indole-3-acetic Acid Levels of Plant Tissue as Determined by a New High Performance Liquid Chromatographic Method 1

    PubMed Central

    Sweetser, Philip B.; Swartzfager, Dennis G.

    1978-01-01

    A method for the analysis of indole-3-acetic acid (IAA) in plant extracts has been developed based on high performance liquid chromatography separation of IAA on a microparticulate strong anion exchange column followed by quantitation with two selective detectors: an electrochemical, carbon paste amperometric detector and/or a fluorescence detector. The detection limit for IAA is less than 1 nanogram with the fluorescence detector and less than 50 picograms with the electrochemical detector. The IAA levels are reported for various tissues of wheat, pinto beans, soybeans, cotton, and corn. PMID:16660271

  19. Measurement of the rates of oxindole-3-acetic acid turnover, and indole-3-acetic acid oxidation in Zea mays seedlings

    NASA Technical Reports Server (NTRS)

    Nonhebel, H. M.; Bandurski, R. S. (Principal Investigator)

    1986-01-01

    Oxindole-3-acetic acid is the principal catabolite of indole-3-acetic acid in Zea mays seedlings. In this paper measurements of the turnover of oxindole-3-acetic acid are presented and used to calculate the rate of indole-3-acetic acid oxidation. [3H]Oxindole-3-acetic acid was applied to the endosperm of Zea mays seedlings and allowed to equilibrate for 24 h before the start of the experiment. The subsequent decrease in its specific activity was used to calculate the turnover rate. The average half-life of oxindole-3-acetic acid in the shoots was found to be 30 h while that in the kernels had an average half-life of 35h. Using previously published values of the pool sizes of oxindole-3-acetic acid in shoots and kernels from seedlings of the same age and variety, and grown under the same conditions, the rate of indole-3-acetic acid oxidation was calculated to be 1.1 pmol plant-1 h-1 in the shoots and 7.1 pmol plant-1 h-1 in the kernels.

  20. Production of indole-3-acetic acid by the cyanobacterium Arthrospira platensis strain MMG-9.

    PubMed

    Ahmed, Mehboob; Stal, Lucas; Hasnain, Shahida

    2010-09-01

    The filamentous cyanobacterium Arthrospira platensis strain MMG-9 was isolated from a rice field. The ability of this strain to synthesize the bioactive compound indole-3-acetic acid (IAA) was demonstrated. IAA was extracted from the culture A. platensis strain MMG-9 and its identity was confirmed by thin layer chromatography (TLC) as well as by high performance liquid chromatography (HPLC). The IAA precursor L-tryptophan was required for IAA biosynthesis. Released IAA increased with the increase of the initial concentration of L-tryptophan in the medium and with the incubation time. A. platensis strain MMG-9 accumulates more IAA than it released it into the medium. The bioactivity of the secreted IAA was shown by its effect on the formation of roots by Pisum sativum. There was a significant positive effect of the supernatant of cultures of A. platensis strain MMG-9 on the number of lateral roots of P. sativum while a negative effect on root length was observed. PMID:20890089

  1. A mutation affecting the synthesis of 4-chloroindole-3-acetic acid.

    PubMed

    Ross, John J; Tivendale, Nathan D; Davidson, Sandra E; Reid, James B; Davies, Noel W; Quittenden, Laura J; Smith, Jason A

    2012-12-01

    Traditionally, schemes depicting auxin biosynthesis in plants have been notoriously complex. They have involved up to four possible pathways by which the amino acid tryptophan might be converted to the main active auxin, indole-3-acetic acid (IAA), while another pathway was suggested to bypass tryptophan altogether. It was also postulated that different plants use different pathways, further adding to the complexity. In 2011, however, it was suggested that one of the four tryptophan-dependent pathways, via indole-3-pyruvic acid (IPyA), is the main pathway in Arabidopsis thaliana, although concurrent operation of one or more other pathways has not been excluded. We recently showed that, for seeds of Pisum sativum (pea), it is possible to go one step further. Our new evidence indicates that the IPyA pathway is the only tryptophan-dependent IAA synthesis pathway operating in pea seeds. We also demonstrated that the main auxin in developing pea seeds, 4-chloroindole-3-acetic acid (4-Cl-IAA), which accumulates to levels far exceeding those of IAA, is synthesized via a chlorinated version of the IPyA pathway. PMID:23073010

  2. Auxin Biosynthesis: Are the Indole-3-Acetic Acid and Phenylacetic Acid Biosynthesis Pathways Mirror Images?1[OPEN

    PubMed Central

    Nichols, David S.; Smith, Jason; Chourey, Prem S.; McAdam, Erin L.; Quittenden, Laura

    2016-01-01

    The biosynthesis of the main auxin in plants (indole-3-acetic acid [IAA]) has been elucidated recently and is thought to involve the sequential conversion of Trp to indole-3-pyruvic acid to IAA. However, the pathway leading to a less well studied auxin, phenylacetic acid (PAA), remains unclear. Here, we present evidence from metabolism experiments that PAA is synthesized from the amino acid Phe, via phenylpyruvate. In pea (Pisum sativum), the reverse reaction, phenylpyruvate to Phe, is also demonstrated. However, despite similarities between the pathways leading to IAA and PAA, evidence from mutants in pea and maize (Zea mays) indicate that IAA biosynthetic enzymes are not the main enzymes for PAA biosynthesis. Instead, we identified a putative aromatic aminotransferase (PsArAT) from pea that may function in the PAA synthesis pathway. PMID:27208245

  3. Cloning and biochemical characterization of indole-3-acetic acid-amino acid synthetase PsGH3 from pea.

    PubMed

    Ostrowski, Maciej; Mierek-Adamska, Agnieszka; Porowińska, Dorota; Goc, Anna; Jakubowska, Anna

    2016-10-01

    Phytohormone conjugation is one of the mechanisms that maintains a proper hormonal homeostasis and that is necessary for the realization of physiological responses. Gretchen Hagen 3 (GH3) acyl acid amido synthetases convert indole-3-acetic acid (IAA) to IAA-amino acid conjugates by ATP-dependent reactions. IAA-aspartate (IAA-Asp) exists as a predominant amide conjugate of auxin in pea tissues and acts as an intermediate during IAA catabolism. Here we report a novel recombinant indole-3-acetic acid-amido synthetase in Pisum sativum. In silico analysis shows that amino acid sequence of PsGH3 has the highest homology to Medicago truncatula GH3.3. The recombinant His-tag-PsGH3 fusion protein has been obtained in E. coli cells and is a soluble monomeric polypeptide with molecular mass of 69.18 kDa. The PsGH3 was purified using Ni(2+)-affinity chromatography and native PAGE. Kinetic analysis indicates that the enzyme strongly prefers IAA and L-aspartate as substrates for conjugation revealing Km(ATP) = 0.49 mM, Km(L-Asp) = 2.2 mM, and Km(IAA) = 0.28 mM. Diadenosine pentaphosphate (Ap5A) competes with ATP for catalytic site and diminishes the PsGH3 affinity toward ATP approximately 1.11-fold indicating Ki = 8.5 μM. L-Tryptophan acts as an inhibitor of IAA-amido synthesizing activity by competition with L-aspartate. Inorganic pyrophosphatase (PPase) hydrolyzing pyrophosphate to two phosphate ions, potentiates IAA-Asp synthetase activity of PsGH3. Our results demonstrate that PsGH3 is a novel enzyme that is involved in auxin metabolism in pea seeds.

  4. Biosynthesis of the halogenated auxin, 4-chloroindole-3-acetic acid.

    PubMed

    Tivendale, Nathan D; Davidson, Sandra E; Davies, Noel W; Smith, Jason A; Dalmais, Marion; Bendahmane, Abdelhafid I; Quittenden, Laura J; Sutton, Lily; Bala, Raj K; Le Signor, Christine; Thompson, Richard; Horne, James; Reid, James B; Ross, John J

    2012-07-01

    Seeds of several agriculturally important legumes are rich sources of the only halogenated plant hormone, 4-chloroindole-3-acetic acid. However, the biosynthesis of this auxin is poorly understood. Here, we show that in pea (Pisum sativum) seeds, 4-chloroindole-3-acetic acid is synthesized via the novel intermediate 4-chloroindole-3-pyruvic acid, which is produced from 4-chlorotryptophan by two aminotransferases, TRYPTOPHAN AMINOTRANSFERASE RELATED1 and TRYPTOPHAN AMINOTRANSFERASE RELATED2. We characterize a tar2 mutant, obtained by Targeting Induced Local Lesions in Genomes, the seeds of which contain dramatically reduced 4-chloroindole-3-acetic acid levels as they mature. We also show that the widespread auxin, indole-3-acetic acid, is synthesized by a parallel pathway in pea. PMID:22573801

  5. Oxidation of indole-3-acetic acid and oxindole-3-acetic acid to 2,3-dihydro-7-hydroxy-2-oxo-1H indole-3-acetic acid-7'-O-beta-D-glucopyranoside in Zea mays seedlings

    NASA Technical Reports Server (NTRS)

    Nonhebel, H. M.; Bandurski, R. S.

    1984-01-01

    Radiolabeled oxindole-3-acetic acid was metabolized by roots, shoots, and caryopses of dark grown Zea mays seedlings to 2,3-dihydro-7-hydroxy-2-oxo-1H indole-3-acetic acid-7'-O-beta-D-glycopyranoside with the simpler name of 7-hydroxyoxindole-3-acetic acid-glucoside. This compound was also formed from labeled indole-3-acetic acid supplied to intact seedlings and root segments. The glucoside of 7-hydroxyoxindole-3-acetic acid was also isolated as an endogenous compound in the caryopses and shoots of 4-day-old seedlings. It accumulates to a level of 4.8 nanomoles per plant in the kernel, more than 10 times the amount of oxindole-3-acetic acid. In the shoot it is present at levels comparable to that of oxindole-3-acetic acid and indole-3-acetic acid (62 picomoles per shoot). We conclude that 7-hydroxyoxindole-3-acetic acid-glucoside is a natural metabolite of indole-3-acetic acid in Z. mays seedlings. From the data presented in this paper and in previous work, we propose the following route as the principal catabolic pathway for indole-3-acetic acid in Zea seedlings: Indole-3-acetic acid --> Oxindole-3-acetic acid --> 7-Hydroxyoxindole-3-acetic acid --> 7-Hydroxyoxindole-3-acetic acid-glucoside.

  6. Myo-Inositol Esters of Indole-3-acetic Acid as Seed Auxin Precursors of Zea mays L. 1

    PubMed Central

    Nowacki, Janusz; Bandurski, Robert S.

    1980-01-01

    Indole-3-acetyl-myo-inositol esters constitute 30% of the low molecular weight derivatives of indole-3-acetic acid (IAA) in seeds of Zea mays. [14C]Indole-3-acetyl-myo-inositol was applied to a cut in the endosperm of the seed and found to be transported from endosperm to shoot at 400 times the rate of transport of free IAA. The rate of transport of indole-3-acetyl-myo-inositol from endosperm to shoot was 6.3 picomoles per shoot per hour and thus adequate to serve as the seed auxin precursor for the free IAA diffusing downward from the shoot tip. Indole-3-acetyl-myo-inositol is the first seed auxin precursor to be identified. Application of either [14C]IAA or 14C-indole-3-acetyl-myo-inositol ester to the endosperm results in both free and esterified [14C]IAA in the seedling shoot. Esterification of free IAA and hydrolysis of indole-3-acetyl-myo-inositol occurred in the shoot and not the endosperm yielding ratios of ester to free IAA which approximate the ratios of ester to free IAA normally found in corn shoot tissue. This proves, for the first time, that esterified IAA and free IAA are interconvertible in the growing shoot. Since free IAA may be limiting for plant growth, knowledge that the free hormone is in “equilibrium” with its conjugates suggests new methods for the control of plant growth. PMID:16661205

  7. Rate Motifs Tune Auxin/Indole-3-Acetic Acid Degradation Dynamics1[OPEN

    PubMed Central

    Moss, Britney L.; Mao, Haibin; Guseman, Jessica M.; Hinds, Thomas R.; Hellmuth, Antje; Kovenock, Marlies; Noorassa, Anisa; Lanctot, Amy; Villalobos, Luz Irina A. Calderón; Zheng, Ning; Nemhauser, Jennifer L.

    2015-01-01

    Ubiquitin-mediated protein degradation is a common feature in diverse plant cell signaling pathways; however, the factors that control the dynamics of regulated protein turnover are largely unknown. One of the best-characterized families of E3 ubiquitin ligases facilitates ubiquitination of auxin (aux)/indole-3-acetic acid (IAA) repressor proteins in the presence of auxin. Rates of auxin-induced degradation vary widely within the Aux/IAA family, and sequences outside of the characterized degron (the minimum region required for auxin-induced degradation) can accelerate or decelerate degradation. We have used synthetic auxin degradation assays in yeast (Saccharomyces cerevisiae) and in plants to characterize motifs flanking the degron that contribute to tuning the dynamics of Aux/IAA degradation. The presence of these rate motifs is conserved in phylogenetically distant members of the Arabidopsis (Arabidopsis thaliana) Aux/IAA family, as well as in their putative Brassica rapa orthologs. We found that rate motifs can act by enhancing interaction between repressors and the E3, but that this is not the only mechanism of action. Phenotypes of transgenic plants expressing a deletion in a rate motif in IAA28 resembled plants expressing degron mutations, underscoring the functional relevance of Aux/IAA degradation dynamics in regulating auxin responses. PMID:26149575

  8. Rate Motifs Tune Auxin/Indole-3-Acetic Acid Degradation Dynamics.

    PubMed

    Moss, Britney L; Mao, Haibin; Guseman, Jessica M; Hinds, Thomas R; Hellmuth, Antje; Kovenock, Marlies; Noorassa, Anisa; Lanctot, Amy; Villalobos, Luz Irina A Calderón; Zheng, Ning; Nemhauser, Jennifer L

    2015-09-01

    Ubiquitin-mediated protein degradation is a common feature in diverse plant cell signaling pathways; however, the factors that control the dynamics of regulated protein turnover are largely unknown. One of the best-characterized families of E3 ubiquitin ligases facilitates ubiquitination of auxin (aux)/indole-3-acetic acid (IAA) repressor proteins in the presence of auxin. Rates of auxin-induced degradation vary widely within the Aux/IAA family, and sequences outside of the characterized degron (the minimum region required for auxin-induced degradation) can accelerate or decelerate degradation. We have used synthetic auxin degradation assays in yeast (Saccharomyces cerevisiae) and in plants to characterize motifs flanking the degron that contribute to tuning the dynamics of Aux/IAA degradation. The presence of these rate motifs is conserved in phylogenetically distant members of the Arabidopsis (Arabidopsis thaliana) Aux/IAA family, as well as in their putative Brassica rapa orthologs. We found that rate motifs can act by enhancing interaction between repressors and the E3, but that this is not the only mechanism of action. Phenotypes of transgenic plants expressing a deletion in a rate motif in IAA28 resembled plants expressing degron mutations, underscoring the functional relevance of Aux/IAA degradation dynamics in regulating auxin responses.

  9. Rate Motifs Tune Auxin/Indole-3-Acetic Acid Degradation Dynamics.

    PubMed

    Moss, Britney L; Mao, Haibin; Guseman, Jessica M; Hinds, Thomas R; Hellmuth, Antje; Kovenock, Marlies; Noorassa, Anisa; Lanctot, Amy; Villalobos, Luz Irina A Calderón; Zheng, Ning; Nemhauser, Jennifer L

    2015-09-01

    Ubiquitin-mediated protein degradation is a common feature in diverse plant cell signaling pathways; however, the factors that control the dynamics of regulated protein turnover are largely unknown. One of the best-characterized families of E3 ubiquitin ligases facilitates ubiquitination of auxin (aux)/indole-3-acetic acid (IAA) repressor proteins in the presence of auxin. Rates of auxin-induced degradation vary widely within the Aux/IAA family, and sequences outside of the characterized degron (the minimum region required for auxin-induced degradation) can accelerate or decelerate degradation. We have used synthetic auxin degradation assays in yeast (Saccharomyces cerevisiae) and in plants to characterize motifs flanking the degron that contribute to tuning the dynamics of Aux/IAA degradation. The presence of these rate motifs is conserved in phylogenetically distant members of the Arabidopsis (Arabidopsis thaliana) Aux/IAA family, as well as in their putative Brassica rapa orthologs. We found that rate motifs can act by enhancing interaction between repressors and the E3, but that this is not the only mechanism of action. Phenotypes of transgenic plants expressing a deletion in a rate motif in IAA28 resembled plants expressing degron mutations, underscoring the functional relevance of Aux/IAA degradation dynamics in regulating auxin responses. PMID:26149575

  10. Membrane-directed effects of the plant hormones abscisic acid, indole-3-acetic acid and 2,4-dichlorophenoxyacetic acid.

    PubMed

    Schauf, C L; Bringle, B; Stillwell, W

    1987-03-30

    This study examines two ways plant hormones might influence membrane processes, effects on overall permeability and modifications of specific ion channels. Abscisic acid (ABA) and indole-3-acetic acid (IAA) greatly enhanced erythritol permeability in mixed egg lecithin bilayers. In single component dioleoylphosphatidylcholine bilayers ABA was less effective than IAA, while 2,4-dichlorophenoxyacetate (2,4-D) did not affect either system or alter their ABA response. In Myxicola axons ABA and IAA had no effect, while 2,4-D (10 uM) caused a depolarizing shift of voltage-dependent Na+ and K+ activation by 25 +/- 4 mV and 15 +/- 3 mV, consistent with internal negative surface charge changes of -0.002 e-/A2 and -0.0007 e-/A2. We conclude that both generalized and ion channel-directed effects may link plant hormones and intracellular regulation.

  11. Identification of enzyme activity that conjugates indole-3-acetic acid to aspartate in immature seeds of pea (Pisum sativum).

    PubMed

    Ostrowski, Maciej; Jakubowska, Anna

    2008-01-01

    This study describes the first identification of plant enzyme activity catalyzing the conjugation of indole-3-acetic acid to amino acids. Enzymatic synthesis of indole-3-acetylaspartate (IAA-Asp) by a crude enzyme preparation from immature seeds of pea (Pisum sativum) was observed. The reaction yielded a product with the same Rf as IAA-Asp standard after thin layer chromatography. The identity of IAA-Asp was verified by HPLC analysis. IAA-Asp formation was dependent on ATP and Mg2+, and was linear during a 60 min period. The enzyme preparation obtained after poly(ethylene glycol) 6000 fractionation showed optimum activity at pH 8.0, and the temperature optimum for IAA-Asp synthesis was 30 degrees C. PMID:17920159

  12. Dynamics and control of phloem loading of indole-3-acetic acid in seedling cotyledons of Ricinus communis.

    PubMed

    Tamas, Imre A; Davies, Peter J

    2016-08-01

    During seed germination, sugars and auxin are produced from stored precursors or conjugates respectively, and transported to the seedling axis. To elucidate the mode of travel of indole-3-acetic acid (IAA) into the phloem, a solution of [(3)H]IAA, together with [(14)C]sucrose, was injected into the endosperm cavity harboring the cotyledons of germinating seedlings of Ricinus communis Phloem exudate from the cut hypocotyl was collected and the radioactivity recorded. Sucrose loading into the phloem was inhibited at higher IAA levels, and the rate of filling of the transient pool(s) was reduced by IAA. IAA was detected within 10min, with the concentration increasing over 30min and reaching a steady-state by 60min. The kinetics indicated that phloem loading of IAA involving both an active, carrier-based, and a passive, diffusion-based component, with IAA traveling along a pathway containing an intermediary pool, possibly the protoplasts of mesophyll cells. Phloem loading of IAA was altered by sucrose, K(+), and a range of non-specific and IAA-specific analogs and inhibitors in a manner that showed that IAA moves into the phloem from the extra cotyledonary solution by multiple pathways, with a carrier-mediated pathway playing a principal role.

  13. Dynamics and control of phloem loading of indole-3-acetic acid in seedling cotyledons of Ricinus communis.

    PubMed

    Tamas, Imre A; Davies, Peter J

    2016-08-01

    During seed germination, sugars and auxin are produced from stored precursors or conjugates respectively, and transported to the seedling axis. To elucidate the mode of travel of indole-3-acetic acid (IAA) into the phloem, a solution of [(3)H]IAA, together with [(14)C]sucrose, was injected into the endosperm cavity harboring the cotyledons of germinating seedlings of Ricinus communis Phloem exudate from the cut hypocotyl was collected and the radioactivity recorded. Sucrose loading into the phloem was inhibited at higher IAA levels, and the rate of filling of the transient pool(s) was reduced by IAA. IAA was detected within 10min, with the concentration increasing over 30min and reaching a steady-state by 60min. The kinetics indicated that phloem loading of IAA involving both an active, carrier-based, and a passive, diffusion-based component, with IAA traveling along a pathway containing an intermediary pool, possibly the protoplasts of mesophyll cells. Phloem loading of IAA was altered by sucrose, K(+), and a range of non-specific and IAA-specific analogs and inhibitors in a manner that showed that IAA moves into the phloem from the extra cotyledonary solution by multiple pathways, with a carrier-mediated pathway playing a principal role. PMID:27371947

  14. Dynamics and control of phloem loading of indole-3-acetic acid in seedling cotyledons of Ricinus communis

    PubMed Central

    Tamas, Imre A.; Davies, Peter J.

    2016-01-01

    During seed germination, sugars and auxin are produced from stored precursors or conjugates respectively, and transported to the seedling axis. To elucidate the mode of travel of indole-3-acetic acid (IAA) into the phloem, a solution of [3H]IAA, together with [14C]sucrose, was injected into the endosperm cavity harboring the cotyledons of germinating seedlings of Ricinus communis. Phloem exudate from the cut hypocotyl was collected and the radioactivity recorded. Sucrose loading into the phloem was inhibited at higher IAA levels, and the rate of filling of the transient pool(s) was reduced by IAA. IAA was detected within 10min, with the concentration increasing over 30min and reaching a steady-state by 60min. The kinetics indicated that phloem loading of IAA involving both an active, carrier-based, and a passive, diffusion-based component, with IAA traveling along a pathway containing an intermediary pool, possibly the protoplasts of mesophyll cells. Phloem loading of IAA was altered by sucrose, K+, and a range of non-specific and IAA-specific analogs and inhibitors in a manner that showed that IAA moves into the phloem from the extra cotyledonary solution by multiple pathways, with a carrier-mediated pathway playing a principal role. PMID:27371947

  15. Effects of indole-3-acetic acid on Botrytis cinerea isolates obtained from potted plants.

    PubMed

    Martínez, J A; Valdés, R; Gómez-Bellot, M J; Bañón, S

    2011-01-01

    We study the growth of different isolates of Botrytis cinerea collected from potted plants which were affected by Botrytis blight in southern Spain during recent years. These isolates, which show widely phenotypic differences when grown in vitro, are differentially affected by growth temperature, gibberellic acid applications and paclobutrazol, an efficient plant growth retardant and fungicide at the same time. In this work, we have evaluated the effect of the auxin indole-3-acetic acid (IAA) dose (0, 1, 10, and 100 mg/plate) on the growth of the collection of B. cinerea isolates obtained from the following potted plants: Cyclamen persicum, Hydrangea macrophylla, Lantona camara, and Lonicera japonica. B. cinerea produces indolacetic acid, but so far the precise biosynthetic pathway and some effects on this fungal species are still unclear, although recent studies have revealed an antifungal activity of IAA on several fungi, including B. cinerea isolated from harvested fruits. Mycelial growth curves and growth rates assessed from difference in colony areas during the both linear and deceleration phase, conidiation (measured as time of appearance), conidia length (microm), and sclerotia production (number/plate) were evaluated in the isolates, which were grown at 26 degrees C on Petri dishes containing potato dextrose agar for up to 35 days. Mycelial growth curves fitted a typical kinetic equation of fungi grown on solid media. B. cinerea isolates showed a high degree of variability in their growth kinetics, depending on the isolate and auxin dose. This plant growth substance delayed mycelial growth during the linear phase in an isolate-dependent manner, thus isolates from C. persicum, H. macrophylla and L. camara were more affected by IAA than L. japonica. On the other hand, 100 mg of IAA was the critical dose to significantly reduce the growth rate in all isolates and to promote brown-striped hyphae development, especially in isolate from C. persicum. 10 and 100 mg

  16. Regulation of indole-3-acetic acid biosynthesis by branched-chain amino acids in Enterobacter cloacae UW5.

    PubMed

    Parsons, Cassandra V; Harris, Danielle M M; Patten, Cheryl L

    2015-09-01

    The soil bacterium Enterobacter cloacae UW5 produces the rhizosphere signaling molecule indole-3-acetic acid (IAA) via the indolepyruvate pathway. Expression of indolepyruvate decarboxylase, a key pathway enzyme encoded by ipdC, is upregulated by the transcription factor TyrR in response to aromatic amino acids. Some members of the TyrR regulon may also be controlled by branched-chain amino acids and here we show that expression from the ipdC promoter and production of IAA are downregulated by valine, leucine and isoleucine. Regulation of the IAA synthesis pathway by both aromatic and branched-chain amino acids suggests a broader role for this pathway in bacterial physiology, beyond plant interactions.

  17. Circadian changes in endogenous concentrations of indole-3-acetic acid, melatonin, serotonin, abscisic acid and jasmonic acid in Characeae (Chara australis Brown).

    PubMed

    Beilby, Mary J; Turi, Christina E; Baker, Teesha C; Tymm, Fiona Jm; Murch, Susan J

    2015-01-01

    Giant-celled Characeae (Chara australis Brown), grown for 4 months on 12/12 hr day/night cycle and summer/autumn temperatures, exhibited distinct concentration maxima in auxin (indole-3-acetic acid; IAA), melatonin and serotonin about 4 hr after subjective daybreak. These concentration peaks persisted after 3 day pretreatment in continuous darkness: confirming a circadian rhythm, rather than a response to "light on." The plants pretreated for 3 d in continuous light exhibited several large IAA concentration maxima throughout the 24 hr. The melatonin and serotonin concentrations decreased and were less synchronized with IAA. Chara plants grown on 9/15 hr day/night cycle for 4 months and winter/spring temperatures contained much smaller concentrations of IAA, melatonin and serotonin. The IAA concentration maxima were observed in subjective dark phase. Serotonin concentration peaks were weakly correlated with those of IAA. Melatonin concentration was low and mostly independent of circadian cycle. The "dark" IAA concentration peaks persisted in plants treated for 3 d in the dark. The plants pretreated for 3 d in the light again developed more IAA concentration peaks. In this case the concentration maxima in melatonin and serotonin became more synchronous with those in IAA. The abscisic acid (ABA) and jasmonic acid (JA) concentrations were also measured in plants on winter regime. The ABA concentration did not exhibit circadian pattern, while JA concentration peaks were out of phase with those of IAA. The data are discussed in terms of crosstalk between metabolic pathways. PMID:26382914

  18. Circadian changes in endogenous concentrations of indole-3-acetic acid, melatonin, serotonin, abscisic acid and jasmonic acid in Characeae (Chara australis Brown).

    PubMed

    Beilby, Mary J; Turi, Christina E; Baker, Teesha C; Tymm, Fiona Jm; Murch, Susan J

    2015-01-01

    Giant-celled Characeae (Chara australis Brown), grown for 4 months on 12/12 hr day/night cycle and summer/autumn temperatures, exhibited distinct concentration maxima in auxin (indole-3-acetic acid; IAA), melatonin and serotonin about 4 hr after subjective daybreak. These concentration peaks persisted after 3 day pretreatment in continuous darkness: confirming a circadian rhythm, rather than a response to "light on." The plants pretreated for 3 d in continuous light exhibited several large IAA concentration maxima throughout the 24 hr. The melatonin and serotonin concentrations decreased and were less synchronized with IAA. Chara plants grown on 9/15 hr day/night cycle for 4 months and winter/spring temperatures contained much smaller concentrations of IAA, melatonin and serotonin. The IAA concentration maxima were observed in subjective dark phase. Serotonin concentration peaks were weakly correlated with those of IAA. Melatonin concentration was low and mostly independent of circadian cycle. The "dark" IAA concentration peaks persisted in plants treated for 3 d in the dark. The plants pretreated for 3 d in the light again developed more IAA concentration peaks. In this case the concentration maxima in melatonin and serotonin became more synchronous with those in IAA. The abscisic acid (ABA) and jasmonic acid (JA) concentrations were also measured in plants on winter regime. The ABA concentration did not exhibit circadian pattern, while JA concentration peaks were out of phase with those of IAA. The data are discussed in terms of crosstalk between metabolic pathways.

  19. Simultaneous determination of 2-naphthoxyacetic acid and indole-3-acetic acid by first derivation synchronous fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Xiangxiang; Wan, Yiqun

    2013-07-01

    A simple, rapid, sensitive and selective method for simultaneously determining 2-naphthoxyacetic acid (BNOA) and Indole-3-Acetic Acid (IAA) in mixtures has been developed using derivation synchronous fluorescence spectroscopy based on their synchronous fluorescence. The synchronous fluorescence spectra were obtained with Δλ = 100 nm in a pH 8.5 NaH2PO4-NaOH buffer solution, and the detected wavelengths of quantitative analysis were set at 239 nm for BNOA and 293 nm for IAA respectively. The over lapped fluorescence spectra were well separated by the synchronous derivative method. Under optimized conditions, the limits of detection (LOD) were 0.003 μg/mL for BNOA and 0.012 μg/mL for IAA. This method is simple and expeditious, and it has been successfully applied to the determination of 2-naphthoxyacetic acid and indole-3-acetic acid in fruit juice samples with satisfactory results. The samples were only filtrated through a 0.45 μm membrane filter, which was free from the tedious separation procedures. The obtaining recoveries were in the range of 83.88-87.43% for BNOA and 80.76-86.68% for IAA, and the relative standard deviations were all less than 5.0%. Statistical comparison of the results with high performance liquid chromatography Mass Spectrometry (HPLC-MS) method revealed good agreement and proved that there were no significant difference in the accuracy and precision between these two methods.

  20. Global effect of indole-3-acetic acid biosynthesis on multiple virulence factors of Erwinia chrysanthemi 3937.

    PubMed

    Yang, Shihui; Zhang, Qiu; Guo, Jianhua; Charkowski, Amy O; Glick, Bernard R; Ibekwe, A Mark; Cooksey, Donald A; Yang, Ching-Hong

    2007-02-01

    Production of the plant hormone indole-3-acetic acid (IAA) is widespread among plant-associated microorganisms. The non-gall-forming phytopathogen Erwinia chrysanthemi 3937 (strain Ech3937) possesses iaaM (ASAP16562) and iaaH (ASAP16563) gene homologues. In this work, the null knockout iaaM mutant strain Ech138 was constructed. The IAA production by Ech138 was reduced in M9 minimal medium supplemented with l-tryptophan. Compared with wild-type Ech3937, Ech138 exhibited reduced ability to produce local maceration, but its multiplication in Saintpaulia ionantha was unaffected. The pectate lyase production of Ech138 was diminished. Compared with wild-type Ech3937, the expression levels of an oligogalacturonate lyase gene, ogl, and three endopectate lyase genes, pelD, pelI, and pelL, were reduced in Ech138 as determined by a green fluorescent protein-based fluorescence-activated cell sorting promoter activity assay. In addition, the transcription of type III secretion system (T3SS) genes, dspE (a putative T3SS effector) and hrpN (T3SS harpin), was found to be diminished in the iaaM mutant Ech138. Compared with Ech3937, reduced expression of hrpL (a T3SS alternative sigma factor) and gacA but increased expression of rsmA in Ech138 was also observed, suggesting that the regulation of T3SS and pectate lyase genes by IAA biosynthesis might be partially due to the posttranscriptional regulation of the Gac-Rsm regulatory pathway. PMID:17189441

  1. Branching Mutant rms-2 in Pisum sativum (Grafting Studies and Endogenous Indole-3-Acetic Acid Levels).

    PubMed Central

    Beveridge, C. A.; Ross, J. J.; Murfet, I. C.

    1994-01-01

    Isogenic lines of pea (Pisum sativum L.) were used to determine the physiological site of action of the Rms-2 gene, which maintains apical dominance, and its effect on endogenous free indole-3-acetic acid (IAA) levels. In mutant rms-2 scions, which normally produce lateral branches below node 3 and above node 7, apical dominance was almost fully restored by grafting to Rms-2 (wild-type) stocks. In the reciprocal grafts, rms-2 stocks did not promote branching in wild-type shoots. Together, these results suggest that the Rms-2 gene inhibits branching in the shoot of pea by controlling the synthesis of a translocatable (hormone-like) substance that is produced in the roots and/or cotyledons and in the shoot. At all stages, including the stage at which aerial lateral buds commence outgrowth, the level of IAA in rms-2 shoots was elevated (up to 5-fold) in comparison with that in wild-type shoots. The internode length of rms-2 plants was 40% less than in wild-type plants, and the mutant plants allocated significantly more dry weight to the shoot than to the root in comparison with wild-type plants. Grafting to wild-type stocks did not normalize IAA levels or internode length in rms-2 scions, even though it inhibited branching, suggesting that the involvement of Rms-2 in the control of IAA level and internode length may be confined to processes in the shoot. PMID:12232140

  2. A Simple Purification of Indole-3-Acetic Acid and Abscisic Acid for GC-SIM-MS Analysis by Microfiltration of Aqueous Samples through Nylon

    PubMed Central

    Dunlap, James R.; Guinn, Gene

    1989-01-01

    A simple procedure was developed for the partial purification of plant tissue samples to be analyzed simultaneously for indole-3-acetic acid (IAA) and abscisic acid (ABA). The procedure relies on removal of contaminants by filtration through nylon and partitioning into dichloromethane. This procedure successfully purified both IAA and ABA from muskmelon, cotton, and broccoli tissue. Twenty individual samples can be purified and methylated in 8 h for analysis of free IAA and ABA with gas chromatography-selected ion monitoring-mass spectrometry. The use of microfiltration of aqueous samples through nylon offers new opportunities for improving the efficiency of existing sample purification procedures. PMID:16666735

  3. Influence of 5-Methyltryptophan-Resistant Bradyrhizobium japonicum on Soybean Root Nodule Indole-3-Acetic Acid Content †

    PubMed Central

    Hunter, William J.

    1987-01-01

    Bradyrhizobium japonicum mutants resistant to 5-methyltryptophan were isolated. Some of these mutants were found to accumulate indole-3-acetic acid (IAA) and tryptophan in culture. In greenhouse studies, nodules from control plants inoculated with wild-type bradyrhizobia contained 0.04, 0.10, and 0.58 μg of free, ester-linked, and peptidyl IAA g (fresh weight) of nodules−1, respectively. Nodules from plants inoculated with 5-methyltryptophan-resistant bradyrhizobia contained 0.94, 1.30, and 10.6 μg of free, ester-linked, and peptidyl IAA g (fresh weight) of nodules−1, respectively. This manyfold increase in nodule IAA content indicates that the Bradyrhizobium inoculum can have a considerable influence on the endogenous IAA level of the nodule. Further, these data imply that much of the IAA that accumulated in the high-IAA-containing nodules was of bacterial rather than plant origin. These high-IAA-producing 5-methyltryptophan-resistant bacteria were poor symbiotic nitrogen fixers. Plants inoculated with these bacteria had a lower nodule mass and fixed less nitrogen per gram of nodule than did plants inoculated with wild-type bacteria. PMID:16347335

  4. Biofilm formation and indole-3-acetic acid production by two rhizospheric unicellular cyanobacteria.

    PubMed

    Ahmed, Mehboob; Stal, Lucas J; Hasnain, Shahida

    2014-08-01

    Microorganisms that live in the rhizosphere play a pivotal role in the functioning and maintenance of soil ecosystems. The study of rhizospheric cyanobacteria has been hampered by the difficulty to culture and maintain them in the laboratory. The present work investigated the production of the plant hormone indole-3-acetic acid (IAA) and the potential of biofilm formation on the rhizoplane of pea plants by two cyanobacterial strains, isolated from rice rhizosphere. The unicellular cyanobacteria Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 that were isolated from a rice rhizosphere, were investigated. Production of IAA by Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 was measured under experimental conditions (pH and light). The bioactivity of the cyanobacterial auxin was demonstrated through the alteration of the rooting pattern of Pisum sativum seedlings. The increase in the concentration of L-tryptophan and the time that this amino acid was present in the medium resulted in a significant enhancement of the synthesis of IAA (r > 0.900 at p = 0.01). There was also a significant correlation between the concentration of IAA in the supernatant of the cyanobacteria cultures and the root length and number of the pea seedlings. Observations made by confocal laser scanning microscopy revealed the presence of cyanobacteria on the surface of the roots and also provided evidence for the penetration of the cyanobacteria in the endorhizosphere. We show that the synthesis of IAA by Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 occurs under different environmental conditions and that the auxin is important for the development of the seedling roots and for establishing an intimate symbiosis between cyanobacteria and host plants.

  5. Biofilm formation and indole-3-acetic acid production by two rhizospheric unicellular cyanobacteria.

    PubMed

    Ahmed, Mehboob; Stal, Lucas J; Hasnain, Shahida

    2014-08-01

    Microorganisms that live in the rhizosphere play a pivotal role in the functioning and maintenance of soil ecosystems. The study of rhizospheric cyanobacteria has been hampered by the difficulty to culture and maintain them in the laboratory. The present work investigated the production of the plant hormone indole-3-acetic acid (IAA) and the potential of biofilm formation on the rhizoplane of pea plants by two cyanobacterial strains, isolated from rice rhizosphere. The unicellular cyanobacteria Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 that were isolated from a rice rhizosphere, were investigated. Production of IAA by Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 was measured under experimental conditions (pH and light). The bioactivity of the cyanobacterial auxin was demonstrated through the alteration of the rooting pattern of Pisum sativum seedlings. The increase in the concentration of L-tryptophan and the time that this amino acid was present in the medium resulted in a significant enhancement of the synthesis of IAA (r > 0.900 at p = 0.01). There was also a significant correlation between the concentration of IAA in the supernatant of the cyanobacteria cultures and the root length and number of the pea seedlings. Observations made by confocal laser scanning microscopy revealed the presence of cyanobacteria on the surface of the roots and also provided evidence for the penetration of the cyanobacteria in the endorhizosphere. We show that the synthesis of IAA by Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 occurs under different environmental conditions and that the auxin is important for the development of the seedling roots and for establishing an intimate symbiosis between cyanobacteria and host plants. PMID:24705871

  6. Occurrence and metabolism of 7-hydroxy-2-indolinone-3-acetic acid in Zea mays

    NASA Technical Reports Server (NTRS)

    Lewer, P.; Bandurski, R. S.

    1987-01-01

    7-Hydroxy-2-indolinone-3-acetic acid was identified as a catabolite of indole-3-acetic acid in germinating kernels of Zea mays and found to be present in amounts of ca 3.1 nmol/kernel. 7-Hydroxy-2-indolinone-3-acetic acid was shown to be a biosynthetic intermediate between 2-indolinone-3-acetic acid and 7-hydroxy-2-indolinone-3-acetic acid-7'-O-glucoside in both kernels and roots of Zea mays. Further metabolism of 7-hydroxy-2-[5-3H]-indolinone-3-acetic acid-7'-O-glucoside occurred to yield tritiated water plus, as yet, uncharacterized products.

  7. Transport of Indole-3-Acetic Acid during Gravitropism in Intact Maize Coleoptiles 1

    PubMed Central

    Parker, Karen E.; Briggs, Winslow R.

    1990-01-01

    We have investigated the transport of tritiated indole-3-acetic acid (IAA) in intact, red light-grown maize (Zea mays) coleoptiles during gravitropic induction and the subsequent development of curvature. This auxin is transported down the length of gravistimulated coleoptiles at a rate comparable to that in normal, upright plants. Transport is initially symmetrical across the coleoptile, but between 30 and 40 minutes after plants are turned horizontal a lateral redistribution of the IAA already present in the transport stream occurs. By 60 minutes after the beginning of the gravitropic stimulus, the ratio of tritiated tracer auxin in the lower half with respect to the upper half is approximately 2:1. The redistribution of growth that causes gravitropic curvature follows the IAA redistribution by 5 or 10 minutes at the minimum in most regions of the coleoptile. Immobilization of tracer auxin from the transport stream during gravitropism was not detectable in the most apical 10 millimeters. Previous reports have shown that in intact, red light-grown maize coleoptiles, endogenous auxin is limiting for growth, the tissue is linearly responsive to linearly increasing concentrations of small amounts of added auxin, and the lag time for the stimulation of straight growth by added IAA is approximately 8 or 9 minutes (TI Baskin, M Iino, PB Green, WR Briggs [1985] Plant Cell Environ 8: 595-603; TI Baskin, WR Briggs, M Iino [1986] Plant Physiol 81: 306-309). We conclude that redistribution of IAA in the transport stream occurs in maize coleoptiles during gravitropism, and is sufficient in degree and timing to be the immediate cause of gravitropic curvature. PMID:16667914

  8. Variation in Indole-3-Acetic Acid Production by Wild Saccharomyces cerevisiae and S. paradoxus Strains from Diverse Ecological Sources and Its Effect on Growth

    PubMed Central

    Liu, Yen-Yu; Chen, Hung-Wei; Chou, Jui-Yu

    2016-01-01

    Phytohormone indole-3-acetic acid (IAA) is the most common naturally occurring and most thoroughly studied plant growth regulator. Microbial synthesis of IAA has long been known. Microbial IAA biosynthesis has been proposed as possibly occurring through multiple pathways, as has been proven in plants. However, the biosynthetic pathways of IAA and the ecological roles of IAA in yeast have not been widely studied. In this study, we investigated the variation in IAA production and its effect on the growth of Saccharomyces cerevisiae and its closest relative Saccharomyces paradoxus yeasts from diverse ecological sources. We found that almost all Saccharomyces yeasts produced IAA when cultured in medium supplemented with the primary precursor of IAA, L-tryptophan (L-Trp). However, when cultured in medium without L-Trp, IAA production was only detected in three strains. Furthermore, exogenous added IAA exerted stimulatory and inhibitory effects on yeast growth. Interestingly, a negative correlation was observed between the amount of IAA production in the yeast cultures and the IAA inhibition ratio of their growth. PMID:27483373

  9. Variation in Indole-3-Acetic Acid Production by Wild Saccharomyces cerevisiae and S. paradoxus Strains from Diverse Ecological Sources and Its Effect on Growth.

    PubMed

    Liu, Yen-Yu; Chen, Hung-Wei; Chou, Jui-Yu

    2016-01-01

    Phytohormone indole-3-acetic acid (IAA) is the most common naturally occurring and most thoroughly studied plant growth regulator. Microbial synthesis of IAA has long been known. Microbial IAA biosynthesis has been proposed as possibly occurring through multiple pathways, as has been proven in plants. However, the biosynthetic pathways of IAA and the ecological roles of IAA in yeast have not been widely studied. In this study, we investigated the variation in IAA production and its effect on the growth of Saccharomyces cerevisiae and its closest relative Saccharomyces paradoxus yeasts from diverse ecological sources. We found that almost all Saccharomyces yeasts produced IAA when cultured in medium supplemented with the primary precursor of IAA, L-tryptophan (L-Trp). However, when cultured in medium without L-Trp, IAA production was only detected in three strains. Furthermore, exogenous added IAA exerted stimulatory and inhibitory effects on yeast growth. Interestingly, a negative correlation was observed between the amount of IAA production in the yeast cultures and the IAA inhibition ratio of their growth. PMID:27483373

  10. Azospirillum brasilense Produces the Auxin-Like Phenylacetic Acid by Using the Key Enzyme for Indole-3-Acetic Acid Biosynthesis

    PubMed Central

    Somers, E.; Ptacek, D.; Gysegom, P.; Srinivasan, M.; Vanderleyden, J.

    2005-01-01

    An antimicrobial compound was isolated from Azospirillum brasilense culture extracts by high-performance liquid chromatography and further identified by gas chromatography-mass spectrometry as the auxin-like molecule, phenylacetic acid (PAA). PAA synthesis was found to be mediated by the indole-3-pyruvate decarboxylase, previously identified as a key enzyme in indole-3-acetic acid (IAA) production in A. brasilense. In minimal growth medium, PAA biosynthesis by A. brasilense was only observed in the presence of phenylalanine (or precursors thereof). This observation suggests deamination of phenylalanine, decarboxylation of phenylpyruvate, and subsequent oxidation of phenylacetaldehyde as the most likely pathway for PAA synthesis. Expression analysis revealed that transcription of the ipdC gene is upregulated by PAA, as was previously described for IAA and synthetic auxins, indicating a positive feedback regulation. The synthesis of PAA by A. brasilense is discussed in relation to previously reported biocontrol properties of A. brasilense. PMID:15812004

  11. Surface colonization by Azospirillum brasilense SM in the indole-3-acetic acid dependent growth improvement of sorghum.

    PubMed

    Kochar, Mandira; Srivastava, Sheela

    2012-04-01

    The key to improving plant productivity is successful bacterial-plant interaction in the rhizosphere that can be maintained in the environment. The results presented here confirm Azospirillum brasilense strain SM as a competent plant growth promoting bacterium over mid- and long-term associations with sorghum. This study establishes that plant growth can be directly correlated with the associated bacterium's indole-3-acetic acid (IAA) production capability as IAA over-expressing variants, SMp30 and SMΔi3-6 fared better than the wild type strain. The auxin antagonist, p-chlorophenoxy isobutyric acid confirmed the role of bacterial IAA in plant growth promotion and verified the presence of larger amount of IAA available to the seeds on inoculation with IAA over-expressing mutants. Microscopic analysis identified the bacterial association at root tips, root-shoot junction and elongation zone and their surface colonizing nature. Scanning electron microscopy identified larger number of root hairs and extensive exopolysaccharide covering in comparison to untreated ones. In addition, vibroid-shaped Azospirilla attached by means of fibrillar material were dispersed along the elongation zone. The notable difference with IAA over-expressing variants was enhanced number of root hairs. Thus, the variant strains may be more efficient surface colonizers of the sorghum root and used as superior bio-inoculants for improving plant productivity.

  12. Location of Transported Auxin in Etiolated Maize Shoots Using 5-Azidoindole-3-Acetic Acid 1

    PubMed Central

    Jones, Alan M.

    1990-01-01

    A study was undertaken using the photoaffinity labeling agent, tritiated 5-azidoindole-3-acetic acid ([3H],5-N3IAA), to identify cells in the etiolated maize (Zea mays L.) shoot which transport auxin. Transport of [3H],5-N3IAA was shown to be polar, inhibited by 2,3,5-triiodobenzoic acid (TIBA) and essentially freely mobile. There was no detectable radiodecomposition of [3H],5-N3IAA within tissue kept in darkness for 4 hours. Shoot tissue which had taken up [3H],5-N3IAA was irradiated with ultraviolet light to covalently fix the photoaffinity labeling agent within cells that contained it at the time of photolysis. Subsequent microautoradiography showed that all cells contained radioactivity; however, the amount of radioactivity varied among different cell types. Epidermal cells contained the most radioactivity per area, approximately twofold more than other cells. Parenchyma cells in the mature stelar region contained the next largest amount and cortical cells, sieve tube cells, tracheary cells, and all cells in the leaf base contained the least amount of the radioactive label. Two observations suggest that the auxin within the epidermal cells is transported in a polar manner: (a) the amount of auxin in the epidermal cells is greatly reduced in the presence of TIBA, and (b) auxin accumulates on the apical side of a wound in the epidermis and is absent on the basal side. While these results indicate that auxin in the epidermis is polarly transported, this tissue cannot be the only pathway since the epidermis is only a small fraction of the shoot volume. The greater than twofold difference between the concentration of auxin in the epidermal and subtending cells demonstrates that physiological differences in the concentration of auxin can occur between adjacent cells. Images Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 PMID:16667572

  13. Transport of Indole-3-Butyric Acid and Indole-3-Acetic Acid in Arabidopsis Hypocotyls Using Stable Isotope Labeling1[C][W][OA

    PubMed Central

    Liu, Xing; Barkawi, Lana; Gardner, Gary; Cohen, Jerry D.

    2012-01-01

    The polar transport of the natural auxins indole-3-butyric acid (IBA) and indole-3-acetic acid (IAA) has been described in Arabidopsis (Arabidopsis thaliana) hypocotyls using radioactive tracers. Because radioactive assays alone cannot distinguish IBA from its metabolites, the detected transport from applied [3H]IBA may have resulted from the transport of IBA metabolites, including IAA. To test this hypothesis, we used a mass spectrometry-based method to quantify the transport of IBA in Arabidopsis hypocotyls by following the movement of [13C1]IBA and the [13C1]IAA derived from [13C1]IBA. We also assayed [13C6]IAA transport in a parallel control experiment. We found that the amount of transported [13C1]IBA was dramatically lower than [13C6]IAA, and the IBA transport was not reduced by the auxin transport inhibitor N-1-naphthylphthalamic acid. Significant amounts of the applied [13C1]IBA were converted to [13C1]IAA during transport, but [13C1]IBA transport was independent of IBA-to-IAA conversion. We also found that most of the [13C1]IBA was converted to ester-linked [13C1]IBA at the apical end of hypocotyls, and ester-linked [13C1]IBA was also found in the basal end at a level higher than free [13C1]IBA. In contrast, most of the [13C6]IAA was converted to amide-linked [13C6]IAA at the apical end of hypocotyls, but very little conjugated [13C6]IAA was found in the basal end. Our results demonstrate that the polar transport of IBA is much lower than IAA in Arabidopsis hypocotyls, and the transport mechanism is distinct from IAA transport. These experiments also establish a method for quantifying the movement of small molecules in plants using stable isotope labeling. PMID:22323783

  14. Ethylene-enhanced catabolism of ( sup 14 C)indole-3-acetic acid to indole-3-carboxylic acid in citrus leaf tissues. [Citrus sinensis

    SciTech Connect

    Sagee, O.; Riov, J.; Goren, J. )

    1990-01-01

    Exogenous ({sup 14}C)indole-3-acetic acid (IAA) is conjugated in citrus (Citrus sinensis) leaf tissues to one major substance which has been identified as indole-3-acetylaspartic acid (IAAsp). Ethylene pretreatment enhanced the catabolism of ({sup 14}C)IAA to indole-3-carboxylic acid (ICA), which accumulated as glucose esters (ICGlu). Increased formation of ICGlu by ethylene was accompanied by a concomitant decrease in IAAsp formation. IAAsp and ICGlu were identified by combined gas chromatography-mass spectrometry. Formation of ICGlu was dependent on the concentration of ethylene and the duration of the ethylene pretreatment. It is suggested that the catabolism of IAA to ICA may be one of the mechanisms by which ethylene endogenous IAA levels.

  15. Circadian changes in endogenous concentrations of indole-3-acetic acid, melatonin, serotonin, abscisic acid and jasmonic acid in Characeae (Chara australis Brown)

    PubMed Central

    Beilby, Mary J; Turi, Christina E; Baker, Teesha C; Tymm, Fiona JM; Murch, Susan J

    2015-01-01

    Giant-celled Characeae (Chara australis Brown), grown for 4 months on 12/12 hr day/night cycle and summer/autumn temperatures, exhibited distinct concentration maxima in auxin (indole-3-acetic acid; IAA), melatonin and serotonin about 4 hr after subjective daybreak. These concentration peaks persisted after 3 day pretreatment in continuous darkness: confirming a circadian rhythm, rather than a response to “light on.” The plants pretreated for 3 d in continuous light exhibited several large IAA concentration maxima throughout the 24 hr. The melatonin and serotonin concentrations decreased and were less synchronized with IAA. Chara plants grown on 9/15 hr day/night cycle for 4 months and winter/spring temperatures contained much smaller concentrations of IAA, melatonin and serotonin. The IAA concentration maxima were observed in subjective dark phase. Serotonin concentration peaks were weakly correlated with those of IAA. Melatonin concentration was low and mostly independent of circadian cycle. The “dark” IAA concentration peaks persisted in plants treated for 3 d in the dark. The plants pretreated for 3 d in the light again developed more IAA concentration peaks. In this case the concentration maxima in melatonin and serotonin became more synchronous with those in IAA. The abscisic acid (ABA) and jasmonic acid (JA) concentrations were also measured in plants on winter regime. The ABA concentration did not exhibit circadian pattern, while JA concentration peaks were out of phase with those of IAA. The data are discussed in terms of crosstalk between metabolic pathways. PMID:26382914

  16. Involvement of indole-3-acetic acid produced by Azospirillum brasilense in accumulating intracellular ammonium in Chlorella vulgaris.

    PubMed

    Meza, Beatriz; de-Bashan, Luz E; Bashan, Yoav

    2015-01-01

    Accumulation of intracellular ammonium and activities of the enzymes glutamine synthetase (GS) and glutamate dehydrogenase (GDH) were measured when the microalgae Chlorella vulgaris was immobilized in alginate with either of two wild type strains of Azospirillum brasilense or their corresponding indole-3-acetic acid (IAA)-attenuated mutants. After 48 h of immobilization, both wild types induced higher levels of intracellular ammonium in the microalgae than their respective mutants; the more IAA produced, the higher the intracellular ammonium accumulated. Accumulation of intracellular ammonium in the cells of C. vulgaris followed application of four levels of exogenous IAA reported for A. brasilense and its IAA-attenuated mutants, which had a similar pattern for the first 24 h. This effect was transient and disappeared after 48 h of incubation. Immobilization of C. vulgaris with any bacteria strain induced higher GS activity. The bacterial strains also had GS activity, comparable to the activity detected in C. vulgaris, but weaker than when immobilized with the bacteria. When net activity was calculated, the wild type always induced higher GS activity than IAA-attenuated mutants. GDH activity in most microalgae/bacteria interactions resembled GS activity. When complementing IAA-attenuated mutants with exogenous IAA, GS activity in co-immobilized cultures matched those of the wild type A. brasilense immobilized with the microalga. Similarity occurred when the net GS activity was measured, and was higher with greater quantities of exogenous IAA. It is proposed that IAA produced by A. brasilense is involved in ammonium uptake and later assimilation by C. vulgaris.

  17. Indole-3-acetic acid improves postharvest biological control of blue mold rot of apple by Cryptococcus laurentii.

    PubMed

    Yu, Ting; Chen, Jishuang; Lu, Huangping; Zheng, Xiaodong

    2009-03-01

    Cryptococcus laurentii is a well-known postharvest biocontrol yeast; however, it cannot provide satisfactory levels of decay control when used alone. Here, we evaluated the effects of indole-3-acetic acid (IAA), a plant growth regulator, on the biocontrol efficacy of the yeast antagonist C. laurentii against blue mold rot caused by Penicillium expansum in apple fruit. Results showed that the addition of IAA at 20 microg/ml to suspensions of C. laurentii greatly enhanced inhibition of mold rot in apple wounds compared with that observed with C. laurentii alone. The addition of IAA at 20 microg/ml or lower did not influence the population growth of C. laurentii in wounds, but adverse effects were seen on C. laurentii when the concentration of IAA was increased to 200 microg/ml or above in vitro and in vivo. P. expansum infection in apple wounds was not inhibited when the pathogen was inoculated into the fruit wounds within 2 h after application of IAA; however, infection was reduced when inoculated more than 12 h after IAA application. Treatment of wounds with IAA at 20 microg/ml 24 h before pathogen inoculation resulted in significant inhibition of P. expansum spore germination and host infection. Application of IAA at 20 microg/ml also reduced P. expansum infection when it was applied 48 h before pathogen inoculation in the intact fruit. Thus, IAA could reinforce the biocontrol efficacy of C. laurentii in inhibiting blue mold of apple fruit by induction of the natural resistance of the fruit.

  18. Biosynthesis of Indole-3-Acetic Acid by New Klebsiella oxytoca Free and Immobilized Cells on Inorganic Matrices

    PubMed Central

    Celloto, Valéria R.; Oliveira, Arildo J. B.; Gonçalves, José E.; Watanabe, Cecília S. F.; Matioli, Graciette; Gonçalves, Regina A. C.

    2012-01-01

    While many natural and synthetic compounds exhibit auxin-like activity in bioassays, indole-3-acetic acid (IAA) is recognized as the key auxin in most plants. IAA has been implicated in almost all aspects of plant growth and development and a large array of bacteria have been reported to enhance plant growth. Cells of Klebsiella oxytoca isolated from the rhizosphere of Aspidosperma polyneuron and immobilized by adsorption on different inorganic matrices were used for IAA production. The matrices were prepared by the sol-gel method and the silica-titanium was the most suitable matrix for effective immobilization. In operational stability assays, IAA production was maintained after four cycles of production, obtaining 42.80 ± 2.03 μg mL−1 of IAA in the third cycle, which corresponds to a 54% increase in production in relation to the first cycle, whereas free cells began losing activity after the first cycle. After 90 days of storage at 4°C the immobilized cells showed the slight reduction of IAA production without significant loss of activity. PMID:22623901

  19. Indole-3-Acetic Acid Is Produced by Emiliania huxleyi Coccolith-Bearing Cells and Triggers a Physiological Response in Bald Cells

    PubMed Central

    Labeeuw, Leen; Khey, Joleen; Bramucci, Anna R.; Atwal, Harjot; de la Mata, A. Paulina; Harynuk, James; Case, Rebecca J.

    2016-01-01

    Indole-3-acetic acid (IAA) is an auxin produced by terrestrial plants which influences development through a variety of cellular mechanisms, such as altering cell orientation, organ development, fertility, and cell elongation. IAA is also produced by bacterial pathogens and symbionts of plants and algae, allowing them to manipulate growth and development of their host. They do so by either producing excess exogenous IAA or hijacking the IAA biosynthesis pathway of their host. The endogenous production of IAA by algae remains contentious. Using Emiliania huxleyi, a globally abundant marine haptophyte, we investigated the presence and potential role of IAA in algae. Homologs of genes involved in several tryptophan-dependent IAA biosynthesis pathways were identified in E. huxleyi. This suggests that this haptophyte can synthesize IAA using various precursors derived from tryptophan. Addition of L-tryptophan to E. huxleyi stimulated IAA production, which could be detected using Salkowski's reagent and GC × GC-TOFMS in the C cell type (coccolith bearing), but not in the N cell type (bald). Various concentrations of IAA were exogenously added to these two cell types to identify a physiological response in E. huxleyi. The N cell type, which did not produce IAA, was more sensitive to it, showing an increased variation in cell size, membrane permeability, and a corresponding increase in the photosynthetic potential quantum yield of Photosystem II (PSII). A roseobacter (bacteria commonly associated with E. huxleyi) Ruegeria sp. R11, previously shown to produce IAA, was co-cultured with E. huxleyi C and N cells. IAA could not be detected from these co-cultures, and even when stimulated by addition of L-tryptophan, they produced less IAA than axenic C type culture similarly induced. This suggests that IAA plays a novel role signaling between different E. huxleyi cell types, rather than between a bacteria and its algal host. PMID:27375567

  20. Indole-3-Acetic Acid Is Produced by Emiliania huxleyi Coccolith-Bearing Cells and Triggers a Physiological Response in Bald Cells.

    PubMed

    Labeeuw, Leen; Khey, Joleen; Bramucci, Anna R; Atwal, Harjot; de la Mata, A Paulina; Harynuk, James; Case, Rebecca J

    2016-01-01

    Indole-3-acetic acid (IAA) is an auxin produced by terrestrial plants which influences development through a variety of cellular mechanisms, such as altering cell orientation, organ development, fertility, and cell elongation. IAA is also produced by bacterial pathogens and symbionts of plants and algae, allowing them to manipulate growth and development of their host. They do so by either producing excess exogenous IAA or hijacking the IAA biosynthesis pathway of their host. The endogenous production of IAA by algae remains contentious. Using Emiliania huxleyi, a globally abundant marine haptophyte, we investigated the presence and potential role of IAA in algae. Homologs of genes involved in several tryptophan-dependent IAA biosynthesis pathways were identified in E. huxleyi. This suggests that this haptophyte can synthesize IAA using various precursors derived from tryptophan. Addition of L-tryptophan to E. huxleyi stimulated IAA production, which could be detected using Salkowski's reagent and GC × GC-TOFMS in the C cell type (coccolith bearing), but not in the N cell type (bald). Various concentrations of IAA were exogenously added to these two cell types to identify a physiological response in E. huxleyi. The N cell type, which did not produce IAA, was more sensitive to it, showing an increased variation in cell size, membrane permeability, and a corresponding increase in the photosynthetic potential quantum yield of Photosystem II (PSII). A roseobacter (bacteria commonly associated with E. huxleyi) Ruegeria sp. R11, previously shown to produce IAA, was co-cultured with E. huxleyi C and N cells. IAA could not be detected from these co-cultures, and even when stimulated by addition of L-tryptophan, they produced less IAA than axenic C type culture similarly induced. This suggests that IAA plays a novel role signaling between different E. huxleyi cell types, rather than between a bacteria and its algal host. PMID:27375567

  1. Variation in indole-3-acetic acid transport and its relationship with growth in etiolated lupin hypocotyls.

    PubMed

    Nicolás, Juana Inés López; Acosta, Manuel; Sánchez-Bravo, José

    2007-07-01

    The relationship between the variation in polar auxin transport (PAT) and elongating growth in etiolated Lupinus albus hypocotyls was investigated. Parameters of auxin transport, such as the amount transported, intensity of the transport and sensitivity to 1-N-naphthylphthalamic acid (NPA) inhibition were measured in isolated sections from different sites (apical, middle and basal) along the hypocotyls in seedlings of different ages. Auxin transport was studied by applying radioactive indole-3-acetic acid (IAA) to upright and inverted sections. Basipetal transport was much higher than acropetal and very sensitive to NPA inhibition, which indicates that transport is polarized. Polarity was expressed as the NPA-induced inhibition and the basipetal/acropetal ratio. As a rule, both the amount of IAA transported and the polarity varied with the age of the seedlings, with values increasing from 3 to 5d and then decreasing. Both parameters were higher in apical (where most growth is localized) than in middle and basal regions, although this longitudinal gradient tended to disappear with aging as hypocotyl growth slowed and finally ceased. The application of NPA did not modify hypocotyl elongation in 5-d-old intact seedlings. Derooting of the seedlings drastically reduced elongation in the control, while NPA partially restored the growth, which suggests that NPA induces an increase in auxin in the elongation region. These results suggest that a basipetally decreasing gradient in PAT along the hypocotyl, which changes with age, may be responsible for auxin distribution pattern controlling growth.

  2. Indole-3-acetic acid biosynthesis in the biocontrol strain Pseudomonas fluorescens Psd and plant growth regulation by hormone overexpression.

    PubMed

    Kochar, Mandira; Upadhyay, Ashutosh; Srivastava, Sheela

    2011-05-01

    Pseudomonas fluorescens is an important biological component of agricultural soils that bestows a number of direct and indirect beneficial attributes to the plants. We analyzed the biocontrol strain P. fluorescens Psd for indole-3-acetic acid (IAA) biosynthesis and studied the effect of its consequent manipulation on its plant-growth-promoting (PGP) potential. While the indole pyruvic acid (IPyA) pathway commonly associated with PGP bacteria was lacking, the indole acetamide (IAM) pathway generally observed in phytopathogens was expressed in strain Psd. Overexpression of IAM pathway genes iaaM-iaaH, from Pseudomonas syringae subsp. savastanoi drastically increased IAA levels and showed a detrimental effect on sorghum root development. On the other hand, heterologous expression of the indole-3-pyruvate decarboxylase/phenylpyruvate decarboxylase gene (ipdC/ppdC) of the IPyA pathway from the PGP bacterium Azospirillum brasilense SM led to enhancement of the IAA level. A more favorable effect of this recombinant strain on sorghum root growth and development suggests that metabolic engineering could be used to generate strains with improved PGP function.

  3. Changes in the level of ( sup 14 C)indole-3-acetic acid and ( sup 14 C)indoleacetylaspartic acid during root formation in mung bean cuttings. [Vigna radiata

    SciTech Connect

    Norcini, J.G.; Heuser, C.W. )

    1988-04-01

    Changes in the levels of ({sup 14}C)indole-3-acetic acid (IAA) and ({sup 14}C)indoleacetylaspartic acid (IAAsp) were examined during adventitious root formation in mung bean (Vigna radiata (L.) R. Wilcz. Berken) stem cuttings. IAAsp was identified by GC-MS as the primary conjugate in IAA-treated cuttings. During root formation in IAA-treated cuttings, the level of ({sup 14}C)IAAsp increased rapidly the first day and then declined; ({sup 14}C)IAA was rapidly metabolized and not detected after 12 hours.

  4. Tryptophan, thiamine and indole-3-acetic acid exchange between Chlorella sorokiniana and the plant growth-promoting bacterium Azospirillum brasilense.

    PubMed

    Palacios, Oskar A; Gomez-Anduro, Gracia; Bashan, Yoav; de-Bashan, Luz E

    2016-06-01

    During synthetic mutualistic interactions between the microalga Chlorella sorokiniana and the plant growth-promoting bacterium (PGPB) Azospirillum brasilense, mutual exchange of resources involved in producing and releasing the phytohormone indole-3-acetic acid (IAA) by the bacterium, using tryptophan and thiamine released by the microalga, were measured. Although increased activities of tryptophan synthase in C. sorokiniana and indole pyruvate decarboxylase (IPDC) in A. brasilense were observed, we could not detect tryptophan or IAA in the culture medium when both organisms were co-immobilized. This indicates that no extra tryptophan or IAA is produced, apart from the quantities required to sustain the interaction. Over-expression of the ipdC gene occurs at different incubation times: after 48 h, when A. brasilense was immobilized alone and grown in exudates of C. sorokiniana and at 96 h, when A. brasilense was co-immobilized with the microalga. When A. brasilense was cultured in exudates of C. sorokiniana, increased expression of the ipdC gene, corresponding increase in activity of IPDC encoded by the ipdC gene, and increase in IAA production were measured during the first 48 h of incubation. IAA production and release by A. brasilense was found only when tryptophan and thiamine were present in a synthetic growth medium (SGM). The absence of thiamine in SGM yielded no detectable IAA. In summary, this study demonstrates that C. sorokiniana can exude sufficient tryptophan and thiamine to allow IAA production by a PGPB during their interaction. Thiamine is essential for IAA production by A. brasilense and these three metabolites are part of a communication between the two microorganisms.

  5. The role of calcium in growth induced by indole-3-acetic acid and gravity in the leaf-sheath pulvinus of oat (Avena sativa)

    NASA Technical Reports Server (NTRS)

    Brock, T. G.; Burg, J.; Ghosheh, N. S.; Kaufman, P. B.

    1992-01-01

    Leaf-sheath pulvini of excised segments from oat (Avena sativa L.) were induced to grow by treatment with 10 micromoles indole-3-acetic acid (IAA), gravistimulation, or both, and the effects of calcium, EGTA, and calcium channel blockers on growth were evaluated. Unilaterally applied calcium (10 mM CaCl2) significantly inhibited IAA-induced growth in upright pulvini but had no effect on growth induced by either gravity or gravity plus IAA. Calcium alone had no effect on upright pulvini. The calcium chelator EGTA alone (10 mM) stimulated growth in upright pulvini. However, EGTA had no effect on either IAA- or gravity-induced growth but slightly diminished growth in IAA-treated gravistimulated pulvini. The calcium channel blockers lanthanum chloride (25 mM), verapamil (2.5 mM), and nifedipine (2.5 mM) greatly inhibited growth as induced by IAA (> or = 50% inhibition) or IAA plus gravity (20% inhibition) but had no effect on gravistimulated pulvini. Combinations of channel blockers were similar in effect on IAA action as individual blockers. Since neither calcium ions nor EGTA significantly affected the graviresponse of pulvini, we conclude that apoplastic calcium is unimportant in leaf-sheath pulvinus gravitropism. The observation that calcium ions and calcium channel blockers inhibit IAA-induced growth, but have no effect on gravistimulated pulvini, further supports previous observations that gravistimulation alters the responsiveness of pulvini to IAA.

  6. Indole-3-acetic acid-producing yeasts in the phyllosphere of the carnivorous plant Drosera indica L.

    PubMed

    Sun, Pei-Feng; Fang, Wei-Ta; Shin, Li-Ying; Wei, Jyuan-Yu; Fu, Shih-Feng; Chou, Jui-Yu

    2014-01-01

    Yeasts are widely distributed in nature and exist in association with other microorganisms as normal inhabitants of soil, vegetation, and aqueous environments. In this study, 12 yeast strains were enriched and isolated from leaf samples of the carnivorous plant Drosera indica L., which is currently threatened because of restricted habitats and use in herbal industries. According to similarities in large subunit and small subunit ribosomal RNA gene sequences, we identified 2 yeast species in 2 genera of the phylum Ascomycota, and 5 yeast species in 5 genera of the phylum Basidiomycota. All of the isolated yeasts produced indole-3-acetic acid (IAA) when cultivated in YPD broth supplemented with 0.1% L-tryptophan. Growth conditions, such as the pH and temperature of the medium, influenced yeast IAA production. Our results also suggested the existence of a tryptophan-independent IAA biosynthetic pathway. We evaluated the effects of various concentrations of exogenous IAA on yeast growth and observed that IAA produced by wild yeasts modifies auxin-inducible gene expression in Arabidopsis. Our data suggest that yeasts can promote plant growth and support ongoing prospecting of yeast strains for inclusion into biofertilizer for sustainable agriculture.

  7. Indole-3-acetic acid-induced oxidative burst and an increase in cytosolic calcium ion concentration in rice suspension culture.

    PubMed

    Nguyen, Hieu T H; Umemura, Kenji; Kawano, Tomonori

    2016-08-01

    Indole-3-acetic acid (IAA) is the major natural auxin involved in the regulation of a variety of growth and developmental processes such as division, elongation, and polarity determination in growing plant cells. It has been shown that dividing and/or elongating plant cells accompanies the generation of reactive oxygen species (ROS) and a number of reports have suggested that hormonal actions can be mediated by ROS through ROS-mediated opening of ion channels. Here, we surveyed the link between the action of IAA, oxidative burst, and calcium channel activation in a transgenic cells of rice expressing aequorin in the cytosol. Application of IAA to the cells induced a rapid and transient generation of superoxide which was followed by a transient increase in cytosolic Ca(2+) concentration ([Ca(2+)]c). The IAA-induced [Ca(2+)]c elevation was inhibited by Ca(2+) channel blockers and a Ca(2+) chelator. Furthermore, ROS scavengers effectively blocked the action of IAA on [Ca(2+)]c elevation.

  8. Indole-3-Acetic Acid-Producing Yeasts in the Phyllosphere of the Carnivorous Plant Drosera indica L

    PubMed Central

    Shin, Li-Ying; Wei, Jyuan-Yu; Fu, Shih-Feng; Chou, Jui-Yu

    2014-01-01

    Yeasts are widely distributed in nature and exist in association with other microorganisms as normal inhabitants of soil, vegetation, and aqueous environments. In this study, 12 yeast strains were enriched and isolated from leaf samples of the carnivorous plant Drosera indica L., which is currently threatened because of restricted habitats and use in herbal industries. According to similarities in large subunit and small subunit ribosomal RNA gene sequences, we identified 2 yeast species in 2 genera of the phylum Ascomycota, and 5 yeast species in 5 genera of the phylum Basidiomycota. All of the isolated yeasts produced indole-3-acetic acid (IAA) when cultivated in YPD broth supplemented with 0.1% L-tryptophan. Growth conditions, such as the pH and temperature of the medium, influenced yeast IAA production. Our results also suggested the existence of a tryptophan-independent IAA biosynthetic pathway. We evaluated the effects of various concentrations of exogenous IAA on yeast growth and observed that IAA produced by wild yeasts modifies auxin-inducible gene expression in Arabidopsis. Our data suggest that yeasts can promote plant growth and support ongoing prospecting of yeast strains for inclusion into biofertilizer for sustainable agriculture. PMID:25464336

  9. Indole-3-acetic acid-producing yeasts in the phyllosphere of the carnivorous plant Drosera indica L.

    PubMed

    Sun, Pei-Feng; Fang, Wei-Ta; Shin, Li-Ying; Wei, Jyuan-Yu; Fu, Shih-Feng; Chou, Jui-Yu

    2014-01-01

    Yeasts are widely distributed in nature and exist in association with other microorganisms as normal inhabitants of soil, vegetation, and aqueous environments. In this study, 12 yeast strains were enriched and isolated from leaf samples of the carnivorous plant Drosera indica L., which is currently threatened because of restricted habitats and use in herbal industries. According to similarities in large subunit and small subunit ribosomal RNA gene sequences, we identified 2 yeast species in 2 genera of the phylum Ascomycota, and 5 yeast species in 5 genera of the phylum Basidiomycota. All of the isolated yeasts produced indole-3-acetic acid (IAA) when cultivated in YPD broth supplemented with 0.1% L-tryptophan. Growth conditions, such as the pH and temperature of the medium, influenced yeast IAA production. Our results also suggested the existence of a tryptophan-independent IAA biosynthetic pathway. We evaluated the effects of various concentrations of exogenous IAA on yeast growth and observed that IAA produced by wild yeasts modifies auxin-inducible gene expression in Arabidopsis. Our data suggest that yeasts can promote plant growth and support ongoing prospecting of yeast strains for inclusion into biofertilizer for sustainable agriculture. PMID:25464336

  10. Indole-3-acetic acid-induced oxidative burst and an increase in cytosolic calcium ion concentration in rice suspension culture.

    PubMed

    Nguyen, Hieu T H; Umemura, Kenji; Kawano, Tomonori

    2016-08-01

    Indole-3-acetic acid (IAA) is the major natural auxin involved in the regulation of a variety of growth and developmental processes such as division, elongation, and polarity determination in growing plant cells. It has been shown that dividing and/or elongating plant cells accompanies the generation of reactive oxygen species (ROS) and a number of reports have suggested that hormonal actions can be mediated by ROS through ROS-mediated opening of ion channels. Here, we surveyed the link between the action of IAA, oxidative burst, and calcium channel activation in a transgenic cells of rice expressing aequorin in the cytosol. Application of IAA to the cells induced a rapid and transient generation of superoxide which was followed by a transient increase in cytosolic Ca(2+) concentration ([Ca(2+)]c). The IAA-induced [Ca(2+)]c elevation was inhibited by Ca(2+) channel blockers and a Ca(2+) chelator. Furthermore, ROS scavengers effectively blocked the action of IAA on [Ca(2+)]c elevation. PMID:27149194

  11. Global Effect of Indole-3-Acetic Acid Biosynthesis on Multiple Virulence Factors of Erwinia chrysanthemi 3937▿

    PubMed Central

    Yang, Shihui; Zhang, Qiu; Guo, Jianhua; Charkowski, Amy O.; Glick, Bernard R.; Ibekwe, A. Mark; Cooksey, Donald A.; Yang, Ching-Hong

    2007-01-01

    Production of the plant hormone indole-3-acetic acid (IAA) is widespread among plant-associated microorganisms. The non-gall-forming phytopathogen Erwinia chrysanthemi 3937 (strain Ech3937) possesses iaaM (ASAP16562) and iaaH (ASAP16563) gene homologues. In this work, the null knockout iaaM mutant strain Ech138 was constructed. The IAA production by Ech138 was reduced in M9 minimal medium supplemented with l-tryptophan. Compared with wild-type Ech3937, Ech138 exhibited reduced ability to produce local maceration, but its multiplication in Saintpaulia ionantha was unaffected. The pectate lyase production of Ech138 was diminished. Compared with wild-type Ech3937, the expression levels of an oligogalacturonate lyase gene, ogl, and three endopectate lyase genes, pelD, pelI, and pelL, were reduced in Ech138 as determined by a green fluorescent protein-based fluorescence-activated cell sorting promoter activity assay. In addition, the transcription of type III secretion system (T3SS) genes, dspE (a putative T3SS effector) and hrpN (T3SS harpin), was found to be diminished in the iaaM mutant Ech138. Compared with Ech3937, reduced expression of hrpL (a T3SS alternative sigma factor) and gacA but increased expression of rsmA in Ech138 was also observed, suggesting that the regulation of T3SS and pectate lyase genes by IAA biosynthesis might be partially due to the posttranscriptional regulation of the Gac-Rsm regulatory pathway. PMID:17189441

  12. Endogenous Abscisic Acid and Indole-3-Acetic Acid and Somatic Embryogenesis in Cultured Leaf Explants of Pennisetum purpureum Schum. 1

    PubMed Central

    Rajasekaran, Kanniah; Hein, Mich B.; Vasil, Indra K.

    1987-01-01

    Effects of application in vivo of glyphosate, fluridone, and paclobutrazol to glasshouse-grown donor plants of Pennisetum purpureum Schum. on endogenous levels of abscisic acid (ABA) and indole-3-acetic acid (IAA) in young leaves and on somatic embryogenesis in cultured leaf explants were studied. Treatment of plants with glyphosate (100 milligrams per liter) resulted in elevated levels of endogenous ABA and IAA in young leaves. In contrast, paclobutrazol (50% active ingredient; 200 milligrams per liter) did not alter the endogenous levels of ABA and IAA. Fluridone (100 milligrams per liter) markedly inhibited synthesis of ABA and leaf explants from fluridone-treated plants lost the capacity for somatic embryogenesis. Explants from glyphosate- or paclobutrazol-treated plants did not show any reduction in embryogenic capacity when compared with untreated control plants. Glyphosate and fluridone were also incorporated into the culture media at various concentrations (0 to 20 milligrams per liter) to study their effects in vitro on somatic embryogenesis in leaf explants from untreated, field-grown plants. Glyphosate was inhibitory to somatic embryogenesis but only at concentrations above 5 milligrams per liter. Fluridone inhibited somatic embryogenesis at all concentrations tested. Inhibition of somatic embryogenesis by fluridone, by either in vivo or in vitro application, could be overcome partially by (±)-ABA added to the culture medium. Exogenous application of (±)-ABA enhanced somatic embryogenesis and reduced the formation of nonembryogenic callus. Application of IAA or gibberellic acid (GA3; >5 milligrams per liter) was inhibitory to somatic embryogenesis. These results indicate that endogenous ABA is one of the important factors controlling the embryogenic capacity of leaf explants in Napier grass. PMID:16665403

  13. Oxidation of indole-3-acetic acid by dioxygen catalysed by plant peroxidases: specificity for the enzyme structure.

    PubMed

    Savitsky, P A; Gazaryan, I G; Tishkov, V I; Lagrimini, L M; Ruzgas, T; Gorton, L

    1999-06-15

    Indole-3-acetic acid (IAA) can be oxidized via two mechanisms: a conventional hydrogen-peroxide-dependent pathway, and one that is hydrogen-peroxide-independent and requires oxygen. It has been shown here for the first time that only plant peroxidases are able to catalyse the reaction of IAA oxidation with molecular oxygen. Cytochrome c peroxidase (CcP), fungal peroxidases (manganese-dependent peroxidase, lignin peroxidase and Arthromyces ramosus peroxidase) and microperoxidase were essentially inactive towards IAA in the absence of added H2O2. An analysis of amino acid sequences allowed five structurally similar fragments to be identified in auxin-binding proteins and plant peroxidases. The corresponding fragments in CcP and fungal peroxidases showed no similarity with auxin-binding proteins. Five structurally similar fragments form a subdomain including the catalytic centre and two residues highly conserved among 'classical' plant peroxidases only, namely His-40 and Trp-117. The subdomain identified above with the two residues might be responsible for the oxidation of the physiological substrate of classical plant peroxidases, IAA. PMID:10359640

  14. Oxidation of indole-3-acetic acid by dioxygen catalysed by plant peroxidases: specificity for the enzyme structure.

    PubMed Central

    Savitsky, P A; Gazaryan, I G; Tishkov, V I; Lagrimini, L M; Ruzgas, T; Gorton, L

    1999-01-01

    Indole-3-acetic acid (IAA) can be oxidized via two mechanisms: a conventional hydrogen-peroxide-dependent pathway, and one that is hydrogen-peroxide-independent and requires oxygen. It has been shown here for the first time that only plant peroxidases are able to catalyse the reaction of IAA oxidation with molecular oxygen. Cytochrome c peroxidase (CcP), fungal peroxidases (manganese-dependent peroxidase, lignin peroxidase and Arthromyces ramosus peroxidase) and microperoxidase were essentially inactive towards IAA in the absence of added H2O2. An analysis of amino acid sequences allowed five structurally similar fragments to be identified in auxin-binding proteins and plant peroxidases. The corresponding fragments in CcP and fungal peroxidases showed no similarity with auxin-binding proteins. Five structurally similar fragments form a subdomain including the catalytic centre and two residues highly conserved among 'classical' plant peroxidases only, namely His-40 and Trp-117. The subdomain identified above with the two residues might be responsible for the oxidation of the physiological substrate of classical plant peroxidases, IAA. PMID:10359640

  15. Amide-conjugated indole-3-acetic acid and adventitious root formation in mung bean cuttings

    SciTech Connect

    Norcini, J.G.

    1986-01-01

    The purpose of this research was to investigate further the relationship between amide-conjugated auxin and adventitious root formation. Indoleacetylaspartic acid (IAA-aspartate) was positively identified as the predominant conjugate isolated from mung bean cuttings after the cuttings has been treated with 10/sup -3/ M IAA. In cuttings treated with (1-/sup 14/C)IAA immediately after excision (0 hr), the percent of extractable /sup 14/C in IAA-aspartate in the hypocotyl sharply increased until 36 hr, then steadily declined. (/sup 14/C)IAA was completely metabolized between 12 and 24 hr. The rooting activities of IAA-L-aspartate, IAA-L-alanine, and IAA-glycine were determined at various stages of root formation; some cuttings were pretreated with 10/sup -3/ M IAA at 0 hr. Pretreated cuttings that were treated with IAA-glycine at 12, 24, 36 hr exhibited the greatest consistency between replications, the greatest number of long roots, and the longest roots. The conjugates did not stimulate rooting as effectively as IAA, yet like IAA, generally enhanced rooting the greatest when applied before the first cell division (24 hr).

  16. Identification of Genes Involved in Indole-3-Acetic Acid Biosynthesis by Gluconacetobacter diazotrophicus PAL5 Strain Using Transposon Mutagenesis

    PubMed Central

    Rodrigues, Elisete P.; Soares, Cleiton de Paula; Galvão, Patrícia G.; Imada, Eddie L.; Simões-Araújo, Jean L.; Rouws, Luc F. M.; de Oliveira, André L. M.; Vidal, Márcia S.; Baldani, José I.

    2016-01-01

    Gluconacetobacter diazotrophicus is a beneficial nitrogen-fixing endophyte found in association with sugarcane plants and other important crops. Beneficial effects of G. diazotrophicus on sugarcane growth and productivity have been attributed to biological nitrogen fixation process and production of phytohormones especially indole-3-acetic acid (IAA); however, information about the biosynthesis and function of IAA in G. diazotrophicus is still scarce. Therefore, the aim of this work was to identify genes and pathways involved in IAA biosynthesis in this bacterium. In our study, the screening of two independent Tn5 mutant libraries of PAL5T strain using the Salkowski colorimetric assay revealed two mutants (Gdiaa34 and Gdiaa01), which exhibited 95% less indolic compounds than the parental strain when grown in LGIP medium supplemented with L-tryptophan. HPLC chromatograms of the wild-type strain revealed the presence of IAA and of the biosynthetic intermediates indole-3-pyruvic acid (IPyA) and indole-3-lactate (ILA). In contrast, the HPLC profiles of both mutants showed no IAA but only a large peak of non-metabolized tryptophan and low levels of IPyA and ILA were detected. Molecular characterization revealed that Gdiaa01 and Gdiaa34 mutants had unique Tn5 insertions at different sites within the GDI2456 open read frame, which is predicted to encode a L-amino acid oxidase (LAAO). GDI2456 (lao gene) forms a cluster with GDI2455 and GDI2454 ORFs, which are predicted to encode a cytochrome C and an RidA protein, respectively. RT-qPCR showed that transcript levels of lao. cccA, and ridA genes were reduced in the Gdiaa01 as compared to PAL5T. In addition, rice plants inoculated with Gdiaa01 showed significantly smaller root development (length, surface area, number of forks and tips) than those plants inoculated with PAL5T. In conclusion, our study demonstrated that G. diazotrophicus PAL5T produces IAA via the IPyA pathway in cultures supplemented with tryptophan and

  17. A genome-wide analysis of the auxin/indole-3-acetic acid gene family in hexaploid bread wheat (Triticum aestivum L.)

    PubMed Central

    Qiao, Linyi; Zhang, Xiaojun; Han, Xiao; Zhang, Lei; Li, Xin; Zhan, Haixian; Ma, Jian; Luo, Peigao; Zhang, Wenping; Cui, Lei; Li, Xiaoyan; Chang, Zhijian

    2015-01-01

    The Auxin/indole-3-acetic acid (Aux/IAA) gene family plays key roles in the primary auxin-response process and controls a number of important traits in plants. However, the characteristics of the Aux/IAA gene family in hexaploid bread wheat (Triticum aestivum L.) have long been unknown. In this study, a comprehensive identification of the Aux/IAA gene family was performed using the latest draft genome sequence of the bread wheat “Chinese Spring.” Thirty-four Aux/IAA genes were identified, 30 of which have duplicated genes on the A, B or D sub-genome, with a total of 84 Aux/IAA sequences. These predicted Aux/IAA genes were non-randomly distributed in all the wheat chromosomes except for chromosome 2D. The information of wheat Aux/IAA proteins is also described. Based on an analysis of phylogeny, expression and adaptive evolution, we prove that the Aux/IAA family in wheat has been replicated twice in the two allopolyploidization events of bread wheat, when the tandem duplication also occurred. The duplicated genes have undergone an evolutionary process of purifying selection, resulting in the high conservation of copy genes among sub-genomes and functional redundancy among several members of the TaIAA family. However, functional divergence probably existed in most TaIAA members due to the diversity of the functional domain and expression pattern. Our research provides useful information for further research into the function of Aux/IAA genes in wheat. PMID:26483801

  18. Indole-3-Acetic Acid Produced by Burkholderia heleia Acts as a Phenylacetic Acid Antagonist to Disrupt Tropolone Biosynthesis in Burkholderia plantarii

    PubMed Central

    Wang, Mengcen; Tachibana, Seiji; Murai, Yuta; Li, Li; Lau, Sharon Yu Ling; Cao, Mengchao; Zhu, Guonian; Hashimoto, Makoto; Hashidoko, Yasuyuki

    2016-01-01

    Burkholderia heleia PAK1-2 is a potent biocontrol agent isolated from rice rhizosphere, as it prevents bacterial rice seedling blight disease caused by Burkholderia plantarii. Here, we isolated a non-antibacterial metabolite from the culture fluid of B. heleia PAK1-2 that was able to suppress B. plantarii virulence and subsequently identified as indole-3-acetic acid (IAA). IAA suppressed the production of tropolone in B. plantarii in a dose-dependent manner without any antibacterial and quorum quenching activity, suggesting that IAA inhibited steps of tropolone biosynthesis. Consistent with this, supplementing cultures of B. plantarii with either L-[ring-2H5]phenylalanine or [ring-2H2~5]phenylacetic acid revealed that phenylacetic acid (PAA), which is the dominant metabolite during the early growth stage, is a direct precursor of tropolone. Exposure of B. plantarii to IAA suppressed production of both PAA and tropolone. These data particularly showed that IAA produced by B. heleia PAK1-2 disrupts tropolone production during bioconversion of PAA to tropolone via the ring-rearrangement on the phenyl group of the precursor to attenuate the virulence of B. plantarii. B. heleia PAK1-2 is thus likely a microbial community coordinating bacterium in rhizosphere ecosystems, which never eliminates phytopathogens but only represses production of phytotoxins or bacteriocidal substances. PMID:26935539

  19. Distinct Characteristics of Indole-3-Acetic Acid and Phenylacetic Acid, Two Common Auxins in Plants.

    PubMed

    Sugawara, Satoko; Mashiguchi, Kiyoshi; Tanaka, Keita; Hishiyama, Shojiro; Sakai, Tatsuya; Hanada, Kousuke; Kinoshita-Tsujimura, Kaori; Yu, Hong; Dai, Xinhua; Takebayashi, Yumiko; Takeda-Kamiya, Noriko; Kakimoto, Tatsuo; Kawaide, Hiroshi; Natsume, Masahiro; Estelle, Mark; Zhao, Yunde; Hayashi, Ken-Ichiro; Kamiya, Yuji; Kasahara, Hiroyuki

    2015-08-01

    The phytohormone auxin plays a central role in many aspects of plant growth and development. IAA is the most studied natural auxin that possesses the property of polar transport in plants. Phenylacetic acid (PAA) has also been recognized as a natural auxin for >40 years, but its role in plant growth and development remains unclear. In this study, we show that IAA and PAA have overlapping regulatory roles but distinct transport characteristics as auxins in plants. PAA is widely distributed in vascular and non-vascular plants. Although the biological activities of PAA are lower than those of IAA, the endogenous levels of PAA are much higher than those of IAA in various plant tissues in Arabidopsis. PAA and IAA can regulate the same set of auxin-responsive genes through the TIR1/AFB pathway in Arabidopsis. IAA actively forms concentration gradients in maize coleoptiles in response to gravitropic stimulation, whereas PAA does not, indicating that PAA is not actively transported in a polar manner. The induction of the YUCCA (YUC) genes increases PAA metabolite levels in Arabidopsis, indicating that YUC flavin-containing monooxygenases may play a role in PAA biosynthesis. Our results provide new insights into the regulation of plant growth and development by different types of auxins. PMID:26076971

  20. Distinct Characteristics of Indole-3-Acetic Acid and Phenylacetic Acid, Two Common Auxins in Plants

    PubMed Central

    Sugawara, Satoko; Mashiguchi, Kiyoshi; Tanaka, Keita; Hishiyama, Shojiro; Sakai, Tatsuya; Hanada, Kousuke; Kinoshita-Tsujimura, Kaori; Yu, Hong; Dai, Xinhua; Takebayashi, Yumiko; Takeda-Kamiya, Noriko; Kakimoto, Tatsuo; Kawaide, Hiroshi; Natsume, Masahiro; Estelle, Mark; Zhao, Yunde; Hayashi, Ken-ichiro; Kamiya, Yuji; Kasahara, Hiroyuki

    2015-01-01

    The phytohormone auxin plays a central role in many aspects of plant growth and development. IAA is the most studied natural auxin that possesses the property of polar transport in plants. Phenylacetic acid (PAA) has also been recognized as a natural auxin for >40 years, but its role in plant growth and development remains unclear. In this study, we show that IAA and PAA have overlapping regulatory roles but distinct transport characteristics as auxins in plants. PAA is widely distributed in vascular and non-vascular plants. Although the biological activities of PAA are lower than those of IAA, the endogenous levels of PAA are much higher than those of IAA in various plant tissues in Arabidopsis. PAA and IAA can regulate the same set of auxin-responsive genes through the TIR1/AFB pathway in Arabidopsis. IAA actively forms concentration gradients in maize coleoptiles in response to gravitropic stimulation, whereas PAA does not, indicating that PAA is not actively transported in a polar manner. The induction of the YUCCA (YUC) genes increases PAA metabolite levels in Arabidopsis, indicating that YUC flavin-containing monooxygenases may play a role in PAA biosynthesis. Our results provide new insights into the regulation of plant growth and development by different types of auxins. PMID:26076971

  1. Distinct Characteristics of Indole-3-Acetic Acid and Phenylacetic Acid, Two Common Auxins in Plants.

    PubMed

    Sugawara, Satoko; Mashiguchi, Kiyoshi; Tanaka, Keita; Hishiyama, Shojiro; Sakai, Tatsuya; Hanada, Kousuke; Kinoshita-Tsujimura, Kaori; Yu, Hong; Dai, Xinhua; Takebayashi, Yumiko; Takeda-Kamiya, Noriko; Kakimoto, Tatsuo; Kawaide, Hiroshi; Natsume, Masahiro; Estelle, Mark; Zhao, Yunde; Hayashi, Ken-Ichiro; Kamiya, Yuji; Kasahara, Hiroyuki

    2015-08-01

    The phytohormone auxin plays a central role in many aspects of plant growth and development. IAA is the most studied natural auxin that possesses the property of polar transport in plants. Phenylacetic acid (PAA) has also been recognized as a natural auxin for >40 years, but its role in plant growth and development remains unclear. In this study, we show that IAA and PAA have overlapping regulatory roles but distinct transport characteristics as auxins in plants. PAA is widely distributed in vascular and non-vascular plants. Although the biological activities of PAA are lower than those of IAA, the endogenous levels of PAA are much higher than those of IAA in various plant tissues in Arabidopsis. PAA and IAA can regulate the same set of auxin-responsive genes through the TIR1/AFB pathway in Arabidopsis. IAA actively forms concentration gradients in maize coleoptiles in response to gravitropic stimulation, whereas PAA does not, indicating that PAA is not actively transported in a polar manner. The induction of the YUCCA (YUC) genes increases PAA metabolite levels in Arabidopsis, indicating that YUC flavin-containing monooxygenases may play a role in PAA biosynthesis. Our results provide new insights into the regulation of plant growth and development by different types of auxins.

  2. Lysine Residues Are Not Required for Proteasome-Mediated Proteolysis of the Auxin/Indole Acidic Acid Protein IAA1.

    PubMed

    Gilkerson, Jonathan; Kelley, Dior R; Tam, Raymond; Estelle, Mark; Callis, Judy

    2015-06-01

    Although many ubiquitin-proteasome substrates have been characterized in plants, very little is known about the corresponding ubiquitin attachment(s) underlying regulated proteolysis. Current dogma asserts that ubiquitin is typically covalently attached to a substrate through an isopeptide bond between the ubiquitin carboxy terminus and a substrate lysyl amino group. However, nonlysine (non-Lys) ubiquitin attachment has been observed in other eukaryotes, including the N terminus, cysteine, and serine/threonine modification. Here, we investigate site(s) of ubiquitin attachment on indole-3-acetic acid1 (IAA1), a short-lived Arabidopsis (Arabidopsis thaliana) Auxin/indole-3-acetic acid (Aux/IAA) family member. Most Aux/IAA proteins function as negative regulators of auxin responses and are targeted for degradation after ubiquitination by the ubiquitin ligase SCF(TIR1/AFB) (for S-Phase Kinase-Associated Protein1, Cullin, F-box [SCF] with Transport Inhibitor Response1 [TIR1]/Auxin Signaling F-box [AFB]) by an interaction directly facilitated by auxin. Surprisingly, using a Histidine-Hemaglutinin (HIS(6x)-HA(3x)) epitope-tagged version expressed in vivo, Lys-less IAA1 was ubiquitinated and rapidly degraded in vivo. Lys-substituted versions of IAA1 localized to the nucleus as Yellow Fluorescent Protein fusions and interacted with both TIR1 and IAA7 in yeast (Saccharomyces cerevisiae) two-hybrid experiments, indicating that these proteins were functional. Ubiquitination on both HIS(6x)-HA(3x)-IAA1 and Lys-less HIS(6x)-HA(3x)-IAA1 proteins was sensitive to sodium hydroxide treatment, indicative of ubiquitin oxyester formation on serine or threonine residues. Additionally, base-resistant forms of ubiquitinated IAA1 were observed for HIS(6x)-HA(3x)-IAA1, suggesting additional lysyl-linked ubiquitin on this protein. Characterization of other Aux/IAA proteins showed that they have diverse degradation rates, adding additional complexity to auxin signaling. Altogether, these data

  3. Lysine Residues Are Not Required for Proteasome-Mediated Proteolysis of the Auxin/Indole Acidic Acid Protein IAA1.

    PubMed

    Gilkerson, Jonathan; Kelley, Dior R; Tam, Raymond; Estelle, Mark; Callis, Judy

    2015-06-01

    Although many ubiquitin-proteasome substrates have been characterized in plants, very little is known about the corresponding ubiquitin attachment(s) underlying regulated proteolysis. Current dogma asserts that ubiquitin is typically covalently attached to a substrate through an isopeptide bond between the ubiquitin carboxy terminus and a substrate lysyl amino group. However, nonlysine (non-Lys) ubiquitin attachment has been observed in other eukaryotes, including the N terminus, cysteine, and serine/threonine modification. Here, we investigate site(s) of ubiquitin attachment on indole-3-acetic acid1 (IAA1), a short-lived Arabidopsis (Arabidopsis thaliana) Auxin/indole-3-acetic acid (Aux/IAA) family member. Most Aux/IAA proteins function as negative regulators of auxin responses and are targeted for degradation after ubiquitination by the ubiquitin ligase SCF(TIR1/AFB) (for S-Phase Kinase-Associated Protein1, Cullin, F-box [SCF] with Transport Inhibitor Response1 [TIR1]/Auxin Signaling F-box [AFB]) by an interaction directly facilitated by auxin. Surprisingly, using a Histidine-Hemaglutinin (HIS(6x)-HA(3x)) epitope-tagged version expressed in vivo, Lys-less IAA1 was ubiquitinated and rapidly degraded in vivo. Lys-substituted versions of IAA1 localized to the nucleus as Yellow Fluorescent Protein fusions and interacted with both TIR1 and IAA7 in yeast (Saccharomyces cerevisiae) two-hybrid experiments, indicating that these proteins were functional. Ubiquitination on both HIS(6x)-HA(3x)-IAA1 and Lys-less HIS(6x)-HA(3x)-IAA1 proteins was sensitive to sodium hydroxide treatment, indicative of ubiquitin oxyester formation on serine or threonine residues. Additionally, base-resistant forms of ubiquitinated IAA1 were observed for HIS(6x)-HA(3x)-IAA1, suggesting additional lysyl-linked ubiquitin on this protein. Characterization of other Aux/IAA proteins showed that they have diverse degradation rates, adding additional complexity to auxin signaling. Altogether, these data

  4. Stable isotope labeling, in vivo, of D- and L-tryptophan pools in lemna gibba and the low incorporation of label into indole-3-acetic acid

    SciTech Connect

    Baldi, B.G. ); Maher, B.R. ); Slovin, J.P.; Cohen, J.D. Univ. of Maryland, College Park )

    1991-04-01

    The authors present evidence that the role of tryptophan and other potential intermediates in the pathways that could lead to indole derivatives needs to be reexamined. Two lines of Lemna gibba were tested for uptake of ({sup 15}N-indole)-labeled tryptophan isomers and incorporation of that label into free indole-3-acetic acid (IAA). Both lines required levels of L-({sup 15}N)tryptophan 2 to 3 orders of magnitude over endogenous levels in order to obtain measurable incorporation of label into IAA. Labeled L-tryptophan was extractable from plant tissue after feeding and showed no measurable isomerization into D-tryptophan. D-({sup 15}N)trytophan supplied to Lemna at rates of approximately 400 times excess of endogenous D-tryptophan levels (to yield an isotopic enrichment equal to that which allowed detection of the incorporation of L-tryptophan into IAA), did not result in measurable incorporation of label into free IAA. These results demonstrate that L-tryptophan is a more direct precursor to IAA than the D isomer and suggest (a) that the availability of tryptophan in vivo is not a limiting factor in the biosynthesis of IAA, thus implying that other regulatory mechanisms are in operation and (b) that L-tryptophan also may not be a primary precursor to IAA in plants.

  5. Biosynthesis of the Halogenated Auxin, 4-Chloroindole-3-Acetic Acid1[W][OA

    PubMed Central

    Tivendale, Nathan D.; Davidson, Sandra E.; Davies, Noel W.; Smith, Jason A.; Dalmais, Marion; Bendahmane, Abdelhafid I.; Quittenden, Laura J.; Sutton, Lily; Bala, Raj K.; Le Signor, Christine; Thompson, Richard; Horne, James; Reid, James B.; Ross, John J.

    2012-01-01

    Seeds of several agriculturally important legumes are rich sources of the only halogenated plant hormone, 4-chloroindole-3-acetic acid. However, the biosynthesis of this auxin is poorly understood. Here, we show that in pea (Pisum sativum) seeds, 4-chloroindole-3-acetic acid is synthesized via the novel intermediate 4-chloroindole-3-pyruvic acid, which is produced from 4-chlorotryptophan by two aminotransferases, TRYPTOPHAN AMINOTRANSFERASE RELATED1 and TRYPTOPHAN AMINOTRANSFERASE RELATED2. We characterize a tar2 mutant, obtained by Targeting Induced Local Lesions in Genomes, the seeds of which contain dramatically reduced 4-chloroindole-3-acetic acid levels as they mature. We also show that the widespread auxin, indole-3-acetic acid, is synthesized by a parallel pathway in pea. PMID:22573801

  6. Crystal Structure of an Indole-3-Acetic Acid Amido Synthetase from Grapevine Involved in Auxin Homeostasis[W

    PubMed Central

    Peat, Thomas S.; Böttcher, Christine; Newman, Janet; Lucent, Del; Cowieson, Nathan; Davies, Christopher

    2012-01-01

    Auxins are important for plant growth and development, including the control of fruit ripening. Conjugation to amino acids by indole-3-acetic acid (IAA)-amido synthetases is an important part of auxin homeostasis. The structure of the auxin-conjugating Gretchen Hagen3-1 (GH3-1) enzyme from grapevine (Vitis vinifera), in complex with an inhibitor (adenosine-5′-[2-(1H-indol-3-yl)ethyl]phosphate), is presented. Comparison with a previously published benzoate-conjugating enzyme from Arabidopsis thaliana indicates that grapevine GH3-1 has a highly similar domain structure and also undergoes a large conformational change during catalysis. Mutational analyses and structural comparisons with other proteins have identified residues likely to be involved in acyl group, amino acid, and ATP substrate binding. Vv GH3-1 is a monomer in solution and requires magnesium ions solely for the adenlyation reaction. Modeling of IAA and two synthetic auxins, benzothiazole-2-oxyacetic acid (BTOA) and 1-naphthaleneacetic acid (NAA), into the active site indicates that NAA and BTOA are likely to be poor substrates for this enzyme, confirming previous enzyme kinetic studies. This suggests a reason for the increased effectiveness of NAA and BTOA as auxins in planta and provides a tool for designing new and effective auxins. PMID:23136372

  7. Location of transported auxin in etiolated maize shoots using 5-azidoindole-3-acetic acid. [Zea mays L

    SciTech Connect

    Jones, A.M. )

    1990-07-01

    A study was undertaken using the photoaffinity labeling agent, tritiated 5-azidoindole-3-acetic acid (({sup 3}H),5-N{sub 3}IAA), to identify cells in the etiolated maize (Zea mays L.) shoot which transport auxin. Transport of ({sup 3}H),5-N{sub 3}IAA was shown to be polar, inhibited by 2,3,5-triiodobenzoic acid (TIBA) and essentially freely mobile. There was no detectable radiodecomposition of ({sup 3}H),5-N{sub 3}IAA within tissue kept in darkness for 4 hours. Shoot tissue which had taken up ({sup 3}H),5-N{sub 3}IAA was irradiated with ultraviolet light to covalently fix the photoaffinity labeling agent within cells that contained it at the time of photolysis. Subsequent microautoradiography showed that all cells contained radioactivity; however, the amount of radioactivity varied among different cell types. Epidermal cells contained the most radioactivity per area, approximately twofold more than other cells. Parenchyma cells in the mature stelar region contained the next largest amount and cortical cells, sieve tube cells, tracheary cells, and all cells in the leaf base contained the least amount of the radioactive label. Two observations suggest that the auxin within the epidermal cells is transported in a polar manner: (a) the amount of auxin in the epidermal cells is greatly reduced in the presence of TIBA, and (b) auxin accumulates on the apical side of a wound in the epidermis and is absent on the basal side. While these results indicate that auxin in the epidermis is polarly transported, this tissue cannot be the only pathway since the epidermis is only a small fraction of the shoot volume.

  8. Gibberellic acid, kinetin, and the mixture indole-3-acetic acid-kinetin assisted with EDTA-induced lead hyperaccumnulation in alfalfa plants.

    PubMed

    López, Martha L; Peralta-Videa, José R; Parsons, Jason G; Benitez, Tenoch; Gardea-Torresdey, Jorge L

    2007-12-01

    There are a few plant species considered potential hyperaccumulators for heavy metals, particularly lead (Pb). In this study, alfalfa plants grown in hydroponics were exposed to Pb at 40 mg/L, ethylenediaminetetraacetic acid (EDTA) equimolar to Pb, and 1, 10, and 100 microM concentrations of the phytohormones indole-3-acetic acid (IAA), gibberellic acid (GA), and kinetin (KN) and a mixture of IAA and KN at 100 microM each. Metal quantification by inductively coupled plasma/optical emission spectroscopy demonstrated that plants treated with Pb/EDTA plus KN at 1, 10, and 100 microM increased the Pb concentration in alfalfa leaves (compared to Pb alone) by factors of 17, 43, and 67, respectively, and by factors of 2, 5, and 8, respectively, compared to the Pb/EDTA treatment. The correlation coefficient between the Pb concentration in leaves and the concentrations of KN in the medium was 0.9993. In addition, the leaves of plants exposed to a Pb/EDTA/100 microM IAA-KN mixture had approximately 9500 mg of Pb/kg of dry weight, demonstrating that non-Pb hyperaccumulating plants could hyperaccumulate Pb when treated with EDTA and a mixture of IAA-KN. The X-ray absorption spectroscopic studies demonstrated that the absorption and translocation of Pb was in the same oxidation state as the supplied Pb(II).

  9. Improvement of phosphate solubilization and Medicago plant yield by an indole-3-acetic acid-overproducing strain of Sinorhizobium meliloti.

    PubMed

    Bianco, Carmen; Defez, Roberto

    2010-07-01

    Nitrogen (N) and phosphorus (P) are the most limiting factors for plant growth. Some microorganisms improve the uptake and availability of N and P, minimizing chemical fertilizer dependence. It has been published that the RD64 strain, a Sinorhizobium meliloti 1021 strain engineered to overproduce indole-3-acetic acid (IAA), showed improved nitrogen fixation ability compared to the wild-type 1021 strain. Here, we present data showing that RD64 is also highly effective in mobilizing P from insoluble sources, such as phosphate rock (PR). Under P-limiting conditions, the higher level of P-mobilizing activity of RD64 than of the 1021 wild-type strain is connected with the upregulation of genes coding for the high-affinity P transport system, the induction of acid phosphatase activity, and the increased secretion into the growth medium of malic, succinic, and fumaric acids. Medicago truncatula plants nodulated by RD64 (Mt-RD64), when grown under P-deficient conditions, released larger amounts of another P-solubilizing organic acid, 2-hydroxyglutaric acid, than plants nodulated by the wild-type strain (Mt-1021). It has already been shown that Mt-RD64 plants exhibited higher levels of dry-weight production than Mt-1021 plants. Here, we also report that P-starved Mt-RD64 plants show significant increases in both shoot and root fresh weights when compared to P-starved Mt-1021 plants. We discuss how, in a Rhizobium-legume model system, a balanced interplay of different factors linked to bacterial IAA overproduction rather than IAA production per se stimulates plant growth under stressful environmental conditions and, in particular, under P starvation. PMID:20511434

  10. Influence of tryptophan and indole-3-acetic acid on starch accumulation in the synthetic mutualistic Chlorella sorokiniana-Azospirillum brasilense system under heterotrophic conditions.

    PubMed

    Palacios, Oskar A; Choix, Francisco J; Bashan, Yoav; de-Bashan, Luz E

    2016-06-01

    This study measured the relations between tryptophan production, the phytohormone indole-3-acetic acid (IAA) and the metabolism and accumulation of starch during synthetic mutualism between the microalgae Chlorella sorokiniana and the microalgae growth-promoting bacteria Azospirillum brasilense, created by co-immobilization in alginate beads. Experiments used two wild-type A. brasilense strains (Cd and Sp6) and an IAA-attenuated mutant (SpM7918) grown under nitrogen-replete and nitrogen-starved conditions tested under dark, heterotrophic and aerobic growth conditions. Under all incubating conditions, C. sorokiniana, but not A. brasilense, produced tryptophan. A significant correlation between IAA-production by A. brasilense and starch accumulation in C. sorokiniana was found, since the IAA-attenuated mutant was not producing increased starch levels. The highest ADP-glucose pyrophosphorylase (AGPase) activity, starch content and glucose uptake were found during the interaction of A. brasilense wild type strains with the microalgae. When the microalgae were grown alone, they produced only small amounts of starch. Supplementation with synthetic IAA to C. sorokiniana grown alone enhanced the above parameters, but only transiently. Activity of α-amylase decreased under nitrogen-replete conditions, but increased under nitrogen-starved conditions. In summary, this study demonstrated that, during synthetic mutualism, the exchange of tryptophan and IAA between the partners is a mechanism that governs several changes in starch metabolism of C. sorokiniana, yielding an increase in starch content.

  11. Selection and Characterization of [alpha]-Methyltryptophan-Resistant Lines of Lemna gibba Showing a Rapid Rate of Indole-3-Acetic Acid Turnover.

    PubMed Central

    Tam, Y. Y.; Slovin, J. P.; Cohen, J. D.

    1995-01-01

    Turnover rate is an important aspect of the regulation of plant processes by plant growth substances. To study turnover of indole-3-acetic acid (IAA), two [alpha]-methyltryptophan-resistant lines (MTR1 and MTR2) of Lemna gibba were generated by nitrosomethyl urea treatment of an inbred line derived from L. gibba G-3. In this report we describe: (a) the development of a selection system using this near isogenic line of L. gibba; (b) techniques for chemical mutation of the lines and selection for [alpha]-methyltryptophan resistance; and (c) the partial characterization of the selected lines. MTR lines contained 3-fold higher levels of anthranilate synthase activity. The enzyme in the MTR lines required higher levels of tryptophan for feedback inhibition. MTR lines also contained 8-fold higher levels of tryptophan, 3-fold higher levels of free IAA, and similar levels of total IAA compared to the inbred line. Turnover rates in the inbred and selected lines were calculated, using the first-order rate equation, based on the decrease over time in isotopic enrichment of I3C6-IAA introduced into L. gibba during a 1-h pulse period. Isotope enrichment in IAA was determined by using gas chromatography-mass spectrometry. Both MTR lines had an approximately 10-fold higher rate of IAA turnover than the parent inbred line. PMID:12228344

  12. Effect of Exogenous Indole-3-Acetic Acid and Indole-3-Butyric Acid on Internal Levels of the Respective Auxins and Their Conjugation with Aspartic Acid during Adventitious Root Formation in Pea Cuttings.

    PubMed

    Nordström, A C; Jacobs, F A; Eliasson, L

    1991-07-01

    The influence of exogenous indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) on the internal levels of these auxins was studied during the first 4 days of adventitious root formation in cuttings of Pisum sativum L. The quantitations were done by high performance liquid chromatography with spectrofluorometric detection. IBA, identified by combined gas chromatography-mass spectrometry (GC-MS), was found to naturally occur in this plant material. The root inducing ability of exogenous IBA was superior to that of IAA. The IAA level in the tissue increased considerably on the first day after application of IAA, but rapidly decreased again, returning to a level twice the control by day 3. The predominant metabolic route was conjugation with aspartic acid, as reflected by the increase in the level of indole-3-acetylaspartic acid. The IBA treatment resulted in increases in the levels of IBA, IAA, and indole-3-acetylaspartic acid. The IAA content rapidly returned to control levels, whereas the IBA level remained high throughout the experimental period. High amounts of indole-3-butyrylaspartic acid were found in the tissue after feeding with IBA. The identity of the conjugate was confirmed by (1)H-nuclear magnetic resonance and GC-MS. IBA was much more stable in solution than IAA. No IAA was detected after 48 hours, whereas 70% IBA was still recovered after this time. The relatively higher root inducing ability of IBA is ascribed to the fact that its level remained elevated longer than that of IAA, even though IBA was metabolized in the tissue. Adventitious root formation is discussed on the basis of these findings. PMID:16668265

  13. Orchid-associated bacteria produce indole-3-acetic acid, promote seed germination, and increase their microbial yield in response to exogenous auxin.

    PubMed

    Tsavkelova, Elena A; Cherdyntseva, Tatiana A; Klimova, Svetlana Yu; Shestakov, Andrey I; Botina, Svetlana G; Netrusov, Alexander I

    2007-12-01

    Germination of orchid seeds is a complex process. In this paper we focus on interactions between the host-plant and its bacterial partners via indole-3-acetic acid (IAA). Originally isolated from the roots of the epiphytic orchid Dendrobium moschatum, the strains of Rhizobium, Microbacterium, Sphingomonas, and Mycobacterium genera were among the most active IAA producers. Addition of exogenous tryptophan significantly enhanced auxin formation both in mineral and complex media. The presence of IAA and indole-3-acetaldehyde was confirmed by HPLC. Indole-3-pyruvic and indole-3-lactic acids were also detected in supernatants of culture filtrates of Sphingomonas sp., Rhizobium sp., and Microbacterium sp., while indole-3-acetamide was identified only in Mycobacterium sp. Some concentration- and strain-dependent effects of exogenous IAA on bacterial development were also established. Treatment of the cultures with 10 and 100 microg/ml of auxin resulted in an increase in microbial yield. None of the investigated strains was able to utilize IAA as a source of carbon and energy. Furthermore, inoculation of D. moschatum seeds with Sphingomonas sp. and Mycobacterium sp. resulted in considerable enhancement of orchid seeds germination. This growth-promoting activity was observed in the absence of any plant growth stimulators or mycorrhizal fungi, usually required for orchid germination.

  14. Induction of oxidative stress in Prototheca zopfii by indole-3-acetic acid/HRP or 2,4-pentanedione/HRP systems and their oxidation products.

    PubMed

    Cunha, L T; Pugine, S M P; Lins, P G; Brunetti, I L; De Melo, M P

    2015-02-01

    We investigated the toxic effects on Prototheca zopfii of indole-3-acetic acid (IAA) and 2,4-pentanedione (PD) combined with horseradish peroxidase (HRP) alongside the oxidation products of 3-methyl-2-oxindole (MOI) and indole-3-carbinol (I3C) from the IAA/HRP system and methylglyoxal (MGO) from the PD/HRP system. The microorganism was incubated in the absence (control) or presence of IAA, PD, IAA/HRP, PD/HRP, MOI, I3C and MGO and determined: (1) cytotoxicity by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium) assay; (2) growth inhibitory concentration by resazurin assay and (3) antioxidant enzymes activities of: catalase (CAT), glutathione reductase (GR) and superoxide dismutase (SOD). P. zopfii was more susceptible to IAA at 40 mM than PD at the same concentration, which seems to indicate that IAA was more effective at initiating cell death. These data corroborate results from the resazurin assay. Concentrations of 40 mM of IAA, IAA/HRP and PD/HRP, 20 mM of PD/HRP, 10 mM of MOI, 2 mM of I3C and 8 mM of MGO inhibited the growth of P. zopfii. With sub-inhibitory concentrations of IAA and IAA/HRP at 30 mM, MOI at 8 mM and I3C at 1 mM, the activities of CAT and GR increased, whereas no statistical difference was observed for CAT activity with IAA/HRP. Thus, PD at 30 mM and MGO at 6 mM increased the activities of CAT and GR, whereas PD/HRP system at 15 mM decreased CAT activity and PD/HRP and MGO showed no statistical difference for SOD activity. In conclusion, IAA/HRP or PD/HRP systems and their oxidation products exert cytotoxic effects on P. zopffi; however, I3C and MGO appear to exert greater microbicidal effect on P. zopfii. PMID:25173924

  15. Overproduction of Indole-3-Acetic Acid in Free-Living Rhizobia Induces Transcriptional Changes Resembling Those Occurring in Nodule Bacteroids.

    PubMed

    Defez, Roberto; Esposito, Roberta; Angelini, Claudia; Bianco, Carmen

    2016-06-01

    Free-living bacteria grown under aerobic conditions were used to investigate, by next-generation RNA sequencing analysis, the transcriptional profiles of Sinorhizobium meliloti wild-type 1021 and its derivative, RD64, overproducing the main auxin indole-3-acetic acid (IAA). Among the upregulated genes in RD64 cells, we detected the main nitrogen-fixation regulator fixJ, the two intermediate regulators fixK and nifA, and several other genes known to be FixJ targets. The gene coding for the sigma factor RpoH1 and other genes involved in stress response, regulated in a RpoH1-dependent manner in S. meliloti, were also induced in RD64 cells. Under microaerobic condition, quantitative real-time polymerase chain reaction analysis revealed that the genes fixJL and nifA were up-regulated in RD64 cells as compared with 1021 cells. This work provided evidence that the overexpression of IAA in S. meliloti free-living cells induced many of the transcriptional changes that normally occur in nitrogen-fixing root nodule. PMID:27003799

  16. Diversity of culturable yeasts in phylloplane of sugarcane in Thailand and their capability to produce indole-3-acetic acid.

    PubMed

    Limtong, Savitree; Kaewwichian, Rungluk; Yongmanitchai, Wichien; Kawasaki, Hiroko

    2014-06-01

    Yeasts were isolated by the enrichment technique from the phylloplane of 94 samples of sugarcane leaf collected from seven provinces in Thailand. All sugarcane leaf samples contained yeasts and 158 yeast strains were obtained. On the basis of the D1/D2 domain of the large subunit rRNA gene sequence analysis, 144 strains were identified to 24 known species in 14 genera belonging to the Ascomycota viz. Candida akabanensis, Candida dendronema, Candida mesorugosa, Candida michaelii, Candida nivariensis, Candida rugosa, Candida orthopsilosis, Candida quercitrusa, Candida tropicalis, Candida xylopsoci, Cyberlindnera fabianii, Cyberlindnera rhodanensis, Debaryomyces nepalensis, Hannaella aff. coprosmaensis, Hanseniaspora guilliermondii, Kluyveromyces marxianus, Lachancea thermotolerans, Lodderomyces elongisporus, Metschnikowia koreensis, Meyerozyma caribbica, Millerozyma koratensis, Pichia kudriavzevii, Torulaspora delbrueckii and Wickerhamomyces edaphicus, and 12 species in six genera of the Basidiomycota viz . Cryptococcus flavescens, Cryptococcus laurentii, Cryptococcus rajasthanensis, Kwoniella heveanensis, Rhodosporidium fluviale, Rhodosporidium paludigenum, Rhodotorula mucilaginosa, Rhodotorula sesimbrana, Rhodotorula taiwanensis, Sporidiobolus ruineniae, Sporobolomyces carnicolor and Sporobolomyces nylandii. Seven strains were identical or similar to four undescribed species. Another seven strains represented four novels species in the genus Metschnikowia, Nakazawaea, Wickerhamomyces and Yamadazyma. The results revealed 69 % of the isolated strains were ascomycete yeasts and 31 % were basidiomycete yeast. The most prevalent species was M. caribbica with a 23 % frequency of occurrence followed by Rh. taiwanensis (11 %) and C. tropicalis (10 %). All strains were assessed for indole-3-acetic acid (IAA) producing capability showing that 69 strains had the capability of producing IAA when cultivated in yeast extract peptone dextrose broth supplemented with 1

  17. Diversity of culturable yeasts in phylloplane of sugarcane in Thailand and their capability to produce indole-3-acetic acid.

    PubMed

    Limtong, Savitree; Kaewwichian, Rungluk; Yongmanitchai, Wichien; Kawasaki, Hiroko

    2014-06-01

    Yeasts were isolated by the enrichment technique from the phylloplane of 94 samples of sugarcane leaf collected from seven provinces in Thailand. All sugarcane leaf samples contained yeasts and 158 yeast strains were obtained. On the basis of the D1/D2 domain of the large subunit rRNA gene sequence analysis, 144 strains were identified to 24 known species in 14 genera belonging to the Ascomycota viz. Candida akabanensis, Candida dendronema, Candida mesorugosa, Candida michaelii, Candida nivariensis, Candida rugosa, Candida orthopsilosis, Candida quercitrusa, Candida tropicalis, Candida xylopsoci, Cyberlindnera fabianii, Cyberlindnera rhodanensis, Debaryomyces nepalensis, Hannaella aff. coprosmaensis, Hanseniaspora guilliermondii, Kluyveromyces marxianus, Lachancea thermotolerans, Lodderomyces elongisporus, Metschnikowia koreensis, Meyerozyma caribbica, Millerozyma koratensis, Pichia kudriavzevii, Torulaspora delbrueckii and Wickerhamomyces edaphicus, and 12 species in six genera of the Basidiomycota viz . Cryptococcus flavescens, Cryptococcus laurentii, Cryptococcus rajasthanensis, Kwoniella heveanensis, Rhodosporidium fluviale, Rhodosporidium paludigenum, Rhodotorula mucilaginosa, Rhodotorula sesimbrana, Rhodotorula taiwanensis, Sporidiobolus ruineniae, Sporobolomyces carnicolor and Sporobolomyces nylandii. Seven strains were identical or similar to four undescribed species. Another seven strains represented four novels species in the genus Metschnikowia, Nakazawaea, Wickerhamomyces and Yamadazyma. The results revealed 69 % of the isolated strains were ascomycete yeasts and 31 % were basidiomycete yeast. The most prevalent species was M. caribbica with a 23 % frequency of occurrence followed by Rh. taiwanensis (11 %) and C. tropicalis (10 %). All strains were assessed for indole-3-acetic acid (IAA) producing capability showing that 69 strains had the capability of producing IAA when cultivated in yeast extract peptone dextrose broth supplemented with 1

  18. Comparative Indole-3-Acetic Acid Levels in the Slender Pea and Other Pea Phenotypes 1

    PubMed Central

    Law, David M.; Davies, Peter J.

    1990-01-01

    Free indole-3-acetic acid levels were measured by gas chromatography-mass spectrometry in three ultra-tall `slender' Pisum sativum L. lines differing in gibberellin content. Measurements were made for apices and stem elongation zones of light-grown plants and values were compared with wild-type, dwarf, and nana phenotypes in which internode length is genetically regulated, purportedly via the gibberellin level. Indole-3-acetic acid levels of growing stems paralleled growth rates in all lines, and were high in all three slender genotypes. Growth was inhibited by p-chlorophenoxyisobutyric acid, demonstrating the requirement of auxin activity for stem elongation, and also by the ethylene precursor 1-aminocyclopropane-1-carboxylic acid. It is concluded that the slender phenotype may arise from constant activation of a gibberellin receptor or transduction chain event leading directly or indirectly to elevated levels of indole-3-acetic acid, and that increased indole-3-acetic acid levels are a significant factor in the promotion of stem elongation. PMID:16667653

  19. Isolation and characterization of esters of indole-3-acetic acid from the liquid endosperm of the horse chestnut (Aesculus species)

    NASA Technical Reports Server (NTRS)

    Domagalski, W.; Schulze, A.; Bandurski, R. S.

    1987-01-01

    Esters of indole-3-acetic acid were extracted and purified from the liquid endosperm of immature fruits of various species of the horse chestnut (Aesculus parviflora, A. baumanni, A. pavia rubra, and A. pavia humulis). The liquid endosperm contained, at least 12 chromatographically distinct esters. One of these compounds was purified and characterized as an ester of indole-3-acetic acid and myo-inositol. A second compound was found to be an ester of indole-3-acetic acid and the disaccharide rutinose (glucosyl-rhamnose). A third compound was partially characterized as an ester of indole-3-acetic acid and a desoxyaminohexose.

  20. Induction of karyopherin α1 expression by indole-3-acetic acid in auxin-treated or overproducing tobacco plants.

    PubMed

    Rand, Karin; Kobrinsky-Aaronowitz, Irina; Levy, Yael; Shaul, Orit; Aloni, Roni; Gafni, Yedidya

    2011-06-01

    Macromolecules may transfer between the cytoplasm and the nucleus only through specific gates - the nuclear pore complexes (NPCs). Translocation of nucleic acids and large proteins requires the presence of a nuclear localization signal (NLS) within the transported molecule. This NLS is recognized by a class of soluble transport receptors termed karyopherins α and beta. We previously characterized the expression pattern of the tomato karyopherin α 1 (LeKAPα1) promoter in transformed tobacco plants. Expression of LeKAPα1 was mainly observed in growing tissues where cell division and extension is rapid. The expression pattern of LeKAPα1 resembled that of auxin-responsive genes. This led us to suggest that auxin participates in the regulation of LeKAPα1 expression. Here we characterized the correlation between auxin level and the activity of the LeKAPα1 promoter. To this end, transgenic tobacco plants carrying the GUS reporter gene under the control of the LeKAPα1 promoter were treated with various levels of exogenous auxin. We also studied transgenic plants in which we increased the endogenous levels of auxin. For this, we expressed in plants both the LeKAPα1 promoter-GUS reporter and the Agrobacterium tumefaciens iaaM gene, which increases the endogenous levels of auxin. The results indicate that the auxin indole-3-acetic acid (IAA) can induce LeKAPα1 expression. We also identified that the sites and levels of LeKAPα1 expression correlated with the endogenous pathways of polar auxin transport.

  1. An ipdC gene knock-out of Azospirillum brasilense strain SM and its implications on indole-3-acetic acid biosynthesis and plant growth promotion.

    PubMed

    Malhotra, Mandira; Srivastava, Sheela

    2008-05-01

    The indole-3-pyruvate decarboxylase gene (ipdC), coding for a key enzyme of the indole-3-pyruvic acid pathway of IAA biosynthesis in Azospirillum brasilense SM was functionally disrupted in a site-specific manner. This disruption was brought about by group II intron-based Targetron gene knock-out system as other conventional methods were unsuccessful in generating an IAA-attenuated mutant. Intron insertion was targeted to position 568 on the sense strand of ipdC, resulting in the knock-out strain, SMIT568s10 which showed a significant (~50%) decrease in the levels of indole-3-acetic acid, indole-3-acetaldehyde and tryptophol compared to the wild type strain SM. In addition, a significant decrease in indole-3-pyruvate decarboxylase enzyme activity by approximately 50% was identified confirming a functional knock-out. Consequently, a reduction in the plant growth promoting response of strain SMIT568s10 was observed in terms of root length and lateral root proliferation as well as the total dry weight of the treated plants. Residual indole-3-pyruvate decarboxylase enzyme activity, and indole-3-acetic acid, tryptophol and indole-3-acetaldehyde formed along with the plant growth promoting response by strain SMIT568s10 in comparison with an untreated set suggest the presence of more than one copy of ipdC in the A. brasilense SM genome.

  2. Pseudomonas induces salinity tolerance in cotton (Gossypium hirsutum) and resistance to Fusarium root rot through the modulation of indole-3-acetic acid

    PubMed Central

    Egamberdieva, Dilfuza; Jabborova, Dilfuza; Hashem, Abeer

    2015-01-01

    Abiotic stresses cause changes in the balance of phytohormones in plants and result in inhibited root growth and an increase in the susceptibility of plants to root rot disease. The aim of this work was to ascertain whether microbial indole-3-acetic acid (IAA) plays a role in the regulation of root growth and microbially mediated control of root rot of cotton caused by Fusarium solani. Seed germination and seedling growth were improved by both NaCl and Mg2SO4 (100 mM) solutions when treated with root-associated bacterial strains Pseudomonas putida R4 and Pseudomonas chlororaphis R5, which are able to produce IAA. These bacterial strains were also able to reduce the infection rate of cotton root rot (from 70 to 39%) caused by F. solani under gnotobiotic conditions. The application of a low concentration of IAA (0.01 and 0.001 μg/ml) stimulated plant growth and reduced disease incidence caused by F. solani (from 70 to 41–56%, respectively). Shoot and root growth and dry matter increased significantly and disease incidence was reduced by bacterial inoculants in natural saline soil. These results suggest that bacterial IAA plays a major role in salt stress tolerance and may be involved in induced resistance against root rot disease of cotton. PMID:26587006

  3. Interference-free determination of indole-3-acetic acid in two real systems using second-order calibration method coupled with excitation-emission matrix fluorescence.

    PubMed

    Yan, Xiu-Fang; Wu, Hai-Long; Qing, Xiang-Dong; Sun, Yan-Mei; Yu, Ru-Qin

    2014-01-01

    In this work, a simple and practicable method that combines excitation-emission matrix (EEMs) fluorescence with a second-order calibration method based on parallel factor analysis-alternative least-squares (PARAFAC-ALS) algorithm was developed for the direct interference-free determination of indole-3-acetic acid (IAA) in two real systems, coconut water (CW) and coconut milk (CM). Although the excitation and emission profiles of IAA heavily overlapped with that of unknown interferents in the complex real systems, the actual contents and satisfactory recoveries were still obtained successfully. The contents of IAA in CW and CM were 10.8 ± 0.3 and 4.9 ± 0.2 μg mL(-1), respectively, which were consistent with those reported by LC-MS/MS assays in the reference material. The average spike recoveries of IAA in the validation set based on CW and CM were 102.1 ± 3.2 and 98.0 ± 1.9%, respectively. In addition, routine experiments were performed for establishing the validity of the assay to internationally accepted criteria. PMID:24717659

  4. The involvement of indole-3-acetic acid in the control of stem elongation in dark- and light-grown pea (Pisum sativum) seedlings.

    PubMed

    Sorce, Carlo; Picciarelli, Piero; Calistri, Gianni; Lercari, Bartolomeo; Ceccarelli, Nello

    2008-01-01

    We investigated the role of auxin on stem elongation in pea (Pisum sativum L.) grown for 10d in continuous darkness or under low-irradiance blue, red, far red and white light. The third internode of treated seedlings was peeled and the tissues (epidermis and cortex+central cylinder) were separately analyzed for the concentration of free and conjugated indole-3-acetic acid (IAA). Under red, far red and white light internode elongation was linearly related with the free IAA content of all internode tissues, suggesting that phytochrome-dependent inhibition of stem growth may be mediated by a decrease of free IAA levels in pea seedlings. The correlation between IAA and internode elongation, however, did not hold for blue light-grown seedlings. The hypothesis that the growth response under low-irradiance blue light might be correlated with the lack of phytochrome B signalling and changes in gibberellin metabolism is discussed in view of current knowledge on hormonal control of stem growth. PMID:17706834

  5. Screening and optimization of indole-3-acetic acid production and phosphate solubilization from rhizobacteria aimed at improving plant growth.

    PubMed

    Chaiharn, Mathurot; Lumyong, Saisamorn

    2011-01-01

    A total of 216 bacterial strains were isolated from rice rhizospheric soils in Northern Thailand. The bacterial strains were initially tested for solubilization of inorganic phosphate, indole acetic acid (IAA) production, selected strains were then tested for optimized conditions for IAA production and whether these caused stimulatory effects on bean and maize seedling growth. It was found that all strains had solubilized inorganic phosphate (P), but only 18.05% produced IAA. The best IAA producer was identified by biochemical testing and 16S rDNA sequence analysis as Klebsiella SN 1.1. In addition to being the best IAA producer, this strain was a high P-solubilizer and produced the highest amount of IAA (291.97 ± 0.19 ppm) in culture media supplemented with L-tryptophan. The maximum production of IAA was achieved after 9 days of incubation. The culture requirements were optimized for maximum IAA production. The tested of IAA production by selected isolates was studied in a medium with 0, 0.1, 0.2, 0.5, 0.7, and 0.9% (v/v) L-tryptophan. Low levels (12.6 ppm) of IAA production was recorded without tryptophan addition. Production of IAA in Klebsiella SN 1.1 increased with an increase to 0.2% (v/v) tryptophan concentration. The production of IAA was further confirmed by extraction of crude IAA from this isolate and subsequent Thin Layer Chromatography (TLC) analysis. A specific spot from the extracted IAA production was found to correspond with a standard spot of IAA with the same R (f) value. The Klebsiella strain SN 1.1 also demonstrated stimulatory effects on bean seedlings in vivo. PMID:20552360

  6. Effect of K+ and Ca2+ on the indole-3-acetic acid- and fusicoccin-induced growth and membrane potential in maize coleoptile cells.

    PubMed

    Siemieniuk, Agnieszka; Karcz, Waldemar

    2015-06-30

    The role of potassium (K(+)) and calcium (Ca(2+)) in the regulation of plant growth and development is complex and needs a diverse range of physiological studies. Both elements are essential for satisfactory crop production. Here, the effects of K(+) and Ca(2+) ions on endogenous growth and growth in the presence of either indole-3-acetic acid (IAA) or fusicoccin (FC) were studied in maize (Zea mays) coleoptiles. Membrane potentials of coleoptile parenchymal cells, incubated in media containing IAA, FC and different concentrations of K(+) and Ca(2+), were also determined. Growth experiments have shown that in the absence of K(+) in the incubation medium, both endogenous and IAA- or FC-induced growth were significantly inhibited by 0.1 and 1 mM Ca(2+), respectively, while in the presence of 1 mM K(+) they were inhibited only by 1 mM Ca(2+). At 10 mM K(+), endogenous growth and growth induced by either IAA or FC did not depend on Ca(2+) concentration. TEA-Cl, a potassium channel blocker, added 1 h before IAA or FC, caused a reduction of growth by 59 or 45 %, respectively. In contrast to TEA-Cl, verapamil, the Ca(2+) channel blocker, did not affect IAA- and FC-induced growth. It was also found that in parenchymal cells of maize coleoptile segments, membrane potential (Em) was strongly affected by the medium K(+), independently of Ca(2+). However, lack of Ca(2+) in the incubation medium significantly reduced the IAA- and FC-induced membrane potential hyperpolarization. TEA-Cl applied to the control medium in the same way as in growth experiments caused Em hyperpolarization synergistic with hyperpolarization produced by IAA or FC. Verapamil did not change either the Em of parenchymal cells incubated in the control medium or the IAA- and FC-induced membrane hyperpolarization. The data presented here have been discussed considering the role of K(+) uptake channels in regulation of plant cell growth.

  7. Effect of K+ and Ca2+ on the indole-3-acetic acid- and fusicoccin-induced growth and membrane potential in maize coleoptile cells

    PubMed Central

    Siemieniuk, Agnieszka; Karcz, Waldemar

    2015-01-01

    The role of potassium (K+) and calcium (Ca2+) in the regulation of plant growth and development is complex and needs a diverse range of physiological studies. Both elements are essential for satisfactory crop production. Here, the effects of K+ and Ca2+ ions on endogenous growth and growth in the presence of either indole-3-acetic acid (IAA) or fusicoccin (FC) were studied in maize (Zea mays) coleoptiles. Membrane potentials of coleoptile parenchymal cells, incubated in media containing IAA, FC and different concentrations of K+ and Ca2+, were also determined. Growth experiments have shown that in the absence of K+ in the incubation medium, both endogenous and IAA- or FC-induced growth were significantly inhibited by 0.1 and 1 mM Ca2+, respectively, while in the presence of 1 mM K+ they were inhibited only by 1 mM Ca2+. At 10 mM K+, endogenous growth and growth induced by either IAA or FC did not depend on Ca2+ concentration. TEA-Cl, a potassium channel blocker, added 1 h before IAA or FC, caused a reduction of growth by 59 or 45 %, respectively. In contrast to TEA-Cl, verapamil, the Ca2+ channel blocker, did not affect IAA- and FC-induced growth. It was also found that in parenchymal cells of maize coleoptile segments, membrane potential (Em) was strongly affected by the medium K+, independently of Ca2+. However, lack of Ca2+ in the incubation medium significantly reduced the IAA- and FC-induced membrane potential hyperpolarization. TEA-Cl applied to the control medium in the same way as in growth experiments caused Em hyperpolarization synergistic with hyperpolarization produced by IAA or FC. Verapamil did not change either the Em of parenchymal cells incubated in the control medium or the IAA- and FC-induced membrane hyperpolarization. The data presented here have been discussed considering the role of K+ uptake channels in regulation of plant cell growth. PMID:26134122

  8. Enterococcus faecium LKE12 Cell-Free Extract Accelerates Host Plant Growth via Gibberellin and Indole-3-Acetic Acid Secretion.

    PubMed

    Lee, Ko-Eun; Radhakrishnan, Ramalingam; Kang, Sang-Mo; You, Young-Hyun; Joo, Gil-Jae; Lee, In-Jung; Ko, Jae-Hwan; Kim, Jin-Ho

    2015-09-01

    The use of microbial extracts containing plant hormones is a promising technique to improve crop growth. Little is known about the effect of bacterial cell-free extracts on plant growth promotion. This study, based on phytohormonal analyses, aimed at exploring the potential mechanisms by which Enterococcus faecium LKE12 enhances plant growth in oriental melon. A bacterial strain, LKE12, was isolated from soil, and further identified as E. faecium by 16S rDNA sequencing and phylogenetic analysis. The plant growth-promoting ability of an LKE12 bacterial culture was tested in a gibberellin (GA)-deficient rice dwarf mutant (waito-C) and a normal GA biosynthesis rice cultivar (Hwayongbyeo). E. faecium LKE12 significantly improved the length and biomass of rice shoots in both normal and dwarf cultivars through the secretion of an array of gibberellins (GA1, GA3, GA7, GA8, GA9, GA12, GA19, GA20, GA24, and GA53), as well as indole-3-acetic acid (IAA). To the best of our knowledge, this is the first study indicating that E. faecium can produce GAs. Increases in shoot and root lengths, plant fresh weight, and chlorophyll content promoted by E. faecium LKE12 and its cell-free extract inoculated in oriental melon plants revealed a favorable interaction of E. faecium LKE12 with plants. Higher plant growth rates and nutrient contents of magnesium, calcium, sodium, iron, manganese, silicon, zinc, and nitrogen were found in cell-free extract-treated plants than in control plants. The results of the current study suggest that E. faecium LKE12 promotes plant growth by producing GAs and IAA; interestingly, the exogenous application of its cell-free culture extract can be a potential strategy to accelerate plant growth.

  9. Indole-3-acetic acid biosynthetic pathway and aromatic amino acid aminotransferase activities in Pantoea dispersa strain GPK.

    PubMed

    Kulkarni, G B; Nayak, A S; Sajjan, S S; Oblesha, A; Karegoudar, T B

    2013-05-01

    This investigation deals with the production of IAA by a bacterial isolate Pantoea dispersa strain GPK (PDG) identified by 16S rRNA gene sequence analysis. HPLC and Mass spectral analysis of metabolites from bacterial spent medium revealed that, IAA production by PDG is Trp-dependent and follows indole-3-pyruvic acid (IPyA) pathway. Substrate specificity study of aromatic amino acid aminotransferase (AAT) showed high activities, only when tryptophan (Trp) and α-ketoglutarate (α-kg) were used as substrates. AAT is highly specific for Trp and α-kg as amino group donor and acceptor, respectively. The effect of exogenous IAA on bacterial growth was established. Low concentration of exogenous IAA induced the growth, whereas high concentration decreased the growth of bacterium. PDG treatment significantly increased the root length, shoot length and dry mass of the chickpea and pigeon pea plants. PMID:23448265

  10. Polar transport and accumulation of indole-3-acetic acid during root regeneration by Pinus lambertiana embryos.

    PubMed

    Greenwood, M S; Goldsmith, M H

    1970-12-01

    The relation of indoleacetic acid (IAA) transport to accumulation of auxin at the base of cuttings and to polar root formation was investigated with small cuttings from germinating embryos of Pinus lambertiana.The transport of endogenous auxin participates in regeneration of roots. This is shown by the facts that (1) more than 40% of the cuttings rooted without addition of exogenous indoleacetic acid; (2) the first regeneration always occurred at the basal tip of a slanting cut; and (3) 2,3,5-triiodobenzoic acid (TIBA), a specific inhibitor of auxin transport, totally inhibited rooting. Addition of IAA to the medium increased the number of roots formed per rooting hypocotyl.Sections of hypocotyls excised from dormant embryos and tested immediately after 2 h hydration were capable of polar transport of IAA. This polarity increased during the first 3 days of culture because of a marked increase in basipetal transport. Culturing the cuttings in 1 μM IAA for 3-5 days doubled both the basipetal transport of 1-(14)C-IAA by hypocotyl segments and the accumulation of radioactivity at the base of cuttings.The extent of the accumulation at the base of cuttings was similar at early (2 days, first mitoses) and late stages (5 days, organized meristem) of regeneration and was not affected by removal of the regenerating region immediately prior to uptake and transport of (14)C-IAA. The accumulation was inhibited by TIBA. In terms of increase in wet and dry weight and mitotic activity, the cotyledons rather than the regenerating root meristems were the most actively growing region of the cuttings. The upper part of the hypocotyl elongated more than the region of the slanting cut where regeneration was occurring.These results provide no support for the idea that the regenerating root controls the direction of polar transport by acting as a sink. The results are consistent with the view that polar auxin transport delivers auxin to the base of the cutting and raises the local

  11. Molecular dynamics simulations of the auxin-binding protein 1 in complex with indole-3-acetic acid and naphthalen-1-acetic acid.

    PubMed

    Grandits, Melanie; Oostenbrink, Chris

    2014-10-01

    Auxin-binding protein 1 (ABP1) is suggested to be an auxin receptor which plays an important role in several processes in green plants. Maize ABP1 was simulated with the natural auxin indole-3-acetic acid (IAA) and the synthetic analog naphthalen-1-acetic acid (NAA), to elucidate the role of the KDEL sequence and the helix at the C-terminus. The KDEL sequence weakens the intermolecular interactions between the monomers but stabilizes the C-terminal helix. Conformational changes at the C-terminus occur within the KDEL sequence and are influenced by the binding of the simulated ligands. This observation helps to explain experimental findings on ABP1 interactions with antibodies that are modulated by the presence of auxin, and supports the hypothesis that ABP1 acts as an auxin receptor. Stable hydrogen bonds between the monomers are formed between Glu40 and Glu62, Arg10 and Thr97, Lys39, and Glu62 in all simulations. The amino acids Ile22, Leu25, Trp44, Pro55, Ile130, and Phe149 are located in the binding pocket and are involved in hydrophobic interactions with the ring system of the ligand. Trp151 is stably involved in a face to end interaction with the ligand. The calculated free energy of binding using the linear interaction energy approach showed a higher binding affinity for NAA as compared to IAA. Our simulations confirm the asymmetric behavior of the two monomers, the stronger interaction of NAA than IAA and offers insight into the possible mechanism of ABP1 as an auxin receptor.

  12. Potential antibacterial activity of coumarin and coumarin-3-acetic acid derivatives.

    PubMed

    Chattha, Fauzia Anjum; Munawar, Munawar Ali; Nisa, Mehrun; Ashraf, Mohammad; Kousar, Samina; Arshad, Shafia

    2015-05-01

    Coumarin and coumarin-3-acetic acid derivatives were synthesized by reacting phenols with malic acid, ethyl acetoacetate and ethyl acetylsuccinate in appropriate reaction conditions. All synthesized compounds were subjected to test for their antimicrobial activities against variety of gram positive (Bacillus subtilis, Staphylococcus aureus) and gram negative bacterial stains (Shigella sonnei, Escherichia coli) by agar dilution method. Several of them exhibited appreciable good antibacterial activity against the different strains of gram positive and gram negative bacteria. These findings suggest a great potential of these compounds for screening and use as antibacterial agents for further studies with a battery of bacteria.

  13. Production of Indole-3-Acetic Acid via the Indole-3-Acetamide Pathway in the Plant-Beneficial Bacterium Pseudomonas chlororaphis O6 Is Inhibited by ZnO Nanoparticles but Enhanced by CuO Nanoparticles

    PubMed Central

    Zeng, Jia; McLean, Joan E.; Britt, David W.; Zhan, Jixun; Anderson, Anne J.

    2012-01-01

    The beneficial bacterium Pseudomonas chlororaphis O6 produces indole-3-acetic acid (IAA), a plant growth regulator. However, the pathway involved in IAA production in this bacterium has not been reported. In this paper we describe the involvement of the indole-3-acetamide (IAM) pathway in IAA production in P. chlororaphis O6 and the effects of CuO and ZnO nanoparticles (NPs). Sublethal levels of CuO and ZnO NPs differentially affected the levels of IAA secreted in medium containing tryptophan as the precursor. After 15 h of growth, CuO NP-exposed cells had metabolized more tryptophan than the control and ZnO NP-challenged cells. The CuO NP-treated cells produced higher IAA levels than control cultures lacking NPs. In contrast, ZnO NPs inhibited IAA production. Mixing of CuO and ZnO NPs resulted in an intermediate level of IAA production relative to the levels in the separate CuO and ZnO NP treatments. The effect of CuO NPs on IAA levels could be duplicated by ions at the concentrations released from the NPs. However, ion release did not account for the inhibition caused by the ZnO NPs. The mechanism underlying changes in IAA levels cannot be accounted for by effects on transcript accumulation from genes encoding a tryptophan permease or the IAM hydrolase in 15-h cultures. These findings raise the issue of whether sublethal doses of NPs would modify the beneficial effects of association between plants and bacteria. PMID:22210218

  14. Rhodanine-3-acetic acid derivatives as inhibitors of fungal protein mannosyl transferase 1 (PMT1).

    PubMed

    Orchard, Michael G; Neuss, Judi C; Galley, Carl M S; Carr, Andrew; Porter, David W; Smith, Phillip; Scopes, David I C; Haydon, David; Vousden, Katherine; Stubberfield, Colin R; Young, Kate; Page, Martin

    2004-08-01

    The first inhibitors of fungal protein: mannosyl transferase 1 (PMT1) are described. They are based upon rhodanine-3-acetic acid and several compounds have been identified, for example, 5-[[3-(1-phenylethoxy)-4-(2-phenylethoxy)phenyl]methylene]-4-oxo-2-thioxo-3-thiazolidineacetic acid (5a), which inhibit Candida albicans PMT1 with IC(50)s in the range 0.2-0.5 microM. Members of the series are effective in inducing changes in morphology of C. albicans in vitro that have previously been associated with loss of the transferase activity. These compounds could serve as useful tools for studying the effects of protein O-mannosylation and its relevance in the search for novel antifungal agents. PMID:15225710

  15. Epibrassinolide induces changes in indole-3-acetic acid, abscisic acid and polyamine concentrations and enhances antioxidant potential of radish seedlings under copper stress.

    PubMed

    Choudhary, Sikander Pal; Bhardwaj, Renu; Gupta, Bishan Datt; Dutt, Prabhu; Gupta, Rajinder Kumar; Biondi, Stefania; Kanwar, Mukesh

    2010-11-01

    In the present study, the effects of epibrassinolide (EBL) on indole-3-acetic acid (IAA), abscisic acid (ABA) and polyamine (PA) tissue concentrations and antioxidant potential of 7-day-old Raphanus sativus L. cv. 'Pusa chetki' seedlings grown under Cu stress were investigated. EBL treatment alone or in combination with Cu enhanced free and bound IAA titers when compared with the metal alone. Modest increases in free and bound ABA contents were observed for EBL treatment alone. However, the combination of EBL with Cu caused major increases in both forms of ABA, over Cu alone. Among the PAs analyzed, only putrescine and cadaverine concentrations were enhanced by EBL treatment alone. By contrast, a significant decline in putrescine and spermine contents was found in seedlings treated with EBL plus Cu. EBL treatments alone or in combination with Cu enhanced activities of guaiacol peroxidase (EC1.11.1.7), catalase (EC 1.11.1.6), superoxide dismutase (EC 1.15.1.1) and glutathione reductase (EC 1.6.4.2) and protein contents in comparison with metal and control treatments. A major decrease in malondialdehyde content was also recorded for EBL treatments with or without Cu. An increase in phytochelatin content was also observed in seedlings treated with EBL alone or in combination with Cu. Major improvement in radical scavenging activities, as attested by the antioxidant activity assay using DPPH (1,1-diphenylpicrylhydrazyl), and elevated deoxyribose and reducing powers, along with increased contents of ascorbic acid, total phenols and proline, also suggest a major influence of EBL application in mitigating copper-induced oxidative stress in radish seedlings.

  16. Sensitizers containing donor cascade and rhodanine-3-acetic acid moieties for dye-sensitized solar cells

    SciTech Connect

    Wu, Quan-Ping; Zhang, Lu; Liang, Mao; Sun, Zhe; Xue, Song

    2011-01-15

    Three organic dyes with D-{pi}-D-{pi}-A structure based on triarylamine, dimethylarylamine, and rhodanine-3-acetic acid moieties are designed and synthesized. Incorporating thiophene moieties into the system affords sensitizers with high molar extinction coefficients. These dyes were applied into nanocrystalline TiO{sub 2} dye-sensitized solar cells through standard operations. For a typical device the maximal monochromatic incident photon-to-current conversion efficiency (IPCE) can reach 73%, with a short-circuit photocurrent density (J{sub sc}) of 7.3 mA/cm{sup 2}, an open-circuit voltage (V{sub oc}) of 636 mV, and a fill factor (ff) of 0.61, corresponding to an overall conversion efficiency ({eta}) of 2.86%. (author)

  17. Indole-3-acetic acid UDP-glucosyltransferase from immature seeds of pea is involved in modification of glycoproteins.

    PubMed

    Ostrowski, Maciej; Hetmann, Anna; Jakubowska, Anna

    2015-09-01

    The glycosylation of auxin is one of mechanisms contributing to hormonal homeostasis. The enzyme UDPG: indole-3-ylacetyl-β-D-glucosyltransferase (IAA glucosyltransferase, IAGlc synthase) catalyzes the reversible reaction: IAA+UDPG↔1-O-IA-glucose+UDP, which is the first step in the biosynthesis of IAA-ester conjugates in monocotyledonous plants. In this study, we report IAA-glucosyltransferase isolated using a biochemical approach from immature seed of pea (Pisum sativum). The enzyme was purified by PEG fractionation, DEAE-Sephacel anion-exchange chromatography and preparative PAGE. LC-MS/MS analysis of tryptic peptides of the enzyme revealed the high identity with maize IAGlc synthase, but lack of homology with other IAA-glucosyltransferases from dicots. Biochemical characterization showed that of several acyl acceptors tested, the enzyme had the highest activity on IAA as the glucosyl acceptor (Km=0.52 mM, Vmax=161 nmol min(-1), kcat/Km=4.36 mM s(-1)) and lower activity on indole-3-propionic acid and 1-naphthalene acetic acid. Whereas indole-3-butyric acid and indole-3-propionic acid were competitive inhibitors of IAGlc synthase, D-gluconic acid lactone, an inhibitor of β-glucosidase activity, potentiated the enzyme activity at the optimal concentration of 0.3mM. Moreover, we demonstrated that the 1-O-IA-glucose synthesized by IAGlc synthase is the substrate for IAA labeling of glycoproteins from pea seeds indicating a possible role of this enzyme in the covalent modification of a class of proteins by a plant hormone.

  18. Indole-3-acetic acid UDP-glucosyltransferase from immature seeds of pea is involved in modification of glycoproteins.

    PubMed

    Ostrowski, Maciej; Hetmann, Anna; Jakubowska, Anna

    2015-09-01

    The glycosylation of auxin is one of mechanisms contributing to hormonal homeostasis. The enzyme UDPG: indole-3-ylacetyl-β-D-glucosyltransferase (IAA glucosyltransferase, IAGlc synthase) catalyzes the reversible reaction: IAA+UDPG↔1-O-IA-glucose+UDP, which is the first step in the biosynthesis of IAA-ester conjugates in monocotyledonous plants. In this study, we report IAA-glucosyltransferase isolated using a biochemical approach from immature seed of pea (Pisum sativum). The enzyme was purified by PEG fractionation, DEAE-Sephacel anion-exchange chromatography and preparative PAGE. LC-MS/MS analysis of tryptic peptides of the enzyme revealed the high identity with maize IAGlc synthase, but lack of homology with other IAA-glucosyltransferases from dicots. Biochemical characterization showed that of several acyl acceptors tested, the enzyme had the highest activity on IAA as the glucosyl acceptor (Km=0.52 mM, Vmax=161 nmol min(-1), kcat/Km=4.36 mM s(-1)) and lower activity on indole-3-propionic acid and 1-naphthalene acetic acid. Whereas indole-3-butyric acid and indole-3-propionic acid were competitive inhibitors of IAGlc synthase, D-gluconic acid lactone, an inhibitor of β-glucosidase activity, potentiated the enzyme activity at the optimal concentration of 0.3mM. Moreover, we demonstrated that the 1-O-IA-glucose synthesized by IAGlc synthase is the substrate for IAA labeling of glycoproteins from pea seeds indicating a possible role of this enzyme in the covalent modification of a class of proteins by a plant hormone. PMID:26057226

  19. Structural, Biochemical, and Phylogenetic Analyses Suggest That Indole-3-Acetic Acid Methyltransferase Is an Evolutionarily Ancient Member of the SABATH Family1[W][OA

    PubMed Central

    Zhao, Nan; Ferrer, Jean-Luc; Ross, Jeannine; Guan, Ju; Yang, Yue; Pichersky, Eran; Noel, Joseph P.; Chen, Feng

    2008-01-01

    The plant SABATH protein family encompasses a group of related small-molecule methyltransferases (MTs) that catalyze the S-adenosyl-l-methionine-dependent methylation of natural chemicals encompassing widely divergent structures. Indole-3-acetic acid (IAA) methyltransferase (IAMT) is a member of the SABATH family that modulates IAA homeostasis in plant tissues through methylation of IAA's free carboxyl group. The crystal structure of Arabidopsis (Arabidopsis thaliana) IAMT (AtIAMT1) was determined and refined to 2.75 Å resolution. The overall tertiary and quaternary structures closely resemble the two-domain bilobed monomer and the dimeric arrangement, respectively, previously observed for the related salicylic acid carboxyl methyltransferase from Clarkia breweri (CbSAMT). To further our understanding of the biological function and evolution of SABATHs, especially of IAMT, we analyzed the SABATH gene family in the rice (Oryza sativa) genome. Forty-one OsSABATH genes were identified. Expression analysis showed that more than one-half of the OsSABATH genes were transcribed in one or multiple organs. The OsSABATH gene most similar to AtIAMT1 is OsSABATH4. Escherichia coli-expressed OsSABATH4 protein displayed the highest level of catalytic activity toward IAA and was therefore named OsIAMT1. OsIAMT1 exhibited kinetic properties similar to AtIAMT1 and poplar IAMT (PtIAMT1). Structural modeling of OsIAMT1 and PtIAMT1 using the experimentally determined structure of AtIAMT1 reported here as a template revealed conserved structural features of IAMTs within the active-site cavity that are divergent from functionally distinct members of the SABATH family, such as CbSAMT. Phylogenetic analysis revealed that IAMTs from Arabidopsis, rice, and poplar (Populus spp.) form a monophyletic group. Thus, structural, biochemical, and phylogenetic evidence supports the hypothesis that IAMT is an evolutionarily ancient member of the SABATH family likely to play a critical role in IAA

  20. Structural, Biochemical, and Phylogenetic Analyses Suggest That Indole-3-Acetic Acid Methyltransferase Is an Evolutionarily Ancient Member of the SABATH Family

    SciTech Connect

    Zhao,N.; Ferrer, J.; Ross, J.; Guan, J.; Yang, Y.; Pichersky, E.; Noel, J.; Chen, F.

    2008-01-01

    The plant SABATH protein family encompasses a group of related small-molecule methyltransferases (MTs) that catalyze the S-adenosyl-L-methionine-dependent methylation of natural chemicals encompassing widely divergent structures. Indole-3-acetic acid (IAA) methyltransferase (IAMT) is a member of the SABATH family that modulates IAA homeostasis in plant tissues through methylation of IAA's free carboxyl group. The crystal structure of Arabidopsis (Arabidopsis thaliana) IAMT (AtIAMT1) was determined and refined to 2.75 Angstroms resolution. The overall tertiary and quaternary structures closely resemble the two-domain bilobed monomer and the dimeric arrangement, respectively, previously observed for the related salicylic acid carboxyl methyltransferase from Clarkia breweri (CbSAMT). To further our understanding of the biological function and evolution of SABATHs, especially of IAMT, we analyzed the SABATH gene family in the rice (Oryza sativa) genome. Forty-one OsSABATH genes were identified. Expression analysis showed that more than one-half of the OsSABATH genes were transcribed in one or multiple organs. The OsSABATH gene most similar to AtIAMT1 is OsSABATH4. Escherichia coli-expressed OsSABATH4 protein displayed the highest level of catalytic activity toward IAA and was therefore named OsIAMT1. OsIAMT1 exhibited kinetic properties similar to AtIAMT1 and poplar IAMT (PtIAMT1). Structural modeling of OsIAMT1 and PtIAMT1 using the experimentally determined structure of AtIAMT1 reported here as a template revealed conserved structural features of IAMTs within the active-site cavity that are divergent from functionally distinct members of the SABATH family, such as CbSAMT. Phylogenetic analysis revealed that IAMTs from Arabidopsis, rice, and poplar (Populus spp.) form a monophyletic group. Thus, structural, biochemical, and phylogenetic evidence supports the hypothesis that IAMT is an evolutionarily ancient member of the SABATH family likely to play a critical role in

  1. Effect of indole-3-acetic acid (plant auxin) on the preservation at 15 degrees C of boar semen for artificial insemination.

    PubMed

    Toniolli, R; Bussière, J; Courot, M; Magistrini, M; Combarnous, Y

    1996-01-01

    In order to extend the duration of boar sperm survival at 15 degrees C for artificial insemination, we tested the effect of indole-3-acetic acid (IAA), which appeared to be the main sperm protective substance present in the Coco nucifera endosperm (coconut water). Two IAA concentrations (10 and 100 ng/mL) in Beltsville extender (BTS) were studied for their in vitro effects. The motility, the percentage of motile spermatozoa and the acrosome morphology of sperm were recorded each day over 13 days of storage at 15 degrees C, after 5 min and 3 h of incubation at 39 degrees C. The IAA effect on sperm preservation was also studied in vivo at a concentration of 10 ng/mL in BTS by inseminating groups of females twice at 24 h intervals either at D0 (day of sperm collection) and D1 (D0/1) or at D5 and D6 (D5/6). At D0/1, the two groups of females (control and IAA) were inseminated with a total of 6.3 x 10(9) spermatozoa (3.15 x 10(9) at D0 and the same dose at D1) whereas at D5/6, on IAA group was inseminated with a total of 6.3 x 10(9) spermatozoa and another one with 12.6 x 10(9) spermatozoa. The animals in the D5/6 control group were inseminated each with a total of 12.6 x 10(9) spermatozoa. For each group of females (n = 106-140), fertility rate (% farrowing) and prolificacy rate (litter size) were recorded. No effect of IAA in vitro on the motility rate and on the percentage of motile spermatozoa was observed over a 13 day storage. However, IAA (10 ng/mL) had a significant positive effect on the percentage of living spermatozoa with intact acrosomes after 13 days (66 vs 54%, P < 0.05). The fertility and prolificacy rates after 5-6 days of sperm preservation in BTS extender alone did not differ significantly between D5/6 and D0/1 but the total number of inseminated spermatozoa was 12.6 x 10(9) at D5/6 instead of 6.3 x 10(9) at D0/1. When the spermatozoa were stored in the presence of 10 ng/mL IAA for 5-6 days at 15 degrees C, the fertility and prolificacy of the females

  2. Estimation of Free, Conjugated, and Diffusible Indole-3-acetic Acid in Etiolated Maize Shoots by the Indolo-α-pyrone Fluorescence Method

    PubMed Central

    Iino, Moritoshi; Carr, Denis J.

    1982-01-01

    Procedures for estimating free indoleacetic acid (IAA extracted from tissue homogenates by aqueous acetone), conjugated IAA (extracted by aqueous acetone and hydrolyzed by 1 n KOH), and diffusible IAA (diffused from the excised tissue into water), in shoots of etiolated 3-day-old maize (Zea mays L. cv. GH 390) seedlings are described, the indolo-α-pyrone fluorescence method being used to assay IAA. The reliability of the procedure is shown by comparative IAA determinations of the extracts using the gas chromatography-mass spectrometry method in which the methyl ester, heptafluorobutyryl derivative of IAA is assayed using the selected-ion-monitoring technique with deuterated IAA as an internal standard. A 3-millimeter-long coleoptile tip, a coleoptile with its included leaves and nodal region (whole coleoptile), and a mesocotyl each contains 0.2, 1.7, and 1.5 nanograms of free IAA, respectively. The whole coleoptile and the mesocotyl contain slightly less conjugated IAA than their content of free IAA. IAA diffuses from the coleoptile tip at the rate of 1.0 nanograms per tip per hour; from the base of the whole coleoptile and a set of leaves excised from a coleoptile, IAA diffuses at the rate of 0.62 and 0.17 nanogram per plant part per hour, respectively. The data obtained support the classical assumption that the coleoptile tip produces IAA. It is also suggested that some IAA is decomposed during its downward transport in the coleoptile. PMID:16662325

  3. Gravimorphism in current-year shoots of Abies balsamea: involvement of compensatory growth, indole-3-acetic acid transport and compression wood formation.

    PubMed

    Little, C H A; Lavigne, M B

    2002-04-01

    We investigated the cause of gravimorphic growth inhibition in current-year shoots of balsam fir (Abies balsamea (L.) Mill.) seedlings displaced from their normal orientation in the gravitational field. Tilting the main stem of seedlings decreased shoot elongation, cambial growth as measured by tracheid production, and leaf dry weight of the terminal shoot and the lateral shoots on the lower side of the tilted stem. Removing either the terminal shoot or all lateral shoots induced compensatory growth in the remaining shoots, but did not reduce the inhibitory effect of tilting on shoot growth. Bending the apical part of a tilted main stem to restore it to the vertical did not fully reverse the inhibition of terminal shoot growth caused by stem tilting. Stem tilting inhibited cambial activity at the base of decapitated terminal shoots treated apically with indole-3-acetic acid (IAA) and decreased the basipetal transport of a [1-(14)C]-IAA pulse. Stem tilting also induced compression wood formation on the lower side of the tilted stem. Compression wood formation was associated with increases in cambial activity and stem respiration. Stem tilting did not affect either the net photosynthetic rate in 1-year-old leaves or the xylem water potential in current-year lateral shoots. These results support the hypothesis that gravimorphic growth inhibition in a current-year shoot on a tilted stem involves reductions in (1) the shoot's capacity to export IAA, and hence to mobilize photoassimilates, and (2) the supply of photoassimilates available for import by the shoot, as a result of increased cambial sink activity associated with compression wood formation outside that shoot. PMID:11960755

  4. Role of Indole-3-acetic Acid in Modification of Geotropic Responses in Clinostat Rotated Avena Seedlings.

    PubMed

    Dedolph, R R; Naqvi, S M; Gordon, S A

    1966-05-01

    Oat seedlings were grown in a sand medium on clinostats with horizontal axes of rotation to nullify the directional component of the gravity-force vector. Coleoptile segments from such seedlings showed an enhanced absorption of apically applied exogenous auxin (indole-3-acetic acid), compared to segments from vertically rotated or stationary controls. Absorption of basally applied auxin and auxin transport were unaffected by the gravity treatments. Horizontal rotation did not materially change the amount of auxin produced and transported from excised coleoptile tips: however, plants so rotated showed an enhanced curvature response to unilaterally applied auxin.Collectively, these experiments indicate that enhanced plant responses to horizontal clinostat rotation, where rates of rotation are sufficient to nullify the directional component of the gravity-force vector, are caused primarily by increases in metabolism and not by a modification of auxin availability. These data do not support recently advanced hypotheses that the polarity of auxin transport is based on gravitational sedimentation of cell inclusions.

  5. Expression and regulation of pear 1-aminocyclopropane-1-carboxylic acid synthase gene (PpACS1a) during fruit ripening, under salicylic acid and indole-3-acetic acid treatment, and in diseased fruit.

    PubMed

    Shi, Hai-Yan; Zhang, Yu-Xing

    2014-06-01

    In plants, the level of ethylene is determined by the activity of the key enzyme 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS). A gene encoding an ACC synthase protein was isolated from pear (Pyrus pyrifolia). This gene designated PpACS1a (GenBank accession no. KC632526) was 1488 bp in length with an open reading frame (ORF) encoding a protein of 495 amino acids that shared high similarity with other pear ACC synthase proteins. The PpACS1a was grouped into type-1 subfamily of plant ACS based on its conserved domain and phylogenetic status. Real-time quantitative PCR indicated that PpACS1a was differentially expressed in pear tissues and predominantly expressed in anthers. The expression signal of PpACS1a was also detected in fruit and leaves, but no signal was detected in shoots and petals. Furthermore, the PpACS1a expression was regulated during fruit ripening. In addition, the PpACS1a gene expression was regulated by salicylic acid (SA) and indole-3-acetic acid (IAA) in fruit. Moreover, the expression of the PpACS1a was up-regulated in diseased pear fruit. These results indicated that PpACS1a might be involved in fruit ripening and response to SA, IAA and disease.

  6. Myo-inositol esters of indole-3-acetic acid are endogenous components of Zea mays L. shoot tissue

    NASA Technical Reports Server (NTRS)

    Chisnell, J. R.

    1984-01-01

    Indole-3-acetyl-myo-inositol esters have been demonstrated to be endogenous components of etiolated Zea mays shoots tissue. This was accomplished by comparison of the putative compounds with authentic, synthetic esters. The properties compared were liquid and gas-liquid chromatographic retention times and the 70-ev mass spectral fragmentation pattern of the pentaacetyl derivative. The amount of indole-3-acetyl-myo-inositol esters in the shoots was determined to be 74 nanomoles per kilogram fresh weight as measured by isotope dilution, accounting for 19% of the ester indole-3-acetic acid of the shoot. This work is the first characterization of an ester conjugate of indole-3-acetate acid from vegetative shoot tissue using multiple chromatographic properties and mass spectral identification. The kernel and the seedling shoot both contain indole-3-acetyl-myo-inositol esters, and these esters comprise approximately the same percentage of the total ester content of the kernel and of the shoot.

  7. [Molecular cloning and expression analysis of an Aux/IAA gene (RgIAA1) from Rehmannia glutinosa].

    PubMed

    Wang, Feng-Qing; Tian, Yun-He; Li, Ming-Jie; Yang, Jin-Feng; Zhang, Bao; Lin, Wen-Xiong; Chen, Xin-Jian; Zhang, Zhong-Yi

    2013-12-01

    To clone and analyze a member of the Auxin/indole-3-acetic acid (Aux/IAA) gene family, RgIAA1, from Rehmannia glutinosa. The transcriptional EST database of R. glutinosa was used to clone the new Aux/IAA gene by cDNA probe of AtIAA14. Bioinformatics was applied to analyze the sequence characteristics of RgIAA1 protein and construct phylogenetiC trees. Quantitative RT-PCR has been applied to detect the transcription level of RgIAA1 in seven tissues as well as in leaves under three stresses. The results showed that, the cDNA sequence of RgIAA1 contains 903 bp was obtained. The open reading frame (ORF) of RgIAA1 was 681 bp encoding 226 amino acids, which has typical structural domains and characteristic sequence of Aux/IAA family proteins. RgIAA1 showed the highest expression level in unfolded leaf, followed by the stem. And the expression of RglAA1 was quickly decreased with leaf growing up. The transcription level increased under continuous cropping conditions while it reduced both in salinity and waterlogging stresses. RgIAA1, an Aux/IAA gene from R. glutinosa has been obtained for the first time, which can lay the foundation for further studies about its molecular function in development and responses to stress.

  8. Epibrassinolide ameliorates Cr (VI) stress via influencing the levels of indole-3-acetic acid, abscisic acid, polyamines and antioxidant system of radish seedlings.

    PubMed

    Choudhary, Sikander Pal; Kanwar, Mukesh; Bhardwaj, Renu; Gupta, B D; Gupta, R K

    2011-07-01

    The present investigation determined the effects of epibrassinolide (EBL) on the levels of indole-3-acetic acid (IAA), abscisic acid (ABA), and polyamine (PA) and antioxidant potential of 7-d old Raphanus sativus L. cv. 'Pusa chetki' seedlings grown under Cr (VI) metal stress. Reduced titers of free (0.767 μg g(-1) FW) and bound (0.545 μg g(-1) FW) IAA in Cr (VI) stressed seedlings were observed over untreated control. Supplementations of EBL to Cr (VI) stressed seedlings were able to enhance both free (2.14-5.68 μg g(-1) FW) and bound IAA (2.45-7.78 μg g(-1) FW) concentrations in comparison to Cr (VI) metal treatment alone. Significant rise in free (13.49 μg g(-1) FW) and bound (12.17 μg g(-1) FW) ABA contents were noticed for Cr (VI) stressed seedlings when compared to untreated control. No significant increase in ABA contents were recorded for Cr (VI) stressed seedlings upon supplementation with EBL over Cr (VI) treatment alone. A significant increase in Put (18.40 μg g(-1) FW) and Cad (9.08 μg g(-1) FW) contents were found for 10(-9)M EBL plus Cr (VI) metal treatments when compared to Cr (VI) treatment alone. Spermidine (Spd) contents were found to decline significantly for EBL treatment alone or when supplemented with Cr (VI) treatments over untreated controls and Cr (VI) treatment alone. Antioxidant levels were found to enhance, with glutathione (57.98 mg g(-1) FW), proline (4.97 mg g(-1) FW), glycinebetaine (39.01 μmol mL(-1)), ascorbic acid (3.17 mg g(-1) FW) and phytochelatins (65.69 μmol g(-1) FW) contents noted for EBL supplemented to Cr (VI) metal solution over Cr (VI) treatment alone. Reduced activities of guaiacol peroxidase (0.391 U mg(-1) protein) and catalase (0.221 U mg(-1) protein) and enhanced activities of glutathione reductase (7.14 U mg(-1) protein), superoxide dismutase (15.20 U mg(-1) protein) and ascorbate peroxidase (4.31 U mg(-1) protein) were observed in seedlings treated with EBL plus Cr (VI) over Cr metal treatment alone

  9. Polar Movement of Indole-3-acetic Acid-C in Roots of Lens and Phaseolus.

    PubMed

    Kirk, S C; Jacobs, W P

    1968-05-01

    A critical review of the few papers on IAA-(14)C movement in roots revealed apparent contradictions, as well as flaws in experimental design that would be apt to cause artifacts. The movement of (14)C from IAA-(14)C was studied in sections of Lens and Phaseolus roots, using a system 20 or more times as sensitive as any previously used. To make sure that our results with roots could be compared validly with published work on petioles and stems, we used the same techniques as we had earlier used for shoot structures. The results with Lens were similar in many ways to those for shoots: net movement into receiver blocks was very strongly polar, followed a linear course for several hours, and showed a velocity of the same order of magnitude as in shoots (and, in fact, very close in absolute value to that found in Coleus stem cylinders). Also, as with shoots, all the radioactivity in receiver blocks ran to the R(F) of IAA. The time-course of loss of counts from donor blocks was similar to that found in shoots. The 2 most striking differences from shoots were 1) the very low percentage of added (14)C that was moved into the receivers (about one-tenth of the values for bean petioles), and 2) the fact that the polar movement was acropetal in roots, rather than basipetal as in shoots. Results with Phaseolus roots were similar to those for Lens, although an additional complication with Phaseolus roots was the indication of a transitory stage of weak basipetal polarity in the first few hours after excising the section. This stage was followed in a few hours by a stronger acropetal polarity.

  10. Diversity of Stability, Localization, Interaction and Control of Downstream Gene Activity in the Maize Aux/IAA Protein Family

    PubMed Central

    Ludwig, Yvonne; Berendzen, Kenneth W.; Xu, Changzheng; Piepho, Hans-Peter; Hochholdinger, Frank

    2014-01-01

    AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) proteins are central regulators of auxin signal transduction. They control many aspects of plant development, share a conserved domain structure and are localized in the nucleus. In the present study, five maize Aux/IAA proteins (ZmIAA2, ZmIAA11, ZmIAA15, ZmIAA20 and ZmIAA33) representing the evolutionary, phylogenetic and expression diversity of this gene family were characterized. Subcellular localization studies revealed that ZmIAA2, ZmIAA11 and ZmIAA15 are confined to the nucleus while ZmIAA20 and ZmIAA33 are localized in both the nucleus and the cytoplasm. Introduction of specific point mutations in the degron sequence (VGWPPV) of domain II by substituting the first proline by serine or the second proline by leucine stabilized the Aux/IAA proteins. While protein half-life times between ∼11 min (ZmIAA2) to ∼120 min (ZmIAA15) were observed in wild-type proteins, the mutated forms of all five proteins were almost as stable as GFP control proteins. Moreover, all five maize Aux/IAA proteins repressed downstream gene expression in luciferase assays to different degrees. In addition, bimolecular fluorescence complementation (BiFC) analyses demonstrated interaction of all five Aux/IAA proteins with RUM1 (ROOTLESS WITH UNDETECTABLE MERISTEM 1, ZmIAA10) while only ZmIAA15 and ZmIAA33 interacted with the RUM1 paralog RUL1 (RUM-LIKE 1, ZmIAA29). Moreover, ZmIAA11, ZmIAA15 ZmIAA33 displayed homotypic interaction. Hence, despite their conserved domain structure, maize Aux/IAA proteins display a significant variability in their molecular characteristics which is likely associated with the wide spectrum of their developmental functions. PMID:25203637

  11. Effects of two plant growth regulators, indole-3-acetic acid and β-naphthoxyacetic acid, on genotoxicity in Drosophila SMART assay and on proliferation and viability of HEK293 cells from the perspective of carcinogenesis.

    PubMed

    Karadeniz, Asuman; Kaya, Bülent; Savaş, Burhan; Topcuoğlu, Ş Fatih

    2011-10-01

    In this study, the mutagenic and recombinogenic effects of indole-3-acetic acid (IAA), a plant growth regulator naturally synthesized in plants but produced synthetically, and β-naphthoxyacetic acid (BNOA), a synthetic plant growth regulator widely used in agricultural regions, were investigated using the somatic mutation and recombination test (SMART) in Drosophila wings. The effect of the same plant growth regulators against the proliferation and viability of a human immortalized embryonic kidney HEK293 cells which is at the early stage of carcinogenesis were also examined with MTT and trypan-blue exclusion assays. For the SMART assay, two different crosses were used: a standard and a high-bioactivation (HB) cross, involving the flare-3 and the multiple wing hairs markers. The HB cross involved flies characterized by an increased cytochrome P-450-dependent bioactivation capacity, which permits the more efficient biotransformation of promutagens and procarcinogens. In both crosses, the wings of the two types of progeny, inversion-free marker heterozygotes and balancer heterozygotes, were analyzed. The results show that IAA and BNOA are not mutagenic or recombinogenic in the wing cells of Drosophila. Furthermore, neither plant growth regulator affected the proliferation rate of HEK293 cells; however, both of them induced cell death at high concentrations.

  12. Studies on the growth and indole-3-acetic acid and abscisic acid content of Zea mays seedlings grown in microgravity

    NASA Technical Reports Server (NTRS)

    Schulze, A.; Jensen, P. J.; Desrosiers, M.; Buta, J. G.; Bandurski, R. S.

    1992-01-01

    Measurements were made of the fresh weight, dry weight, dry weight-fresh weight ratio, free and conjugated indole-3-acetic acid, and free and conjugated abscisic acid in seedlings of Zea mays grown in darkness in microgravity and on earth. Imbibition of the dry kernels was 17 h prior to launch. Growth was for 5 d at ambient orbiter temperature and at a chronic accelerational force of the order of 3 x 10(-5) times earth gravity. Weights and hormone content of the microgravity seedlings were, with minor exceptions, not statistically different from seedlings grown in normal gravity. The tissues of the shuttle-grown plants appeared normal and the seedlings differed only in the lack of orientation of roots and shoots. These findings, based upon 5 d of growth in microgravity, cannot be extrapolated to growth in microgravity for weeks, months, and years, as might occur on a space station. Nonetheless, it is encouraging, for prospects of bioregeneration of the atmosphere and food production in a space station, that no pronounced differences in the parameters measured were apparent during the 5 d of plant seedling growth in microgravity.

  13. Oxidation of indole-3-acetic acid by peroxidase: involvement of reduced peroxidase and compound III with superoxide as a product.

    PubMed

    Smith, A M; Morrison, W L; Milham, P J

    1982-08-31

    Kinetic and spectral data establish that peroxidase may oxidize indole-3-acetic acid by either of two pathways depending on the enzyme/substrate ratio. When relatively low enzyme/substrate ratios are employed, the oxidation proceeds through a reduced peroxidase in equilibrium compound III shuttle. Conversely, peroxidase operates through the conventionally accepted pathway involving native enzyme and compounds I and II only when high enzyme/substrate ratios are used. Compound III, a specific oxidase, constitutes the dominant steady-state form of peroxidase when the reduced peroxidase in equilibrium compound III shuttle is operational. Activation of this shuttle also produces a flux of superoxide anion radical at the expense of molecular oxygen. Thus, important biological consequences may follow activation of this shuttle under physiological conditions.

  14. Preparation of magnetic indole-3-acetic acid imprinted polymer beads with 4-vinylpyridine and β-cyclodextrin as binary monomer via microwave heating initiated polymerization and their application to trace analysis of auxins in plant tissues.

    PubMed

    Zhang, Yi; Li, Yuanwen; Hu, Yuling; Li, Gongke; Chen, Yueqin

    2010-11-19

    Auxin is a crucial phytohormone for precise control of growth and development of plants. Due to its low concentration in plant tissues which are rich in interfering substances, the accurate determination of auxins remains a challenge. In this paper, a new strategy for isolation and enrichment of auxins from plant tissues was obtained by the magnetic molecularly imprinted polymer (mag-MIP) beads, which were prepared by microwave heating initiated suspension polymerization using indole-3-acetic acid (IAA) as template. In order to obtain higher selective recognition cavities, an enhanced imprinting method based on binary functional monomers, 4-vinylpyridine (4-VP) and β-cyclodextrin (β-CD), was adopted for IAA imprinting. The morphological and magnetic characteristics of the mag-MIP beads were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy and vibrating sample magnetometry. A majority of resultant beads were within the size range of 80-150μm. Porous surface morphology and good magnetic property were observed. Furthermore, the mag-MIP beads fabricated with 4-VP and β-CD as binary functional monomers exhibited improved recognition ability to IAA, as compared with the mag-MIP beads prepared with the individual monomer separately. Competitive rebinding experiment results revealed that the mag-MIP beads exhibited a higher specific recognition for the template than the non-imprinted polymer (mag-NIP) beads. An extraction method by mag-MIP beads coupled with high performance liquid chromatography (HPLC) was developed for determination of IAA and indole-3-butyric acid (IBA) in plant tissues. Linear ranges for IAA and IBA were in the range of 7.00-100.0μgL(-1) and 10.0-100.0μgL(-1), and the detection limits were 3.9 and 7.4μgL(-1), respectively. The analytical performance was also estimated by seedlings or immature embryos samples from three different plant tissues, pea, rice and wheat. Recoveries were in the range of 70

  15. Crystal structure of 3-acet-oxy-2-methyl-benzoic acid.

    PubMed

    Saranya, Matheswaran; Subashini, Annamalai; Arunagiri, Chidambaram; Muthiah, Packianathan Thomas

    2015-07-01

    In the title mol-ecule, C10H10O4, the carb-oxy-lic acid group is twisted by 11.37 (15)° from the plane of the benzene ring and the acet-oxy group is twisted from this plane by 86.60 (17)°. In the crystal, mol-ecules are linked by pairs of O-H⋯O hydrogen bonds, forming inversion dimers with the expected R 2 (2)(8) graph-set motif. PMID:26279915

  16. The tomato Aux/IAA transcription factor IAA9 is involved in fruit development and leaf morphogenesis.

    PubMed

    Wang, Hua; Jones, Brian; Li, Zhengguo; Frasse, Pierre; Delalande, Corinne; Regad, Farid; Chaabouni, Salma; Latché, Alain; Pech, Jean-Claude; Bouzayen, Mondher

    2005-10-01

    Auxin/indole-3-acetic acid (Aux/IAA) proteins are transcriptional regulators that mediate many aspects of plant responses to auxin. While functions of most Aux/IAAs have been defined mainly by gain-of-function mutant alleles in Arabidopsis thaliana, phenotypes associated with loss-of-function mutations have been scarce and subtle. We report here that the downregulation of IAA9, a tomato (Solanum lycopersicum) gene from a distinct subfamily of Aux/IAA genes, results in a pleiotropic phenotype, consistent with its ubiquitous expression pattern. IAA9-inhibited lines have simple leaves instead of wild-type compound leaves, and fruit development is triggered before fertilization, giving rise to parthenocarpy. This indicates that IAA9 is a key mediator of leaf morphogenesis and fruit set. In addition, antisense plants displayed auxin-related growth alterations, including enhanced hypocotyl/stem elongation, increased leaf vascularization, and reduced apical dominance. Auxin dose-response assays revealed that IAA9 downregulated lines were hypersensitive to auxin, although the only early auxin-responsive gene that was found to be upregulated in the antisense lines was IAA3. The activity of the IAA3 promoter was stimulated in the IAA9 antisense genetic background, indicating that IAA9 acts in planta as a transcriptional repressor of auxin signaling. While no mutation in any member of subfamily IV has been reported to date, the phenotypes associated with the downregulation of IAA9 reveal distinct and novel roles for members of the Aux/IAA gene family. PMID:16126837

  17. On the role of calcium in indole-3-acetic acid movement and graviresponse in etiolated pea epicotyls

    NASA Technical Reports Server (NTRS)

    Migliaccio, F.; Galston, A. W.

    1989-01-01

    To determine whether Ca2+ plays a special role in the early graviresponse of shoots, as has been reported for roots, we treated etiolated pea epicotyls with substances known to antagonize Ca2+ (La3+), to remove Ca2+ from the wall (spermidine, EGTA), to inhibit calmodulin mediated reactions (chlorpromazine), or to inhibit IAA transport (TIBA). We studied the effect of these substances on IAA and Ca2+ uptake into 7 mm long subapical 3rd internode etiolated pea epicotyl sections and pea leaf protoplasts, on pea epicotyl growth, and graviresponse and on lateral IAA redistribution during gravistimulation. Our results support the view that adequate Ca2+ in the apoplast is required for normal IAA uptake, transport and graviresponse. Experiments with protoplasts indicate that Ca2+ may be controlling a labile membrane porter, possibly located on the external surface of cell membrane, while inhibitor experiments suggest that calmodulin is also implicated in both the movement of IAA and graviresponse. Since a major transfer of Ca2+ through free space during graviresponse has not yet been demonstrated, and since inhibition of calcium channels does not affect IAA redistribution (Migliaccio and Galston, 1987, Plant Physiology 85:542), we conclude that no clear evidence links prior Ca2+ movement with IAA redistribution during graviresponse in stems.

  18. Effect of surface and membrane potentials on IAA (indoleactic acid) uptake and binding by zucchini membrane vesicles

    SciTech Connect

    Clark, K.A.; Goldsmith, M.H.M.

    1986-08-01

    The polar transport of the endogenous hormone controlling extension growth of plant cells, indoleacetic acid (IAA), is thought to depend on transmembrane pH and electrical gradients resulting in part from the action of proton ATPases in the plasma membrane. Elements of this transport process are permeation of the membrane by the undissociated lipophilic indoleacetic acid (IAAH) from the acidic apoplast, followed by dissociation of the weak acid and accumulation of the IAA anion (IAA/sup -/) in the alkaline cytoplasm; a saturable symport of IAA/sup -/ with one or more protons; a carrier-mediated efflux of IAA/sup -/ down a considerable electrochemical gradient. The efflux is greater from the basal than the apical end of cells and is thought to be responsible for the overall polarity of the process. This step is also the site of action of napthylphthalamic acid (NPA) and herbicides that inhibit polar transport but stimulate net accumulation of auxin by tissues and cells. We are using membrane vesicles as a simplified system for studying the mechanisms involved in the transport and accumulation of auxin. In particular, we are interested in determining the involvement of the transmembrane pH (pH/sub o/ < pH/sub i/) and voltage gradients (K/sup +/ diffusion potential, (K/sup +/)/sub in/ > (K/sup +/)/sub out/) in IAA uptake. 19 refs., 6 figs.

  19. Concurrent profiling of indole-3-acetic acid, abscisic acid, and cytokinins and structurally related purines by high-performance-liquid-chromatography tandem electrospray mass spectrometry

    PubMed Central

    2012-01-01

    Background Cytokinins (CKs) are a group of plant growth regulators that are involved in several plant developmental processes. Despite the breadth of knowledge surrounding CKs and their diverse functions, much remains to be discovered about the full potential of CKs, including their relationship with the purine salvage pathway, and other phytohormones. The most widely used approach to query unknown facets of CK biology utilized functional genomics coupled with CK metabolite assays and screening of CK associated phenotypes. There are numerous different types of assays for determining CK quantity, however, none of these methods screen for the compendium of metabolites that are necessary for elucidating all roles, including purine salvage pathway enzymes in CK metabolism, and CK cross-talk with other phytohormones. Furthermore, all published analytical methods have drawbacks ranging from the required use of radiolabelled compounds, or hazardous derivatization reagents, poor sensitivity, lack of resolution between CK isomers and lengthy run times. Results In this paper, a method is described for the concurrent extraction, purification and analysis of several CKs (freebases, ribosides, glucosides, nucleotides), purines (adenosine monophosphate, inosine, adenosine, and adenine), indole-3-acetic acid, and abscisic acid from hundred-milligram (mg) quantities of Arabidopsis thaliana leaf tissue. This method utilizes conventional Bieleski solvents extraction, solid phase purification, and is unique because of its diverse range of detectable analytes, and implementation of a conventional HPLC system with a fused core column that enables good sensitivity without the requirement of a UHPLC system. Using this method we were able to resolve CKs about twice as fast as our previous method. Similarly, analysis of adenosine, indole-3-acetic acid, and abscisic acid, was comparatively rapid. A further enhancement of the method was the utilization of a QTRAP 5500 mass analyzer, which

  20. Validation of a multi-analyte HPLC-DAD method for determination of uric acid, creatinine, homovanillic acid, niacinamide, hippuric acid, indole-3-acetic acid and 2-methylhippuric acid in human urine.

    PubMed

    Remane, Daniela; Grunwald, Soeren; Hoeke, Henrike; Mueller, Andrea; Roeder, Stefan; von Bergen, Martin; Wissenbach, Dirk K

    2015-08-15

    During the last decades exposure sciences and epidemiological studies attracts more attention to unravel the mechanisms for the development of chronic diseases. According to this an existing HPLC-DAD method for determination of creatinine in urine samples was expended for seven analytes and validated. Creatinine, uric acid, homovanillic acid, niacinamide, hippuric acid, indole-3-acetic acid, and 2-methylhippuric acid were separated by gradient elution (formate buffer/methanol) using an Eclipse Plus C18 Rapid Resolution column (4.6mm×100mm). No interfering signals were detected in mobile phase. After injection of blank urine samples signals for the endogenous compounds but no interferences were detected. All analytes were linear in the selected calibration range and a non weighted calibration model was chosen. Bias, intra-day and inter-day precision for all analytes were below 20% for quality control (QC) low and below 10% for QC medium and high. The limits of quantification in mobile phase were in line with reported reference values but had to be adjusted in urine for homovanillic acid (45mg/L), niacinamide 58.5(mg/L), and indole-3-acetic acid (63mg/L). Comparison of creatinine data obtained by the existing method with those of the developed method showing differences from -120mg/L to +110mg/L with a mean of differences of 29.0mg/L for 50 authentic urine samples. Analyzing 50 authentic urine samples, uric acid, creatinine, hippuric acid, and 2-methylhippuric acid were detected in (nearly) all samples. However, homovanillic acid was detected in 40%, niacinamide in 4% and indole-3-acetic acid was never detected within the selected samples.

  1. Identification and expression analysis of primary auxin-responsive Aux/IAA gene family in cucumber (Cucumis sativus).

    PubMed

    Gan, Defang; Zhuang, Dan; Ding, Fei; Yu, Zhenzhou; Zhao, Yang

    2013-12-01

    Aux/IAA is an important gene family involved in many aspects of growth and development. Aux/IAA proteins are short-lived nuclear proteins that are induced primarily by various phytohormones. In this study, 29 Aux/IAA family genes (CsIAA01-CsIAA29) were identified and characterized in cucumber, including gene structures, phylogenetic relationships, conserved protein motifs and chromosomal locations. These genes show distinct organizational patterns of their putative motifs. The distributions of the genes vary: except for five CsIAA genes in cucumber that were not located, seven CsIAA genes were found on scaffold, while the other 17 CsIAA genes were distributed on seven other chromosomes. Based on a phylogenetic analysis of the Aux/IAA protein sequences from cucumber, Arabidopsis and other plants, the Aux/IAA genes in cucumber were categorized into seven subfamilies. To investigate whether the expression of CsIAA genes is associated with auxin induction, their transcript levels were monitored in seedlings treated with IAA (indole-3-acetic acid), and their expression patterns were analysed by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). The results showed that 11/29 CsIAA genes were expressed in leaves whether treated with IAA or not and the time course of processing and compared with the control, five CsIAA genes showed low expression only after 60 min treatment with IAA, while 11 genes showed no expression. These results provide useful information for further functional analysis of Aux/IAA gene family in cucumber.

  2. Solanum lycopersicum IAA15 functions in the 2,4-dichlorophenoxyacetic acid herbicide mechanism of action by mediating abscisic acid signalling.

    PubMed

    Xu, Tao; Wang, Yanling; Liu, Xin; Gao, Song; Qi, Mingfang; Li, Tianlai

    2015-07-01

    2,4-Dichlorophenoxyacetic acid (2,4-D), an important plant growth regulator, is the herbicide most commonly used worldwide to control weeds. However, broad-leaf fruits and vegetables are extremely sensitive to herbicides, which can cause damage and result in lost crops when applied in a manner inconsistent with the directions. Despite detailed knowledge of the mechanism of 2,4-D, the regulation of auxin signalling is still unclear. For example, although the major mediators of auxin signalling, including auxin/indole acetic acid (AUX/IAA) proteins and auxin response factors (ARFs), are known to mediate auxinic herbicides, the underlying mechanisms are still unclear. In this study, the effects of 2,4-D on AUX/IAA gene expression in tomato were investigated, and the two most notably up-regulated genes, SlIAA15 and SlIAA29, were selected for further study. Western blotting revealed the substantial accumulation of both SlIAA15 and SlIAA29, and the expression levels of the corresponding genes were increased following abscisic acid (ABA) and ethylene treatment. Overexpressing SlIAA15, but not SlIAA29, induced a 2,4-D herbicide damage phenotype. The 35S::SlIAA15 line exhibited a strong reduction in leaf stomatal density and altered expression of some R2R3 MYB genes that are putatively involved in the regulation of stomatal differentiation. Further study revealed that root elongation in 35S::SlIAA15 was sensitive to ABA treatment, and was most probably due to the altered expression of an ABA signal transduction gene. In addition, the altered auxin sensitivities of SlIAA15 transformants were also explored. These results suggested that SlIAA15 plays an important role in determining the effects of the herbicide 2,4-D.

  3. Genome-wide analysis of Aux/IAA and ARF gene families in Populus trichocarpa

    SciTech Connect

    Kalluri, Udaya C; DiFazio, Stephen P; Brunner, A.; Tuskan, Gerald A

    2007-01-01

    Auxin/Indole-3-Acetic Acid (Aux/IAA) and Auxin Response Factor (ARF) transcription factors are key regulators of auxin responses in plants. A total of 35 Aux/IAA and 39 ARF genes were identified in the Populus genome. Comparative phylogenetic analysis revealed that the subgroups PoptrARF2, 6, 9 and 16 and PoptrIAA3, 16, 27 and 29 have differentially expanded in Populus relative to Arabidopsis. Activator ARFs were found to be two fold-overrepresented in the Populus genome. PoptrIAA and PoptrARF gene families appear to have expanded due to high segmental and low tandem duplication events. Furthermore, expression studies showed that genes in the expanded PoptrIAA3 subgroup display differential expression. The gene-family analysis reported here will be useful in conducting future functional genomics studies to understand how the molecular roles of these large gene families translate into a diversity of biologically meaningful auxin effects.

  4. Dioxygenase-encoding AtDAO1 gene controls IAA oxidation and homeostasis in Arabidopsis.

    PubMed

    Porco, Silvana; Pěnčík, Aleš; Rashed, Afaf; Voß, Ute; Casanova-Sáez, Rubén; Bishopp, Anthony; Golebiowska, Agata; Bhosale, Rahul; Swarup, Ranjan; Swarup, Kamal; Peňáková, Pavlína; Novák, Ondřej; Staswick, Paul; Hedden, Peter; Phillips, Andrew L; Vissenberg, Kris; Bennett, Malcolm J; Ljung, Karin

    2016-09-27

    Auxin represents a key signal in plants, regulating almost every aspect of their growth and development. Major breakthroughs have been made dissecting the molecular basis of auxin transport, perception, and response. In contrast, how plants control the metabolism and homeostasis of the major form of auxin in plants, indole-3-acetic acid (IAA), remains unclear. In this paper, we initially describe the function of the Arabidopsis thaliana gene DIOXYGENASE FOR AUXIN OXIDATION 1 (AtDAO1). Transcriptional and translational reporter lines revealed that AtDAO1 encodes a highly root-expressed, cytoplasmically localized IAA oxidase. Stable isotope-labeled IAA feeding studies of loss and gain of function AtDAO1 lines showed that this oxidase represents the major regulator of auxin degradation to 2-oxoindole-3-acetic acid (oxIAA) in Arabidopsis Surprisingly, AtDAO1 loss and gain of function lines exhibited relatively subtle auxin-related phenotypes, such as altered root hair length. Metabolite profiling of mutant lines revealed that disrupting AtDAO1 regulation resulted in major changes in steady-state levels of oxIAA and IAA conjugates but not IAA. Hence, IAA conjugation and catabolism seem to regulate auxin levels in Arabidopsis in a highly redundant manner. We observed that transcripts of AtDOA1 IAA oxidase and GH3 IAA-conjugating enzymes are auxin-inducible, providing a molecular basis for their observed functional redundancy. We conclude that the AtDAO1 gene plays a key role regulating auxin homeostasis in Arabidopsis, acting in concert with GH3 genes, to maintain auxin concentration at optimal levels for plant growth and development. PMID:27651491

  5. Dioxygenase-encoding AtDAO1 gene controls IAA oxidation and homeostasis in Arabidopsis

    PubMed Central

    Porco, Silvana; Pěnčík, Aleš; Rashed, Afaf; Voß, Ute; Casanova-Sáez, Rubén; Bishopp, Anthony; Golebiowska, Agata; Swarup, Ranjan; Swarup, Kamal; Peňáková, Pavlína; Novák, Ondřej; Staswick, Paul; Hedden, Peter; Phillips, Andrew L.; Vissenberg, Kris

    2016-01-01

    Auxin represents a key signal in plants, regulating almost every aspect of their growth and development. Major breakthroughs have been made dissecting the molecular basis of auxin transport, perception, and response. In contrast, how plants control the metabolism and homeostasis of the major form of auxin in plants, indole-3-acetic acid (IAA), remains unclear. In this paper, we initially describe the function of the Arabidopsis thaliana gene DIOXYGENASE FOR AUXIN OXIDATION 1 (AtDAO1). Transcriptional and translational reporter lines revealed that AtDAO1 encodes a highly root-expressed, cytoplasmically localized IAA oxidase. Stable isotope-labeled IAA feeding studies of loss and gain of function AtDAO1 lines showed that this oxidase represents the major regulator of auxin degradation to 2-oxoindole-3-acetic acid (oxIAA) in Arabidopsis. Surprisingly, AtDAO1 loss and gain of function lines exhibited relatively subtle auxin-related phenotypes, such as altered root hair length. Metabolite profiling of mutant lines revealed that disrupting AtDAO1 regulation resulted in major changes in steady-state levels of oxIAA and IAA conjugates but not IAA. Hence, IAA conjugation and catabolism seem to regulate auxin levels in Arabidopsis in a highly redundant manner. We observed that transcripts of AtDOA1 IAA oxidase and GH3 IAA-conjugating enzymes are auxin-inducible, providing a molecular basis for their observed functional redundancy. We conclude that the AtDAO1 gene plays a key role regulating auxin homeostasis in Arabidopsis, acting in concert with GH3 genes, to maintain auxin concentration at optimal levels for plant growth and development. PMID:27651491

  6. [Allosteric regulation of glucosamine synthetase activity by naphthoquinone derivatives and ethyl ester of di-(4-oxycumarinyl-3)-acetic acid].

    PubMed

    Sharaev, P N; Bogdanov, N G; Sarycheva, I K; Zhukova, E E

    1981-02-01

    The effects of derivatives of naphthoquinone, e.g. 2-methyl-3-phytyl-1,4-naphthoquinone (vitamin K1), 2-methyl-1,4-naphthoquinone (vitamin K3), 3-dihydro-2-methyl-1,4-naphthoquinone-2-sodium sulfonate (vicasol), derivatives of naphthohydroxyquinone, e.g. 2-methyl-1,4-naphthohydroxyquinone 1-monoacetate, 2-methyl-1,4-naphthohydroxyquinone 1,4-diacetate and the oxycumarine derivative di-(4-oxycumarinyl-3)-acetate ethyl ester (pelentan) on the activity of purified glutamine synthetase (EC 5.3.1.19) from rat liver were studied. The enzyme activity was increased under effects of vitamins K1 and K3 and was inhibited by pelentan. The data obtained are indicative of the allosteric effect of these compounds on the enzyme. PMID:7195738

  7. Genome-wide survey of Aux/IAA gene family members in potato (Solanum tuberosum): Identification, expression analysis, and evaluation of their roles in tuber development.

    PubMed

    Gao, Junpeng; Cao, Xiaoli; Shi, Shandang; Ma, Yuling; Wang, Kai; Liu, Shengjie; Chen, Dan; Chen, Qin; Ma, Haoli

    2016-03-01

    The Auxin/indole-3-acetic acid (Aux/IAA) genes encode short-lived nuclear proteins that are known to be involved in the primary cellular responses to auxin. To date, systematic analysis of the Aux/IAA genes in potato (Solanum tuberosum) has not been conducted. In this study, a total of 26 potato Aux/IAA genes were identified (designated from StIAA1 to StIAA26), and the distribution of four conserved domains shared by the StIAAs were analyzed based on multiple sequence alignment and a motif-based sequence analysis. A phylogenetic analysis of the Aux/IAA gene families of potato and Arabidopsis was also conducted. In order to assess the roles of StIAA genes in tuber development, the results of RNA-seq studies were reformatted to analyze the expression patterns of StIAA genes, and then verified by quantitative real-time PCR. A large number of StIAA genes (12 genes) were highly expressed in stolon organs and in during the tuber initiation and expansion developmental stages, and most of these genes were responsive to indoleacetic acid treatment. Our results suggested that StIAA genes were involved in the process of tuber development and provided insights into functional roles of potato Aux/IAA genes.

  8. Effect of IAA produced by Klebsiella oxytoca Rs-5 on cotton growth under salt stress.

    PubMed

    Liu, Yan; Shi, Zaiqiang; Yao, Lixia; Yue, Haitao; Li, Hui; Li, Chun

    2013-01-01

    Klebsiella oxytoca Rs-5 isolated with ACC (1-aminocyclopropane-1-carboxylate) deaminase activity as the sole nitrogen source could obviously promote cotton seedling growth under salt stress and produce phytohormone indole-3-acetic acid (IAA). The amount of IAA produced by the strain Rs-5 was measured, and the effect of IAA on cotton growth under salt stress was studied. Different treatments were set to treat cotton seeds with fermentation broth containing strain Rs-5 (FB), strain Rs-5, fermentation broth with bacteria removed (FB-NB), fermentation broth without bacteria or IAA (FB-NB-NI) and single IAA solutions (SI) according to the IAA concentration after strain Rs-5 culturing of 48, 72 and 120 h. The germination rate, dry weight, plant height, root length and malondialdehyde (MDA), proline and endogenous IAA content in roots were determined. The results showed that both IAA produced by strain Rs-5 and the strain were effective in promoting cotton growth under salt stress. The growth and ability to resist salt stress of cotton seedlings were increased with the enhancement of IAA concentration. The treatment of FB containing bacteria and IAA at 120 h obtained the best state of cotton growth, when the IAA content was the highest in the fermentation broth (42.14 μg·L(-1)). The germination rate, dry weight, plant height and root length were increased by 29.4%, 24.3%, 27.2% and 27.2% , respectively, compared to the saline control. The strain Rs-5 and/or IAA could obviously reduce the MDA and proline content and increase the endogenous IAA content in cotton seedlings. However, the efficacy of other components in the fermentation broth was inconspicuous.

  9. Studies on the Growth and Indole-3-Acetic Acid and Abscisic Acid Content of Zea mays Seedlings Grown in Microgravity 1

    PubMed Central

    Schulze, Aga; Jensen, Philip J.; Desrosiers, Mark; Buta, J. George; Bandurski, Robert S.

    1992-01-01

    Measurements were made of the fresh weight, dry weight, dry weight-fresh weight ratio, free and conjugated indole-3-acetic acid, and free and conjugated abscisic acid in seedlings of Zea mays grown in darkness in microgravity and on earth. Imbibition of the dry kernels was for 17 h prior to launch. Growth was for 5 d at ambient orbiter temperature and at a chronic accelerational force of the order of 3 × 10−5 times earth gravity. Weights and hormone content of the microgravity seedlings were, with minor exceptions, not statistically different from seedlings grown in normal gravity. The tissues of the shuttle-grown plants appeared normal and the seedlings differed only in the lack of orientation of roots and shoots. These findings, based upon 5 d of growth in microgravity, cannot be extrapolated to growth in microgravity for weeks, months, and years, as might occur on a space station. Nonetheless, it is encouraging, for prospects of bioregeneration of the atmosphere and food production in a space station, that no pronounced differences in the parameters measured were apparent during the 5 d of plant seedling growth in microgravity. Images Figure 1 Figure 4 Figure 5 PMID:11537869

  10. Effect of gibberellic acid (GA), indole acetic acid (IAA) and benzylaminopurine (BAP) on the synthesis of essential oils and the isomerization of methyl chavicol and trans-anethole in Ocimum gratissimum L.

    PubMed

    Hazzoumi, Zakaria; Moustakime, Youssef; Amrani Joutei, Khalid

    2014-01-01

    Basil (O. gratissimum L) is a aromatic and medicinal plant widely used in traditional medicine in Morocco. The aim of this work was to study the effect of three plant growth regulators gibberellic acid (GA), indole 3-acetic acid (IAA) and benzylaminopurine (BAP) on the content and composition of essential oils of this plant, especially on the main compound (methyl chavicol) and its isomer (the trans-anethole). The results showed a wide variation on yield, content and range of the molecule constituent of oil, with a balance of appearances and/or disappearances of a few molecules. GA caused a slight decrease in the oil yield (0.2%), but it increased the diversity of compounds (17 molecules) with the appearance of four new compounds (naphthalene, camphor, germacrene-D, and ledene) and disappearance of (β cedrene, azulene). This variation also caused a very important decrease in the main compound (methyl chavicol) and increases its isomer (trans-anethole). IAA and BAP caused an increase in the yield of essential oil (0.30% and 0.32% respectively) without much influence on the main compounds, but with some change in the composition such as the appearance of (germacrene-D) and the disappearance of (aristolene). PMID:25045609

  11. Effect of gibberellic acid (GA), indole acetic acid (IAA) and benzylaminopurine (BAP) on the synthesis of essential oils and the isomerization of methyl chavicol and trans-anethole in Ocimum gratissimum L.

    PubMed

    Hazzoumi, Zakaria; Moustakime, Youssef; Amrani Joutei, Khalid

    2014-01-01

    Basil (O. gratissimum L) is a aromatic and medicinal plant widely used in traditional medicine in Morocco. The aim of this work was to study the effect of three plant growth regulators gibberellic acid (GA), indole 3-acetic acid (IAA) and benzylaminopurine (BAP) on the content and composition of essential oils of this plant, especially on the main compound (methyl chavicol) and its isomer (the trans-anethole). The results showed a wide variation on yield, content and range of the molecule constituent of oil, with a balance of appearances and/or disappearances of a few molecules. GA caused a slight decrease in the oil yield (0.2%), but it increased the diversity of compounds (17 molecules) with the appearance of four new compounds (naphthalene, camphor, germacrene-D, and ledene) and disappearance of (β cedrene, azulene). This variation also caused a very important decrease in the main compound (methyl chavicol) and increases its isomer (trans-anethole). IAA and BAP caused an increase in the yield of essential oil (0.30% and 0.32% respectively) without much influence on the main compounds, but with some change in the composition such as the appearance of (germacrene-D) and the disappearance of (aristolene).

  12. Cleavage of INDOLE-3-ACETIC ACID INDUCIBLE28 mRNA by microRNA847 upregulates auxin signaling to modulate cell proliferation and lateral organ growth in Arabidopsis.

    PubMed

    Wang, Jing-Jing; Guo, Hui-Shan

    2015-03-01

    MicroRNAs function in a range of developmental processes. Here, we demonstrate that miR847 targets the mRNA of the auxin/indole acetic acid (Aux/IAA) repressor-encoding gene IAA28 for cleavage. The rapidly increased accumulation of miR847 in Arabidopsis thaliana coincided with reduced IAA28 mRNA levels upon auxin treatment. This induction of miR847 by auxin was abolished in auxin receptor tir1-1 and auxin-resistant axr1-3 mutants. Further analysis demonstrates that miR847 functions as a positive regulator of auxin-mediated lateral organ development by cleaving IAA28 mRNA. Importantly, the ectopic expression of miR847 increases the expression of cell cycle genes as well as the neoplastic activity of leaf cells, prolonging later-stage rosette leaf growth and producing leaves with serrated margins. Moreover, both miR847 and IAA28 mRNAs are specifically expressed in marginal meristems of rosette leaves and lateral root initiation sites. Our data indicate that auxin-dependent induction of miR847 positively regulates meristematic competence by clearing IAA28 mRNA to upregulate auxin signaling, thereby determining the duration of cell proliferation and lateral organ growth in Arabidopsis. IAA28 mRNA encodes an Aux/IAA repressor protein, which is degraded through the proteasome in response to auxin. Altered signal sensitization to IAA28 mRNA levels, together with targeted IAA28 degradation, ensures a robust signal derepression.

  13. Genome-Wide Analysis and Characterization of Aux/IAA Family Genes in Brassica rapa.

    PubMed

    Paul, Parameswari; Dhandapani, Vignesh; Rameneni, Jana Jeevan; Li, Xiaonan; Sivanandhan, Ganesan; Choi, Su Ryun; Pang, Wenxing; Im, Subin; Lim, Yong Pyo

    2016-01-01

    Auxins are the key players in plant growth development involving leaf formation, phototropism, root, fruit and embryo development. Auxin/Indole-3-Acetic Acid (Aux/IAA) are early auxin response genes noted as transcriptional repressors in plant auxin signaling. However, many studies focus on Aux/ARF gene families and much less is known about the Aux/IAA gene family in Brassica rapa (B. rapa). Here we performed a comprehensive genome-wide analysis and identified 55 Aux/IAA genes in B. rapa using four conserved motifs of Aux/IAA family (PF02309). Chromosomal mapping of the B. rapa Aux/IAA (BrIAA) genes facilitated understanding cluster rearrangement of the crucifer building blocks in the genome. Phylogenetic analysis of BrIAA with Arabidopsis thaliana, Oryza sativa and Zea mays identified 51 sister pairs including 15 same species (BrIAA-BrIAA) and 36 cross species (BrIAA-AtIAA) IAA genes. Among the 55 BrIAA genes, expression of 43 and 45 genes were verified using Genebank B. rapa ESTs and in home developed microarray data from mature leaves of Chiifu and RcBr lines. Despite their huge morphological difference, tissue specific expression analysis of BrIAA genes between the parental lines Chiifu and RcBr showed that the genes followed a similar pattern of expression during leaf development and a different pattern during bud, flower and siliqua development stages. The response of the BrIAA genes to abiotic and auxin stress at different time intervals revealed their involvement in stress response. Single Nucleotide Polymorphisms between IAA genes of reference genome Chiifu and RcBr were focused and identified. Our study examines the scope of conservation and divergence of Aux/IAA genes and their structures in B. rapa. Analyzing the expression and structural variation between two parental lines will significantly contribute to functional genomics of Brassica crops and we belive our study would provide a foundation in understanding the Aux/IAA genes in B. rapa.

  14. Genome-Wide Analysis and Characterization of Aux/IAA Family Genes in Brassica rapa.

    PubMed

    Paul, Parameswari; Dhandapani, Vignesh; Rameneni, Jana Jeevan; Li, Xiaonan; Sivanandhan, Ganesan; Choi, Su Ryun; Pang, Wenxing; Im, Subin; Lim, Yong Pyo

    2016-01-01

    Auxins are the key players in plant growth development involving leaf formation, phototropism, root, fruit and embryo development. Auxin/Indole-3-Acetic Acid (Aux/IAA) are early auxin response genes noted as transcriptional repressors in plant auxin signaling. However, many studies focus on Aux/ARF gene families and much less is known about the Aux/IAA gene family in Brassica rapa (B. rapa). Here we performed a comprehensive genome-wide analysis and identified 55 Aux/IAA genes in B. rapa using four conserved motifs of Aux/IAA family (PF02309). Chromosomal mapping of the B. rapa Aux/IAA (BrIAA) genes facilitated understanding cluster rearrangement of the crucifer building blocks in the genome. Phylogenetic analysis of BrIAA with Arabidopsis thaliana, Oryza sativa and Zea mays identified 51 sister pairs including 15 same species (BrIAA-BrIAA) and 36 cross species (BrIAA-AtIAA) IAA genes. Among the 55 BrIAA genes, expression of 43 and 45 genes were verified using Genebank B. rapa ESTs and in home developed microarray data from mature leaves of Chiifu and RcBr lines. Despite their huge morphological difference, tissue specific expression analysis of BrIAA genes between the parental lines Chiifu and RcBr showed that the genes followed a similar pattern of expression during leaf development and a different pattern during bud, flower and siliqua development stages. The response of the BrIAA genes to abiotic and auxin stress at different time intervals revealed their involvement in stress response. Single Nucleotide Polymorphisms between IAA genes of reference genome Chiifu and RcBr were focused and identified. Our study examines the scope of conservation and divergence of Aux/IAA genes and their structures in B. rapa. Analyzing the expression and structural variation between two parental lines will significantly contribute to functional genomics of Brassica crops and we belive our study would provide a foundation in understanding the Aux/IAA genes in B. rapa. PMID

  15. Constitutive Expression of OsIAA9 Affects Starch Granules Accumulation and Root Gravitropic Response in Arabidopsis

    PubMed Central

    Luo, Sha; Li, Qianqian; Liu, Shanda; Pinas, Nicholaas M.; Tian, Hainan; Wang, Shucai

    2015-01-01

    Auxin/Indole-3-Acetic Acid (Aux/IAA) genes are early auxin response genes ecoding short-lived transcriptional repressors, which regulate auxin signaling in plants by interplay with Auxin Response Factors (ARFs). Most of the Aux/IAA proteins contain four different domains, namely Domain I, Domain II, Domain III, and Domain IV. So far all Aux/IAA mutants with auxin-related phenotypes identified in both Arabidopsis and rice (Oryza sativa) are dominant gain-of-function mutants with mutations in Domain II of the corresponding Aux/IAA proteins, suggest that Aux/IAA proteins in both Arabidopsis and rice are largely functional redundantly, and they may have conserved functions. We report here the functional characterization of a rice Aux/IAA gene, OsIAA9. RT-PCR results showed that expression of OsIAA9 was induced by exogenously applied auxin, suggesting that OsIAA9 is an auxin response gene. Bioinformatic analysis showed that OsIAA9 has a repressor motif in Domain I, a degron in Domain II, and the conserved amino acid signatures for protein-protein interactions in Domain III and Domain IV. By generating transgenic plants expressing GFP-OsIAA9 and examining florescence in the transgenic plants, we found that OsIAA9 is localized in the nucleus. When transfected into protoplasts isolated from rosette leaves of Arabidopsis, OsIAA9 repressed reporter gene expression, and the repression was partially released by exogenously IAA. These results suggest that OsIAA9 is a canonical Aux/IAA protein. Protoplast transfection assays showed that OsIAA9 interacted ARF5, but not ARF6, 7, 8 and 19. Transgenic Arabidopsis plants expressing OsIAA9 have increased number of lateral roots, and reduced gravitropic response. Further analysis showed that OsIAA9 transgenic Arabidopsis plants accumulated fewer granules in their root tips and the distribution of granules was also affected. Taken together, our study showed that OsIAA9 is a transcriptional repressor, and it regulates gravitropic

  16. Accumulation of intra-cellular polyphosphate in Chlorella vulgaris cells is related to indole-3-acetic acid produced by Azospirillum brasilense.

    PubMed

    Meza, Beatriz; de-Bashan, Luz E; Hernandez, Juan-Pablo; Bashan, Yoav

    2015-06-01

    Accumulation of intra-cellular phosphate, as polyphosphate, was measured when the microalga Chlorella vulgaris was immobilized in alginate with either of two wild-type strains of the microalgae growth-promoting bacterium Azospirillum brasilense or their corresponding IAA-attenuated mutants. Wild type strains of A. brasilense induced higher amounts of intra-cellular phosphate in Chlorella than their respective mutants. Calculations comparing intra-cellular phosphate accumulation by culture or net accumulation by the cell and the amount of IAA that was produced by each of these strains revealed that higher IAA was linked to higher accumulations of intra-cellular phosphate. Application of four levels of exogenous IAA reported for A. brasilense and their IAA-attenuated mutants to cultures of C. vulgaris enhanced accumulation of intra-cellular phosphate; the higher the content of IAA per culture or per single cell, the higher was the amount of accumulated phosphate. When an IAA-attenuated mutant was complemented with exogenous IAA, accumulation of intra-cellular phosphate at the culture level was even higher than phosphate accumulation with the respective wild type strains. When calculating the net accumulation of intra-cellular phosphate in the complementation experiment, net intra-cellular phosphate induced by the IAA-attenuated mutant was completely restored and was similar to the wild strains. We propose that IAA produced by A. brasilense is linked to polyphosphate accumulation in C. vulgaris.

  17. Does the Induction of Flowering by Photoperiod Change the Polarity or Other Characteristics of Indole-3-acetic Acid Transport in Petioles for the Short Day Plant, Xanthium?

    PubMed

    Jacobs, W P

    1978-03-01

    To test the hypothesis that photoinduction acts by changing the ability of the plant to transport hormones, rather than by changing the ability of organs to synthesize them, the transport of carboxy-labeled indole-3-acetic acid was measured in the short day plant Xanthium pensylvanicum. Plants grown under noninductive conditions were matched for developmental stage, then assigned by a mathematically random method to either short day or noninductive conditions of "short day + light break." After the plants had been subjected to one to seven cycles, the movement of auxin was followed through sections cut from the middle of petioles of various ages. Photoinduction, even with as many as seven cycles, had no effect on auxin movement in either the basipetal or acropetal direction. Auxin movement in vegetative Xanthium was similar to that in Coleus and Phaseolus: strongly polar in a basipetal direction through younger petioles, but with polarity declining with increasing petiole age and concomitant decreasing elongation.

  18. Protein-protein interaction and gene co-expression maps of ARFs and Aux/IAAs in Arabidopsis

    PubMed Central

    Piya, Sarbottam; Shrestha, Sandesh K.; Binder, Brad; Stewart, C. Neal; Hewezi, Tarek

    2014-01-01

    The phytohormone auxin regulates nearly all aspects of plant growth and development. Based on the current model in Arabidopsis thaliana, Auxin/indole-3-acetic acid (Aux/IAA) proteins repress auxin-inducible genes by inhibiting auxin response transcription factors (ARFs). Experimental evidence suggests that heterodimerization between Aux/IAA and ARF proteins are related to their unique biological functions. The objective of this study was to generate the Aux/IAA-ARF protein-protein interaction map using full length sequences and locate the interacting protein pairs to specific gene co-expression networks in order to define tissue-specific responses of the Aux/IAA-ARF interactome. Pairwise interactions between 19 ARFs and 29 Aux/IAAs resulted in the identification of 213 specific interactions of which 79 interactions were previously unknown. The incorporation of co-expression profiles with protein-protein interaction data revealed a strong correlation of gene co-expression for 70% of the ARF-Aux/IAA interacting pairs in at least one tissue/organ, indicative of the biological significance of these interactions. Importantly, ARF4-8 and 19, which were found to interact with almost all Aux-Aux/IAA showed broad co-expression relationships with Aux/IAA genes, thus, formed the central hubs of the co-expression network. Our analyses provide new insights into the biological significance of ARF-Aux/IAA associations in the morphogenesis and development of various plant tissues and organs. PMID:25566309

  19. Recognition of the folded conformation of plant hormone (auxin, IAA) conjugates with glutamic and aspartic acids and their amides

    NASA Astrophysics Data System (ADS)

    Antolić, S.; Kveder, M.; Klaić, B.; Magnus, V.; Kojić-Prodić, B.

    2001-01-01

    The molecular structure of the endogenous plant hormone (auxin) conjugate, N-(indol-3-ylacetyl)- L-glutamic acid, is deduced by comparison with N2-(indol-3-ylacetyl)glutamine (IAA-Gln), N2-(indol-3-ylacetyl)asparagine (IAA-Asn) and N-(indol-3-ylacetyl)- L-aspartic acid using X-ray structure analysis, 1H-NMR spectroscopy (NOE measurements) and molecular modelling. The significance of the overall molecular shape, and of the resulting amphiphilic properties, of the compounds studied are discussed in terms of possible implications for trafficking between cell compartments. Both in the solid state and in solution, the molecules are in the hair-pin (folded) conformation in which the side chain is folded over the indole ring. While extended conformations can be detected by molecular dynamics simulations, they are so short-lived that any major influence on the biological properties of the compounds studied is unlikely.

  20. Genome-Wide Analysis and Characterization of Aux/IAA Family Genes in Brassica rapa

    PubMed Central

    Rameneni, Jana Jeevan; Li, Xiaonan; Sivanandhan, Ganesan; Choi, Su Ryun; Pang, Wenxing; Im, Subin; Lim, Yong Pyo

    2016-01-01

    Auxins are the key players in plant growth development involving leaf formation, phototropism, root, fruit and embryo development. Auxin/Indole-3-Acetic Acid (Aux/IAA) are early auxin response genes noted as transcriptional repressors in plant auxin signaling. However, many studies focus on Aux/ARF gene families and much less is known about the Aux/IAA gene family in Brassica rapa (B. rapa). Here we performed a comprehensive genome-wide analysis and identified 55 Aux/IAA genes in B. rapa using four conserved motifs of Aux/IAA family (PF02309). Chromosomal mapping of the B. rapa Aux/IAA (BrIAA) genes facilitated understanding cluster rearrangement of the crucifer building blocks in the genome. Phylogenetic analysis of BrIAA with Arabidopsis thaliana, Oryza sativa and Zea mays identified 51 sister pairs including 15 same species (BrIAA—BrIAA) and 36 cross species (BrIAA—AtIAA) IAA genes. Among the 55 BrIAA genes, expression of 43 and 45 genes were verified using Genebank B. rapa ESTs and in home developed microarray data from mature leaves of Chiifu and RcBr lines. Despite their huge morphological difference, tissue specific expression analysis of BrIAA genes between the parental lines Chiifu and RcBr showed that the genes followed a similar pattern of expression during leaf development and a different pattern during bud, flower and siliqua development stages. The response of the BrIAA genes to abiotic and auxin stress at different time intervals revealed their involvement in stress response. Single Nucleotide Polymorphisms between IAA genes of reference genome Chiifu and RcBr were focused and identified. Our study examines the scope of conservation and divergence of Aux/IAA genes and their structures in B. rapa. Analyzing the expression and structural variation between two parental lines will significantly contribute to functional genomics of Brassica crops and we belive our study would provide a foundation in understanding the Aux/IAA genes in B. rapa. PMID

  1. Lysinibacillus endophyticus sp. nov., an indole-3-acetic acid producing endophytic bacterium isolated from corn root (Zea mays cv. Xinken-5).

    PubMed

    Yu, Jiang; Guan, Xuejiao; Liu, Chongxi; Xiang, Wensheng; Yu, Zhenhua; Liu, Xiaobing; Wang, Guanghua

    2016-10-01

    A Gram-positive, aerobic, motile, rod-shaped bacterium, designated strain C9(T), was isolated from surface sterilised corn roots (Zea mays cv. Xinken-5) and found to be able to produce indole-3-acetic acid. A polyphasic taxonomic study was carried out to determine the status of strain C9(T). The major cellular fatty acids were found to contain iso-C15:0, anteiso-C15:0 and anteiso-C17:0, and the only menaquinone was identified as MK-7. The polar lipid profile was found to contain diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids and an unidentified lipid. The cell wall peptidoglycan was found to be of the A4α L-Lys-D-Asp type and the whole cell sugar was found to be glucose. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain C9(T) belongs to the genus Lysinibacillus and is closely related to Lysinibacillus chungkukjangi NBRC 108948(T) (98.1 % similarity) and Lysinibacillus sinduriensis DSM 27595(T) (98.0 %). However, the low levels of DNA-DNA relatedness and some differential phenotypic characteristics allowed the strain to be distinguished from its close relatives. Therefore, it is concluded that strain C9(T) represents a novel species of the genus Lysinibacillus, for which the name Lysinibacillus endophyticus sp. nov. is proposed. The type strain is C9(T) (=DSM 100506(T) = CGMCC 1.15291(T)).

  2. Solution structure of the PsIAA4 oligomerization domain reveals interaction modes for transcription factors in early auxin response.

    PubMed

    Dinesh, Dhurvas Chandrasekaran; Kovermann, Michael; Gopalswamy, Mohanraj; Hellmuth, Antje; Calderón Villalobos, Luz Irina A; Lilie, Hauke; Balbach, Jochen; Abel, Steffen

    2015-05-12

    The plant hormone auxin activates primary response genes by facilitating proteolytic removal of auxin/indole-3-acetic acid (AUX/IAA)-inducible repressors, which directly bind to transcriptional auxin response factors (ARF). Most AUX/IAA and ARF proteins share highly conserved C-termini mediating homotypic and heterotypic interactions within and between both protein families. The high-resolution NMR structure of C-terminal domains III and IV of the AUX/IAA protein PsIAA4 from pea (Pisum sativum) revealed a globular ubiquitin-like β-grasp fold with homologies to the Phox and Bem1p (PB1) domain. The PB1 domain of wild-type PsIAA4 features two distinct surface patches of oppositely charged amino acid residues, mediating front-to-back multimerization via electrostatic interactions. Mutations of conserved basic or acidic residues on either face suppressed PsIAA4 PB1 homo-oligomerization in vitro and confirmed directional interaction of full-length PsIAA4 in vivo (yeast two-hybrid system). Mixing of oppositely mutated PsIAA4 PB1 monomers enabled NMR mapping of the negatively charged interface of the reconstituted PsIAA4 PB1 homodimer variant, whose stoichiometry (1:1) and equilibrium binding constant (KD ∼ 6.4 μM) were determined by isothermal titration calorimetry. In silico protein-protein docking studies based on NMR and yeast interaction data derived a model of the PsIAA4 PB1 homodimer, which is comparable with other PB1 domain dimers, but indicated considerable differences between the homodimeric interfaces of AUX/IAA and ARF PB1 domains. Our study provides an impetus for elucidating the molecular determinants that confer specificity to complex protein-protein interaction circuits between members of the two central families of transcription factors important to the regulation of auxin-responsive gene expression. PMID:25918389

  3. Solution structure of the PsIAA4 oligomerization domain reveals interaction modes for transcription factors in early auxin response.

    PubMed

    Dinesh, Dhurvas Chandrasekaran; Kovermann, Michael; Gopalswamy, Mohanraj; Hellmuth, Antje; Calderón Villalobos, Luz Irina A; Lilie, Hauke; Balbach, Jochen; Abel, Steffen

    2015-05-12

    The plant hormone auxin activates primary response genes by facilitating proteolytic removal of auxin/indole-3-acetic acid (AUX/IAA)-inducible repressors, which directly bind to transcriptional auxin response factors (ARF). Most AUX/IAA and ARF proteins share highly conserved C-termini mediating homotypic and heterotypic interactions within and between both protein families. The high-resolution NMR structure of C-terminal domains III and IV of the AUX/IAA protein PsIAA4 from pea (Pisum sativum) revealed a globular ubiquitin-like β-grasp fold with homologies to the Phox and Bem1p (PB1) domain. The PB1 domain of wild-type PsIAA4 features two distinct surface patches of oppositely charged amino acid residues, mediating front-to-back multimerization via electrostatic interactions. Mutations of conserved basic or acidic residues on either face suppressed PsIAA4 PB1 homo-oligomerization in vitro and confirmed directional interaction of full-length PsIAA4 in vivo (yeast two-hybrid system). Mixing of oppositely mutated PsIAA4 PB1 monomers enabled NMR mapping of the negatively charged interface of the reconstituted PsIAA4 PB1 homodimer variant, whose stoichiometry (1:1) and equilibrium binding constant (KD ∼ 6.4 μM) were determined by isothermal titration calorimetry. In silico protein-protein docking studies based on NMR and yeast interaction data derived a model of the PsIAA4 PB1 homodimer, which is comparable with other PB1 domain dimers, but indicated considerable differences between the homodimeric interfaces of AUX/IAA and ARF PB1 domains. Our study provides an impetus for elucidating the molecular determinants that confer specificity to complex protein-protein interaction circuits between members of the two central families of transcription factors important to the regulation of auxin-responsive gene expression.

  4. Both Free Indole-3-Acetic Acid and Photosynthetic Performance are Important Players in the Response of Medicago truncatula to Urea and Ammonium Nutrition Under Axenic Conditions

    PubMed Central

    Esteban, Raquel; Royo, Beatriz; Urarte, Estibaliz; Zamarreño, Ángel M.; Garcia-Mina, José M.; Moran, Jose F.

    2016-01-01

    We aimed to identify the early stress response and plant performance of Medicago truncatula growing in axenic medium with ammonium or urea as the sole source of nitrogen, with respect to nitrate-based nutrition. Biomass measurements, auxin content analyses, root system architecture (RSA) response analyses, and physiological parameters were determined. Both ammonium and ureic nutrition severely affected the RSA, resulting in changes in the main elongation rate, lateral root development, and insert position from the root base. The auxin content decreased in both urea- and ammonium-treated roots; however, only the ammonium-treated plants were affected at the shoot level. The analysis of chlorophyll a fluorescence transients showed that ammonium affected photosystem II, but urea did not impair photosynthetic activity. Superoxide dismutase isoenzymes in the plastids were moderately affected by urea and ammonium in the roots. Overall, our results showed that low N doses from different sources had no remarkable effects on M. truncatula, with the exception of the differential phenotypic root response. High doses of both ammonium and urea caused great changes in plant length, auxin contents and physiological measurements. Interesting correlations were found between the shoot auxin pool and both plant length and the “performance index” parameter, which is obtained from measurements of the kinetics of chlorophyll a fluorescence. Taken together, these data demonstrate that both the indole-3-acetic acid pool and performance index are important components of the response of M. truncatula under ammonium or urea as the sole N source. PMID:26909089

  5. Lysinibacillus endophyticus sp. nov., an indole-3-acetic acid producing endophytic bacterium isolated from corn root (Zea mays cv. Xinken-5).

    PubMed

    Yu, Jiang; Guan, Xuejiao; Liu, Chongxi; Xiang, Wensheng; Yu, Zhenhua; Liu, Xiaobing; Wang, Guanghua

    2016-10-01

    A Gram-positive, aerobic, motile, rod-shaped bacterium, designated strain C9(T), was isolated from surface sterilised corn roots (Zea mays cv. Xinken-5) and found to be able to produce indole-3-acetic acid. A polyphasic taxonomic study was carried out to determine the status of strain C9(T). The major cellular fatty acids were found to contain iso-C15:0, anteiso-C15:0 and anteiso-C17:0, and the only menaquinone was identified as MK-7. The polar lipid profile was found to contain diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids and an unidentified lipid. The cell wall peptidoglycan was found to be of the A4α L-Lys-D-Asp type and the whole cell sugar was found to be glucose. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain C9(T) belongs to the genus Lysinibacillus and is closely related to Lysinibacillus chungkukjangi NBRC 108948(T) (98.1 % similarity) and Lysinibacillus sinduriensis DSM 27595(T) (98.0 %). However, the low levels of DNA-DNA relatedness and some differential phenotypic characteristics allowed the strain to be distinguished from its close relatives. Therefore, it is concluded that strain C9(T) represents a novel species of the genus Lysinibacillus, for which the name Lysinibacillus endophyticus sp. nov. is proposed. The type strain is C9(T) (=DSM 100506(T) = CGMCC 1.15291(T)). PMID:27401830

  6. How phytohormone IAA and chelator EDTA affect lead uptake by Zn/Cd hyperaccumulator Picris divaricata.

    PubMed

    Du, Rui-Jun; He, Er-Kai; Tang, Ye-Tao; Hu, Peng-Jie; Ying, Rong-Rong; Morel, Jean-Louis; Qiu, Rong-Liang

    2011-01-01

    In this paper, the effects of indole-3-acetic acid (IAA) and/or ethylenediaminetetraacetic acid (EDTA) on lead uptake by a Zn/Cd hyperaccumulator Picris divaricata were studied. P. divaricata responded to Pb by better root system and increased biomass in presence of phytohormone IAA, which was able to reduce the inhibiting effects of Pb on transpiration without reducing the uptake of Pb The application of 100 microM IAA increased plant transpiration rate by about 20% and Pb concentration in leaves by about 37.3% as compared to treatment exposed to Pb alone. The enhanced phytoextraction efficiency could be attributed to the mechanisms played by IAA through alleviating Pb toxicity, creating better root system and plant biomass, promoting a higher transpiration rate as well as regulating the level of nutrient elements. On the contrary, inefficiency of phytoextraction was found with EDTA or the combination of IAA and EDTA probably because most Pb was in the form of Pb-EDTA complex which blocked the uptake by P. divaricata. The present study demonstrated that IAA was able to enhance the phytoextraction of Pb by Zn/Cd hyperaccumulator P. divaricata, providing a feasible method for the phytoremediation of polymetallic contaminated soils. PMID:21972569

  7. Introduction of a novel pathway for IAA biosynthesis to rhizobia alters vetch root nodule development.

    PubMed

    Camerini, Serena; Senatore, Beatrice; Lonardo, Enza; Imperlini, Esther; Bianco, Carmen; Moschetti, Giancarlo; Rotino, Giuseppe L; Campion, Bruno; Defez, Roberto

    2008-07-01

    We introduced into Rhizobium leguminosarum bv. viciae LPR1105 a new pathway for the biosynthesis of the auxin, indole-3-acetic acid (IAA), under the control of a stationary phase-activated promoter active both in free-living bacteria and bacteroids. The newly introduced genes are the iaaM gene from Pseudomonas savastanoi and the tms2 gene from Agrobacterium tumefaciens. Free-living bacteria harbouring the promoter-iaaMtms2 construct release into the growth medium 14-fold more IAA than the wild-type parental strain. This IAA overproducing R. l. viciae, the RD20 strain, elicits the development of vetch root nodules containing up to 60-fold more IAA than nodules infected by the wild-type strain LPR1105. Vetch root nodules derived from RD20 are fewer in number per plant, heavier in terms of dry weight and show an enlarged and more active meristem. A significant increase in acetylene reduction activity was measured in nodules elicited in vetch by RD20.

  8. Dynamics of the concentration of IAA and some of its conjugates during the induction of somatic embryogenesis in Coffea canephora

    PubMed Central

    Ayil-Gutiérrez, Benajmín; Galaz-Ávalos, Rosa María; Peña-Cabrera, Eduardo; Loyola-Vargas, Victor Manuel

    2013-01-01

    Most of the somatic embryogenesis (SE) process requires the presence, either before or during the embryogenic process, of at least one exogenous auxin. This exogenous auxin induces the presence of endogenous auxins, which appears to be essential for SE induction. We found that during the preincubation period of SE in Coffea canephora, there is an important increase in both free and conjugated indole-3-acetic acid (IAA), as well as indole-3-butyric acid. This increase is accompanied by an increase in the expression of YUCCA (CcYUC), TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS 1 (CcTAA1), and GRETCHEN HAGEN 3 (GH3) genes. On the other hand, most of the IAA compounds decreased during the induction of SE. The results presented in this research suggest that a balance between free IAA and its amide conjugates is necessary to allow the expression of SE-related genes. PMID:24299659

  9. Increased levels of IAA are required for system 2 ethylene synthesis causing fruit softening in peach (Prunus persica L. Batsch).

    PubMed

    Tatsuki, Miho; Nakajima, Naoko; Fujii, Hiroshi; Shimada, Takehiko; Nakano, Michiharu; Hayashi, Ken-ichiro; Hayama, Hiroko; Yoshioka, Hirohito; Nakamura, Yuri

    2013-02-01

    The fruit of melting-flesh peach (Prunus persica L. Batsch) cultivars produce high levels of ethylene caused by high expression of PpACS1 (an isogene of 1-aminocyclopropane-1-carboxylic acid synthase), resulting in rapid fruit softening at the late-ripening stage. In contrast, the fruit of stony hard peach cultivars do not soften and produce little ethylene due to low expression of PpACS1. To elucidate the mechanism for suppressing PpACS1 expression in stony hard peaches, a microarray analysis was performed. Several genes that displayed similar expression patterns as PpACS1 were identified and shown to be indole-3-acetic acid (IAA)-inducible genes (Aux/IAA, SAUR). That is, expression of IAA-inducible genes increased at the late-ripening stage in melting flesh peaches; however, these transcripts were low in mature fruit of stony hard peaches. The IAA concentration increased suddenly just before harvest time in melting flesh peaches exactly coinciding with system 2 ethylene production. In contrast, the IAA concentration did not increase in stony hard peaches. Application of 1-naphthalene acetic acid, a synthetic auxin, to stony hard peaches induced a high level of PpACS1 expression, a large amount of ethylene production and softening. Application of an anti-auxin, α-(phenylethyl-2-one)-IAA, to melting flesh peaches reduced levels of PpACS1 expression and ethylene production. These observations indicate that suppression of PpACS1 expression at the late-ripening stage of stony hard peach may result from a low level of IAA and that a high concentration of IAA is required to generate a large amount of system 2 ethylene in peaches.

  10. Studies on the longitudinal and lateral transport of IAA in the shoots of etiolated corn seedlings

    NASA Technical Reports Server (NTRS)

    Epel, B. L.; Warmbrodt, R. P.; Bandurski, R. S.

    1992-01-01

    The auxin, indole-3-acetic acid, and the symplastic probe, carboxyfluorescein diacetate, were applied to the cut mesocotyl base or coleoptile apex of etiolated Zea mays seedlings and their transport measured and tissue distribution determined. The longitudinal transport of indole-3-acetate was strongly basipolar, while that of carboxyfluorescein was essentially apolar. The longitudinal transport of IAA, like carboxyfluorescein, was mainly in the stele. IAA exhibited a much higher lateral mobility from stele to cortex than did carboxyfluorescein. Based on the calculation of moles probe/kg fw, IAA is 4 times more concentrated in the stele than in the cortex while CF is 24 times higher in concentration in the stele than in the cortex. The structure of the node and the mesocotyl regions just below the node, regions of maximum growth, were examined and plasmodesmatal structure and frequency in these regions determined. The plasmodesmatal frequency, about 3 per micrometer2, between all cell types of the mesocotyl was found to be about 5-8 fold higher than that found for the root. Hypotheses of lateral auxin transport are discussed.

  11. Genome-wide survey and comprehensive expression profiling of Aux/IAA gene family in chickpea and soybean

    PubMed Central

    Singh, Vikash K.; Jain, Mukesh

    2015-01-01

    Auxin plays a central role in many aspects of plant growth and development. Auxin/Indole-3-Acetic Acid (Aux/IAA) genes cooperate with several other components in the perception and signaling of plant hormone auxin. An investigation of chickpea and soybean genomes revealed 22 and 63 putative Aux/IAA genes, respectively. These genes were classified into six subfamilies on the basis of phylogenetic analysis. Among 63 soybean Aux/IAA genes, 57 (90.5%) were found to be duplicated via whole genome duplication (WGD)/segmental events. Transposed duplication played a significant role in tandem arrangements between the members of different subfamilies. Analysis of Ka/Ks ratio of duplicated Aux/IAA genes revealed purifying selection pressure with restricted functional divergence. Promoter sequence analysis revealed several cis-regulatory elements related to auxin, abscisic acid, desiccation, salt, seed, and endosperm, indicating their role in development and stress responses. Expression analysis of chickpea and soybean Aux/IAA genes in various tissues and stages of development demonstrated tissue/stage specific differential expression. In soybean, at least 16 paralog pairs, duplicated via WGD/segmental events, showed almost indistinguishable expression pattern, but eight pairs exhibited significantly diverse expression patterns. Under abiotic stress conditions, such as desiccation, salinity and/or cold, many Aux/IAA genes of chickpea and soybean revealed differential expression. qRT-PCR analysis confirmed the differential expression patterns of selected Aux/IAA genes in chickpea. The analyses presented here provide insights on putative roles of chickpea and soybean Aux/IAA genes and will facilitate elucidation of their precise functions during development and abiotic stress responses. PMID:26579165

  12. Rice Dwarf Virus P2 Protein Hijacks Auxin Signaling by Directly Targeting the Rice OsIAA10 Protein, Enhancing Viral Infection and Disease Development.

    PubMed

    Jin, Lian; Qin, Qingqing; Wang, Yu; Pu, Yingying; Liu, Lifang; Wen, Xing; Ji, Shaoyi; Wu, Jianguo; Wei, Chunhong; Ding, Biao; Li, Yi

    2016-09-01

    The phytohormone auxin plays critical roles in regulating myriads of plant growth and developmental processes. Microbe infection can disturb auxin signaling resulting in defects in these processes, but the underlying mechanisms are poorly understood. Auxin signaling begins with perception of auxin by a transient co-receptor complex consisting of an F-box transport inhibitor response 1/auxin signaling F-box (TIR1/AFB) protein and an auxin/indole-3-acetic acid (Aux/IAA) protein. Auxin binding to the co-receptor triggers ubiquitination and 26S proteasome degradation of the Aux/IAA proteins, leading to subsequent events, including expression of auxin-responsive genes. Here we report that Rice dwarf virus (RDV), a devastating pathogen of rice, causes disease symptoms including dwarfing, increased tiller number and short crown roots in infected rice as a result of reduced sensitivity to auxin signaling. The RDV capsid protein P2 binds OsIAA10, blocking the interaction between OsIAA10 and OsTIR1 and inhibiting 26S proteasome-mediated OsIAA10 degradation. Transgenic rice plants overexpressing wild-type or a dominant-negative (degradation-resistant) mutant of OsIAA10 phenocopy RDV symptoms are more susceptible to RDV infection; however, knockdown of OsIAA10 enhances the resistance of rice to RDV infection. Our findings reveal a previously unknown mechanism of viral protein reprogramming of a key step in auxin signaling initiation that enhances viral infection and pathogenesis. PMID:27606959

  13. Rice Dwarf Virus P2 Protein Hijacks Auxin Signaling by Directly Targeting the Rice OsIAA10 Protein, Enhancing Viral Infection and Disease Development

    PubMed Central

    Jin, Lian; Qin, Qingqing; Wang, Yu; Pu, Yingying; Liu, Lifang; Wen, Xing; Ji, Shaoyi; Wu, Jianguo; Wei, Chunhong; Li, Yi

    2016-01-01

    The phytohormone auxin plays critical roles in regulating myriads of plant growth and developmental processes. Microbe infection can disturb auxin signaling resulting in defects in these processes, but the underlying mechanisms are poorly understood. Auxin signaling begins with perception of auxin by a transient co-receptor complex consisting of an F-box transport inhibitor response 1/auxin signaling F-box (TIR1/AFB) protein and an auxin/indole-3-acetic acid (Aux/IAA) protein. Auxin binding to the co-receptor triggers ubiquitination and 26S proteasome degradation of the Aux/IAA proteins, leading to subsequent events, including expression of auxin-responsive genes. Here we report that Rice dwarf virus (RDV), a devastating pathogen of rice, causes disease symptoms including dwarfing, increased tiller number and short crown roots in infected rice as a result of reduced sensitivity to auxin signaling. The RDV capsid protein P2 binds OsIAA10, blocking the interaction between OsIAA10 and OsTIR1 and inhibiting 26S proteasome-mediated OsIAA10 degradation. Transgenic rice plants overexpressing wild-type or a dominant-negative (degradation-resistant) mutant of OsIAA10 phenocopy RDV symptoms are more susceptible to RDV infection; however, knockdown of OsIAA10 enhances the resistance of rice to RDV infection. Our findings reveal a previously unknown mechanism of viral protein reprogramming of a key step in auxin signaling initiation that enhances viral infection and pathogenesis. PMID:27606959

  14. Participation of IAA in transduction of gravistimulus in apical cells of moss protonema

    NASA Astrophysics Data System (ADS)

    Oksyniuk, U. A.; Khorkavtsiv, O. Y.; Lesniak, Y. I.

    Growth movements of vascular plant axis organs -- photo-, gravi- and other tropisms -- are tightly connected with IAA transport (Hertel, 1983; Medvedev, 1996; Kiss, 2000). Moss protonema synthesizes IAA (indole-3-acetic acid) and transports it basipetally favouring growth and differentiation of caulonema (Bopp, 1979; Rose, Bopp, 1983; Rose et al., 1983). We aimed at studying the role of IAA in moss protonema gravitropism using exogenous IAA, 1-NAA (1-naphthaleneacetic acid), 2,4D (2,4-dichlorophenoxyacetic acid) and inhibitors of polar IAA transport -- phytotropins NPA (N-1-naphthylphthalamic acid) and TIBA (2,3,5-triiodobenzoic acid). Six-day gravitropic protonema of Ceratodon purpureus and Pohlia nutans were taken for experiments. Auxin and phytotropins solutions were laid on protonema mats the latters being kept in solutions for 30 min. Then the surplus of solutions were poured off and Petri dishes were placed vertically for 6 h. 20 μ M of IAA and of other synthetic auxins did not significantly influence the angle of protonema gravity bending, 40 μ M of the agents, howewer, reduced the per cent of apical cells bendings and their angles. The most expressed influence on the angles of bending had the inhibitors of polar IAA transport -- NPA. 0,1 -- 3,0 μ M of this phytotropin did not change the form of apical cell, did not disturb the general distribution of amyloplasts and did not significantly lower the per cent and the value of gravity bending angle, though 10 μ M of the phytotropin - inhibited gravity bending. The mixture of 1-NAA and NPA having been added into the medium the influence of NPA was lowered and gravitropic growth renewed in course of time. 10 μ M of other phytopropin TIBA also inhibited gravitropism of Ceratodon purpureus and Pohlia nutans protonema. The analysis of basipetal transport of IAA in moss rhizoids and protonema may indicate the availability of special IAA transport in these structures (Bopp, Cerier, 1988). On the basis of the

  15. Effect of IAA on in vitro growth and colonization of Nostoc in plant roots

    PubMed Central

    Hussain, Anwar; Shah, Syed T.; Rahman, Hazir; Irshad, Muhammad; Iqbal, Amjad

    2015-01-01

    Nostoc is widely known for its ability to fix atmospheric nitrogen and the establishment of symbiotic relationship with a wide range of plants from various taxonomic groups. Several strains of Nostoc produce phytohormones that promote growth of its plant partners. Nostoc OS-1 was therefore selected for study because of the presence of putative ipdC gene that encodes a key enzyme to produce Indole-3-acetic acid (IAA). The results indicated that both cellular and released IAA was found high with increasing incubation time and reached to a peak value (i.e., 21 pmol mg-1ch-a) on the third week as determined by UPLC-ESI-MS/MS. Also the Nostoc OS-1 strain efficiently colonized the roots and promoted the growth of rice as well as wheat under axenic conditions and induced ipdC gene that suggested the possible involvement of IAA in these phenotypes. To confirm the impact of IAA on root colonization efficiency and plant promoting phenotypes of Nostoc OS-1, an ipdC knockout mutant was generated by homologous recombinant method. The amount of releasing IAA, in vitro growth, root colonization, and plant promoting efficiency of the ipdC knockout mutant was observed significantly lower than wild type strain under axenic conditions. Importantly, these phenotypes were restored to wild-type levels when the ipdC knockout mutant was complemented with wild type ipdC gene. These results together suggested that ipdC and/or synthesized IAA of Nostoc OS-1 is required for its efficient root colonization and plant promoting activity. PMID:25699072

  16. Assessing the effects of heavy metals in ACC deaminase and IAA production on plant growth-promoting bacteria.

    PubMed

    Carlos, Mendoza-Hernández José; Stefani, Perea-Vélez Yazmin; Janette, Arriola-Morales; Melani, Martínez-Simón Sara; Gabriela, Pérez-Osorio

    2016-01-01

    This study poses a methodology in order to simultaneously quantify ACC deaminase and IAA levels in the same culture medium. Ten bacterial strains isolated from plant rhizosphere naturally settled in mining residues were chosen. These bacterial strains were characterized as PGPB, and all of them showed at least three characteristics (indole-3 acetic acid and siderophore production, ACC deaminase enzyme activity, and inorganic phosphate solubilization). Taxonomic identification showed that the strains belong to Enterobacter, Serratia, Klebsiella, and Escherichia genera. Similarly, both the ACC deaminase enzyme activity and the IAA synthesis in the presence of Cu, As, Pb, Ni, Cd, and Mn were measured. The results showed that both the ACC deaminase enzyme activity and the IAA synthesis were higher with the Pb, As, and Cu treatments than with the Escherichia N16, Enterobacter K131, Enterobacter N9, and Serratia K120 control treatments. On the other hand, Ni, Cd, and Mn negatively affected both the ACC deaminase enzyme activity and the IAA production on every bacterium except on the Klebsiella Mc173 strain. Serratia K120 bacterium got a positive correlation between ACC deaminase and IAA in the presence of every heavy metal, and it also promoted Helianthus annuus plant growth, showing a potential use in phytoremediation systems.

  17. Assessing the effects of heavy metals in ACC deaminase and IAA production on plant growth-promoting bacteria.

    PubMed

    Carlos, Mendoza-Hernández José; Stefani, Perea-Vélez Yazmin; Janette, Arriola-Morales; Melani, Martínez-Simón Sara; Gabriela, Pérez-Osorio

    2016-01-01

    This study poses a methodology in order to simultaneously quantify ACC deaminase and IAA levels in the same culture medium. Ten bacterial strains isolated from plant rhizosphere naturally settled in mining residues were chosen. These bacterial strains were characterized as PGPB, and all of them showed at least three characteristics (indole-3 acetic acid and siderophore production, ACC deaminase enzyme activity, and inorganic phosphate solubilization). Taxonomic identification showed that the strains belong to Enterobacter, Serratia, Klebsiella, and Escherichia genera. Similarly, both the ACC deaminase enzyme activity and the IAA synthesis in the presence of Cu, As, Pb, Ni, Cd, and Mn were measured. The results showed that both the ACC deaminase enzyme activity and the IAA synthesis were higher with the Pb, As, and Cu treatments than with the Escherichia N16, Enterobacter K131, Enterobacter N9, and Serratia K120 control treatments. On the other hand, Ni, Cd, and Mn negatively affected both the ACC deaminase enzyme activity and the IAA production on every bacterium except on the Klebsiella Mc173 strain. Serratia K120 bacterium got a positive correlation between ACC deaminase and IAA in the presence of every heavy metal, and it also promoted Helianthus annuus plant growth, showing a potential use in phytoremediation systems. PMID:27296962

  18. The improved phytoextraction of lead (Pb) and the growth of maize (Zeamays L.): the role of plant growth regulators (GA3 and IAA) and EDTA alone and in combinations.

    PubMed

    Hadi, Fazal; Bano, Asghari; Fuller, Michael P

    2010-06-01

    This investigation was made to examine the role of gibberellic acid (GA(3)), indole-3-acetic acid (IAA) and EDTA in improving phytoextraction of the Pb and plant growth on Pb added soil. GA(3), IAA and EDTA were applied separately and in combinations. GA(3) and IAA were applied as foliar spray and seed soaking. EDTA was applied in single and split doses. Analysis of the Pb in different parts of plant was carried out using atomic absorption/flame spectrophotometer. EDTA significantly reduced the plant growth and dry biomass, whereas GA(3) and IAA foliar spray increased it significantly when compared with control (only Pb added soil). In combined treatments of EDTA+GA(3) and EDTA+IAA, the growth and biomass was restored, which shows that GA(3) and IAA did compensate the negative effect of EDTA on plant growth. The separate treatments of EDTA, GA(3) and IAA increased the Pb uptake and translocation significantly moreover in combine treatments, synergistic effect was found and remarkable increase in Pb uptake and translocation into shoot was observed. EDTA increased the Pb uptake but declined the biomass; subsequently the total Pb accumulation was decreased in plant. The maximum total Pb was found in combined treatment of EDTA+GA(3). These findings suggest more investigation to find a combination of GA(3) with a very low concentration of EDTA, as in high concentration it causes soil and ground water pollution.

  19. IAA-producing rhizobacteria from chickpea (Cicer arietinum L.) induce changes in root architecture and increase root biomass.

    PubMed

    Fierro-Coronado, Rosario Alicia; Quiroz-Figueroa, Francisco Roberto; García-Pérez, Luz María; Ramírez-Chávez, Enrique; Molina-Torres, Jorge; Maldonado-Mendoza, Ignacio Eduardo

    2014-10-01

    Rhizobacteria promote and have beneficial effects on plant growth, making them useful to agriculture. Nevertheless, the rhizosphere of the chickpea plant has not been extensively examined. The aim of the present study was to select indole-3-acetic acid (IAA) producing rhizobacteria from the rhizosphere of chickpea plants for their potential use as biofertilizers. After obtaining a collection of 864 bacterial isolates, we performed a screen using the Salkowski reaction for the presence of auxin compounds (such as IAA) in bacterial Luria-Bertani supernatant (BLBS). Our results demonstrate that the Salkowski reaction has a greater specificity for detecting IAA than other tested auxins. Ten bacterial isolates displaying a wide range of auxin accumulation were selected, producing IAA levels of 5 to 90 μmol/L (according to the Salkowski reaction). Bacterial isolates were identified on the basis of 16S rDNA partial sequences: 9 isolates belonged to Enterobacter, and 1 isolate was classified as Serratia. The effect of BLBS on root morphology was evaluated in Arabidopsis thaliana. IAA production by rhizobacteria was confirmed by means of a DR5::GFP construct that is responsive to IAA, and also by HPLC-GC/MS. Finally, we observed that IAA secreted by rhizobacteria (i) modified the root architecture of A. thaliana, (ii) caused an increase in chickpea root biomass, and (iii) activated the green fluorescent protein (GFP) reporter gene driven by the DR5 promoter. These findings provide evidence that these novel bacterial isolates may be considered as putative plant-growth-promoting rhizobacteria modifying root architecture and increasing root biomass.

  20. IAA Correlator Center

    NASA Technical Reports Server (NTRS)

    Surkis, Igor; Ken, Voitsekh; Melnikov, Alexey; Mishin, Vladimir; Sokolova, Nadezda; Shantyr, Violet; Zimovsky, Vladimir

    2013-01-01

    The activities of the six-station IAA RAS correlator include regular processing of national geodetic VLBI programs Ru-E, Ru-U, and Ru-F. The Ru-U sessions have been transferred in e-VLBI mode and correlated in the IAA Correlator Center automatically since 2011. The DiFX software correlator is used at the IAA in some astrophysical experiments.

  1. Growth Promotion of Yunnan Pine Early Seedlings in Response to Foliar Application of IAA and IBA

    PubMed Central

    Xu, Yulan; Zhang, Yuemin; Li, Yunfei; Li, Genqian; Liu, Daiyi; Zhao, Minchong; Cai, Nianhui

    2012-01-01

    A field experiment was conducted using a 3 × 3 orthogonal regression design to explore the growth promotion of one-year-old Yunnan pine seedlings (Pinus yunnanensis Franch.) in response to foliar application of IAA (indole-3-acetic acid) at rates of 0, 200 and 400 mg·L−1 and IBA (indole-3-butyric acid) at rates of 0, 200 and 400 mg·L−1 in order to promote the growth during the seedlings’ early stage. The experiment was conducted at the Lufeng Village Forest Farm of Yiliang County in Kunming, Yunnan, China. The results showed that IAA and IBA were effective in growth promotion of Yunnan pine seedlings. The response of both growth increment and biomass accumulation to the concentration of IAA and IBA can be modeled using a bivariate surface response, and each growth index had a peak value. Growth indexes increased with the increase of the dosage of photohormones before reaching a peak value, and then decreased. The different growth indexes had various responses to the concentrations and ratio of IAA and IBA. The foliar application of IAA in combination with IBA showed the largest improvement on the biomass of the needles, followed by stems and roots. The higher ratio of IAA promoted stem diameter growth, root system development and biomass accumulation in the needles, while a higher ratio of IBA contributed to height growth and biomass accumulation in the stem. Based on the auxin effect equations on the different growth indexes and surface response, the optimum concentrations and the (IAA:IBA) ratios can be obtained. The optimum concentrations of IAA and IBA were 167 and 186, 310 and 217, 193 and 159, 191 and 221, and 206 and 186 mg·L−1, with corresponding ratios of 1:1.11, 1:0.70, 1:0.82, 1:1.15 and 1:0.90, respectively, at the maximum seedling height and collar diameter growth as well as biomass accumulation at the root, stem and needle. The above growth indexes were 22.00%, 79.80%, 48.65%, 82.20% and 107.00% higher than the control treatment. PMID

  2. Acyl substrate preferences of an IAA-amido synthetase account for variations in grape (Vitis vinifera L.) berry ripening caused by different auxinic compounds indicating the importance of auxin conjugation in plant development

    PubMed Central

    Böttcher, Christine; Boss, Paul K.; Davies, Christopher

    2011-01-01

    Nine Gretchen Hagen (GH3) genes were identified in grapevine (Vitis vinifera L.) and six of these were predicted on the basis of protein sequence similarity to act as indole-3-acetic acid (IAA)-amido synthetases. The activity of these enzymes is thought to be important in controlling free IAA levels and one auxin-inducible grapevine GH3 protein, GH3-1, has previously been implicated in the berry ripening process. Ex planta assays showed that the expression of only one other GH3 gene, GH3-2, increased following the treatment of grape berries with auxinic compounds. One of these was the naturally occurring IAA and the other two were synthetic, α-naphthalene acetic acid (NAA) and benzothiazole-2-oxyacetic acid (BTOA). The determination of steady-state kinetic parameters for the recombinant GH3-1 and GH3-2 proteins revealed that both enzymes efficiently conjugated aspartic acid (Asp) to IAA and less well to NAA, while BTOA was a poor substrate. GH3-2 gene expression was induced by IAA treatment of pre-ripening berries with an associated increase in levels of IAA-Asp and a decrease in free IAA levels. This indicates that GH3-2 responded to excess auxin to maintain low levels of free IAA. Grape berry ripening was not affected by IAA application prior to veraison (ripening onset) but was considerably delayed by NAA and even more so by BTOA. The differential effects of the three auxinic compounds on berry ripening can therefore be explained by the induction and acyl substrate specificity of GH3-2. These results further indicate an important role for GH3 proteins in controlling auxin-related plant developmental processes. PMID:21543520

  3. Acyl substrate preferences of an IAA-amido synthetase account for variations in grape (Vitis vinifera L.) berry ripening caused by different auxinic compounds indicating the importance of auxin conjugation in plant development.

    PubMed

    Böttcher, Christine; Boss, Paul K; Davies, Christopher

    2011-08-01

    Nine Gretchen Hagen (GH3) genes were identified in grapevine (Vitis vinifera L.) and six of these were predicted on the basis of protein sequence similarity to act as indole-3-acetic acid (IAA)-amido synthetases. The activity of these enzymes is thought to be important in controlling free IAA levels and one auxin-inducible grapevine GH3 protein, GH3-1, has previously been implicated in the berry ripening process. Ex planta assays showed that the expression of only one other GH3 gene, GH3-2, increased following the treatment of grape berries with auxinic compounds. One of these was the naturally occurring IAA and the other two were synthetic, α-naphthalene acetic acid (NAA) and benzothiazole-2-oxyacetic acid (BTOA). The determination of steady-state kinetic parameters for the recombinant GH3-1 and GH3-2 proteins revealed that both enzymes efficiently conjugated aspartic acid (Asp) to IAA and less well to NAA, while BTOA was a poor substrate. GH3-2 gene expression was induced by IAA treatment of pre-ripening berries with an associated increase in levels of IAA-Asp and a decrease in free IAA levels. This indicates that GH3-2 responded to excess auxin to maintain low levels of free IAA. Grape berry ripening was not affected by IAA application prior to veraison (ripening onset) but was considerably delayed by NAA and even more so by BTOA. The differential effects of the three auxinic compounds on berry ripening can therefore be explained by the induction and acyl substrate specificity of GH3-2. These results further indicate an important role for GH3 proteins in controlling auxin-related plant developmental processes.

  4. The studies on the toxicity mechanism of environmentally hazardous natural (IAA) and synthetic (NAA) auxin--The experiments on model Arabidopsis thaliana and rat liver plasma membranes.

    PubMed

    Hąc-Wydro, Katarzyna; Flasiński, Michał

    2015-06-01

    This paper concerns the studies towards membrane-damage effect of two auxins: indole-3-acetic acid - IAA and 1-naphthaleneacetic acid - NAA on plant (Arabidopsis thaliana) and animal (rat liver) model membranes. The foregoing auxins are plant growth regulators widely used in agriculture to control the quality of the crop. However, their accumulation in the environment makes them hazardous for the living organisms. The aim of our investigations was to compare the effect of natural (IAA) vs. synthetic (NAA) auxin on the organization of plant and animal model membranes and find a possible correlation between membrane-disturbing effect of these compounds and their toxicity. The collected data evidenced that auxins cause destabilization of membranes, decrease their condensation and weakens interactions of molecules. The alterations in the morphology of model systems were also noticed. The foregoing effects of auxins are concentration-dependent and additionally NAA was found to act on animal vs. plant membranes more selectively than IAA. Interestingly, both IAA and NAA induce the strongest disordering in model lipid system at the concentration, which is frequently reported as toxic to animal and plants. Based on the above findings it was proposed that membrane-damage effect induced by IAA and NAA may be important from the point of view of the mechanism of toxicity of these compounds and cannot be ignored in further investigations in this area.

  5. Influence of zygomycete-derived D'orenone on IAA signalling in Tricholoma-spruce ectomycorrhiza.

    PubMed

    Wagner, Katharina; Krause, Katrin; David, Anja; Kai, Marco; Jung, Elke-Martina; Sammer, Dominik; Kniemeyer, Olaf; Boland, Wilhelm; Kothe, Erika

    2016-09-01

    Despite the rising interest in microbial communication, only few studies relate to mycorrhization and the pool of potential morphogenic substances produced by the surrounding soil community. Here, we investigated the effect exerted by the C18 - ketone β-apo-13-carotenone, D'orenone, on the ectomycorrhizal basidiomycete Tricholoma vaccinum and its symbiosis with the economically important host tree, spruce (Picea abies). D'orenone is an early intermediate in the biosynthesis of morphogens in sexual development of mucoromycetes, the trisporoids. In the ectomycorrhizal fungus T. vaccinum, D'orenone increased the production and/or release of the phytohormone indole-3-acetic acid (IAA) which had been proposed to be involved in the mutual symbiosis. The induced expression of the fungal aldehyde dehydrogenase, Ald5 is associated with IAA synthesis and excretion. In the host tree, D'orenone modulated root architecture by increasing lateral root length and hypertrophy of root cortex cells, likely via changed IAA concentrations and flux. Thus, we report for the first time on carotenoid metabolites from soil fungi affecting both ectomycorrhizal partners. The data imply a complex network of functions for secondary metabolites which act in an inter-kingdom signalling in soil. PMID:26636983

  6. The ipdC, hisC1 and hisC2 genes involved in indole-3-acetic production used as alternative phylogenetic markers in Azospirillum brasilense.

    PubMed

    Jijón-Moreno, Saúl; Marcos-Jiménez, Cynthia; Pedraza, Raúl O; Ramírez-Mata, Alberto; de Salamone, I García; Fernández-Scavino, Ana; Vásquez-Hernández, Claudia A; Soto-Urzúa, Lucia; Baca, Beatriz E

    2015-06-01

    Plant growth-promoting bacteria of the genus Azospirillum are present in the rhizosphere and as endophytes of many crops. In this research we studied 40 Azospirillum strains isolated from different plants and geographic regions. They were first characterized by 16S rDNA restriction analysis, and their phylogenetic position was established by sequencing the genes 16S rDNA, ipdC, hisC1, and hisC2. The latter three genes are involved in the indole-3-pyruvic acid (IPyA) biosynthesis pathway of indole-3-acetic acid (IAA). Furthermore, the suitability of the 16S-23S rDNA intergenic spacer sequence (IGS) for the differentiation of closely related Azospirillum taxa and development of PCR protocols allows for specific detection of strains. The IGS-RFLP analysis enabled intraspecies differentiation, particularly of Azospirillum brasilense and Azospirillum lipoferum strains. Results demonstrated that the ipdC, hisC1, and hisC2 genes are highly conserved in all the assessed A. brasilense isolates, suggesting that these genes can be used as an alternative phylogenetic marker. In addition, IAA production determined by HPLC ranged from 0.17 to 98.2 μg mg(-1) protein. Southern hybridization with the A. brasilense ipdC gene probe did not show, a hybridization signal with A. lipoferum, Azospirillum amazonense, Azospirillum halopreferans and Azospirillum irakense genomic DNA. This suggests that these species produce IAA by other pathways. Because IAA is mainly synthesized via the IPyA pathway in A. brasilense strains, a species that is used worldwide in agriculture, the identification of ipdC, hisC1, and hisC2 genes by PCR may be suitable for selecting exploitable strains.

  7. Nitric oxide metabolism and indole acetic acid biosynthesis cross-talk in Azospirillum brasilense SM.

    PubMed

    Koul, Vatsala; Tripathi, Chandrakant; Adholeya, Alok; Kochar, Mandira

    2015-04-01

    Production of nitric oxide (NO) and the presence of NO metabolism genes, nitrous oxide reductase (nosZ), nitrous oxide reductase regulator (nosR) and nitric oxide reductase (norB) were identified in the plant-associated bacterium (PAB) Azospirillum brasilense SM. NO presence was confirmed in all overexpressing strains, while improvement in the plant growth response of these strains was mediated by increased NO and indole-3-acetic acid (IAA) levels in the strains. Electron microscopy showed random distribution to biofilm, with surface colonization of pleiomorphic Azospirilla. Quantitative IAA estimation highlighted a crucial role of nosR and norBC in regulating IAA biosynthesis. The NO quencher and donor reduced/blocked IAA biosynthesis by all strains, indicating their common regulatory role in IAA biosynthesis. Tryptophan (Trp) and l-Arginine (Arg) showed higher expression of NO genes tested, while in the case of ipdC, only Trp and IAA increased expression, while Arg had no significant effect. The highest nosR expression in SMnosR in the presence of IAA and Trp, along with its 2-fold IAA level, confirmed the relationship of nosR overexpression with Trp in increasing IAA. These results indicate a strong correlation between IAA and NO in A. brasilense SM and suggest the existence of cross-talk or shared signaling mechanisms in these two growth regulators.

  8. Combination of the auxins NAA, IBA, and IAA with GA3 improves the commercial seed-tuber production of potato (Solanum tuberosum L.) under in vitro conditions.

    PubMed

    Kumlay, Ahmet Metin

    2014-01-01

    The study compared the effects of 1.0 × MS medium containing various concentrations of α-naphthaleneacetic acid (NAA), indole-3-acetic acid (IAA), and indole-3-butyric acid (IBA), alone or in combination with gibberellic acid (GA3) in micropropagation of three potato (Solanum tuberosum L.) cultivars Pasinler, Granola, and Caspar using binodal stem cuttings. The results testified improved regeneration on 1.0 × MS medium containing variants of NAA, IAA, and IBA plus GA3 on all cultivars. The minimum days to shoot induction on three cultivars ranged 4.25-5 d on 1.0 × MS medium containing 0.25 mg L(-1) GA3 + 1 mg L(-1) NAA. The longest shoots (11.8 cm), maximum number of nodes (13.50), and maximum number of leaves (11.00) were recorded on cv. Caspar on 1.0 × MS medium containing 1 mg L(-1) NAA + 0.25 mg L(-1) GA3. The minimum time to root induction (12.25 d) was noted on cv. Pasinler on the same medium. All of the regenerated shoots could be easily rooted. The results showed that the combined effect of various concentrations of NAA, IAA, and IBA plus GA3 was more pronounced compared to the auxins used alone. The results of this research are of significant importance for potato breeders. PMID:25028654

  9. Combination of the auxins NAA, IBA, and IAA with GA3 improves the commercial seed-tuber production of potato (Solanum tuberosum L.) under in vitro conditions.

    PubMed

    Kumlay, Ahmet Metin

    2014-01-01

    The study compared the effects of 1.0 × MS medium containing various concentrations of α-naphthaleneacetic acid (NAA), indole-3-acetic acid (IAA), and indole-3-butyric acid (IBA), alone or in combination with gibberellic acid (GA3) in micropropagation of three potato (Solanum tuberosum L.) cultivars Pasinler, Granola, and Caspar using binodal stem cuttings. The results testified improved regeneration on 1.0 × MS medium containing variants of NAA, IAA, and IBA plus GA3 on all cultivars. The minimum days to shoot induction on three cultivars ranged 4.25-5 d on 1.0 × MS medium containing 0.25 mg L(-1) GA3 + 1 mg L(-1) NAA. The longest shoots (11.8 cm), maximum number of nodes (13.50), and maximum number of leaves (11.00) were recorded on cv. Caspar on 1.0 × MS medium containing 1 mg L(-1) NAA + 0.25 mg L(-1) GA3. The minimum time to root induction (12.25 d) was noted on cv. Pasinler on the same medium. All of the regenerated shoots could be easily rooted. The results showed that the combined effect of various concentrations of NAA, IAA, and IBA plus GA3 was more pronounced compared to the auxins used alone. The results of this research are of significant importance for potato breeders.

  10. Knockout of GH3 genes in the moss Physcomitrella patens leads to increased IAA levels at elevated temperature and in darkness.

    PubMed

    Mittag, Jennifer; Gabrielyan, Anastasia; Ludwig-Müller, Jutta

    2015-12-01

    Two proteins of the GRETCHEN HAGEN3 (GH3) family of acyl acid amido synthetases from the moss Physcomitrella patens conjugate indole-3-acetic acid (IAA) to a series of amino acids. The possible function of altered auxin levels in the moss in response to two different growth perturbations, elevated temperatures and darkness, was analyzed using a) the recently described double knockout lines in both P. patens GH3 genes (GH3-doKO) and b) a previously characterized line harboring an auxin-inducible soybean GH3 promoter::reporter fused to β-glucuronidase (G1-GUS). The GUS activity as marker of the auxin response increased at higher temperatures and after cultivation in the darkness for a period of up to four weeks. Generally, the double knockout plants grew more slowly than the wild type (WT). The altered growth conditions influenced the phenotypes of the double knockout lines differently from that of WT moss. Higher temperatures negatively affected GH3-doKO plants compared to WT which was shown by stronger loss of chlorophyll. On the other hand, a positive effect was found on the concentrations of free IAA which increased at 28 °C in the GH3-doKO lines compared to WT plants. A different factor, namely darkness vs. a light/dark cycle caused the adverse phenotype concerning chlorophyll concentrations. Mutant moss plants showed higher chlorophyll concentrations than WT and these correlated with higher free IAA in the plant population that was classified as green. Our data show that growth perturbations result in higher free IAA levels in the GH3-doKO mutants, but in one case - growth in darkness - the mutants could cope better with the condition, whereas at elevated temperatures the mutants were more sensitive than WT. Thus, GH3 function in P. patens WT could lie in the regulation of IAA concentrations under unfavorable environmental conditions.

  11. Basipetally polarised transport of [(3)H]gibberellin A 1 and [ (14)C]gibberellin A 3, and acropetal polarity of [ (14)C]indole-3-acetic acid transport, in stelar tissues of Phaseolus coccineus roots.

    PubMed

    Hartung, W; Phillips, I D

    1974-12-01

    Movement of both [(3)H]GA1 and [(14)C]GA3 through root segments from P. coccineus seedlings was basipetally polarised. The basipetal/acropetal ratio of radioactivity from [(3)H]GA1 in agar receiver blocks was 9.2 for apical, elongating segments, and 4.0 for more basal, non-elongating segments. Polarity of gibberellin transport was restricted to the stele, and absent from cortical tissues. Transport of [(14)C]IAA through root segments to agar receivers was preferentially acropetal, particularly so in the stele. Despite the existence of basipetal polarity of gibberellin transport in the root, [(3)H]GA1 injected into cotyledons moved into and acropetally along the seedling root.

  12. MASSUGU2 encodes Aux/IAA19, an auxin-regulated protein that functions together with the transcriptional activator NPH4/ARF7 to regulate differential growth responses of hypocotyl and formation of lateral roots in Arabidopsis thaliana.

    PubMed

    Tatematsu, Kiyoshi; Kumagai, Satoshi; Muto, Hideki; Sato, Atsuko; Watahiki, Masaaki K; Harper, Reneé M; Liscum, Emmanuel; Yamamoto, Kotaro T

    2004-02-01

    We have isolated a dominant, auxin-insensitive mutant of Arabidopsis thaliana, massugu2 (msg2), that displays neither hypocotyl gravitropism nor phototropism, fails to maintain an apical hook as an etiolated seedling, and is defective in lateral root formation. Yet other aspects of growth and development of msg2 plants are almost normal. These characteristics of msg2 are similar to those of another auxin-insensitive mutant, non-phototropic hypocotyl4 (nph4), which is a loss-of-function mutant of AUXIN RESPONSE FACTOR7 (ARF7) (Harper et al., 2000). Map-based cloning of the MSG2 locus reveals that all four mutant alleles result in amino acid substitutions in the conserved domain II of an Auxin/Indole-3-Acetic Acid protein, IAA19. Interestingly, auxin inducibility of MSG2/IAA19 gene expression is reduced by 65% in nph4/arf7. Moreover, MSG2/IAA19 protein binds to the C-terminal domain of NPH4/ARF7 in a Saccharomyces cerevisiae (yeast) two-hybrid assay and to the whole latter protein in vitro by pull-down assay. These results suggest that MSG2/IAA19 and NPH4/ARF7 may constitute a negative feedback loop to regulate differential growth responses of hypocotyls and lateral root formation.

  13. Identification, Expression and IAA-Amide Synthetase Activity Analysis of Gretchen Hagen 3 in Papaya Fruit (Carica papaya L.) during Postharvest Process

    PubMed Central

    Liu, Kaidong; Wang, Jinxiang; Li, Haili; Zhong, Jundi; Feng, Shaoxian; Pan, Yaoliang; Yuan, Changchun

    2016-01-01

    Auxin plays essential roles in plant development. Gretchen Hagen 3 (GH3) genes belong to a major auxin response gene family and GH3 proteins conjugate a range of acylsubstrates to alter the levels of hormones. Currently, the role of GH3 genes in postharvest physiological regulation of ripening and softening processes in papaya fruit is unclear. In this study, we identified seven CpGH3 genes in a papaya genome database. The CpGH3.1a, CpGH3.1b, CpGH3.5, CpGH3.6, and CpGH3.9 proteins were identified as indole-3-acetic acid (IAA)-specific amido synthetases. We analyzed the changes in IAA-amido synthetase activity using aspartate as a substrate for conjugation and found a large increase (over 5-fold) during the postharvest stages. Ascorbic acid (AsA) application can extend the shelf life of papaya fruit. Our data showed that AsA treatment regulates postharvest fruit maturation processes by promoting endogenous IAA levels. Our findings demonstrate the important role of GH3 genes in the regulation of auxin-associated postharvest physiology in papaya. PMID:27812360

  14. FTIR spectroscopic study of the phytohormone auxin (Indol-3-ylacetic Acid, IAA) and its n-alkylated and monohalogenated derivatives

    NASA Astrophysics Data System (ADS)

    Lutz, Bert T. G.; van der Windt, Erik; Kanters, Jan; Klämbt, Dieter; Kojić-Prodić, Biserka; Ramek, Michael

    1996-09-01

    In the framework of structure/activity correlation studies the plant growth hormone auxin and its natural analogue 4-Cl-IAA, as well as their synthetic congeners, were studied by FTIR spectroscopy. The analysis was focused on the NH and CO stretching vibrations which can be the most sensitive probes of intra- and intermolecular interactions, particularly to hydrogen bonds. However, it emerged that vC = O vibrations of both monomer and dimer are not affected by substitution. The aliphatic CH 2 group acts as an insulator between the conjugated π-system of indole and the carboxylic group, thus prohibiting a direct effect on the vibration CO. On the contrary, the stretching vibrations NH are influenced by halogenation and hydrogen bonding. The experimental data are in good agreement with the results of quantum chemical ab initio calculations of NH vibrations for IAA and several chlorine substituted IAAs. However, a simple correlation between substitution and spectral properties of indole NH cannot be found. The measurements were performed in the solid state (KBr pellets) and in polar (diethylether) and nonpolar (CDCI 3) solutions. From the measurements in diethylether, it follows that in dilute solution IAA and derivatives are predominantly present as monomer, whereas in CDCl 3 the equilibrium is in favour of the dimer form. In aqueous solution at the concentrations used in growth experiments solvated monomer will be the active component. Bioactivity of auxin and analogues with their NH stretching frequency shifts cannot be correlated in a simple way.

  15. Expression of wild-type PtrIAA14.1, a poplar Aux/IAA gene causes morphological changes in Arabidopsis

    PubMed Central

    Liu, Shanda; Hu, Qingnan; Luo, Sha; Li, Qianqian; Yang, Xiyu; Wang, Xianling; Wang, Shucai

    2015-01-01

    Aux/IAA proteins are transcriptional repressors that control auxin signaling by interacting with auxin response factors (ARFs). So far all of the identified Aux/IAA mutants with auxin-related phenotypes in Arabidopsis and rice (Oryza sativa) are dominant gain-of-function mutants, with mutations in Domain II that affected stability of the corresponding Aux/IAA proteins. On the other hand, morphological changes were observed in knock-down mutants of Aux/IAA genes in tomato (Solanum lycopersicum), suggesting that functions of Aux/IAA proteins may be specific for certain plant species. We report here the characterization of PtrIAA14.1, a poplar (Populus trichocarpa) homolog of IAA7. Bioinformatics analysis showed that PtrIAA14.1 is a classic Aux/IAA protein. It contains four conserved domains with the repressor motif in Domain I, the degron in Domain II, and the conserved amino acid signatures for protein–protein interactions in Domain III and Domain IV. Protoplast transfection assays showed that PtrIAA14.1 is localized in nucleus. It is unable in the presence of auxin, and it represses auxin response reporter gene expression. Expression of wild-type PtrIAA14.1 in Arabidopsis resulted in auxin-related phenotypes including down-curling leaves, semi-draft with increased number of branches, and greatly reduced fertility, but expression of the Arabidopsis Aux/IAA genes tested remain largely unchanged in the transgenic plants. Protein–protein interaction assays in yeast and protoplasts showed that PtrIAA14.1 interacted with ARF5, but not other ARFs. Consistent with this observation, vascular patterning was altered in the transgenic plants, and the expression of AtHB8 (Arabidopsis thaliana homeobox gene 8) was reduced in transgenic plants. PMID:26082787

  16. IAA-Ala Resistant3, an Evolutionarily Conserved Target of miR167, Mediates Arabidopsis Root Architecture Changes during High Osmotic Stress[W

    PubMed Central

    Kinoshita, Natsuko; Wang, Huan; Kasahara, Hiroyuki; Liu, Jun; MacPherson, Cameron; Machida, Yasunori; Kamiya, Yuji; Hannah, Matthew A.; Chua, Nam-Hai

    2012-01-01

    The functions of microRNAs and their target mRNAs in Arabidopsis thaliana development have been widely documented; however, roles of stress-responsive microRNAs and their targets are not as well understood. Using small RNA deep sequencing and ATH1 microarrays to profile mRNAs, we identified IAA-Ala Resistant3 (IAR3) as a new target of miR167a. As expected, IAR3 mRNA was cleaved at the miR167a complementary site and under high osmotic stress miR167a levels decreased, whereas IAR3 mRNA levels increased. IAR3 hydrolyzes an inactive form of auxin (indole-3-acetic acid [IAA]-alanine) and releases bioactive auxin (IAA), a central phytohormone for root development. In contrast with the wild type, iar3 mutants accumulated reduced IAA levels and did not display high osmotic stress–induced root architecture changes. Transgenic plants expressing a cleavage-resistant form of IAR3 mRNA accumulated high levels of IAR3 mRNAs and showed increased lateral root development compared with transgenic plants expressing wild-type IAR3. Expression of an inducible noncoding RNA to sequester miR167a by target mimicry led to an increase in IAR3 mRNA levels, further confirming the inverse relationship between the two partners. Sequence comparison revealed the miR167 target site on IAR3 mRNA is conserved in evolutionarily distant plant species. Finally, we showed that IAR3 is required for drought tolerance. PMID:22960911

  17. PpYUC11, a strong candidate gene for the stony hard phenotype in peach (Prunus persica L. Batsch), participates in IAA biosynthesis during fruit ripening

    PubMed Central

    Pan, Lei; Zeng, Wenfang; Niu, Liang; Lu, Zhenhua; Liu, Hui; Cui, Guochao; Zhu, Yunqin; Chu, Jinfang; Li, Weiping; Fang, Weichao; Cai, Zuguo; Li, Guohuai; Wang, Zhiqiang

    2015-01-01

    High concentrations of indole-3-acetic acid (IAA) are required for climacteric ethylene biosynthesis to cause fruit softening in melting flesh peaches at the late ripening stage. By contrast, the fruits of stony hard peach cultivars do not soften and produce little ethylene due to the low IAA concentrations. To investigate the regulation of IAA accumulation during peach ripening [the transition from stage S3 to stage S4 III (climacteric)], a digital gene expression (DGE) analysis was performed. The expression patterns of auxin-homeostasis-related genes were compared in fruits of the melting flesh peach ‘Goldhoney 3’ and the stony hard flesh peach ‘Yumyeong’ during the ripening stage. It is revealed here that a YUCCA flavin mono-oxygenase gene (PpYUC11, ppa008176m), a key gene in auxin biosynthesis, displayed an identical differential expression profile to the profiles of IAA accumulation and PpACS1 transcription: the mRNA transcripts increased at the late ripening stage in melting flesh peaches but were below the limit of detection in mature fruits of stony hard peaches. In addition, the strong association between intron TC microsatellite genotypes of PpYUC11 and the flesh texture (normal or stony hard) is described in 43 peach varieties, indicating that this locus may be responsible for the stony hard phenotype in peach. These findings support the hypothesis that PpYUC11 may play an essential role in auxin biosynthesis during peach fruit ripening and is a candidate gene for the control of the stony hard phenotype in peach. PMID:26307136

  18. PpYUC11, a strong candidate gene for the stony hard phenotype in peach (Prunus persica L. Batsch), participates in IAA biosynthesis during fruit ripening.

    PubMed

    Pan, Lei; Zeng, Wenfang; Niu, Liang; Lu, Zhenhua; Liu, Hui; Cui, Guochao; Zhu, Yunqin; Chu, Jinfang; Li, Weiping; Fang, Weichao; Cai, Zuguo; Li, Guohuai; Wang, Zhiqiang

    2015-12-01

    High concentrations of indole-3-acetic acid (IAA) are required for climacteric ethylene biosynthesis to cause fruit softening in melting flesh peaches at the late ripening stage. By contrast, the fruits of stony hard peach cultivars do not soften and produce little ethylene due to the low IAA concentrations. To investigate the regulation of IAA accumulation during peach ripening [the transition from stage S3 to stage S4 III (climacteric)], a digital gene expression (DGE) analysis was performed. The expression patterns of auxin-homeostasis-related genes were compared in fruits of the melting flesh peach 'Goldhoney 3' and the stony hard flesh peach 'Yumyeong' during the ripening stage. It is revealed here that a YUCCA flavin mono-oxygenase gene (PpYUC11, ppa008176m), a key gene in auxin biosynthesis, displayed an identical differential expression profile to the profiles of IAA accumulation and PpACS1 transcription: the mRNA transcripts increased at the late ripening stage in melting flesh peaches but were below the limit of detection in mature fruits of stony hard peaches. In addition, the strong association between intron TC microsatellite genotypes of PpYUC11 and the flesh texture (normal or stony hard) is described in 43 peach varieties, indicating that this locus may be responsible for the stony hard phenotype in peach. These findings support the hypothesis that PpYUC11 may play an essential role in auxin biosynthesis during peach fruit ripening and is a candidate gene for the control of the stony hard phenotype in peach.

  19. IAA-Ala Resistant3, an evolutionarily conserved target of miR167, mediates Arabidopsis root architecture changes during high osmotic stress.

    PubMed

    Kinoshita, Natsuko; Wang, Huan; Kasahara, Hiroyuki; Liu, Jun; Macpherson, Cameron; Machida, Yasunori; Kamiya, Yuji; Hannah, Matthew A; Chua, Nam-Hai

    2012-09-01

    The functions of microRNAs and their target mRNAs in Arabidopsis thaliana development have been widely documented; however, roles of stress-responsive microRNAs and their targets are not as well understood. Using small RNA deep sequencing and ATH1 microarrays to profile mRNAs, we identified IAA-Ala Resistant3 (IAR3) as a new target of miR167a. As expected, IAR3 mRNA was cleaved at the miR167a complementary site and under high osmotic stress miR167a levels decreased, whereas IAR3 mRNA levels increased. IAR3 hydrolyzes an inactive form of auxin (indole-3-acetic acid [IAA]-alanine) and releases bioactive auxin (IAA), a central phytohormone for root development. In contrast with the wild type, iar3 mutants accumulated reduced IAA levels and did not display high osmotic stress-induced root architecture changes. Transgenic plants expressing a cleavage-resistant form of IAR3 mRNA accumulated high levels of IAR3 mRNAs and showed increased lateral root development compared with transgenic plants expressing wild-type IAR3. Expression of an inducible noncoding RNA to sequester miR167a by target mimicry led to an increase in IAR3 mRNA levels, further confirming the inverse relationship between the two partners. Sequence comparison revealed the miR167 target site on IAR3 mRNA is conserved in evolutionarily distant plant species. Finally, we showed that IAR3 is required for drought tolerance.

  20. Combination of the Auxins NAA, IBA, and IAA with GA3 Improves the Commercial Seed-Tuber Production of Potato (Solanum tuberosum L.) under In Vitro Conditions

    PubMed Central

    Kumlay, Ahmet Metin

    2014-01-01

    The study compared the effects of 1.0 × MS medium containing various concentrations of α-naphthaleneacetic acid (NAA), indole-3-acetic acid (IAA), and indole-3-butyric acid (IBA), alone or in combination with gibberellic acid (GA3) in micropropagation of three potato (Solanum tuberosum L.) cultivars Pasinler, Granola, and Caspar using binodal stem cuttings. The results testified improved regeneration on 1.0 × MS medium containing variants of NAA, IAA, and IBA plus GA3 on all cultivars. The minimum days to shoot induction on three cultivars ranged 4.25–5 d on 1.0 × MS medium containing 0.25 mg L−1  GA3 + 1 mg L−1 NAA. The longest shoots (11.8 cm), maximum number of nodes (13.50), and maximum number of leaves (11.00) were recorded on cv. Caspar on 1.0 × MS medium containing 1 mg L−1  NAA + 0.25 mg L−1 GA3. The minimum time to root induction (12.25 d) was noted on cv. Pasinler on the same medium. All of the regenerated shoots could be easily rooted. The results showed that the combined effect of various concentrations of NAA, IAA, and IBA plus GA3 was more pronounced compared to the auxins used alone. The results of this research are of significant importance for potato breeders. PMID:25028654

  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. Canalization of auxin flow by Aux/IAA-ARF-dependent feedback regulation of PIN polarity.

    PubMed

    Sauer, Michael; Balla, Jozef; Luschnig, Christian; Wisniewska, Justyna; Reinöhl, Vilém; Friml, Jirí; Benková, Eva

    2006-10-15

    Plant development is characterized by a profound ability to regenerate and form tissues with new axes of polarity. An unsolved question concerns how the position within a tissue and cues from neighboring cells are integrated to specify the polarity of individual cells. The canalization hypothesis proposes a feedback effect of the phytohormone auxin on the directionality of intercellular auxin flow as a means to polarize tissues. Here we identify a cellular and molecular mechanism for canalization. Local auxin application, wounding, or auxin accumulation during de novo organ formation lead to rearrangements in the subcellular polar localization of PIN auxin transport components. This auxin effect on PIN polarity is cell-specific, does not depend on PIN transcription, and involves the Aux/IAA-ARF (indole-3-acetic acid-auxin response factor) signaling pathway. Our data suggest that auxin acts as polarizing cue, which links individual cell polarity with tissue and organ polarity through control of PIN polar targeting. This feedback regulation provides a conceptual framework for polarization during multiple regenerative and patterning processes in plants.

  4. Canalization of auxin flow by Aux/IAA-ARF-dependent feedback regulation of PIN polarity.

    PubMed

    Sauer, Michael; Balla, Jozef; Luschnig, Christian; Wisniewska, Justyna; Reinöhl, Vilém; Friml, Jirí; Benková, Eva

    2006-10-15

    Plant development is characterized by a profound ability to regenerate and form tissues with new axes of polarity. An unsolved question concerns how the position within a tissue and cues from neighboring cells are integrated to specify the polarity of individual cells. The canalization hypothesis proposes a feedback effect of the phytohormone auxin on the directionality of intercellular auxin flow as a means to polarize tissues. Here we identify a cellular and molecular mechanism for canalization. Local auxin application, wounding, or auxin accumulation during de novo organ formation lead to rearrangements in the subcellular polar localization of PIN auxin transport components. This auxin effect on PIN polarity is cell-specific, does not depend on PIN transcription, and involves the Aux/IAA-ARF (indole-3-acetic acid-auxin response factor) signaling pathway. Our data suggest that auxin acts as polarizing cue, which links individual cell polarity with tissue and organ polarity through control of PIN polar targeting. This feedback regulation provides a conceptual framework for polarization during multiple regenerative and patterning processes in plants. PMID:17043314

  5. The virtual machine (VM) scaler: an infrastructure manager supporting environmental modeling on IaaS clouds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infrastructure-as-a-service (IaaS) clouds provide a new medium for deployment of environmental modeling applications. Harnessing advancements in virtualization, IaaS clouds can provide dynamic scalable infrastructure to better support scientific modeling computational demands. Providing scientific m...

  6. GA3 and other signal regulators (MeJA and IAA) improve xanthumin biosynthesis in different manners in Xanthium strumarium L.

    PubMed

    Li, Changfu; Chen, Fangfang; Zhang, Yansheng

    2014-01-01

    Xanthanolides from Xanthium strumarium L. exhibit various pharmacological activities and these compounds are mainly produced in the glandular trichomes of aerial plant parts. The regulation of xanthanolide biosynthesis has never been reported in the literature. In this study, the effects of phytohormonal stimulation on xanthumin (a xanthanolide compound) biosynthesis, glandular trichomes and germacrene A synthase (GAS) gene expression in X. strumarium L. young leaves were investigated. The exogenous applications of methyl jasmonate (MeJA), indole-3-acetic acid (IAA), and gibberrellin A3 (GA3) at appropriate concentrations were all found to improve xanthumin biosynthesis, but in different ways. It was suggested that a higher gland density stimulated by MeJA (400 µM) or IAA (200 µM) treatment caused at least in part an improvement in xanthumin production, whereas GA3 (10 µM) led to an improvement by up-regulating xanthumin biosynthetic genes within gland cells, not by forming more glandular trichomes. Compared to the plants before the flowering stage, plants that had initiated flowering showed enhanced xanthumin biosynthesis, but no higher gland density, an effect was similar to that caused by exogenous GA3 treatment. PMID:25157461

  7. The Systemic Acquired Resistance Regulator OsNPR1 Attenuates Growth by Repressing Auxin Signaling through Promoting IAA-Amido Synthase Expression.

    PubMed

    Li, Xiaozun; Yang, Dong-Lei; Sun, Li; Li, Qun; Mao, Bizeng; He, Zuhua

    2016-09-01

    Systemic acquired resistance is a long-lasting and broad-spectrum disease resistance to pathogens. Our previous study demonstrated that overexpression of NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 (OsNPR1), a master gene for systemic acquired resistance in rice (Oryza sativa), greatly enhanced resistance to bacterial blight caused by Xanthomonas oryzae pv oryzae However, the growth and development of the OsNPR1 overexpression (OsNPR1-OX) plants were restrained, and the mechanism remained elusive. In this study, we dissected the OsNPR1-induced growth inhibition. We found that the OsNPR1-OX lines displayed phenotypes mimicking auxin-defective mutants, with decreases in root system, seed number and weight, internode elongation, and tiller number. Whole-genome expression analysis revealed that genes related to the auxin metabolism and signaling pathway were differentially expressed between the OsNPR1-OX and wild-type plants. Consistently, the indole-3-acetic acid (IAA) content was decreased and the auxin distribution pattern was altered in OsNPR1-OX plants. Importantly, we found that some GH3 family members, in particular OsGH3.8 coding IAA-amido synthetase, were constitutively up-regulated in OsNPR1-OX plants. Decreased OsGH3.8 expression by RNA interference could partially restore IAA level and largely rescue the restrained growth and development phenotypes but did not affect the disease resistance of OsNPR1-OX plants. Taken together, we revealed that OsNPR1 affects rice growth and development by disrupting the auxin pathway at least partially through indirectly up-regulating OsGH3.8 expression. PMID:27378815

  8. The Systemic Acquired Resistance Regulator OsNPR1 Attenuates Growth by Repressing Auxin Signaling through Promoting IAA-Amido Synthase Expression1[OPEN

    PubMed Central

    2016-01-01

    Systemic acquired resistance is a long-lasting and broad-spectrum disease resistance to pathogens. Our previous study demonstrated that overexpression of NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 (OsNPR1), a master gene for systemic acquired resistance in rice (Oryza sativa), greatly enhanced resistance to bacterial blight caused by Xanthomonas oryzae pv oryzae. However, the growth and development of the OsNPR1 overexpression (OsNPR1-OX) plants were restrained, and the mechanism remained elusive. In this study, we dissected the OsNPR1-induced growth inhibition. We found that the OsNPR1-OX lines displayed phenotypes mimicking auxin-defective mutants, with decreases in root system, seed number and weight, internode elongation, and tiller number. Whole-genome expression analysis revealed that genes related to the auxin metabolism and signaling pathway were differentially expressed between the OsNPR1-OX and wild-type plants. Consistently, the indole-3-acetic acid (IAA) content was decreased and the auxin distribution pattern was altered in OsNPR1-OX plants. Importantly, we found that some GH3 family members, in particular OsGH3.8 coding IAA-amido synthetase, were constitutively up-regulated in OsNPR1-OX plants. Decreased OsGH3.8 expression by RNA interference could partially restore IAA level and largely rescue the restrained growth and development phenotypes but did not affect the disease resistance of OsNPR1-OX plants. Taken together, we revealed that OsNPR1 affects rice growth and development by disrupting the auxin pathway at least partially through indirectly up-regulating OsGH3.8 expression. PMID:27378815

  9. Role of IAA-Oxidase in Abscission Control in Cotton 123

    PubMed Central

    Schwertner, Harvey A.; Morgan, Page W.

    1966-01-01

    The potential role of indoleactic acid (IAA)-oxidase as an in vivo abscission regulating system in the cotton (Gossypium hirsutum L.) cotyledonary explant was investigated. Phenols (usually monophenols), which are cofactors of cotton IAA-oxidase in vitro, accelerated abscission. Phenols (usually orthodihydroxyphenols), which inhibit cotton IAA-oxidase in vitro, inhibited abscission. Inhibition or stimulation of abscission was accomplished by phenols both with and without IAA. Results were similar when treatments were applied as lanolin pastes to the cut petiole ends or as solutions in which explants were submerged. An abscission accelerating phenol stimulated the decarboxylation of IAA-1-14C by explants and an abscission inhibiting phenol inhibited the decarboxylation of IAA-1-14C. The mechanism of abscission regulation by the phenolic compounds was concluded to involve auxin destruction via IAA-oxidase. In addition to the direct relationship of this study to abscission, the results support the more general hypothesis that IAA-oxidase acts in vivo to regulate auxin levels. PMID:16656432

  10. Apigenin and quercetin promote. Delta. pH-dependent accumulation of IAA in membrane vesicles

    SciTech Connect

    Woolard, D.D.; Clark, K.A. )

    1990-05-01

    Flavonoids may act as regulators of polar auxin transport. In the presence of a pH gradient (pH 8{sub in}/6{sub out}) the flavonoids quercetin and apigenin, as well as the synthetic herbicide napthylphthalamic acid (NPA), promote the accumulation of IAA in membrane vesicles from dark-grown zucchini hypocotyls. Simultaneous accumulation of {sup 3}H-IAA (10 nM) and {sup 14}C-butyric acid (5 {mu}M; included as a pH probe) was determined by a filtration assay after incubating the vesicles with 3 nM to 100 {mu}M quercetin, apigenin, NPA or unlabeled IAA. Maximal stimulation (% of Control) was observed with 3 {mu}M NPA (130%), 1 {mu}M quercetin (120%), or 3 {mu}M apigenin (115%); {Delta}pH was not affected by these concentrations. As reported by others, IAA uptake was saturable: 1 {mu}M unlabeled IAA eliminated {Delta}pH-dependent uptake of {sup 3}H-IAA without altering {Delta}pH. However, at 30 to 100 {mu}M, every compound tested collapsed the imposed pH gradient and therefore abolished specific {sup 3}H-IAA uptake.

  11. Genome-wide analysis of Aux/IAA gene family in Solanaceae species using tomato as a model.

    PubMed

    Wu, Jian; Peng, Zhen; Liu, Songyu; He, Yanjun; Cheng, Lin; Kong, Fuling; Wang, Jie; Lu, Gang

    2012-04-01

    Auxin plays key roles in a wide variety of plant activities, including embryo development, leaf formation, phototropism, fruit development and root initiation and development. Auxin/indoleacetic acid (Aux/IAA) genes, encoding short-lived nuclear proteins, are key regulators in the auxin transduction pathway. But how they work is still unknown. In order to conduct a systematic analysis of this gene family in Solanaceae species, a genome-wide search for the homologues of auxin response genes was carried out. Here, 26 and 27 non redundant AUX/IAAs were identified in tomato and potato, respectively. Using tomato as a model, a comprehensive overview of SlIAA gene family is presented, including the gene structures, phylogeny, chromosome locations, conserved motifs and cis-elements in promoter sequences. A phylogenetic tree generated from alignments of the predicted protein sequences of 31 OsIAAs, 29 AtIAAs, 31 ZmIAAs, and 26 SlIAAs revealed that these IAAs were clustered into three major groups and ten subgroups. Among them, seven subgroups were present in both monocot and dicot species, which indicated that the major functional diversification within the IAA family predated the monocot/dicot divergence. In contrast, group C and some other subgroups seemed to be species-specific. Quantitative real-time PCR (qRT-PCR) analysis showed that 19 of the 26 SlIAA genes could be detected in all tomato organs/tissues, however, seven of them were specifically expressed in some of tomato tissues. The transcript abundance of 17 SlIAA genes were increased within a few hours when the seedlings were treated with exogenous IAA. However, those of other six SlIAAs were decreased. The results of stress treatments showed that most SIIAA family genes responded to at least one of the three stress treatments, however, they exhibited diverse expression levels under different abiotic stress conditions in tomato seedlings. SlIAA20, SlIAA21 and SlIAA22 were not significantly influenced by stress

  12. Identification of IAA transport inhibitors including compounds affecting cellular PIN trafficking by two chemical screening approaches using maize coleoptile systems.

    PubMed

    Nishimura, Takeshi; Matano, Naoyuki; Morishima, Taichi; Kakinuma, Chieko; Hayashi, Ken-Ichiro; Komano, Teruya; Kubo, Minoru; Hasebe, Mitsuyasu; Kasahara, Hiroyuki; Kamiya, Yuji; Koshiba, Tomokazu

    2012-10-01

    The monocot coleoptile tip region has been generally supposed to be the source of IAA to supply IAA to basal parts by the polar IAA transport system, which results in gravi- and phototropic curvature of coleoptiles. Based on this IAA transport system and gravitropism of maize coleoptiles, we have developed two screening methods to identify small molecules from a large chemical library that inhibit IAA transport. The methods detect molecules that affect (i) gravitropic curvature of coleoptiles; and (ii) the amount of IAA transported from the tip. From 10,000 chemicals, eight compounds were identified and categorized into two groups. Four chemicals in group A decreased IAA transport from the tip, and increased endogenous IAA levels in the tip. The structures of two compounds resembled that of 1-N-naphthylphthalamic acid (NPA), but those of the other two differed from structures of known IAA transport inhibitors. Four chemicals in group B strongly inhibited IAA transport from the tip, but IAA levels at the tip were only slightly affected. At higher concentrations, group B compounds inhibited germination of Arabidopsis, similarly to brefeldin A (BFA). Analysis of the cellular distribution of PIN2-green fluorescent protein (GFP) and PIN1-GFP in Arabidopsis revealed that one of the four chemicals in group B induced internalization of PIN1 and PIN2 proteins into vesicles smaller than BFA bodies, suggesting that this compound affects cellular vesicle trafficking systems related to PIN trafficking. The eight chemicals identified here will be a useful tool for understanding the mechanisms of IAA transport in plants. PMID:22875609

  13. Cinnamic acid increases lignin production and inhibits soybean root growth.

    PubMed

    Salvador, Victor Hugo; Lima, Rogério Barbosa; dos Santos, Wanderley Dantas; Soares, Anderson Ricardo; Böhm, Paulo Alfredo Feitoza; Marchiosi, Rogério; Ferrarese, Maria de Lourdes Lucio; Ferrarese-Filho, Osvaldo

    2013-01-01

    Cinnamic acid is a known allelochemical that affects seed germination and plant root growth and therefore influences several metabolic processes. In the present work, we evaluated its effects on growth, indole-3-acetic acid (IAA) oxidase and cinnamate 4-hydroxylase (C4H) activities and lignin monomer composition in soybean (Glycine max) roots. The results revealed that exogenously applied cinnamic acid inhibited root growth and increased IAA oxidase and C4H activities. The allelochemical increased the total lignin content, thus altering the sum and ratios of the p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) lignin monomers. When applied alone or with cinnamic acid, piperonylic acid (PIP, a quasi-irreversible inhibitor of C4H) reduced C4H activity, lignin and the H, G, S monomer content compared to the cinnamic acid treatment. Taken together, these results indicate that exogenously applied cinnamic acid can be channeled into the phenylpropanoid pathway via the C4H reaction, resulting in an increase in H lignin. In conjunction with enhanced IAA oxidase activity, these metabolic responses lead to the stiffening of the cell wall and are followed by a reduction in soybean root growth.

  14. Cinnamic acid increases lignin production and inhibits soybean root growth.

    PubMed

    Salvador, Victor Hugo; Lima, Rogério Barbosa; dos Santos, Wanderley Dantas; Soares, Anderson Ricardo; Böhm, Paulo Alfredo Feitoza; Marchiosi, Rogério; Ferrarese, Maria de Lourdes Lucio; Ferrarese-Filho, Osvaldo

    2013-01-01

    Cinnamic acid is a known allelochemical that affects seed germination and plant root growth and therefore influences several metabolic processes. In the present work, we evaluated its effects on growth, indole-3-acetic acid (IAA) oxidase and cinnamate 4-hydroxylase (C4H) activities and lignin monomer composition in soybean (Glycine max) roots. The results revealed that exogenously applied cinnamic acid inhibited root growth and increased IAA oxidase and C4H activities. The allelochemical increased the total lignin content, thus altering the sum and ratios of the p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) lignin monomers. When applied alone or with cinnamic acid, piperonylic acid (PIP, a quasi-irreversible inhibitor of C4H) reduced C4H activity, lignin and the H, G, S monomer content compared to the cinnamic acid treatment. Taken together, these results indicate that exogenously applied cinnamic acid can be channeled into the phenylpropanoid pathway via the C4H reaction, resulting in an increase in H lignin. In conjunction with enhanced IAA oxidase activity, these metabolic responses lead to the stiffening of the cell wall and are followed by a reduction in soybean root growth. PMID:23922685

  15. Synergism of VAM and Rhizobium on production and metabolism of IAA in roots and root nodules of Vigna mungo.

    PubMed

    Chakrabarti, Jayanta; Chatterjee, Sabyasachi; Ghosh, Sisir; Chatterjee, Narayan Chandra; Dutta, Sikha

    2010-09-01

    Mature and healthy root nodules of Vigna mungo appeared to contain higher amount of indole-acetic acid (IAA) than non-nodulated roots. Dual effect of VAM fungus, Glomus fasciculatum and the nitrogen-fixing bacteria, Rhizobium sp. on the nodulation of roots of V. mungo was studied. It was recorded that the roots which were inoculated simultaneously with both the symbionts i.e., G. fasciculatum and Rhizobium exhibited greater amount of IAA production than the non-inoculated roots. A tryptophan pool present in the mature nodules and young leaves might serve as a precursor for IAA production in the roots and in the nodules. Activity of IAA-metabolizing enzymes, such as IAA oxidase, peroxidase, and polyphenol oxidase was investigated which indicates the active metabolism of IAA in roots and nodules. The Rhizobium symbiont isolated from fresh nodules of V. mungo produced significant amount of IAA under in vitro condition when tryptophan was added to the medium as precursor. Present study represents some beneficial effects of Rhizobium and G. fasciculatum on the production and metabolism of IAA in roots and nodules of V. mungo. The important physiological implication of the study on IAA production and its metabolism in Rhizobium-Legume-VAM tripartite symbiosis is certainly representing a new approach to satisfy the hormonal balance in the host plant.

  16. Dynamic web cache publishing for IaaS clouds using Shoal

    NASA Astrophysics Data System (ADS)

    Gable, Ian; Chester, Michael; Armstrong, Patrick; Berghaus, Frank; Charbonneau, Andre; Leavett-Brown, Colin; Paterson, Michael; Prior, Robert; Sobie, Randall; Taylor, Ryan

    2014-06-01

    We have developed a highly scalable application, called Shoal, for tracking and utilizing a distributed set of HTTP web caches. Our application uses the Squid HTTP cache. Squid servers advertise their existence to the Shoal server via AMQP messaging by running Shoal Agent. The Shoal server provides a simple REST interface that allows clients to determine their closest Squid cache. Our goal is to dynamically instantiate Squid caches on IaaS clouds in response to client demand. Shoal provides the VMs on IaaS clouds with the location of the nearest dynamically instantiated Squid Cache.

  17. Gibberellin Application at Pre-Bloom in Grapevines Down-Regulates the Expressions of VvIAA9 and VvARF7, Negative Regulators of Fruit Set Initiation, during Parthenocarpic Fruit Development

    PubMed Central

    Jung, Chan Jin; Hur, Youn Young; Yu, Hee-Ju; Noh, Jung-Ho; Park, Kyo-Sun; Lee, Hee Jae

    2014-01-01

    Fruit set is initiated only after fertilization and is tightly regulated primarily by gibberellins (GAs) and auxins. The application of either of these hormones induces parthenocarpy, fruit set without fertilization, but the molecular mechanism underlying this induction is poorly understood. In the present study, we have shown that the parthenocarpic fruits induced by GA application at pre-bloom result from the interaction of GA with auxin signaling. The transcriptional levels of the putative negative regulators of fruit set initiation, including Vitis auxin/indole-3-acetic acid transcription factor 9 (VvIAA9), Vitis auxin response factor 7 (VvARF7), and VvARF8 were monitored during inflorescence development in seeded diploid ‘Tamnara’ grapevines with or without GA application. Without GA application, VvIAA9, VvARF7, and VvARF8 were expressed at a relatively high level before full bloom, but decreased thereafter following pollination. After GA application at 14 days before full bloom (DBF); however, the expression levels of VvIAA9 and VvARF7 declined at 5 DBF prior to pollination. The effects of GA application on auxin levels or auxin signaling were also analyzed by monitoring the expression patterns of auxin biosynthesis genes and auxin-responsive genes with or without GA application. Transcription levels of the auxin biosynthesis genes Vitis anthranilate synthase β subunit (VvASB1-like), Vitis YUCCA2 (VvYUC2), and VvYUC6 were not significantly changed by GA application. However, the expressions of Vitis Gretchen Hagen3.2 (VvGH3.2) and VvGH3.3, auxin-responsive genes, were up-regulated from 2 DBF to full bloom with GA application. Furthermore, the Vitis GA signaling gene, VvDELLA was up-regulated by GA application during 12 DBF to 7 DBF, prior to down-regulation of VvIAA9 and VvARF7. These results suggest that VvIAA9 and VvARF7 are negative regulators of fruit set initiation in grapevines, and GA signaling is integrated with auxin signaling via VvDELLA during

  18. Gibberellin application at pre-bloom in grapevines down-regulates the expressions of VvIAA9 and VvARF7, negative regulators of fruit set initiation, during parthenocarpic fruit development.

    PubMed

    Jung, Chan Jin; Hur, Youn Young; Yu, Hee-Ju; Noh, Jung-Ho; Park, Kyo-Sun; Lee, Hee Jae

    2014-01-01

    Fruit set is initiated only after fertilization and is tightly regulated primarily by gibberellins (GAs) and auxins. The application of either of these hormones induces parthenocarpy, fruit set without fertilization, but the molecular mechanism underlying this induction is poorly understood. In the present study, we have shown that the parthenocarpic fruits induced by GA application at pre-bloom result from the interaction of GA with auxin signaling. The transcriptional levels of the putative negative regulators of fruit set initiation, including Vitis auxin/indole-3-acetic acid transcription factor 9 (VvIAA9), Vitis auxin response factor 7 (VvARF7), and VvARF8 were monitored during inflorescence development in seeded diploid 'Tamnara' grapevines with or without GA application. Without GA application, VvIAA9, VvARF7, and VvARF8 were expressed at a relatively high level before full bloom, but decreased thereafter following pollination. After GA application at 14 days before full bloom (DBF); however, the expression levels of VvIAA9 and VvARF7 declined at 5 DBF prior to pollination. The effects of GA application on auxin levels or auxin signaling were also analyzed by monitoring the expression patterns of auxin biosynthesis genes and auxin-responsive genes with or without GA application. Transcription levels of the auxin biosynthesis genes Vitis anthranilate synthase β subunit (VvASB1-like), Vitis YUCCA2 (VvYUC2), and VvYUC6 were not significantly changed by GA application. However, the expressions of Vitis Gretchen Hagen3.2 (VvGH3.2) and VvGH3.3, auxin-responsive genes, were up-regulated from 2 DBF to full bloom with GA application. Furthermore, the Vitis GA signaling gene, VvDELLA was up-regulated by GA application during 12 DBF to 7 DBF, prior to down-regulation of VvIAA9 and VvARF7. These results suggest that VvIAA9 and VvARF7 are negative regulators of fruit set initiation in grapevines, and GA signaling is integrated with auxin signaling via VvDELLA during

  19. Increased IAA transport in axillary buds upon release from apical dominance

    SciTech Connect

    Tamas, I.A.; Reimels, A.J. )

    1989-04-01

    To investigate the transport of indoleacetic acid (IAA) simultaneously in the stem and the axillary bud, bud-bearing nodal stem segments of Phaseolus vulgaris L. were excised and agar blocks containing {sup 14}C-IAA or {sup 3}H-IAA were placed on the apical cut surface and the bud stump respectively. A plain receiver block was placed on the basal end. After a period of transport, the stem segment and the attached bud stump were sectioned, and the activity of sections and agar blocks was counted. We found that the transport of {sup 3}H-IAA from the bud stump to the receiver was greatly accelerated in plants decapitated one or two days prior to the experiment, compared to the intact controls. Decapitation also caused a decrease in the ability of the stem axis to transport {sup 14}C-IAA from the apical to the basal end of the stem segment. The increased ability of the axillary bud to transport IAA, relative to that of the stem axis, may play a role int he release of the bud from apical dominance.

  20. VM Capacity-Aware Scheduling within Budget Constraints in IaaS Clouds.

    PubMed

    Thanasias, Vasileios; Lee, Choonhwa; Hanif, Muhammad; Kim, Eunsam; Helal, Sumi

    2016-01-01

    Recently, cloud computing has drawn significant attention from both industry and academia, bringing unprecedented changes to computing and information technology. The infrastructure-as-a-Service (IaaS) model offers new abilities such as the elastic provisioning and relinquishing of computing resources in response to workload fluctuations. However, because the demand for resources dynamically changes over time, the provisioning of resources in a way that a given budget is efficiently utilized while maintaining a sufficing performance remains a key challenge. This paper addresses the problem of task scheduling and resource provisioning for a set of tasks running on IaaS clouds; it presents novel provisioning and scheduling algorithms capable of executing tasks within a given budget, while minimizing the slowdown due to the budget constraint. Our simulation study demonstrates a substantial reduction up to 70% in the overall task slowdown rate by the proposed algorithms. PMID:27501046

  1. VM Capacity-Aware Scheduling within Budget Constraints in IaaS Clouds.

    PubMed

    Thanasias, Vasileios; Lee, Choonhwa; Hanif, Muhammad; Kim, Eunsam; Helal, Sumi

    2016-01-01

    Recently, cloud computing has drawn significant attention from both industry and academia, bringing unprecedented changes to computing and information technology. The infrastructure-as-a-Service (IaaS) model offers new abilities such as the elastic provisioning and relinquishing of computing resources in response to workload fluctuations. However, because the demand for resources dynamically changes over time, the provisioning of resources in a way that a given budget is efficiently utilized while maintaining a sufficing performance remains a key challenge. This paper addresses the problem of task scheduling and resource provisioning for a set of tasks running on IaaS clouds; it presents novel provisioning and scheduling algorithms capable of executing tasks within a given budget, while minimizing the slowdown due to the budget constraint. Our simulation study demonstrates a substantial reduction up to 70% in the overall task slowdown rate by the proposed algorithms.

  2. VM Capacity-Aware Scheduling within Budget Constraints in IaaS Clouds

    PubMed Central

    Thanasias, Vasileios; Lee, Choonhwa; Hanif, Muhammad; Kim, Eunsam; Helal, Sumi

    2016-01-01

    Recently, cloud computing has drawn significant attention from both industry and academia, bringing unprecedented changes to computing and information technology. The infrastructure-as-a-Service (IaaS) model offers new abilities such as the elastic provisioning and relinquishing of computing resources in response to workload fluctuations. However, because the demand for resources dynamically changes over time, the provisioning of resources in a way that a given budget is efficiently utilized while maintaining a sufficing performance remains a key challenge. This paper addresses the problem of task scheduling and resource provisioning for a set of tasks running on IaaS clouds; it presents novel provisioning and scheduling algorithms capable of executing tasks within a given budget, while minimizing the slowdown due to the budget constraint. Our simulation study demonstrates a substantial reduction up to 70% in the overall task slowdown rate by the proposed algorithms. PMID:27501046

  3. The Aux/IAA, Sl-IAA17 regulates quality parameters over tomato fruit development.

    PubMed

    Su, L Y; Audran, C; Bouzayen, M; Roustan, J P; Chervin, C

    2015-01-01

    Auxin is known to be involved in all the stages of fruit development. Aux/IAAs are regulators of the auxin signaling at the transcription level. In a recent study, using RNAi strategy to limit the expression Sl-IAA17, it was shown that this tomato AuxIAA regulates fruit size mainly through altering the ploidy level of pericarp cells. Indeed, Sl-IAA17 down-regulated lines showed fruit with larger diameter, bigger volume and heavier weight than wild-type. The increase in fruit size was associated with thicker pericarp rather than larger locular spaces. The thicker pericarp was linked to larger cells harboring higher ploidy level, probably due to more active endoreduplication at the beginning of fruit development. The present report describes some additional phenotypes, not described in the initial article, among which are soluble solid content, juice pH, firmness, seed weight and fruit morphology.

  4. Cloning and expression analysis of novel Aux/IAA family genes in Gossypium hirsutum.

    PubMed

    Han, Xiaoyong; Xu, Xiaoyang; Fang, David D; Zhang, Tianzhen; Guo, Wangzhen

    2012-07-15

    Members of the Aux/IAA gene family encode proteins that mediate the responses of auxin-regulated gene expression and regulate various aspects of plant morphological development. Here, we provide the first identification and characterization of nine cDNAs encoding the complete open reading frame (ORF) of the Aux/IAA family in cotton. These were designated GhAux1 to GhAux9 (Gossypiumhirsutum Aux/IAA). The proteins encoded by these nine genes had either whole or partially conserved domains of the Aux/IAA superfamily, with sequence identity ranging from 14% to 69%. A pair of homeologs exists for each Aux/IAA in G. hirsutum acc. TM-1 with high identity both in ORF sequences and amino acid level. Tissue- and organ-specific analysis showed that transcripts of GhAux1, GhAux2, and GhAux3 were abundant in vegetative organs, whereas GhAux4, GhAux5, GhAux6, and GhAux7 were preferentially expressed in ovules on the day of anthesis. GhAux8 and GhIAA16 (previously reported) were also preferentially expressed during fiber developmental stages, especially GhAux8 in fiber early elongation stages, and GhIAA16 in fiber initiation and secondary cell wall thickening stage. GhAux9 was specifically expressed in developing fibers. During the fiber initiation stage, except for GhAux3 and GhAux6, the expression of the other eight GhAuxs in various lintless-fuzzless and linted-fuzzless mutants demonstrated that they were significantly up-regulated compared with linted-fuzzy TM-1. PMID:22575728

  5. Monitoring of IaaS and scientific applications on the Cloud using the Elasticsearch ecosystem

    NASA Astrophysics Data System (ADS)

    Bagnasco, S.; Berzano, D.; Guarise, A.; Lusso, S.; Masera, M.; Vallero, S.

    2015-05-01

    The private Cloud at the Torino INFN computing centre offers IaaS services to different scientific computing applications. The infrastructure is managed with the OpenNebula cloud controller. The main stakeholders of the facility are a grid Tier-2 site for the ALICE collaboration at LHC, an interactive analysis facility for the same experiment and a grid Tier-2 site for the BES-III collaboration, plus an increasing number of other small tenants. Besides keeping track of the usage, the automation of dynamic allocation of resources to tenants requires detailed monitoring and accounting of the resource usage. As a first investigation towards this, we set up a monitoring system to inspect the site activities both in terms of IaaS and applications running on the hosted virtual instances. For this purpose we used the Elasticsearch, Logstash and Kibana stack. In the current implementation, the heterogeneous accounting information is fed to different MySQL databases and sent to Elasticsearch via a custom Logstash plugin. For the IaaS metering, we developed sensors for the OpenNebula API. The IaaS level information gathered through the API is sent to the MySQL database through an ad-hoc developed RESTful web service, which is also used for other accounting purposes. Concerning the application level, we used the Root plugin TProofMonSenderSQL to collect accounting data from the interactive analysis facility. The BES-III virtual instances used to be monitored with Zabbix, as a proof of concept we also retrieve the information contained in the Zabbix database. Each of these three cases is indexed separately in Elasticsearch. We are now starting to consider dismissing the intermediate level provided by the SQL database and evaluating a NoSQL option as a unique central database for all the monitoring information. We setup a set of Kibana dashboards with pre-defined queries in order to monitor the relevant information in each case. In this way we have achieved a uniform monitoring

  6. Transcriptome Profiling of Petal Abscission Zone and Functional Analysis of an Aux/IAA Family Gene RhIAA16 Involved in Petal Shedding in Rose

    PubMed Central

    Gao, Yuerong; Liu, Chun; Li, Xiaodong; Xu, Haiqian; Liang, Yue; Ma, Nan; Fei, Zhangjun; Gao, Junping; Jiang, Cai-Zhong; Ma, Chao

    2016-01-01

    Roses are one of the most important cut flowers among ornamental plants. Rose flower longevity is largely dependent on the timing of petal shedding occurrence. To understand the molecular mechanism underlying petal abscission in rose, we performed transcriptome profiling of the petal abscission zone during petal shedding using Illumina technology. We identified a total of 2592 differentially transcribed genes (DTGs) during rose petal shedding. Gene ontology term enrichment and pathway analysis revealed that major biochemical pathways the DTGs were involved in included ethylene biosynthesis, starch degradation, superpathway of cytosolic glycolysis, pyruvate dehydrogenase and TCA cycle, photorespiration and the lactose degradation III pathway. This suggests that alterations in carbon metabolism are an important part of rose petal abscission. Among these DTGs, approximately 150 genes putatively encoding transcription factors were identified in rose abscission zone. These included zinc finger, WRKY, ERF, and Aux/IAA gene families, suggesting that petal abscission involves complex transcriptional reprogramming. Approximately 108 DTGs were related to hormone pathways, of which auxin and ethylene related DTGs were the largest groups including 52 and 41 genes, respectively. These also included 12 DTGs related to gibberellin and 6 DTGs in jasmonic acid pathway. Surprisingly, no DTGs involved in the biosynthesis/signaling of abscisic acid, cytokinin, brassinosteroid, and salicylic acid pathways were detected. Moreover, among DTGs related to auxin, we identified an Aux/IAA gene RhIAA16 that was up-regulated in response to petal shedding. Down-regulation of RhIAA16 by virus-induced gene silencing in rose promoted petal abscission, suggesting that RhIAA16 plays an important role in rose petal abscission. PMID:27695465

  7. Transcriptome Profiling of Petal Abscission Zone and Functional Analysis of an Aux/IAA Family Gene RhIAA16 Involved in Petal Shedding in Rose

    PubMed Central

    Gao, Yuerong; Liu, Chun; Li, Xiaodong; Xu, Haiqian; Liang, Yue; Ma, Nan; Fei, Zhangjun; Gao, Junping; Jiang, Cai-Zhong; Ma, Chao

    2016-01-01

    Roses are one of the most important cut flowers among ornamental plants. Rose flower longevity is largely dependent on the timing of petal shedding occurrence. To understand the molecular mechanism underlying petal abscission in rose, we performed transcriptome profiling of the petal abscission zone during petal shedding using Illumina technology. We identified a total of 2592 differentially transcribed genes (DTGs) during rose petal shedding. Gene ontology term enrichment and pathway analysis revealed that major biochemical pathways the DTGs were involved in included ethylene biosynthesis, starch degradation, superpathway of cytosolic glycolysis, pyruvate dehydrogenase and TCA cycle, photorespiration and the lactose degradation III pathway. This suggests that alterations in carbon metabolism are an important part of rose petal abscission. Among these DTGs, approximately 150 genes putatively encoding transcription factors were identified in rose abscission zone. These included zinc finger, WRKY, ERF, and Aux/IAA gene families, suggesting that petal abscission involves complex transcriptional reprogramming. Approximately 108 DTGs were related to hormone pathways, of which auxin and ethylene related DTGs were the largest groups including 52 and 41 genes, respectively. These also included 12 DTGs related to gibberellin and 6 DTGs in jasmonic acid pathway. Surprisingly, no DTGs involved in the biosynthesis/signaling of abscisic acid, cytokinin, brassinosteroid, and salicylic acid pathways were detected. Moreover, among DTGs related to auxin, we identified an Aux/IAA gene RhIAA16 that was up-regulated in response to petal shedding. Down-regulation of RhIAA16 by virus-induced gene silencing in rose promoted petal abscission, suggesting that RhIAA16 plays an important role in rose petal abscission.

  8. Tetraethylene glycol promoted two-step, one-pot rapid synthesis of indole-3-[1-11C]acetic acid

    DOE PAGES

    Lee, Sojeong; Qu, Wenchao; Alexoff, David L.; Shea, Colleen; Kim, Dohyun; Schueller, Michael; Fowler, Joanna S.

    2014-12-12

    An operationally friendly, two-step, one-pot process has been developed for the rapid synthesis of carbon-11 labeled indole-3-acetic acid ([11]IAA or [11]auxin). By replacing an aprotic polar solvent with tetraethylene glycol, nucleophilic [11]cyanation and alkaline hydrolysis reactions were performed consecutively in a single pot without a time-consuming intermediate purification step. The entire production time for this updated procedure is 55 min, which dramatically simplifies the entire synthesis and reduces the starting radioactivity required for a whole plant imaging study.

  9. Tetraethylene glycol promoted two-step, one-pot rapid synthesis of indole-3-[1-11C]acetic acid

    SciTech Connect

    Lee, Sojeong; Qu, Wenchao; Alexoff, David L.; Shea, Colleen; Kim, Dohyun; Schueller, Michael; Fowler, Joanna S.

    2014-12-12

    An operationally friendly, two-step, one-pot process has been developed for the rapid synthesis of carbon-11 labeled indole-3-acetic acid ([11]IAA or [11]auxin). By replacing an aprotic polar solvent with tetraethylene glycol, nucleophilic [11]cyanation and alkaline hydrolysis reactions were performed consecutively in a single pot without a time-consuming intermediate purification step. The entire production time for this updated procedure is 55 min, which dramatically simplifies the entire synthesis and reduces the starting radioactivity required for a whole plant imaging study.

  10. IAA RAS Radio Telescope Monitoring System

    NASA Astrophysics Data System (ADS)

    Mikhailov, A.; Lavrov, A.

    2007-07-01

    Institute of Applied Astronomy of the Russian Academy of Sciences (IAA RAS) has three identical radio telescopes, the receiving complex of which consists of five two-channel receivers of different bands, six cryogen systems, and additional devices: four local oscillators, phase calibration generators and IF commutator. The design, hardware and data communication protocol are described. The most convenient way to join the devices of the receiving complex into the common monitoring system is to use the interface which allows to connect numerous devices to the data bus. For the purpose of data communication regulation and to exclude conflicts, a data communication protocol has been designed, which operates with complex formatted data sequences. Formation of such sequences requires considerable data processing capability. That is provided by a microcontroller chip in each slave device. The test version of the software for the central computer has been developed in IAA RAS. We are developing the Mark IV FS software extension modules, which will allow us to control the receiving complex of the radio telescope by special SNAP commands from both operator input and schedule files. We are also developing procedures of automatic measurements of SEFD, system noise temperature and other parameters, available both in VLBI and single-dish modes of operation. The system described has been installed on all IAA RAS radio telescopes at "Svetloe", "Zelenchukskaya" and "Badary" observatories. It has proved to be working quite reliably and to show the perfonmance expected.

  11. NGAP: A (Brief) Update PaaS, IaaS, Onbording, and the Future

    NASA Technical Reports Server (NTRS)

    McLaughlin, Brett; Pawloski, Andrew

    2016-01-01

    NASA ESDIS has charged the EED2 program with delivering a NASA-compliant, secure, cloud-based platform for application hosting. More than just a move to the cloud, this has forced us to examine all aspects of application hosting, from resource management to system administration, patching to monitoring, deployment to multiple environments. The result of this mandate is NGAP, the NASA General Application Platform. In this presentation, we will also discuss the various applications we are supporting and targeting, and their architectures including NGAPs move to support both PaaS and IaaS architectures.

  12. The IAA RAS Correlator First Results

    NASA Technical Reports Server (NTRS)

    Surkis, Igor; Melnikov, Alexey; Shantyr, Violet; Zimovsky, Vladimir

    2010-01-01

    In 2009 the national Russian VLBI observations were processed by the new correlator ARC (Astrometric Radiointerferometric Correlator). The ARC is a VSI-H correlator and equipped with Mark 5B playback terminals. During 2009 ARC was used to process a series of VLBI sessions, observed on stations Svetloe, Zelenchukskaya, and Badary. NGS files were formed, and EOP parameters were obtained by IAA RAS Analysis Center. The accuracies of the pole coordinates and UT1-UTC were 1-2 mas and 0.07-0.1 ms, respectively.

  13. A batch system for HEP applications on a distributed IaaS cloud

    NASA Astrophysics Data System (ADS)

    Gable, I.; Agarwal, A.; Anderson, M.; Armstrong, P.; Fransham, K.; Leavett-Brown, D. Harris C.; Paterson, M.; Penfold-Brown, D.; Sobie, R. J.; Vliet, M.; Charbonneau, A.; Impey, R.; Podaima, W.

    2011-12-01

    The emergence of academic and commercial Infrastructure-as-a-Service (IaaS) clouds is opening access to new resources for the HEP community. In this paper we will describe a system we have developed for creating a single dynamic batch environment spanning multiple IaaS clouds of different types (e.g. Nimbus, OpenNebula, Amazon EC2). A HEP user interacting with the system submits a job description file with a pointer to their VM image. VM images can either be created by users directly or provided to the users. We have created a new software component called Cloud Scheduler that detects waiting jobs and boots the user VM required on any one of the available cloud resources. As the user VMs appear, they are attached to the job queues of a central Condor job scheduler, the job scheduler then submits the jobs to the VMs. The number of VMs available to the user is expanded and contracted dynamically depending on the number of user jobs. We present the motivation and design of the system with particular emphasis on Cloud Scheduler. We show that the system provides the ability to exploit academic and commercial cloud sites in a transparent fashion.

  14. The rib1 Mutant Is Resistant to Indole-3-Butyric Acid, an Endogenous Auxin in Arabidopsis1

    PubMed Central

    Poupart, Julie; Waddell, Candace S.

    2000-01-01

    The presence of indole-3-butyric acid (IBA) as an endogenous auxin in Arabidopsis has been recently demonstrated. However, the in vivo role of IBA remains to be elucidated. We present the characterization of a semi-dominant mutant that is affected in its response to IBA, but shows a wild-type response to indole-3-acetic acid (IAA), the predominant and most studied form of auxin. We have named this mutant rib1 for resistant to IBA. Root elongation assays show that rib1 is specifically resistant to IBA, to the synthetic auxin 2,4-dichlorophenoxyacetic acid, and to auxin transport inhibitors. rib1 does not display increased resistance to IAA, to the synthetic auxin naphthalene acetic acid, or to other classes of plant hormones. rib1 individuals also have other root specific phenotypes including a shortened primary root, an increased number of lateral roots, and a more variable response than wild type to a change in gravitational vector. Adult rib1 plants are morphologically indistinguishable from wild-type plants. These phenotypes suggest that rib1 alters IBA activity in the root, thereby affecting root development and response to environmental stimuli. We propose models in which RIB1 has a function in either IBA transport or response. Our experiments also suggest that IBA does not use the same mechanism to exit cells as does IAA and we propose a model for IBA transport. PMID:11115890

  15. Occurrence and in Vivo Biosynthesis of Indole-3-Butyric Acid in Corn (Zea mays L.) 1

    PubMed Central

    Ludwig-Müller, Jutta; Epstein, Ephraim

    1991-01-01

    Indole-3-butyric acid (IBA) was identified as an endogenous compound in leaves and roots of maize (Zea mays L.) var Inrakorn by thin layer chromatography, high-performance liquid chromatography, and gas chromatography-mass spectrometry. Its presence was also confirmed in the variety Hazera 224. Indole-3-acetic acid (IAA) was metabolized to IBA in vivo by seedlings of the two maize varieties. The reaction product was identified by thin layer chromatography, high performance liquid chromatography, and gas chromatography-mass spectrometry after incubating the corn seedlings with [14C]IAA and [13C6]IAA. The in vivo conversion of IAA to IBA and the characteristics of IBA formation in two different maize varieties of Zea mays L. (Hazera 224 and Inrakorn) were investigated. IBA-forming activity was examined in the roots, leaves, and coleoptiles of both maize varieties. Whereas in the variety Hazera 224, IBA was formed mostly in the leaves, in the variety Inrakorn, IBA synthesis was detected in the roots as well as in the leaves. A time course study of IBA formation showed that maximum activity was reached in Inrakorn after 1 hour and in Hazera after 2 hours. The pH optimum for the uptake of IAA was 6.0, and that for IBA formation was 7.0. The Km value for IBA formation was 17 micromolar for Inrakorn and 25 micromolar for Hazera 224. The results are discussed with respect to the possible functions of IBA in the plant. ImagesFigure 5 PMID:16668464

  16. The auxin Sl-IAA17 transcriptional repressor controls fruit size via the regulation of endoreduplication-related cell expansion.

    PubMed

    Su, Liyan; Bassa, Carole; Audran, Corinne; Mila, Isabelle; Cheniclet, Catherine; Chevalier, Christian; Bouzayen, Mondher; Roustan, Jean-Paul; Chervin, Christian

    2014-11-01

    Auxin is known to regulate cell division and cell elongation, thus controlling plant growth and development. Part of the auxin signaling pathway depends on the fine-tuned degradation of the auxin/indole acetic acid (Aux/IAA) transcriptional repressors. Recent evidence indicates that Aux/IAA proteins play a role in fruit development in tomato (Solanum lycopersicum Mill.), a model species for fleshy fruit development. We report here on the functional characterization of Sl-IAA17 during tomato fruit development. Silencing of Sl-IAA17 by an RNA interference (RNAi) strategy resulted in the production of larger fruit than the wild type. Histological analyses of the fruit organ and tissues demonstrated that this phenotype was associated with a thicker pericarp, rather than larger locules and/or a larger number of seeds. Microscopic analysis demonstrated that the higher pericarp thickness in Sl-IAA17 RNAi fruits was not due to a larger number of cells, but to the increase in cell size. Finally, we observed that the cell expansion in the transgenic fruits is tightly coupled with higher ploidy levels than in the wild type, suggesting a stimulation of the endoreduplication process. In conclusion, this work provides new insights into the function of the Aux/IAA pathway in fleshy fruit development, especially fruit size and cell size determination in tomato.

  17. myo-Inositol 1,3-acetals as early intermediates during the synthesis of cyclitol derivatives.

    PubMed

    Gurale, Bharat P; Sardessai, Richa S; Shashidhar, Mysore S

    2014-11-18

    Synthetic sequences starting from commercially available myo-inositol necessarily involve protection-deprotection strategies of its six hydroxyl groups. Several strategies have been developed/attempted over the last several decades leading to the synthesis of naturally occurring phosphoinositols, their analogs, and cyclitol derivatives. Of late, myo-inositol 1,3-acetals, which can be obtained by the reductive cleavage of myo-inositol orthoesters have emerged as early intermediates for the synthesis of phosphorylated and other inositol derivatives. This mini-review is an attempt to illustrate the economy and convenience of using myo-inositol 1,3-acetals as early intermediates during syntheses from myo-inositol.

  18. Oligomerization of SCFTIR1 Is Essential for Aux/IAA Degradation and Auxin Signaling in Arabidopsis.

    PubMed

    Dezfulian, Mohammad H; Jalili, Espanta; Roberto, Don Karl A; Moss, Britney L; Khoo, Kerry; Nemhauser, Jennifer L; Crosby, William L

    2016-09-01

    The phytohormone auxin is a key regulator of plant growth and development. Molecular studies in Arabidopsis have shown that auxin perception and signaling is mediated via TIR1/AFB-Aux/IAA co-receptors that assemble as part of the SCFTIR1/AFB E3 ubiquitin-ligase complex and direct the auxin-regulated degradation of Aux/IAA transcriptional repressors. Despite the importance of auxin signaling, little is known about the functional regulation of the TIR1/AFB receptor family. Here we show that TIR1 can oligomerize in planta via a set of spatially clustered amino acid residues. While none of the residues identified reside in the interaction interface of the TIR1-Aux/IAA degron, they nonetheless regulate the binding of TIR1 to Aux/IAA substrate proteins and their subsequent degradation in vivo as an essential aspect of auxin signaling. We propose oligomerization of TIR1 as a novel regulatory mechanism in the regulation of auxin-mediated plant patterning and development.

  19. Oligomerization of SCFTIR1 Is Essential for Aux/IAA Degradation and Auxin Signaling in Arabidopsis

    PubMed Central

    Dezfulian, Mohammad H.; Jalili, Espanta; Khoo, Kerry; Nemhauser, Jennifer L.; Crosby, William L.

    2016-01-01

    The phytohormone auxin is a key regulator of plant growth and development. Molecular studies in Arabidopsis have shown that auxin perception and signaling is mediated via TIR1/AFB–Aux/IAA co-receptors that assemble as part of the SCFTIR1/AFB E3 ubiquitin-ligase complex and direct the auxin-regulated degradation of Aux/IAA transcriptional repressors. Despite the importance of auxin signaling, little is known about the functional regulation of the TIR1/AFB receptor family. Here we show that TIR1 can oligomerize in planta via a set of spatially clustered amino acid residues. While none of the residues identified reside in the interaction interface of the TIR1-Aux/IAA degron, they nonetheless regulate the binding of TIR1 to Aux/IAA substrate proteins and their subsequent degradation in vivo as an essential aspect of auxin signaling. We propose oligomerization of TIR1 as a novel regulatory mechanism in the regulation of auxin-mediated plant patterning and development. PMID:27618443

  20. Oligomerization of SCFTIR1 Is Essential for Aux/IAA Degradation and Auxin Signaling in Arabidopsis.

    PubMed

    Dezfulian, Mohammad H; Jalili, Espanta; Roberto, Don Karl A; Moss, Britney L; Khoo, Kerry; Nemhauser, Jennifer L; Crosby, William L

    2016-09-01

    The phytohormone auxin is a key regulator of plant growth and development. Molecular studies in Arabidopsis have shown that auxin perception and signaling is mediated via TIR1/AFB-Aux/IAA co-receptors that assemble as part of the SCFTIR1/AFB E3 ubiquitin-ligase complex and direct the auxin-regulated degradation of Aux/IAA transcriptional repressors. Despite the importance of auxin signaling, little is known about the functional regulation of the TIR1/AFB receptor family. Here we show that TIR1 can oligomerize in planta via a set of spatially clustered amino acid residues. While none of the residues identified reside in the interaction interface of the TIR1-Aux/IAA degron, they nonetheless regulate the binding of TIR1 to Aux/IAA substrate proteins and their subsequent degradation in vivo as an essential aspect of auxin signaling. We propose oligomerization of TIR1 as a novel regulatory mechanism in the regulation of auxin-mediated plant patterning and development. PMID:27618443

  1. G2LC: Resources Autoscaling for Real Time Bioinformatics Applications in IaaS

    PubMed Central

    Hu, Rongdong; Liu, Guangming; Jiang, Jingfei; Wang, Lixin

    2015-01-01

    Cloud computing has started to change the way how bioinformatics research is being carried out. Researchers who have taken advantage of this technology can process larger amounts of data and speed up scientific discovery. The variability in data volume results in variable computing requirements. Therefore, bioinformatics researchers are pursuing more reliable and efficient methods for conducting sequencing analyses. This paper proposes an automated resource provisioning method, G2LC, for bioinformatics applications in IaaS. It enables application to output the results in a real time manner. Its main purpose is to guarantee applications performance, while improving resource utilization. Real sequence searching data of BLAST is used to evaluate the effectiveness of G2LC. Experimental results show that G2LC guarantees the application performance, while resource is saved up to 20.14%. PMID:26504488

  2. G2LC: Resources Autoscaling for Real Time Bioinformatics Applications in IaaS.

    PubMed

    Hu, Rongdong; Liu, Guangming; Jiang, Jingfei; Wang, Lixin

    2015-01-01

    Cloud computing has started to change the way how bioinformatics research is being carried out. Researchers who have taken advantage of this technology can process larger amounts of data and speed up scientific discovery. The variability in data volume results in variable computing requirements. Therefore, bioinformatics researchers are pursuing more reliable and efficient methods for conducting sequencing analyses. This paper proposes an automated resource provisioning method, G2LC, for bioinformatics applications in IaaS. It enables application to output the results in a real time manner. Its main purpose is to guarantee applications performance, while improving resource utilization. Real sequence searching data of BLAST is used to evaluate the effectiveness of G2LC. Experimental results show that G2LC guarantees the application performance, while resource is saved up to 20.14%.

  3. Light inhibits gravity-regulated peg formation and asymmetric mRNA accumulation of auxin-inducible CsIAA1 in the cortex of the transition zone in cucumber seedlings

    NASA Astrophysics Data System (ADS)

    Fujii, Nobuharu; Saito, Yuko; Miyazawa, Yutaka; Takahashi, Hideyuki

    When cucumber seedlings are grown horizontally, a specialized protuberance, termed the peg, develops on the lower side of the transition zone between the hypocotyl and the root. Gravimorphogenesis regulates the lateral positioning of the peg in the transition zone and it has been suggested that auxin plays an important role in peg formation in cucumber seedlings. Here, we found that light inhibited auxin-regulated peg formation. In the transition zone of horizontally positioned cucumber seedlings grown in the dark, we detected an asymmetric accumulation of mRNA from the auxin-inducible gene CsIAA1 in the epidermis and cortex. However, in seedlings grown under illumination, this asymmetry was greatly reduced. In dark- and light-grown seedlings, application of 10 -3 M indole-3-acetic acid induced peg formation on both the lower and upper sides of the transition zone. These results suggest that light inhibits peg formation via modification of auxin distribution and/or levels in the transition zone of cucumber seedlings.

  4. Low irradiances affect abscisic acid, indole-3-acidic acid, and cytokinin levels of wheat (Triticum aestivum L.) tissues

    NASA Technical Reports Server (NTRS)

    Nan, R.; Carman, J. G.; Salisbury, F. B.

    1999-01-01

    Wheat (Triticum aestivum L.) plants were grown under four irradiance levels: 1,400, 400, 200, and 100 micromol m-2 s-1. Leaves and roots were sampled before, during, and after the boot stage, and levels of abscisic acid (ABA), indole-3-acetic acid (IAA), zeatin, zeatin riboside, dihydrozeatin, dihydrozeatin riboside, isopentenyl adenine, and isopentenyl adenosine were quantified using noncompetitive indirect ELISA systems. Levels of IAA in leaves and roots of plants exposed to 100 micromol m-2 s-1 of irradiance were 0.7 and 2.9 micromol kg-1 dry mass (DM), respectively. These levels were 0.2 and 1.0 micromol kg-1 DM, respectively, when plants were exposed to 1,400 micromol m-2 s-1. Levels of ABA in leaves and roots of plants exposed to 100 micromol m-2 s-1 were 0.65 and 0.55 micromol kg-1 DM, respectively. They were 0.24 micromol kg-1 DM (both leaves and roots) when plants were exposed to 1,400 micromol m-2 s-1. Levels of isopentenyl adenosine in leaves (24.3 nmol kg-1 DM) and roots (29.9 nmol kg-1 DM) were not affected by differences in the irradiance regime. Similar values were obtained in a second experiment. Other cytokinins could not be detected (<10 nmol kg 1 DM) in either experiment with the sample sizes used (150-600 mg DM for roots and shoots, respectively).

  5. Hormonal and Hydroxycinnamic Acids Profiles in Banana Leaves in Response to Various Periods of Water Stress

    PubMed Central

    López-Climent, María F.; Gómez-Cadenas, Aurelio

    2014-01-01

    The pattern of change in the endogenous levels of several plant hormones and hydroxycinnamic acids in addition to growth and photosynthetic performance was investigated in banana plants (Musa acuminata cv. “Grand Nain”) subjected to various cycles of drought. Water stress was imposed by withholding irrigation for six periods with subsequent rehydration. Data showed an increase in abscisic acid (ABA) and indole-3-acetic acid (IAA) levels, a transient increase in salicylic acid (SA) concentration, and no changes in jasmonic acid (JA) after each period of drought. Moreover, the levels of ferulic (FA) and cinnamic acids (CA) were increased, and plant growth and leaf gas exchange parameters were decreased by drought conditions. Overall, data suggest an involvement of hormones and hydroxycinnamic acids in plant avoidance of tissue dehydration. The increase in IAA concentration might alleviate the senescence of survival leaves and maintained cell elongation, and the accumulation of FA and CA could play a key role as a mechanism of photoprotection through leaf folding, contributing to the effect of ABA on inducing stomatal closure. Data also suggest that the role of SA similarly to JA might be limited to a transient and rapid increase at the onset of the first period of stress. PMID:24977208

  6. Auxin Produced by the Indole-3-Pyruvic Acid Pathway Regulates Development and Gemmae Dormancy in the Liverwort Marchantia polymorpha.

    PubMed

    Eklund, D Magnus; Ishizaki, Kimitsune; Flores-Sandoval, Eduardo; Kikuchi, Saya; Takebayashi, Yumiko; Tsukamoto, Shigeyuki; Hirakawa, Yuki; Nonomura, Maiko; Kato, Hirotaka; Kouno, Masaru; Bhalerao, Rishikesh P; Lagercrantz, Ulf; Kasahara, Hiroyuki; Kohchi, Takayuki; Bowman, John L

    2015-06-01

    The plant hormone auxin (indole-3-acetic acid [IAA]) has previously been suggested to regulate diverse forms of dormancy in both seed plants and liverworts. Here, we use loss- and gain-of-function alleles for auxin synthesis- and signaling-related genes, as well as pharmacological approaches, to study how auxin regulates development and dormancy in the gametophyte generation of the liverwort Marchantia polymorpha. We found that M. polymorpha possess the smallest known toolkit for the indole-3-pyruvic acid (IPyA) pathway in any land plant and that this auxin synthesis pathway mainly is active in meristematic regions of the thallus. Previously a Trp-independent auxin synthesis pathway has been suggested to produce a majority of IAA in bryophytes. Our results indicate that the Trp-dependent IPyA pathway produces IAA that is essential for proper development of the gametophyte thallus of M. polymorpha. Furthermore, we show that dormancy of gemmae is positively regulated by auxin synthesized by the IPyA pathway in the apex of the thallus. Our results indicate that auxin synthesis, transport, and signaling, in addition to its role in growth and development, have a critical role in regulation of gemmae dormancy in M. polymorpha. PMID:26036256

  7. Auxin Produced by the Indole-3-Pyruvic Acid Pathway Regulates Development and Gemmae Dormancy in the Liverwort Marchantia polymorpha.

    PubMed

    Eklund, D Magnus; Ishizaki, Kimitsune; Flores-Sandoval, Eduardo; Kikuchi, Saya; Takebayashi, Yumiko; Tsukamoto, Shigeyuki; Hirakawa, Yuki; Nonomura, Maiko; Kato, Hirotaka; Kouno, Masaru; Bhalerao, Rishikesh P; Lagercrantz, Ulf; Kasahara, Hiroyuki; Kohchi, Takayuki; Bowman, John L

    2015-06-01

    The plant hormone auxin (indole-3-acetic acid [IAA]) has previously been suggested to regulate diverse forms of dormancy in both seed plants and liverworts. Here, we use loss- and gain-of-function alleles for auxin synthesis- and signaling-related genes, as well as pharmacological approaches, to study how auxin regulates development and dormancy in the gametophyte generation of the liverwort Marchantia polymorpha. We found that M. polymorpha possess the smallest known toolkit for the indole-3-pyruvic acid (IPyA) pathway in any land plant and that this auxin synthesis pathway mainly is active in meristematic regions of the thallus. Previously a Trp-independent auxin synthesis pathway has been suggested to produce a majority of IAA in bryophytes. Our results indicate that the Trp-dependent IPyA pathway produces IAA that is essential for proper development of the gametophyte thallus of M. polymorpha. Furthermore, we show that dormancy of gemmae is positively regulated by auxin synthesized by the IPyA pathway in the apex of the thallus. Our results indicate that auxin synthesis, transport, and signaling, in addition to its role in growth and development, have a critical role in regulation of gemmae dormancy in M. polymorpha.

  8. Stimulation of indoleacetic acid production in a Rhizobium isolate of Vigna mungo by root nodule phenolic acids.

    PubMed

    Mandal, Santi M; Mandal, Santi; Mandal, Mahitosh; Das, Amit K; Das, Amit; Pati, Bikas R; Pati, Bikas; Ghosh, Ananta K; Ghosh, Ananta

    2009-04-01

    The influence of endogenous root nodules phenolic acids on indoleacetic acid (IAA) production by its symbiont (Rhizobium) was examined. The root nodules contain higher amount of IAA and phenolic acids than non-nodulated roots. Presence of IAA metabolizing enzymes, IAA oxidase, peroxidase, and polyphenol oxidase indicate the metabolism of IAA in the nodules and roots. Three most abundant endogenous root nodule phenolic acids (protocatechuic acid, 4-hydroxybenzaldehyde and p-coumaric acid) have been identified and their effects on IAA production by the symbiont have been studied in L-tryptophan supplemented yeast extract basal medium. Protocatechuic acid (1.5 microg ml(-1)) showed maximum stimulation (2.15-fold over control) of IAA production in rhizobial culture. These results indicate that the phenolic acids present in the nodule might serve as a stimulator for IAA production by the symbiont (Rhizobium).

  9. [Effect of IAA on the photophosphorylation of pea isolated chloroplasts].

    PubMed

    Akulova, E A; Murzaeva, S V; Taukeleva, Sh N; Ruzieva, R Kh

    1975-01-01

    Effect of IAA (10(-10)-10(-3) M) on photophosphorylation, NADP reduction and the oxygen exchange is investigated. It is shown that low concentrations of IAA (10(-10)-10(-7) M) increase the photophosphorylation reaction and the flow of electrones to NADP under the phosphorylation conditions in the chloroplasts, and their effect on the O2 exchange is not the same in different types of photophosphorylation. It is supposed that the effect of IAA on the photophosphorylation is connected with H292 metabolism in chloroplasts and with catalase and peroxidase functions.

  10. Auxin Produced by the Indole-3-Pyruvic Acid Pathway Regulates Development and Gemmae Dormancy in the Liverwort Marchantia polymorpha[OPEN

    PubMed Central

    Eklund, D. Magnus; Ishizaki, Kimitsune; Flores-Sandoval, Eduardo; Kikuchi, Saya; Takebayashi, Yumiko; Tsukamoto, Shigeyuki; Hirakawa, Yuki; Nonomura, Maiko; Kato, Hirotaka; Kouno, Masaru; Bhalerao, Rishikesh P.; Lagercrantz, Ulf; Kasahara, Hiroyuki; Kohchi, Takayuki; Bowman, John L.

    2015-01-01

    The plant hormone auxin (indole-3-acetic acid [IAA]) has previously been suggested to regulate diverse forms of dormancy in both seed plants and liverworts. Here, we use loss- and gain-of-function alleles for auxin synthesis- and signaling-related genes, as well as pharmacological approaches, to study how auxin regulates development and dormancy in the gametophyte generation of the liverwort Marchantia polymorpha. We found that M. polymorpha possess the smallest known toolkit for the indole-3-pyruvic acid (IPyA) pathway in any land plant and that this auxin synthesis pathway mainly is active in meristematic regions of the thallus. Previously a Trp-independent auxin synthesis pathway has been suggested to produce a majority of IAA in bryophytes. Our results indicate that the Trp-dependent IPyA pathway produces IAA that is essential for proper development of the gametophyte thallus of M. polymorpha. Furthermore, we show that dormancy of gemmae is positively regulated by auxin synthesized by the IPyA pathway in the apex of the thallus. Our results indicate that auxin synthesis, transport, and signaling, in addition to its role in growth and development, have a critical role in regulation of gemmae dormancy in M. polymorpha. PMID:26036256

  11. Perturbation of Indole-3-Butyric Acid Homeostasis by the UDP-Glucosyltransferase UGT74E2 Modulates Arabidopsis Architecture and Water Stress Tolerance[W

    PubMed Central

    Tognetti, Vanesa B.; Van Aken, Olivier; Morreel, Kris; Vandenbroucke, Korneel; van de Cotte, Brigitte; De Clercq, Inge; Chiwocha, Sheila; Fenske, Ricarda; Prinsen, Els; Boerjan, Wout; Genty, Bernard; Stubbs, Keith A.; Inzé, Dirk; Van Breusegem, Frank

    2010-01-01

    Reactive oxygen species and redox signaling undergo synergistic and antagonistic interactions with phytohormones to regulate protective responses of plants against biotic and abiotic stresses. However, molecular insight into the nature of this crosstalk remains scarce. We demonstrate that the hydrogen peroxide–responsive UDP-glucosyltransferase UGT74E2 of Arabidopsis thaliana is involved in the modulation of plant architecture and water stress response through its activity toward the auxin indole-3-butyric acid (IBA). Biochemical characterization of recombinant UGT74E2 demonstrated that it strongly favors IBA as a substrate. Assessment of indole-3-acetic acid (IAA), IBA, and their conjugates in transgenic plants ectopically expressing UGT74E2 indicated that the catalytic specificity was maintained in planta. In these transgenic plants, not only were IBA-Glc concentrations increased, but also free IBA levels were elevated and the conjugated IAA pattern was modified. This perturbed IBA and IAA homeostasis was associated with architectural changes, including increased shoot branching and altered rosette shape, and resulted in significantly improved survival during drought and salt stress treatments. Hence, our results reveal that IBA and IBA-Glc are important regulators of morphological and physiological stress adaptation mechanisms and provide molecular evidence for the interplay between hydrogen peroxide and auxin homeostasis through the action of an IBA UGT. PMID:20798329

  12. Effects of abscisic acid and xanthoxin on elongation and gravitropism in primary roots of Zea mays

    NASA Technical Reports Server (NTRS)

    Lee, J. S.; Hasenstein, K. H.; Mulkey, T. J.; Yang, R. L.; Evans, M. L.

    1990-01-01

    We examined the involvement of abscisic acid (ABA) and xanthoxin (Xan) in maize root gravitropism by (1) testing the ability of ABA to allow positive gravitropism in dark-grown seedlings of the maize cultivar LG11, a cultivar known to require light for positive gravitropism of the primary root, (2) comparing curvature in roots in which half of the cap had been excised and replaced with agar containing either ABA or indole-3-acetic acid (IAA), (3) measuring gravitropism in roots of seedlings submerged in oxygenated solutions of ABA or IAA and (4) testing the effect of Xan on root elongation. Using a variety of methods of applying ABA to the root, we found that ABA did not cause horizontally-oriented primary roots of dark-grown seedlings to become positively gravitropic. Replacing half of the root cap of vertically oriented roots with an agar block containing ABA had little or no effect on curvature relative to that of controls in which the half cap was replaced by a plain agar block. Replacement of the removed half cap with IAA either canceled or reversed the curvature displayed by controls. When light-grown seedlings were submerged in ABA they responded strongly to gravistimulation while those in IAA did not. Xan (up to 0.1 mM) did not affect root elongation. The results indicate that ABA is not a likely mediator of root gravitropism and that the putative ABA precursor, Xan, lacks the appropriate growth-inhibiting properties to serve as a mediator of root gravitropism.

  13. GA4 and IAA were involved in the morphogenesis and development of flowers in Agapanthus praecox ssp. orientalis.

    PubMed

    Zhang, Di; Ren, Li; Yue, Jian-hua; Wang, Ling; Zhuo, Li-huan; Shen, Xiao-hui

    2014-07-01

    The transition from vegetative to reproductive growth represents a major phase change in angiosperms. Hormones play important roles in this process. In this study, gibberellic acid (GA), cytokinins (CKs), indoleacetic acid (IAA), and abscisic acid (ABA) were analyzed during the flowering in Agapanthus praecox ssp. orientalis. Eleven types of endogenous gibberellins in addition to GA1 were detected in various organs. GA9 was detected with the highest concentrations, followed by GA5, GA8, and GA19. However, GA4 was the main bioactive GA that was involved in the regulation of flowering. Eight types of endogenous cytokinins were detected in A. praecox ssp. orientalis, and zeatin, zeatin riboside, zeatin-O-glucoside, and N(6)-isopentenyladenosine-5-monophosphate were present at higher levels throughout the study, of which zeatin plays an important role in the development of various organs. IAA increased by 581% in the shoot tips from the vegetative to inflorescence bud stages and had the most significant changes during flowering. Phytohormone immunolocalization analysis suggested that IAA involved in differentiation and development of each floral organs, GA and zeatin play important roles in floret primordia differentiation and ovule development. Using exogenous plant growth regulators proved that GA signaling regulate the scape elongation and stimulate early-flowering, and IAA signaling is involved in the pedicel and corolla elongation and delay flowering slightly. PMID:24913054

  14. Boron and calcium sites involved in indole-3-acetic Acid transport in sunflower hypocotyl segments.

    PubMed

    Tang, P M; Dela Fuente, R K

    1986-06-01

    Sunflower (Helianthus annuus L. cv Russian Mammoth) hypocotyl segments deficient in either B or Ca exhibited a higher rate of potassium leakage, compared to nondeficient segments. Potassium leakage, used here as an indication of membrane integrity, was completely reversed by the addition of H(3)BO(3) or Ca(NO(3))(2) to the incubation medium of the B-deficient or Ca-deficient hypocotyl segments, respectively. This role of B and Ca in membrane integrity, which may be important in the entry and exit of auxin in cells, is identified as the first site of action for each of these two essential elements in the basipetal secretion of auxin. A second site for B is postulated because auxin transport was not restored, even when K(+) leakage has been completely reversed to the nondeficient level, when B-deficient hypocotyls were incubated in B solution. This lack of reversibility of auxin transport implied that the incubation for 2 h in B solution was not enough to restore the auxin transport process. However, since the transfer of B-deficient seedlings to B solutions prevented further deterioration of auxin transport, these observations suggest that: (a) either an intact seedling, or a longer period of incubation of the hypocotyl in B solution, is required for the synthesis or maintenance of the functional second site for B; (b) B is probably essential in the synthesis of a ligand, which may or may not be needed to bind B, but which is essential in the basipetal transport of auxin. The second site for Ca in auxin transport, is indicated by the complete reversal of its inhibition in Ca-deficient hypocotyl, when incubated in Ca solution. The second site for Ca is thought to be directly involved in the secretion of auxin, in which Ca probably plays the role of a second messenger, as in stimulus-response coupling. The two sites for Ca can be distinguished from each other by their cation specificity. The requirement for Ca in the first site can be substituted by other divalent cations, while the second site is highly specific for Ca. PMID:16664872

  15. Indoleacetic acid movement in the root cap.

    PubMed

    Pernet, J J; Pilet, P E

    1976-01-01

    When applied on the root cap of Zea mays L., indol-3yl-acetic acid (IAA) may enter the root tip and move basipetally inside the cap. From the cap to the apex (quiescent centre and meristem) the IAA transport is very slow. Polarity of IAA movement, in relation to growth, is discussed.

  16. IAA multilingual space dictionary, current status and future prospects

    NASA Astrophysics Data System (ADS)

    Yoshimitsu, Tetsuo; McKenna-Lawlor, Susan; Candel, Danielle; Ninomiya, Keiken; Contant, Jean-Michel

    2015-12-01

    Terminology is a key issue for a better understanding among people using various languages. Since 1986, when the International Academy of Astronautics (IAA) multilingual terminology database committee on astronautics was formed, the committee and its successor IAA study groups on the IAA multilingual space dictionary have made a continuous effort to construct a multilingual dictionary database on astronautical terms. In 2002, the dictionary was computerized using a database server and some recent internet technologies. The database is accessible from all over the world via the internet. You can search for terms at your home and office using a web browser installed on the computer with an internet connection. Since then, the number of terms and languages included in the database has increased. The current version includes about 3500 terms in 22 languages. The flexibility of the database enables the addition and the revision of new terms without much effort. The computerization has also demonstrated another possibility to utilize the database. When total of four paper books about the multilingual space terminology were published on the 50th anniversary of IAA in 2010, one of the lexicon books was edited by a computer program which accessed to the database. In this paper, the authors present the current status of the IAA multilingual database as well as the future possibilities on the utilization of the database.

  17. Characterization of an Indole-3-Acetamide Hydrolase from Alcaligenes faecalis subsp. parafaecalis and Its Application in Efficient Preparation of Both Enantiomers of Chiral Building Block 2,3-Dihydro-1,4-Benzodioxin-2-Carboxylic Acid.

    PubMed

    Mishra, Pradeep; Kaur, Suneet; Sharma, Amar Nath; Jolly, Ravinder S

    2016-01-01

    Both the enantiomers of 2,3-dihydro-1,4-benzodioxin-2-carboxylic acid are valuable chiral synthons for enantiospecific synthesis of therapeutic agents such as (S)-doxazosin mesylate, WB 4101, MKC 242, 2,3-dihydro-2-hydroxymethyl-1,4-benzodioxin, and N-[2,4-oxo-1,3-thiazolidin-3-yl]-2,3-dihydro-1,4-benzodioxin-2-carboxamide. Pharmaceutical applications require these enantiomers in optically pure form. However, currently available methods suffer from one drawback or other, such as low efficiency, uncommon and not so easily accessible chiral resolving agent and less than optimal enantiomeric purity. Our interest in finding a biocatalyst for efficient production of enantiomerically pure 2,3-dihydro-1,4-benzodioxin-2-carboxylic acid lead us to discover an amidase activity from Alcaligenes faecalis subsp. parafaecalis, which was able to kinetically resolve 2,3-dihydro-1,4-benzodioxin-2-carboxyamide with E value of >200. Thus, at about 50% conversion, (R)-2,3-dihydro-1,4-benzodioxin-2-carboxylic acid was produced in >99% e.e. The remaining amide had (S)-configuration and 99% e.e. The amide and acid were easily separated by aqueous (alkaline)-organic two phase extraction method. The same amidase was able to catalyse, albeit at much lower rate the hydrolysis of (S)-amide to (S)-acid without loss of e.e. The amidase activity was identified as indole-3-acetamide hydrolase (IaaH). IaaH is known to catalyse conversion of indole-3-acetamide (IAM) to indole-3-acetic acid (IAA), which is phytohormone of auxin class and is widespread among plants and bacteria that inhabit plant rhizosphere. IaaH exhibited high activity for 2,3-dihydro-1,4-benzodioxin-2-carboxamide, which was about 65% compared to its natural substrate, indole-3-acetamide. The natural substrate for IaaH indole-3-acetamide shared, at least in part a similar bicyclic structure with 2,3-dihydro-1,4-benzodioxin-2-carboxamide, which may account for high activity of enzyme towards this un-natural substrate. To the best of

  18. Characterization of an Indole-3-Acetamide Hydrolase from Alcaligenes faecalis subsp. parafaecalis and Its Application in Efficient Preparation of Both Enantiomers of Chiral Building Block 2,3-Dihydro-1,4-Benzodioxin-2-Carboxylic Acid

    PubMed Central

    Mishra, Pradeep; Kaur, Suneet; Sharma, Amar Nath; Jolly, Ravinder S.

    2016-01-01

    Both the enantiomers of 2,3-dihydro-1,4-benzodioxin-2-carboxylic acid are valuable chiral synthons for enantiospecific synthesis of therapeutic agents such as (S)-doxazosin mesylate, WB 4101, MKC 242, 2,3-dihydro-2-hydroxymethyl-1,4-benzodioxin, and N-[2,4-oxo-1,3-thiazolidin-3-yl]-2,3-dihydro-1,4-benzodioxin-2-carboxamide. Pharmaceutical applications require these enantiomers in optically pure form. However, currently available methods suffer from one drawback or other, such as low efficiency, uncommon and not so easily accessible chiral resolving agent and less than optimal enantiomeric purity. Our interest in finding a biocatalyst for efficient production of enantiomerically pure 2,3-dihydro-1,4-benzodioxin-2-carboxylic acid lead us to discover an amidase activity from Alcaligenes faecalis subsp. parafaecalis, which was able to kinetically resolve 2,3-dihydro-1,4-benzodioxin-2-carboxyamide with E value of >200. Thus, at about 50% conversion, (R)-2,3-dihydro-1,4-benzodioxin-2-carboxylic acid was produced in >99% e.e. The remaining amide had (S)-configuration and 99% e.e. The amide and acid were easily separated by aqueous (alkaline)-organic two phase extraction method. The same amidase was able to catalyse, albeit at much lower rate the hydrolysis of (S)-amide to (S)-acid without loss of e.e. The amidase activity was identified as indole-3-acetamide hydrolase (IaaH). IaaH is known to catalyse conversion of indole-3-acetamide (IAM) to indole-3-acetic acid (IAA), which is phytohormone of auxin class and is widespread among plants and bacteria that inhabit plant rhizosphere. IaaH exhibited high activity for 2,3-dihydro-1,4-benzodioxin-2-carboxamide, which was about 65% compared to its natural substrate, indole-3-acetamide. The natural substrate for IaaH indole-3-acetamide shared, at least in part a similar bicyclic structure with 2,3-dihydro-1,4-benzodioxin-2-carboxamide, which may account for high activity of enzyme towards this un-natural substrate. To the best of

  19. Implementation and use of a highly available and innovative IaaS solution: the Cloud Area Padovana

    NASA Astrophysics Data System (ADS)

    Aiftimiei, C.; Andreetto, P.; Bertocco, S.; Biasotto, M.; Dal Pra, S.; Costa, F.; Crescente, A.; Dorigo, A.; Fantinel, S.; Fanzago, F.; Frizziero, E.; Gulmini, M.; Michelotto, M.; Sgaravatto, M.; Traldi, S.; Venaruzzo, M.; Verlato, M.; Zangrando, L.

    2015-12-01

    While in the business world the cloud paradigm is typically implemented purchasing resources and services from third party providers (e.g. Amazon), in the scientific environment there's usually the need of on-premises IaaS infrastructures which allow efficient usage of the hardware distributed among (and owned by) different scientific administrative domains. In addition, the requirement of open source adoption has led to the choice of products like OpenStack by many organizations. We describe a use case of the Italian National Institute for Nuclear Physics (INFN) which resulted in the implementation of a unique cloud service, called ’Cloud Area Padovana’, which encompasses resources spread over two different sites: the INFN Legnaro National Laboratories and the INFN Padova division. We describe how this IaaS has been implemented, which technologies have been adopted and how services have been configured in high-availability (HA) mode. We also discuss how identity and authorization management were implemented, adopting a widely accepted standard architecture based on SAML2 and OpenID: by leveraging the versatility of those standards the integration with authentication federations like IDEM was implemented. We also discuss some other innovative developments, such as a pluggable scheduler, implemented as an extension of the native OpenStack scheduler, which allows the allocation of resources according to a fair-share based model and which provides a persistent queuing mechanism for handling user requests that can not be immediately served. Tools, technologies, procedures used to install, configure, monitor, operate this cloud service are also discussed. Finally we present some examples that show how this IaaS infrastructure is being used.

  20. An attempt to localize and identify the gravity sensing mechanism of plants

    NASA Technical Reports Server (NTRS)

    Bandurski, R. S.

    1984-01-01

    Gravistimulation causes an asymmetric distribution of the plant growth hormone, indole-3-acetic acid (IAA). In what tissue of the plant the IAA asymmetry arises will be determined so as to better localize the gravity sensing device.

  1. Division IAA Football Players and Risk Factors for Metabolic Syndrome

    ERIC Educational Resources Information Center

    Repovich, Wendy E. S.; Babcock, Garth J.

    2012-01-01

    The purpose of this study was to determine if body composition and blood pressure (BP), two markers for Metabolic Syndrome (MetS), were correlated in college football players. Height, weight, BMI, systolic (SBP) and Diastolic (DBP) blood pressure and body composition (three measures) were assessed in a Division IAA football team (N = 55). Data…

  2. Demonstrations at School Level of the Effects of IAA

    ERIC Educational Resources Information Center

    Falk, Peter

    1973-01-01

    Describes demonstrations suitable for secondary school biology classes relating to the effects of the hormone IAA on plant growth. Demonstrations illustrate how hormone treatments affect stem elongation, callus formation, inhibition of axillary buds, stimulation of secondary growth and initiation of adventitious root development, root elongation,…

  3. Mutation in domain II of IAA1 confers diverse auxin-related phenotypes and represses auxin-activated expression of Aux/IAA genes in steroid regulator-inducible system.

    PubMed

    Park, Jin-Young; Kim, Hye-Joung; Kim, Jungmook

    2002-12-01

    Most of Aux/IAA genes are rapidly induced by auxin. The Aux/IAA proteins are short-lived nuclear proteins sharing the four conserved domains. Domain II is critical for rapid degradation of Aux/IAA proteins. Among these gene family members, IAA1 is one of the earliest auxin-inducible genes. We used a steroid hormone-inducible system to reveal putative roles and downstream signaling of IAA1 in auxin response. Arabidopsis transgenic plants were generated expressing fusion protein of IAA1 (IAA1-GR) or IAA1 with a mutation in domain II (iaa1-GR) and the glucocorticoid hormone-binding domain (GR). IAA1-GR transgenic plants did not exhibit any discernable phenotypic differences by DEX treatment that allows nuclear translocation of the fusion protein. In contrast, diverse auxin-related physiological processes including gravitropism and phototropism were impaired by DEX treatment in roots, hypocotyls, stems, and leaves in iaa1-GR transgenic plants. Auxin induction of seven Aux/IAA mRNAs including IAA1 itself was repressed by DEX treatment, suggesting that IAA1 functions in the nucleus by mediating auxin response and might act as a negative feedback regulator for the expression of Aux/IAA genes including IAA1 itself. Auxin induction of Aux/IAA genes in the presence of cycloheximide can be repressed by DEX treatment, showing that the repression of transcription of the Aux/IAAs by the iaa1 mutant protein is primary. Wild-type IAA1-GR could not suppress auxin induction of IAA1 and IAA2. These results indicate that inhibition of auxin-activated transcription of Aux/IAA genes by the iaa1 mutant protein might be responsible for alteration of various auxin responses.

  4. Exogenous IAA differentially affects growth, oxidative stress and antioxidants system in Cd stressed Trigonella foenum-graecum L. seedlings: Toxicity alleviation by up-regulation of ascorbate-glutathione cycle.

    PubMed

    Bashri, Gausiya; Prasad, Sheo Mohan

    2016-10-01

    In the present study, effect of exogenous indole-3-acetic acid at their different levels (i.e. low; IAAL, 10µM and high; IAAH, 100µM) were studied on growth, oxidative stress biomarkers and antioxidant enzymes (SOD, POD, CAT and GST), and metabolites (AsA and GSH) as well as enzymes (APX, GR and DHAR) of ascorbate-glutathione cycle in Trigonella foenum-graecum L. seedlings grown under cadmium (Cd1, 3mgCd kg(-1) soil and Cd2, 9mgCd kg(-1) soil) stress. Cadmium (Cd) at both doses caused reduction in growth which was correlated with enhanced lipid peroxidation and damage to membrane as a result of excess accumulation of O2(•-) and H2O2. Cd also enhanced the oxidation of AsA and GSH to DHA and GSSG, respectively which give a clear sign of oxidative stress, despite of accelerated activity of enzymatic antioxidants: SOD, CAT, POD, GST as well as APX, DHAR (except in Cd2 stress) and GR. Exogenous application of IAAL resulted further rise in the activities of these enzymes, and maintained the redox status (> ratios: AsA/DHA and GSH/GSSG) of cells. The maintained redox status of cells under IAAL treatment declined the level of ROS in Cd1 and Cd2 treated seedlings thereby alleviated the Cd toxicity and this effect was more pronounced under Cd1 stress. Contrary to this, exogenous IAAH suppressed the activity of DHAR and GR and disturbed the redox status (< ratios: AsA/DHA and GSH/GSSG) of cells, hence excess accumulation of ROS further aggravated the Cd induced damage. Thus, overall results suggest that IAA at low (IAAL) and high (IAAH) doses affected the Cd toxicity differently by regulating the ascorbate-glutathione cycle as well as activity of other antioxidants in Trigonella seedlings. PMID:27344401

  5. Effects of Kinetin, IAA, and Gibberellin on Ethylene Production, and Their Interactions in Growth of Seedlings.

    PubMed

    Fuchs, Y; Lieberman, M

    1968-12-01

    Kinetin in concentrations of 10(-8) to 10(-4)m, stimulated ethylene production in 3 and 4-day old etiolated seedlings of Alaska pea (Pisum sativum L. var. Alaska). Seedlings of other species responded similarly. The response to kinetin depended on the age of the seedlings.Kinetin alone did not influence ethylene production in 6-day old stem sections, but it greatly increased the enhancing effect of IAA.Gibberellic acid had no effect on ethylene production by pea seedlings during the first 6 days of growth. Ethylene and gibberellic acid are antagonistic in their effects on growth of the seedlings; ethylene interfered severely with the action of gibberellic acid but did not completely suppress it.The inhibitors cycloheximide, cupferron, and N-ethylmaleimide, caused considerable inhibition of kinetin-induced ethylene production but were much less effective in the endogenous ethylene-forming system. PMID:16657004

  6. cis-Cinnamic acid selective suppressors distinct from auxin inhibitors.

    PubMed

    Okuda, Katsuhiro; Nishikawa, Keisuke; Fukuda, Hiroshi; Fujii, Yoshiharu; Shindo, Mitsuru

    2014-01-01

    The activity of cis-cinnamic acid (cis-CA), one of the allelochemicals, in plants is very similar to that of indole-3-acetic acid (IAA), a natural auxin, and thus cis-CA has long been believed to be an analog of auxin. We have reported some structure-activity relationships studies by synthesizing over 250 cis-CA derivatives and estimating their inhibitory activities on root growth inhibition in lettuce. In this study, the compounds that showed low- or no-activity on root growth inhibition were recruited as candidates suppressors against cis-CA and/or auxin and tested for their activity. In the presence of cis-CA, lettuce root growth was inhibited; however, the addition of some cis-CA derivatives restored control-level root growth. Four compounds, (Z)-3-(4-isopropylphenyl)acrylic acid, (Z)-3-(3-butoxyphenyl)acrylic acid, (Z)-3-[3-(pentyloxy)phenyl]acrylic acid, and (Z)-3-(naphthalen-1-yl)acrylic acid were selected as candidates for a cis-CA selective suppressor they allowed the recovery of root growth from inhibition by cis-CA treatment without any effects on the IAA-induced effect or elongating activity by themselves. Three candidates significantly ameliorated the root shortening by the potent inhibitor derived from cis-CA. In brief, we have found some cis-CA selective suppressors which have never been reported from inactive cis-CA derivatives for root growth inhibition. cis-CA selective suppressors will play an important role in elucidating the mechanism of plant growth regulation.

  7. The Lunar Farside Radio Lab Study of the IAA

    NASA Astrophysics Data System (ADS)

    Maccone, Claudio

    2002-01-01

    The "Lunar Farside Radio Lab" Study of the IAA, started in 1998 by late French astronomer Jean Heidmann (1923-2000), underwent substantial extensions and revisions since its coordination was taken up by this author. These modifications can be summarized as follows: 1) The goal of the Study was enlarged so as to encompass the whole of radio astronomy, rather 2) It was stressed that, from the Lunar Farside, one can detect radio frequencies lower than 15 3) Lunar Farside Crater Saha, initially selected by Heidmann to host a radiotelescope, was 4) Four different scenarios were envisaged for the relevant space mission, dubbed RadioMoon: Finally, legal protection of Daedalus from radio-pollution was sought, initially by virtue of the IISL. The "Lunar Farside Radio Lab" Study of the IAA should be completed by October 2003 with a number of distinguished contributions. Its present status and prospects are explained and motivated in this paper.

  8. Abscisic Acid Is a General Negative Regulator of Arabidopsis Axillary Bud Growth1[OPEN

    PubMed Central

    Yao, Chi; Finlayson, Scott A.

    2015-01-01

    Branching is an important process controlled by intrinsic programs and by environmental signals transduced by a variety of plant hormones. Abscisic acid (ABA) was previously shown to mediate Arabidopsis (Arabidopsis thaliana) branching responses to the ratio of red light (R) to far-red light (FR; an indicator of competition) by suppressing bud outgrowth from lower rosette positions under low R:FR. However, the role of ABA in regulating branching more generally was not investigated. This study shows that ABA restricts lower bud outgrowth and promotes correlative inhibition under both high and low R:FR. ABA was elevated in buds exhibiting delayed outgrowth resulting from bud position and low R:FR and decreased in elongating buds. ABA was reduced in lower buds of hyperbranching mutants deficient in auxin signaling (AUXIN RESISTANT1), MORE AXILLARY BRANCHING (MAX) signaling (MAX2), and BRANCHED1 (BRC1) function, and partial suppression of branch elongation in these mutants by exogenous ABA suggested that ABA may act downstream of these components. Bud BRC1 expression was not altered by exogenous ABA, consistent with a downstream function for ABA. However, the expression of genes encoding the indole-3-acetic acid (IAA) biosynthesis enzyme TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1, the auxin transporter PIN-FORMED1, and the cell cycle genes CYCLIN A2;1 and PROLIFERATING CELL NUCLEAR ANTIGEN1 in buds was suppressed by ABA, suggesting that it may inhibit bud growth in part by suppressing elements of the cell cycle machinery and bud-autonomous IAA biosynthesis and transport. ABA was found to suppress bud IAA accumulation, thus confirming this aspect of its action. PMID:26149576

  9. Effect of gibberellic acid on growth and indole metabolism of dwarf-pea plants

    SciTech Connect

    Husain, Z.

    1987-01-01

    A study was conducted to describe the pathway of biosynthesis of indole-3-acetic acid (IAA) from tryptophan (TPP) and determine the effect of gibberellic acid (GA/sub 3/) on this system. Treatment of dwarf peas (Pisum sativum L. var Little Marvel) with 0.8 ..mu..g GA/sub 3//plant resulted in increase in plant height along with increased auxin level. A cell-free preparation of pea shoot tissue was able to convert D,L-tryptophan-3-/sup 14/C into different indole metabolites. The acidic and neutral fractions obtained after TPP incubation were subjected to thin-layer chromatography. In the neutral fraction, two peaks of radioactivity were found and these matched the Rfs for indole-acetaldehyde (IAAId) and indole-3-ethanol (IEt). One major peak of radioactivity was observed in the radiochromatograms of the acidic fraction and it corresponded with a authentic IAA. The enzymes involved in the conversion of TPP to IAA involved, in the first step, a transaminase (tryptophan aminotransferase, EC 2 x 6 x 1) reaction. The aminotransferase was purified about 82-fold by acetone precipitation and Sephadex G-200 filtration. It had a pH optimum of 8.5 and a temperature optimum of 40/sup 0/C. With ..cap alpha..-ketoglutarate a co-substrate, the enzyme transaminated aromatic as well as aliphatic amino acids including D,L-tryptophan, D,L-alanine and D,L leucine. D-TPP was found to be more effective than L-TPP as a substrate. GA/sub 3/ treatment to dwarf pea plants results in increase in the specific activity of the enzyme over the observation period. In the second step of TPP conversion, IPyA is decarboxylated by an enzyme to IAAId. In plants treated with GA/sub 3/, the enzyme activity was significantly higher three days after treatment but remained unaffected at all other stages when observations were made. The final step enzyme is a dehydrogenase that can convert IAAId to IAA in the presence of MAD as a co-factor.

  10. Stimulatory effect of cytokinins and interaction with IAA on the release of lateral buds of pea plants from apical dominance.

    PubMed

    Li, Chunjian; Bangerth, Fritz

    2003-09-01

    Lateral buds of pea plants can be released from apical dominance and even be transformed into dominant shoots when repeatedly treated with synthetic exogenous cytokinins (CKs). The mechanism of the effect of CKs, however, is not clear. The results in this work showed that the stimulatory effects of CKs on the growth of lateral buds and the increase in their fresh weights in pea plants depended on the structure and concentration of the CKs used. The effect of N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) was stronger than that of 6-benzylaminopurine (6-BA). Indoleacetic acid (IAA) concentration in shoot, IAA export out of the treated apex and basipetal transport in stems were markedly increased after the application of CPPU or 6-BA to the apex or the second node of pea plant. This increase was positively correlated with the increased concentration of the applied CKs. These results suggest that the increased IAA synthesis and export induced by CKs application might be responsible for the growth of lateral shoots in intact pea plants. PMID:14593807

  11. Aminooxy-naphthylpropionic acid and its derivatives are inhibitors of auxin biosynthesis targeting l-tryptophan aminotransferase: structure-activity relationships.

    PubMed

    Narukawa-Nara, Megumi; Nakamura, Ayako; Kikuzato, Ko; Kakei, Yusuke; Sato, Akiko; Mitani, Yuka; Yamasaki-Kokudo, Yumiko; Ishii, Takahiro; Hayashi, Ken-Ichiro; Asami, Tadao; Ogura, Takehiko; Yoshida, Shigeo; Fujioka, Shozo; Kamakura, Takashi; Kawatsu, Tsutomu; Tachikawa, Masanori; Soeno, Kazuo; Shimada, Yukihisa

    2016-08-01

    We previously reported l-α-aminooxy-phenylpropionic acid (AOPP) to be an inhibitor of auxin biosynthesis, but its precise molecular target was not identified. In this study we found that AOPP targets TRYPTOPHAN AMINOTRANSFERASE of ARABIDOPSIS 1 (TAA1). We then synthesized 14 novel compounds derived from AOPP to study the structure-activity relationships of TAA1 inhibitors in vitro. The aminooxy and carboxy groups of the compounds were essential for inhibition of TAA1 in vitro. Docking simulation analysis revealed that the inhibitory activity of the compounds was correlated with their binding energy with TAA1. These active compounds reduced the endogenous indole-3-acetic acid (IAA) content upon application to Arabidopsis seedlings. Among the compounds, we selected 2-(aminooxy)-3-(naphthalen-2-yl)propanoic acid (KOK1169/AONP) and analyzed its activities in vitro and in vivo. Arabidopsis seedlings treated with KOK1169 showed typical auxin-deficient phenotypes, which were reversed by exogenous IAA. In vitro and in vivo experiments indicated that KOK1169 is more specific for TAA1 than other enzymes, such as phenylalanine ammonia-lyase. We further tested 41 novel compounds with aminooxy and carboxy groups to which we added protection groups to increase their calculated hydrophobicity. Most of these compounds decreased the endogenous auxin level to a greater degree than the original compounds, and resulted in a maximum reduction of about 90% in the endogenous IAA level in Arabidopsis seedlings. We conclude that the newly developed compounds constitute a class of inhibitors of TAA1. We designated them 'pyruvamine'. PMID:27147230

  12. IAA transport in corn roots includes the root cap

    SciTech Connect

    Hasenstein, K.H. )

    1989-04-01

    In earlier reports we concluded that auxin is the growth regulator that controls gravicurvature in roots and that the redistribution of auxin occurs within the root cap. Since other reports did not detect auxin in the root cap, we attempted to confirm the IAA does move through the cap. Agar blocks containing {sup 3}H-IAA were applied to the cut surface of 5 mm long apical segments of primary roots of corn (mo17xB73). After 30 to 120 min radioactivity (RA) of the cap and root tissue was determined. While segments suspended in water-saturated air accumulated very little RA in the cap, application of 0.5 {mu}1 of dist. water to the cap (=controls) increased RA of the cap dramatically. Application to the cap of 0.5 {mu}1 of sorbitol or the Ca{sup 2+} chelator EGTA reduced cap RA to 46% and 70% respectively compared to water, without affecting uptake. Control root segments gravireacted faster than non-treated or osmoticum or EGTA treated segments. The data indicate that both the degree of hydration and calcium control the amount of auxin moving through the cap.

  13. The optimal design of service level agreement in IAAS based on BDIM

    NASA Astrophysics Data System (ADS)

    Liu, Xiaochen; Zhan, Zhiqiang

    2013-03-01

    Cloud Computing has become more and more prevalent over the past few years, and we have seen the importance of Infrastructure-as-a-service (IaaS). This kind of service enables scaling of bandwidth, memory, computing power and storage. But the SLA in IaaS also faces complexity and variety. Users also consider the business of the service. To meet the most users requirements, a methodology for designing optimal SLA in IaaS from the business perspectives is proposed. This method is different from the conventional SLA design method, It not only focuses on service provider perspective, also from the customer to carry on the design. This methodology better captures the linkage between service provider and service client by considering minimizing the business loss originated from performance degradation and IT infrastructure failures and maximizing profits for service provider and clients. An optimal design in an IaaS model is provided and an example are analyzed to show this approach obtain higher profit.

  14. 5'-azido-N-1-naphthylphthalamic acid, a photolabile analog of the auxin transport inhibitor, N-1-naphthylphthalamic acid: synthesis and binding properties

    SciTech Connect

    Voet, J.G.; Howley, K.; Shumsky, J.S.

    1987-05-01

    The polar transport of the plant growth regulator, auxin (indole-3-acetic acid, IAAH), is thought to involve the participation of several proteins in the plasma membrane, including a specific, saturable, voltage independent H/sup +//IAA/sup -/ efflux carrier located preferentially at the basal end of each cell. Auxin transport is specifically inhibited by the herbicide, N-1-naphthylphthalamic acid (NPA), which binds specifically to a protein in the plasma membrane, thought to be either the IAA/sup -/ efflux carrier or an allosteric effector protein. They have synthesized and characterized a photolabile analog of NPA, 5'-azido-N-1-naphthylphthalamic acid (Az-NPA). This potential photoaffinity label for the NPA binding protein competes with /sup 3/H-NPA for binding sites on Curcurbita pepo L. (zucchini) stem cell membranes with K/sub j/ = 1.5 x 10/sup -7/ M. The K/sub i/ for NPA under these conditions is 2 x 10/sup -8/M, indicating that the affinity of Az-NPA for the membranes is only 7.5 fold lower than NPA. While the binding of 4.6 x 10/sup -6/ M Az-NPA to NPA binding sites is reversible in the dark, exposure to light results in a 30% loss in /sup 3/H-NPA binding ability. Pretreatment with 10/sup -4/ M NPA protects the membranes against photodestruction of /sup 3/H-NPA binding sites by Az-NPA, supporting the conclusion that Az-NPA destroys these sites by specific covalent attachment.

  15. The IAA Cosmic Study 'Protecting the Environment of Celestial Bodies'

    NASA Astrophysics Data System (ADS)

    Rettberg, Petra; Hofmann, Mahulena; Williamson, Mark

    The study group tasked with producing this International Academy of Astronautics (IAA) `Cosmic Study' on Protecting the Environment of Celestial Bodies was formed under the aus-pices of IAA Commission V (Space Policy, Law Economy). The members of the international, multidisciplinary team assembled to undertake the Study accept, as a premise, the Planetary Protection Policy guidelines developed by COSPAR, which differentiate the degree of protec-tion according to the type of space activity and the celestial body under investigation (such that fly-by missions have less stringent requirements than lander missions, while Mars is `better protected' than the Moon). However, this Study goes deliberately beyond the interpretation of `Planetary Protection' as a set of methods for protecting the planets from biological con-tamination and extends consideration to the geophysical, industrial and cultural realms. The Study concludes that, from the perspective of current and future activities in outer space, present measures aimed at protecting the space environment are insufficient. Deficiencies in-clude a lack of suitable in-situ methods of chemical and biological detection and the absence of a systematic record of radioactive contaminants. Other issues identified by the Study include an insufficient legal framework, a shortage of effective economic tools and a lack of political will to address these concerns. It is expected that new detection methods under development, and the resultant increase in microbiological knowledge of the planetary surfaces, will lead to changes in the COSPAR planetary protection guidelines and bioburden limits. It is important, however, that any new approaches should not hamper future exploration and exploitation of celestial bodies more than absolutely necessary. The Study addresses the need to find a balance between protection and freedom of action. From a legal perspective, the Study concludes that a general consensus on protection of the

  16. Constitutive auxin response in Physcomitrella reveals complex interactions between Aux/IAA and ARF proteins.

    PubMed

    Lavy, Meirav; Prigge, Michael J; Tao, Sibo; Shain, Stephanie; Kuo, April; Kirchsteiger, Kerstin; Estelle, Mark

    2016-01-01

    The coordinated action of the auxin-sensitive Aux/IAA transcriptional repressors and ARF transcription factors produces complex gene-regulatory networks in plants. Despite their importance, our knowledge of these two protein families is largely based on analysis of stabilized forms of the Aux/IAAs, and studies of a subgroup of ARFs that function as transcriptional activators. To understand how auxin regulates gene expression we generated a Physcomitrella patens line that completely lacks Aux/IAAs. Loss of the repressors causes massive changes in transcription with misregulation of over a third of the annotated genes. Further, we find that the aux/iaa mutant is blind to auxin indicating that auxin regulation of transcription occurs exclusively through Aux/IAA function. We used the aux/iaa mutant as a simplified platform for studies of ARF function and demonstrate that repressing ARFs regulate auxin-induced genes and fine-tune their expression. Further the repressing ARFs coordinate gene induction jointly with activating ARFs and the Aux/IAAs. PMID:27247276

  17. 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

  18. Constitutive auxin response in Physcomitrella reveals complex interactions between Aux/IAA and ARF proteins

    PubMed Central

    Lavy, Meirav; Prigge, Michael J; Tao, Sibo; Shain, Stephanie; Kuo, April; Kirchsteiger, Kerstin; Estelle, Mark

    2016-01-01

    The coordinated action of the auxin-sensitive Aux/IAA transcriptional repressors and ARF transcription factors produces complex gene-regulatory networks in plants. Despite their importance, our knowledge of these two protein families is largely based on analysis of stabilized forms of the Aux/IAAs, and studies of a subgroup of ARFs that function as transcriptional activators. To understand how auxin regulates gene expression we generated a Physcomitrella patens line that completely lacks Aux/IAAs. Loss of the repressors causes massive changes in transcription with misregulation of over a third of the annotated genes. Further, we find that the aux/iaa mutant is blind to auxin indicating that auxin regulation of transcription occurs exclusively through Aux/IAA function. We used the aux/iaa mutant as a simplified platform for studies of ARF function and demonstrate that repressing ARFs regulate auxin-induced genes and fine-tune their expression. Further the repressing ARFs coordinate gene induction jointly with activating ARFs and the Aux/IAAs. DOI: http://dx.doi.org/10.7554/eLife.13325.001 PMID:27247276

  19. Antimicrobial and Cytotoxic Activity of Di-(2-ethylhexyl) Phthalate and Anhydrosophoradiol-3-acetate Isolated from Calotropis gigantea (Linn.) Flower.

    PubMed

    Habib, M Rowshanul; Karim, M Rezaul

    2009-03-01

    A phytochemical study on the flowe r of Calotropis gigantea (Linn.) using silica gel column chromatography and preparative thin layer chromatography, led to the first time isolation of Di-(2-ethylhexyl) phthalate (compound 1) and anhydrosophoradiol-3-acetate (compound 2). The structures of these compounds were confirmed by spectroscopic analyses (IR, HRTOFMS and NMR). The antibacterial and antifungal activities of ethyl acetate extract, compound 1 and compound 2 were measured using the disc diffusion method. Ethyl acetate extract and compound 1 presented better results than compound 2. The minimum inhibitory concentrations (MICs) of the extract and compounds were found to be in the range of 16~128 µg/ml. The cytotoxicity (LC50) against brine shrimp nauplii (Artemia salina) were also evaluated and found to be 14.61 µg/ml for ethyl acetate, 9.19 µg/ml for compound 1 and 15.55 µg/ml for compound 2.

  20. Antimicrobial and Cytotoxic Activity of Di-(2-ethylhexyl) Phthalate and Anhydrosophoradiol-3-acetate Isolated from Calotropis gigantea (Linn.) Flower

    PubMed Central

    Habib, M. Rowshanul

    2009-01-01

    A phytochemical study on the flowe r of Calotropis gigantea (Linn.) using silica gel column chromatography and preparative thin layer chromatography, led to the first time isolation of Di-(2-ethylhexyl) phthalate (compound 1) and anhydrosophoradiol-3-acetate (compound 2). The structures of these compounds were confirmed by spectroscopic analyses (IR, HRTOFMS and NMR). The antibacterial and antifungal activities of ethyl acetate extract, compound 1 and compound 2 were measured using the disc diffusion method. Ethyl acetate extract and compound 1 presented better results than compound 2. The minimum inhibitory concentrations (MICs) of the extract and compounds were found to be in the range of 16~128 µg/ml. The cytotoxicity (LC50) against brine shrimp nauplii (Artemia salina) were also evaluated and found to be 14.61 µg/ml for ethyl acetate, 9.19 µg/ml for compound 1 and 15.55 µg/ml for compound 2. PMID:23983504

  1. IAA8 Involved in Lateral Root Formation Interacts with the TIR1 Auxin Receptor and ARF Transcription Factors in Arabidopsis

    PubMed Central

    Egusa, Mayumi; Nishimoto, Nami; Sakurai, Sumiko; Sakamoto, Naho; Kaminaka, Hironori

    2012-01-01

    The expression of auxin-responsive genes is regulated by the TIR1/AFB auxin receptor-dependent degradation of Aux/IAA transcriptional repressors, which interact with auxin-responsive factors (ARFs). Most of the 29 Aux/IAA genes present in Arabidopsis have not been functionally characterized to date. IAA8 appears to have a distinct function from the other Aux/IAA genes, due to its unique transcriptional response to auxin and the stability of its encoded protein. In this study, we characterized the function of Arabidopsis IAA8 in various developmental processes governed by auxin and in the transcriptional regulation of the auxin response. Transgenic plants expressing estrogen-inducible IAA8 (XVE::IAA8) exhibited significantly fewer lateral roots than the wild type, and an IAA8 loss-of-function mutant exhibited significantly more. Ectopic overexpression of IAA8 resulted in abnormal gravitropism. The strong induction of early auxin-responsive marker genes by auxin treatment was delayed by IAA8 overexpression. GFP-fusion analysis revealed that IAA8 localized not only to the nucleus, but, in contrast to other Aux/IAAs, also to the cytosol. Furthermore, we demonstrated that IAA8 interacts with TIR1, in an auxin-dependent fashion, and with ARF proteins, both in yeast and in planta. Taken together, our results show that IAA8 is involved in lateral root formation, and that this process is regulated through the interaction with the TIR1 auxin receptor and ARF transcription factors in the nucleus. PMID:22912871

  2. Validation of MIPAS IMK/IAA methane profiles

    NASA Astrophysics Data System (ADS)

    Laeng, A.; Plieninger, J.; von Clarmann, T.; Grabowski, U.; Stiller, G.; Eckert, E.; Glatthor, N.; Haenel, F.; Kellmann, S.; Kiefer, M.; Linden, A.; Lossow, S.; Deaver, L.; Engel, A.; Hervig, M.; Levin, I.; McHugh, M.; Noël, S.; Toon, G.; Walker, K.

    2015-06-01

    The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) was an infra-red (IR) limb emission spectrometer on the Envisat platform. It measured during day and night, pole-to-pole, over an altitude range from 6 to 70 km in nominal mode and up to 170 km in special modes, depending on the measurement mode, producing more than 1000 profiles day-1. We present the results of a validation study of methane version V5R_CH4_222 retrieved with the IMK/IAA MIPAS scientific level 2 processor. The level 1 spectra are provided by ESA, the version 5 was used. The time period covered corresponds to the period when MIPAS measured at reduced spectral resolution, i.e. 2005-2012. The comparison with satellite instruments includes the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS), the HALogen Occultation Experiment (HALOE), the Solar Occultation For Ice Experiment (SOFIE) and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). Furthermore, comparisons with MkIV balloon-borne solar occultation measurements and with air sampling measurements performed by the University of Frankfurt are presented. The validation activities include bias determination, in selected cases, assessment of histograms and comparison of corresponding climatologies. Above 50 km altitude, MIPAS methane mixing ratios agree within 3% with ACE-FTS and SOFIE. Between 30 and 40 km an agreement within 3% with SCIAMACHY has been found. In the middle stratosphere, there is no clear indication of a MIPAS bias since comparisons with various instruments contradict each other. In the lower stratosphere (below about 25-30 km) MIPAS CH4 is biased high with respect to satellite instruments, and the most likely estimate of this bias is 14%. However, in the comparison with CH4 data obtained from cryosampler measurements, there is no evidence of a MIPAS high bias between 20 and 25 km altitude. Precision validation is performed on collocated MIPAS-MIPAS pairs

  3. Validation of MIPAS IMK/IAA methane profiles

    NASA Astrophysics Data System (ADS)

    Laeng, A.; Plieninger, J.; von Clarmann, T.; Grabowski, U.; Stiller, G.; Eckert, E.; Glatthor, N.; Haenel, F.; Kellmann, S.; Kiefer, M.; Linden, A.; Lossow, S.; Deaver, L.; Engel, A.; Hervig, M.; Levin, I.; McHugh, M.; Noël, S.; Toon, G.; Walker, K.

    2015-12-01

    The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is an infrared (IR) limb emission spectrometer on the Envisat platform. It measures trace gas distributions during day and night, pole-to-pole, over an altitude range from 6 to 70 km in nominal mode and up to 170 km in special modes, depending on the measurement mode, producing more than 1000 profiles day-1. We present the results of a validation study of methane, version V5R_CH4_222, retrieved with the IMK/IAA (Institut für Meteorologie und Klimaforschung, Karlsruhe/Instituto de Astrofisica de Andalucia, Grenada) MIPAS scientific level 2 processor. The level 1 spectra are provided by the ESA (European Space Agency) and version 5 was used. The time period covered is 2005-2012, which corresponds to the period when MIPAS measured trace gas distributions at a reduced spectral resolution of 0.0625 cm-1. The comparison with satellite instruments includes the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS), the HALogen Occultation Experiment (HALOE), the Solar Occultation For Ice Experiment (SOFIE) and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). Furthermore, comparisons with MkIV balloon-borne solar occultation measurements and with air sampling measurements performed by the University of Frankfurt are presented. The validation activities include bias determination, assessment of stability, precision validation, analysis of histograms and comparison of corresponding climatologies. Above 50 km altitude, MIPAS methane mixing ratios agree within 3 % with ACE-FTS and SOFIE. Between 30 and 40 km an agreement within 3 % with SCIAMACHY has been found. In the middle stratosphere, there is no clear indication of a MIPAS bias since comparisons with various instruments contradict each other. In the lower stratosphere (below 25 km) MIPAS CH4 is biased high with respect to satellite instruments, and the most likely estimate of this bias is 14

  4. Synthesis and characterization of ( sup 3 H)-5 prime azido-N-1-naphthylphthlamic acid, a photolabile N-1-naphthylphthalamic acid analog

    SciTech Connect

    Voet, J.G.; Dodge, B.; Harris, K.; Jacobs, M.; Larkin, L.; Bader, S.; Schnitzler, G.; Sutherland, J. )

    1990-05-01

    The NPA (N-1-naphthylphthalamic acid) receptor is an important protein involved in the regulation of transport of indole-3-acetic acid (IAA). In our attempt to isolate and characterize this protein we have previously synthesized and characterized a photolabile analog of NPA, 5{prime}-azido-NPA (Az-NPA) and shown it to be a competitor of NPA for binding sites on the NPA receptor as well as an inhibitor of auxin transport. We have now synthesized and characterized ({sup 3}H)-Az-NPA. The precursor, 2,3,4,5-Br-5{prime}-amino-NPA was dehydrohalogenated with tritium gas by Research Products International. The amino group was converted to an azido group and the product purified by HPLC. ({sup 3}H)-Az-NPA was found to be photolabile and to co-chromatograph with our synthetic unlabeled Az-NPA. Furthermore, the tritiated material was found to bind to zucchini hypocotyl cell membranes in a manner competitive with NPA as well as unlabeled Az-NPA. Photolysis of zucchini phase-partitioned plasma membranes in the presence of ({sup 3}H)-Az-NPA resulted in covalent association of tritium with the membranes. Much of this covalent association could be prevented by prior treatment of the membranes with excess NPA.

  5. Deletion of MP/ARF5 domains III and IV reveals a requirement for Aux/IAA regulation in Arabidopsis leaf vascular patterning.

    PubMed

    Krogan, Naden T; Ckurshumova, Wenzislava; Marcos, Danielle; Caragea, Adriana E; Berleth, Thomas

    2012-04-01

    Combinatorial interactions of AUXIN RESPONSE FACTORs (ARFs) and auxin/indole acetic acid (Aux/IAA) proteins through their common domains III and IV regulate auxin responses, but insight into the functions of individual proteins is still limited. As a new tool to explore this regulatory network, we generated a gain-of-function ARF genotype by eliminating domains III and IV from the functionally well-characterized ARF MONOPTEROS(MP)/ARF5. This truncated version of MP, termed MPΔ, conferred complementing MP activity, but also displayed a number of semi-dominant traits affecting auxin signaling and organ patterning. In MPΔ, the expression levels of many auxin-inducible genes, as well as rooting properties and vascular tissue abundance, were enhanced. Lateral organs were narrow, pointed and filled with parallel veins. This effect was epistatic over the vascular hypotrophy imposed by certain Aux/IAA mutations. Further, in MPΔ leaves, failure to turn off the procambium-selecting gene PIN1 led to the early establishment of oversized central procambial domains and very limited subsequent lateral growth of the leaf lamina. We conclude that MPΔ can selectively uncouple a single ARF from regulation by Aux/IAA proteins and can be used as a genetic tool to probe auxin pathways and explore leaf development. PMID:22320407

  6. Origin and basipetal transport of the IAA responsible for rooting of carnation cuttings.

    PubMed

    Garrido, Germán; Ramón Guerrero, Juan; Angel Cano, Emilio; Acosta, Manuel; Sánchez-Bravo, José

    2002-02-01

    The origin and transport of the IAA responsible for rooting was studied in carnation (Dianthus caryophyllus L.) cuttings obtained from secondary shoots of the mother plants. The presence of mature leaves in the cuttings was essential for rooting. Removal of the apex and/or the youngest leaves did not reduce the rooting percentage as long as mature leaves remained attached. Removal of mature leaves inhibited rooting for a 24-day period during which the basal leaves grew and reached maturity. After this period rooting progressed as in intact cuttings. Auxin (NAA + IBA) applied to the stem base of defoliated cuttings was about 60% as effective as mature leaves in stimulating rooting. Application of NPA to the basal internode resulted in full inhibition of rooting. The view, deduced from these results, that auxin from mature leaves is the main factor controlling the rooting process was reinforced by the fact that mature leaves contained IAA and exported labelled IAA to the stem. The distribution of radioactivity after application of (5-3H)-IAA to mature leaves showed that auxin movement in the stem was basipetal and sensitive to NPA inhibition. The features of this transport were studied by applying 3H-IAA to the apical cut surface of stem sections excised from cuttings. The intensity of the transport was lower in the oldest node than in the basal internode, probably due to the presence of vascular traces of leaves. Irrespective of the localization of the sections and the carnation cultivar used, basipetal IAA transport was severely reduced when the temperature was lowered from 25 to 4 degrees C. The polar nature of the IAA transport in the sections was confirmed by the inhibition produced by NPA. Local application of IAA to different tissues of the sections revealed that polar auxin transport was associated with the vascular cylinder, the transport in the pith and cortex being low and apolar. The present results strongly support the conclusion that IAA originating

  7. Synthesis, crystal structure and biological activity of 2-hydroxyethylammonium salt of p-aminobenzoic acid.

    PubMed

    Crisan, Manuela E; Bourosh, Paulina; Maffei, Massimo E; Forni, Alessandra; Pieraccini, Stefano; Sironi, Maurizio; Chumakov, Yurii M

    2014-01-01

    p-Aminobenzoic acid (pABA) plays important roles in a wide variety of metabolic processes. Herein we report the synthesis, theoretical calculations, crystallographic investigation, and in vitro determination of the biological activity and phytotoxicity of the pABA salt, 2-hydroxyethylammonium p-aminobenzoate (HEA-pABA). The ability of neutral and anionic forms of pABA to interact with TIR1 pocket was investigated by calculation of molecular electrostatic potential maps on the accessible surface area, docking experiments, Molecular Dynamics and Quantum Mechanics/Molecular Mechanics calculations. The docking study of the folate precursor pABA, its anionic form and natural auxin (indole-3-acetic acid, IAA) with the auxin receptor TIR1 revealed a similar binding mode in the active site. The phytotoxic evaluation of HEA-pABA, pABA and 2-hydroxyethylamine (HEA) was performed on the model plant Arabidopsis thaliana ecotype Col 0 at five different concentrations. HEA-pABA and pABA acted as potential auxin-like regulators of root development in Arabidopsis thaliana (0.1 and 0.2 mM) and displayed an agravitropic root response at high concentration (2 mM). This study suggests that HEA-pABA and pABA might be considered as potential new regulators of plant growth. PMID:25054237

  8. Synthesis, Crystal Structure and Biological Activity of 2-Hydroxyethylammonium Salt of p-Aminobenzoic Acid

    PubMed Central

    Crisan, Manuela E.; Bourosh, Paulina; Maffei, Massimo E.; Forni, Alessandra; Pieraccini, Stefano; Sironi, Maurizio; Chumakov, Yurii M.

    2014-01-01

    p-Aminobenzoic acid (pABA) plays important roles in a wide variety of metabolic processes. Herein we report the synthesis, theoretical calculations, crystallographic investigation, and in vitro determination of the biological activity and phytotoxicity of the pABA salt, 2-hydroxyethylammonium p-aminobenzoate (HEA-pABA). The ability of neutral and anionic forms of pABA to interact with TIR1 pocket was investigated by calculation of molecular electrostatic potential maps on the accessible surface area, docking experiments, Molecular Dynamics and Quantum Mechanics/Molecular Mechanics calculations. The docking study of the folate precursor pABA, its anionic form and natural auxin (indole-3-acetic acid, IAA) with the auxin receptor TIR1 revealed a similar binding mode in the active site. The phytotoxic evaluation of HEA-pABA, pABA and 2-hydroxyethylamine (HEA) was performed on the model plant Arabidopsis thaliana ecotype Col 0 at five different concentrations. HEA-pABA and pABA acted as potential auxin-like regulators of root development in Arabidopsis thaliana (0.1 and 0.2 mM) and displayed an agravitropic root response at high concentration (2 mM). This study suggests that HEA-pABA and pABA might be considered as potential new regulators of plant growth. PMID:25054237

  9. Superiority of radiobinding assay over ELISA for detection of IAAs in newly diagnosed type I diabetic children

    SciTech Connect

    Levy-Marchal, C.; Bridel, M.P.; Sodoyez-Goffaux, F.; Koch, M.; Tichet, J.; Czernichow, P.; Sodoyez, J.C. )

    1991-01-01

    Liquid- or solid-phase assays have been used for insulin autoantibody (IAA) determination, and the method of IAA measurement has not been standardized. IAAs were determined by radiobinding assay (RBA) and enzyme-linked immunosorbent assay (ELISA) in two large age-matched groups of nondiabetic and newly diagnosed insulin-dependent (type I) diabetic children. Positivity for IAA by RBA (greater than or equal to nondiabetic mean + 3SD) was 2 of 178 (1.1%) and 55 of 173 (32%) in nondiabetic and diabetic children, respectively. Prevalence of IAA by RBA was significantly higher in the youngest age-group (63% between 0-4 yr). Positivity for IAA by ELISA was 1 of 178 (0.6%) and 8 of 169 (4.7%) in nondiabetic and diabetic children, respectively. Concordance rates between both assays were 0 of 3 (0%) in control subjects and 5 of 58 (8.6%) in diabetic children. We conclude that RBA is more appropriate than ELISA for IAA detection at the onset of the disease. In addition, because available data suggest that IAAs detected by RBA only are high-affinity antibodies, it is tempting to speculate that IAAs reflect a mature immune reaction against endogenous insulin.

  10. Localization of IAA transporting tissue by tissue printing and autoradiography. [Coleus; maize

    SciTech Connect

    Mee-Rye Cha; Evans, M.L.; Hangarter, R.P. )

    1991-05-01

    Tissue printing on nitrocellulose membranes provides a useful technique for visualizing anatomical details of tissue morphology of cut ends of stem segments. Basal ends of Coleus stem and corn coleoptile segments that were transporting {sup 14}C-IAA were gently blotted onto DEAE-nitrocellulose for several minutes to allow {sup 14}C-IAA to efflux from the tissue. Because of the anion exchange properties of DEAE-nitrocellulose the {sup 14}C-IAA remains on the membrane at the point it leaves the transporting tissue. Autoradiography of the DEAE membrane allowed indirect visualization of the tissues preferentially involved in auxin transport. The authors observed that polar transport through the stem segments occurred primarily through or in association with vascular tissues. However, in Coleus stems, substantial amounts of the label appeared to move through the tissue by diffusion as well as by active transport.

  11. Pseudomonas savastanoi pv. savastanoi Contains Two iaaL Paralogs, One of Which Exhibits a Variable Number of a Trinucleotide (TAC) Tandem Repeat▿ †

    PubMed Central

    Matas, Isabel M.; Pérez-Martínez, Isabel; Quesada, José M.; Rodríguez-Herva, José J.; Penyalver, Ramón; Ramos, Cayo

    2009-01-01

    In this study, Pseudomonas savastanoi pv. savastanoi isolates were demonstrated to contain two iaaL paralogs, which are both chromosomally located in most strains. Comparative analysis of iaaL nucleotide sequences amplified from these two paralogs revealed that one paralog, iaaLPsn, is 100% identical to iaaL from P. savastanoi pv. nerii, while the other paralog, iaaLPsv, exhibited 93% identity to iaaL from Pseudomonas syringae pv. tomato (iaaLPto). A 3-nucleotide motif (TAC) comprised of 3 to 15 repeats, which remained stable after propagation of the strains in olive plants, was found in iaaLPsv. Based on the observed nucleotide sequence variations, a restriction fragment length polymorphism assay was developed that allowed differentiation among iaaLPsn, iaaLPsv, and iaaLPto. In addition, reverse transcriptase PCR on total RNA from P. savastanoi pv. savastanoi strains demonstrated that both iaaLPsv and iaaLPsn containing 14 or fewer TAC repeats are transcribed. Capillary electrophoresis analysis of PCR-amplified DNA fragments containing the TAC repeats from iaaLPsv allowed the differentiation of P. savastanoi pv. savastanoi isolates. PMID:19098222

  12. Auxin Chemical and Molecular Biology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Auxins function as key regulators at the intersection between developmental and environmental events and the response pathways that they trigger. Naturally occurring members of this hormone group include indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), and 4-chloro-indole-3-acetic acid (4-Cl...

  13. Aboveground Whitefly Infestation Modulates Transcriptional Levels of Anthocyanin Biosynthesis and Jasmonic Acid Signaling-Related Genes and Augments the Cope with Drought Stress of Maize

    PubMed Central

    Park, Yong-Soon; Bae, Dong-Won; Ryu, Choong-Min

    2015-01-01

    Up to now, the potential underlying molecular mechanisms by which maize (Zea mays L.) plants elicit defense responses by infestation with a phloem feeding insect whitefly [Bemisia tabaci (Genn.)] have been barely elucidated against (a)biotic stresses. To fill this gap of current knowledge maize plants were infested with whitefly and these plants were subsequently assessed the levels of water loss. To understand the mode of action, plant hormone contents and the stress-related mRNA expression were evaluated. Whitefly-infested maize plants did not display any significant phenotypic differences in above-ground tissues (infested site) compared with controls. By contrast, root (systemic tissue) biomass was increased by 2-fold by whitefly infestation. The levels of endogenous indole-3-acetic acid (IAA), jasmonic acid (JA), and hydrogen peroxide (H2O2) were significantly higher in whitefly-infested plants. The biosynthetic or signaling-related genes for JA and anthocyanins were highly up-regulated. Additionally, we found that healthier plants were obtained in whitefly-infested plants under drought conditions. The weight of whitefly-infested plants was approximately 20% higher than that of control plants at 14 d of drought treatment. The drought tolerance-related genes, ZmbZIP72, ZmSNAC1, and ZmABA1, were highly expressed in the whitefly-infected plants. Collectively, our results suggest that IAA/JA-derived maize physiological changes and correlation of H2O2 production and water loss are modulated by above-ground whitefly infestation in maize plants. PMID:26630288

  14. Oxidative Stress Induced by Pt(IV) Pro-drugs Based on the Cisplatin Scaffold and Indole Carboxylic Acids in Axial Position

    PubMed Central

    Tolan, Dina; Gandin, Valentina; Morrison, Liam; El-Nahas, Ahmed; Marzano, Cristina; Montagner, Diego; Erxleben, Andrea

    2016-01-01

    The use of Pt(IV) complexes as pro-drugs that are activated by intracellular reduction is a widely investigated approach to overcome the limitations of Pt(II) anticancer agents. A series of ten mono- and bis-carboxylated Pt(IV) complexes with axial indole-3-acetic acid (IAA) and indole-3-propionic acid (IPA) ligands were synthesized and characterized by elemental analysis, ESI-MS, FT-IR, 1H and 195Pt NMR spectroscopy. Cellular uptake, DNA platination and cytotoxicity against a panel of human tumor cell lines were evaluated. All the complexes are able to overcome cisplatin-resistance and the most potent complex, cis,cis,trans-[Pt(NH3)2Cl2(IPA)(OH)] was on average three times more active than cisplatin. Mechanistic studies revealed that the trend in cytotoxicity of the Pt(IV) complexes is primarily consistent with their ability to accumulate into cancer cells and to increase intracellular basal reactive oxygen species levels, which in turn results in the loss of mitochondrial membrane potential and apoptosis induction. The role of the indole acid ligand as a redox modulator is discussed. PMID:27404565

  15. Oxidative Stress Induced by Pt(IV) Pro-drugs Based on the Cisplatin Scaffold and Indole Carboxylic Acids in Axial Position.

    PubMed

    Tolan, Dina; Gandin, Valentina; Morrison, Liam; El-Nahas, Ahmed; Marzano, Cristina; Montagner, Diego; Erxleben, Andrea

    2016-01-01

    The use of Pt(IV) complexes as pro-drugs that are activated by intracellular reduction is a widely investigated approach to overcome the limitations of Pt(II) anticancer agents. A series of ten mono- and bis-carboxylated Pt(IV) complexes with axial indole-3-acetic acid (IAA) and indole-3-propionic acid (IPA) ligands were synthesized and characterized by elemental analysis, ESI-MS, FT-IR, (1)H and (195)Pt NMR spectroscopy. Cellular uptake, DNA platination and cytotoxicity against a panel of human tumor cell lines were evaluated. All the complexes are able to overcome cisplatin-resistance and the most potent complex, cis,cis,trans-[Pt(NH3)2Cl2(IPA)(OH)] was on average three times more active than cisplatin. Mechanistic studies revealed that the trend in cytotoxicity of the Pt(IV) complexes is primarily consistent with their ability to accumulate into cancer cells and to increase intracellular basal reactive oxygen species levels, which in turn results in the loss of mitochondrial membrane potential and apoptosis induction. The role of the indole acid ligand as a redox modulator is discussed. PMID:27404565

  16. Oxidative Stress Induced by Pt(IV) Pro-drugs Based on the Cisplatin Scaffold and Indole Carboxylic Acids in Axial Position

    NASA Astrophysics Data System (ADS)

    Tolan, Dina; Gandin, Valentina; Morrison, Liam; El-Nahas, Ahmed; Marzano, Cristina; Montagner, Diego; Erxleben, Andrea

    2016-07-01

    The use of Pt(IV) complexes as pro-drugs that are activated by intracellular reduction is a widely investigated approach to overcome the limitations of Pt(II) anticancer agents. A series of ten mono- and bis-carboxylated Pt(IV) complexes with axial indole-3-acetic acid (IAA) and indole-3-propionic acid (IPA) ligands were synthesized and characterized by elemental analysis, ESI-MS, FT-IR, 1H and 195Pt NMR spectroscopy. Cellular uptake, DNA platination and cytotoxicity against a panel of human tumor cell lines were evaluated. All the complexes are able to overcome cisplatin-resistance and the most potent complex, cis,cis,trans-[Pt(NH3)2Cl2(IPA)(OH)] was on average three times more active than cisplatin. Mechanistic studies revealed that the trend in cytotoxicity of the Pt(IV) complexes is primarily consistent with their ability to accumulate into cancer cells and to increase intracellular basal reactive oxygen species levels, which in turn results in the loss of mitochondrial membrane potential and apoptosis induction. The role of the indole acid ligand as a redox modulator is discussed.

  17. Hydrogen bonding in phytohormone-auxin (IAA) and its derivatives

    NASA Astrophysics Data System (ADS)

    Kojić-Prodić, Biserka; Kroon, Jan; Puntarec, Vitomir

    1994-06-01

    The significant importance of hydrogen bonds in biological structures and enzymatic reactions has been demonstrated in many examples. As a part of the molecular recognition study of auxins (plant growth hormones) the influence of hydrogen bonding on molecular conformation, particularly of the carboxyl group, which is one of the biologically active ligand sites, has been studied by X-ray diffraction and computational chemistry methods. The survey includes about 40 crystal structures of free auxins such as indol-3-ylacetic acid and its n-alkylated and halogenated derivatives but also bound auxins such as N-(indol-3-ylacetyl)- L-amino acids, and carbohydrate conjugates. The study includes hydrogen bonds of the NH⋯O and OH⋯O types. The classification of hydrogen bond patterns based on the discrimination between the centrosymmetric and non-centrosymmetric space groups and several examples of hydrogen bond systematics on graph set analysis are also shown.

  18. Status of the IAA study group on traffic management rules for space operations

    NASA Astrophysics Data System (ADS)

    Contant, Corinne; Lala, Petr; Schrogl, Kai-Uwe

    2007-10-01

    The investigation of space traffic and its management has only recently become a point of wider discussion. In particular, the series of workshops organized by the American Institute of Aeronautics and Astronautics (AIAA) and other international organizations on international cooperation highlighted the issue. It was discussed thoroughly at the workshops, which took place in 1999 and 2001, respectively. It was at the 2001 workshop, when the suggestion was made that an International Academy of Astronautics (IAA) Study on the subject of space traffic management should be prepared. This suggestion was taken up and a proposal was presented to the Board of Trustees of IAA, which, in late 2001, accepted this proposal. Following this, an interdisciplinary study group of around 20 persons was composed. One early milestone in the process of work was the conduct of an International Institute of Space Law (IISL)/European Center of Space Law (ECSL) Symposium alongside the 2002 session of the United Nations Committee on the Peaceful Uses of Outer Space (UNCOPUOS) Legal Subcommittee. This symposium consisted of presentations of members of the IAA study group. Also, close coordination with other study projects of IAA, in particular with the one on space debris, is sought. This paper presents the status of work of the study group, in particular, the approach and the scope of the study as well as its preliminary findings. The study group intends to finalize its work in early 2004, in order to be able to put the study before IAA and launch its review process before the 2004 International Astronautical Congress. Following this review, the study will be published and may be expected to make an impact in fora like the UNCOPUOS. The authors of this paper act as the coordinators/the rapporteur to this study. The paper will be presented in the IAA—as well as the IISL—session dealing with space traffic, by that bridging the two areas and seeking input from various sources.

  19. Abscisic acid and sucrose regulate tomato and strawberry fruit ripening through the abscisic acid-stress-ripening transcription factor.

    PubMed

    Jia, Haifeng; Jiu, Songtao; Zhang, Cheng; Wang, Chen; Tariq, Pervaiz; Liu, Zhongjie; Wang, Baoju; Cui, Liwen; Fang, Jinggui

    2016-10-01

    Although great progress has been made towards understanding the role of abscisic acid (ABA) and sucrose in fruit ripening, the mechanisms underlying the ABA and sucrose signalling pathways remain elusive. In this study, transcription factor ABA-stress-ripening (ASR), which is involved in the transduction of ABA and sucrose signalling pathways, was isolated and analysed in the nonclimacteric fruit, strawberry and the climacteric fruit, tomato. We have identified four ASR isoforms in tomato and one in strawberry. All ASR sequences contained the ABA stress- and ripening-induced proteins and water-deficit stress-induced proteins (ABA/WDS) domain and all ASR transcripts showed increased expression during fruit development. The expression of the ASR gene was influenced not only by sucrose and ABA, but also by jasmonic acid (JA) and indole-3-acetic acid (IAA), and these four factors were correlated with each other during fruit development. ASR bound the hexose transporter (HT) promoter, which contained a sugar box that activated downstream gene expression. Overexpression of the ASR gene promoted fruit softening and ripening, whereas RNA interference delayed fruit ripening, as well as affected fruit physiological changes. Change in ASR gene expression influenced the expression of several ripening-related genes such as CHS, CHI, F3H, DFR, ANS, UFGT, PG, PL, EXP1/2, XET16, Cel1/2 and PME. Taken together, this study may provide new evidence on the important role of ASR in cross-signalling between ABA and sucrose to regulate tomato and strawberry fruit ripening. The findings of this study also provide new insights into the regulatory mechanism underlying fruit development. PMID:27005823

  20. Abscisic acid and sucrose regulate tomato and strawberry fruit ripening through the abscisic acid-stress-ripening transcription factor.

    PubMed

    Jia, Haifeng; Jiu, Songtao; Zhang, Cheng; Wang, Chen; Tariq, Pervaiz; Liu, Zhongjie; Wang, Baoju; Cui, Liwen; Fang, Jinggui

    2016-10-01

    Although great progress has been made towards understanding the role of abscisic acid (ABA) and sucrose in fruit ripening, the mechanisms underlying the ABA and sucrose signalling pathways remain elusive. In this study, transcription factor ABA-stress-ripening (ASR), which is involved in the transduction of ABA and sucrose signalling pathways, was isolated and analysed in the nonclimacteric fruit, strawberry and the climacteric fruit, tomato. We have identified four ASR isoforms in tomato and one in strawberry. All ASR sequences contained the ABA stress- and ripening-induced proteins and water-deficit stress-induced proteins (ABA/WDS) domain and all ASR transcripts showed increased expression during fruit development. The expression of the ASR gene was influenced not only by sucrose and ABA, but also by jasmonic acid (JA) and indole-3-acetic acid (IAA), and these four factors were correlated with each other during fruit development. ASR bound the hexose transporter (HT) promoter, which contained a sugar box that activated downstream gene expression. Overexpression of the ASR gene promoted fruit softening and ripening, whereas RNA interference delayed fruit ripening, as well as affected fruit physiological changes. Change in ASR gene expression influenced the expression of several ripening-related genes such as CHS, CHI, F3H, DFR, ANS, UFGT, PG, PL, EXP1/2, XET16, Cel1/2 and PME. Taken together, this study may provide new evidence on the important role of ASR in cross-signalling between ABA and sucrose to regulate tomato and strawberry fruit ripening. The findings of this study also provide new insights into the regulatory mechanism underlying fruit development.

  1. Evidence That Chlorinated Auxin Is Restricted to the Fabaceae But Not to the Fabeae1[OPEN

    PubMed Central

    McAdam, Scott A.M.; McAdam, Erin L.

    2015-01-01

    Auxin is a pivotal plant hormone, usually occurring in the form of indole-3-acetic acid (IAA). However, in maturing pea (Pisum sativum) seeds, the level of the chlorinated auxin, 4-chloroindole-3-acetic acid (4-Cl-IAA), greatly exceeds that of IAA. A key issue is how plants produce halogenated compounds such as 4-Cl-IAA. To better understand this topic, we investigated the distribution of the chlorinated auxin. We show for the first time, to our knowledge, that 4-Cl-IAA is found in the seeds of Medicago truncatula, Melilotus indicus, and three species of Trifolium. Furthermore, we found no evidence that Pinus spp. synthesize 4-Cl-IAA in seeds, contrary to a previous report. The evidence indicates a single evolutionary origin of 4-Cl-IAA synthesis in the Fabaceae, which may provide an ideal model system to further investigate the action and activity of halogenating enzymes in plants. PMID:25971549

  2. Evidence That Chlorinated Auxin Is Restricted to the Fabaceae But Not to the Fabeae.

    PubMed

    Lam, Hong Kiat; McAdam, Scott A M; McAdam, Erin L; Ross, John J

    2015-07-01

    Auxin is a pivotal plant hormone, usually occurring in the form of indole-3-acetic acid (IAA). However, in maturing pea (Pisum sativum) seeds, the level of the chlorinated auxin, 4-chloroindole-3-acetic acid (4-Cl-IAA), greatly exceeds that of IAA. A key issue is how plants produce halogenated compounds such as 4-Cl-IAA. To better understand this topic, we investigated the distribution of the chlorinated auxin. We show for the first time, to our knowledge, that 4-Cl-IAA is found in the seeds of Medicago truncatula, Melilotus indicus, and three species of Trifolium. Furthermore, we found no evidence that Pinus spp. synthesize 4-Cl-IAA in seeds, contrary to a previous report. The evidence indicates a single evolutionary origin of 4-Cl-IAA synthesis in the Fabaceae, which may provide an ideal model system to further investigate the action and activity of halogenating enzymes in plants. PMID:25971549

  3. Evidence That Chlorinated Auxin Is Restricted to the Fabaceae But Not to the Fabeae.

    PubMed

    Lam, Hong Kiat; McAdam, Scott A M; McAdam, Erin L; Ross, John J

    2015-07-01

    Auxin is a pivotal plant hormone, usually occurring in the form of indole-3-acetic acid (IAA). However, in maturing pea (Pisum sativum) seeds, the level of the chlorinated auxin, 4-chloroindole-3-acetic acid (4-Cl-IAA), greatly exceeds that of IAA. A key issue is how plants produce halogenated compounds such as 4-Cl-IAA. To better understand this topic, we investigated the distribution of the chlorinated auxin. We show for the first time, to our knowledge, that 4-Cl-IAA is found in the seeds of Medicago truncatula, Melilotus indicus, and three species of Trifolium. Furthermore, we found no evidence that Pinus spp. synthesize 4-Cl-IAA in seeds, contrary to a previous report. The evidence indicates a single evolutionary origin of 4-Cl-IAA synthesis in the Fabaceae, which may provide an ideal model system to further investigate the action and activity of halogenating enzymes in plants.

  4. Identification and Analyses of AUX-IAA target genes controlling multiple pathways in developing fiber cells of Gossypium hirsutum L.

    PubMed

    Nigam, Deepti; Sawant, Samir V

    2013-01-01

    Technological development led to an increased interest in systems biological approaches in plants to characterize developmental mechanism and candidate genes relevant to specific tissue or cell morphology. AUX-IAA proteins are important plant-specific putative transcription factors. There are several reports on physiological response of this family in Arabidopsis but in cotton fiber the transcriptional network through which AUX-IAA regulated its target genes is still unknown. in-silico modelling of cotton fiber development specific gene expression data (108 microarrays and 22,737 genes) using Algorithm for the Reconstruction of Accurate Cellular Networks (ARACNe) reveals 3690 putative AUX-IAA target genes of which 139 genes were known to be AUX-IAA co-regulated within Arabidopsis. Further AUX-IAA targeted gene regulatory network (GRN) had substantial impact on the transcriptional dynamics of cotton fiber, as showed by, altered TF networks, and Gene Ontology (GO) biological processes and metabolic pathway associated with its target genes. Analysis of the AUX-IAA-correlated gene network reveals multiple functions for AUX-IAA target genes such as unidimensional cell growth, cellular nitrogen compound metabolic process, nucleosome organization, DNA-protein complex and process related to cell wall. These candidate networks/pathways have a variety of profound impacts on such cellular functions as stress response, cell proliferation, and cell differentiation. While these functions are fairly broad, their underlying TF networks may provide a global view of AUX-IAA regulated gene expression and a GRN that guides future studies in understanding role of AUX-IAA box protein and its targets regulating fiber development.

  5. Interactions of Phenolic Acids, Metallic Ions and Chelating Agents on Auxin-Induced Growth

    PubMed Central

    Tomaszewski, Miroslaw; Thimann, Kenneth V.

    1966-01-01

    By growth experiments in indoleacetic acid-1-14C (IAA), and determination of the 14CO2 evolved, it has been shown directly that polyphenols synergize IAA-induced growth by counteracting IAA decarboxylation. Sinapic and ferulic acids act like polyphenols. Endogenous polyphenols doubtless exert the same influence in intact plants. Monophenols stimulate the decarboxylation of IAA under conditions where they depress growth. When Mn++ is present as well, this effect is enhanced. All these growth effects are paralleled by effects on the isolated IAA oxidizing enzyme of Avena. EDTA acts like the polyphenols in depressing the decarboxylation of IAA, and not synergizing with the growth induced by naphthalene-acetic acid (NAA) and 2,4-D. However, since EDTA synergizes with IAA for growth even at optimal IAA concentrations, its growth promotion probably involves an additional effect. DIECA inhibits powerfully the destruction of IAA, but without causing much growth promotion, apparently because its decomposition products inhibit respiration. Mn++ aloné stimulates the decarboxylation of IAA, i.e. this ion promotes the IAA oxidase in vivo as it does in vitro. Nevertheless, it does not inhibit elongation, but at relatively high concentrations even stimulates it, both at low and high IAA levels. Since Mn++ also promotes the growth induced by NAA and 2,4-D, its growth action cannot rest primarily on modifying the metabolism of the auxins. Cobalt somewhat decreases the decarboxylation of IAA, but this cannot explain its growth promotion, since Co++, like Mn++, stimulates elongation even at optimal IAA concentrations, and acts with NAA just as well as with IAA. Ferrous ion, on the other hand, acts like the polyphenols. Floating pea stem sections exude enough organic matter to support bacteria which after 7 hours cause considerable decarboxylation of IAA. Avena coleoptile sections have a comparable though smaller effect after 12 hours. The present experiments, with those of others

  6. Genetics of Aux/IAA and ARF action in plant growth and development.

    PubMed

    Liscum, E; Reed, J W

    2002-01-01

    Dramatic advances in our understanding of auxin signal-response pathways have been made in recent years. Much of this new knowledge has come through the study of mutants in Arabidopsis thaliana. Mutations have been identified in a wide variety of auxin-response components, including auxin transporters, protein kinases and phosphatases, components of a ubiquitin-proteosome pathway, and transcriptional regulators. This review focuses on mutations that affect auxin-modulated transcription factors, in particular those in the Aux/IAA and AUXIN RESPONSE FACTOR (ARF) genes. Mutants in members of these related gene families exhibit phenotypes that indicate both unique localized functions, as well as overlapping redundant functions, throughout plant development - from embryogenesis to flowering. Effects of specific mutations on Aux/IAA and ARF protein functions at the biochemical and physiological levels will be discussed. We will also discuss potential mechanisms for interactions between auxin and light response pathways that are suggested by these mutants.

  7. Estimated quantitative amino acid requirements for Florida pompano reared in low-salinity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As with most marine carnivores, Florida pompano require relatively high crude protein diets to obtain optimal growth. Precision formulations to match the dietary indispensable amino acid (IAA) pattern to a species’ requirements can be used to lower the overall dietary protein. However IAA requirem...

  8. Production of Thermostable Organic Solvent Tolerant Keratinolytic Protease from Thermoactinomyces sp. RM4: IAA Production and Plant Growth Promotion.

    PubMed

    Verma, Amit; Singh, Hukum; Anwar, Mohammad S; Kumar, Shailendra; Ansari, Mohammad W; Agrawal, Sanjeev

    2016-01-01

    There are several reports about the optimization of protease production, but only few have optimized the production of organic solvent tolerant keratinolytic proteases that show remarkable exploitation in the development of the non-polluting processes in biotechnological industries. The present study was carried with aim to optimize the production of a thermostable organic solvent tolerant keratinolytic protease Thermoactinomyces sp. RM4 utilizing chicken feathers. Thermoactinomyces sp. RM4 isolated from the soil sample collected from a rice mill wasteyard site near Kashipur, Uttrakhand was identified on the basis of 16S rDNA analysis. The production of organic solvent tolerant keratinolytic protease enzyme by Thermoactinomyces sp. RM4 was optimized by varying physical culture conditions such as pH (10.0), temperature (60°C), inoculum percentage (2%), feather concentration (2%) and agitation rate (2 g) for feather degradation. The result showed that Thermoactinomyces sp. RM4 potentially produces extra-cellular thermostable organic solvent tolerant keratinolytic protease in the culture medium. Further, the feather hydrolysate from keratinase production media showed plant growth promoting activity by producing indole-3-acetic acid itself. The present findings suggest that keratinolytic protease from Thermoactinomyces sp. RM4 offers enormous industrial applications due to its organic solvent tolerant property in peptide synthesis, practical role in feather degradation and potential function in plant growth promoting activity, which might be a superior candidate to keep ecosystem healthy and functional. PMID:27555836

  9. Production of Thermostable Organic Solvent Tolerant Keratinolytic Protease from Thermoactinomyces sp. RM4: IAA Production and Plant Growth Promotion

    PubMed Central

    Verma, Amit; Singh, Hukum; Anwar, Mohammad S.; Kumar, Shailendra; Ansari, Mohammad W.; Agrawal, Sanjeev

    2016-01-01

    There are several reports about the optimization of protease production, but only few have optimized the production of organic solvent tolerant keratinolytic proteases that show remarkable exploitation in the development of the non-polluting processes in biotechnological industries. The present study was carried with aim to optimize the production of a thermostable organic solvent tolerant keratinolytic protease Thermoactinomyces sp. RM4 utilizing chicken feathers. Thermoactinomyces sp. RM4 isolated from the soil sample collected from a rice mill wasteyard site near Kashipur, Uttrakhand was identified on the basis of 16S rDNA analysis. The production of organic solvent tolerant keratinolytic protease enzyme by Thermoactinomyces sp. RM4 was optimized by varying physical culture conditions such as pH (10.0), temperature (60°C), inoculum percentage (2%), feather concentration (2%) and agitation rate (2 g) for feather degradation. The result showed that Thermoactinomyces sp. RM4 potentially produces extra-cellular thermostable organic solvent tolerant keratinolytic protease in the culture medium. Further, the feather hydrolysate from keratinase production media showed plant growth promoting activity by producing indole-3-acetic acid itself. The present findings suggest that keratinolytic protease from Thermoactinomyces sp. RM4 offers enormous industrial applications due to its organic solvent tolerant property in peptide synthesis, practical role in feather degradation and potential function in plant growth promoting activity, which might be a superior candidate to keep ecosystem healthy and functional. PMID:27555836

  10. Magnesium deficiency effects on IAA-1-/sup 14/C decarboxylation in Alaska and Little Marvel pea tissues

    SciTech Connect

    Henry, E.W.; Haduck, P.; Haduck, W.; Joyner, M.

    1987-04-01

    This investigation seeks to determine the effects of magnesium deficiency on light and dark exposed Alaska (normal) and Little Marvel (dwarf) pea tissue, with respect to IAA-1-/sup 14/C decarboxylation, in root, stem, and leaf tissues. There is both a higher rate of IAA-1-/sup 14/C decarboxylation and enhanced stem growth in Alaska, vs. Little Marvel pea tissue. The decarboxylation of IAA-1-/sup 14/C is highest in roots, slightly lower in leaves, followed by the proximal and distal designated stem tissues. With respect to light effects, the absence of light causes a decrease in IAA-1-/sup 14/C decarboxylation, the effect being most prominent in the leaves, with the least effect being exhibited in the root tissue. In summary, magnesium deficiency causes a decrease in IAA-1-/sup 14/C decarboxylation in both Alaska and Little Marvel pea tissues. It is suggested that the lack of available magnesium causes general physiological stress, with the plant attempting to redistribute any of the still available endogenous ion. The rate and pathway of IAA metabolism may vary significant between different types of cells in magnesium deficient tissues.

  11. TIR1/AFB-Aux/IAA auxin perception mediates rapid cell wall acidification and growth of Arabidopsis hypocotyls

    PubMed Central

    Fendrych, Matyáš; Leung, Jeffrey; Friml, Jiří

    2016-01-01

    Despite being composed of immobile cells, plants reorient along directional stimuli. The hormone auxin is redistributed in stimulated organs leading to differential growth and bending. Auxin application triggers rapid cell wall acidification and elongation of aerial organs of plants, but the molecular players mediating these effects are still controversial. Here we use genetically-encoded pH and auxin signaling sensors, pharmacological and genetic manipulations available for Arabidopsis etiolated hypocotyls to clarify how auxin is perceived and the downstream growth executed. We show that auxin-induced acidification occurs by local activation of H+-ATPases, which in the context of gravity response is restricted to the lower organ side. This auxin-stimulated acidification and growth require TIR1/AFB-Aux/IAA nuclear auxin perception. In addition, auxin-induced gene transcription and specifically SAUR proteins are crucial downstream mediators of this growth. Our study provides strong experimental support for the acid growth theory and clarified the contribution of the upstream auxin perception mechanisms. DOI: http://dx.doi.org/10.7554/eLife.19048.001 PMID:27627746

  12. Final Report

    SciTech Connect

    Normanly, J.

    1999-11-29

    The primary goal was the characterization of tryptophan (Trp)-independent biosynthesis of the auxin indole-3-acetic acid (IAA). Our work and that of others indicates that indole is a precursor to IAA in a Trp-independent pathway and the objectives of this grant have been the isolation of indole-metabolizing genes from Arabidopsis.

  13. 2,4-D and IAA Amino Acid Conjugates Show Distinct Metabolism in Arabidopsis

    PubMed Central

    Eyer, Luděk; Vain, Thomas; Pařízková, Barbora; Oklestkova, Jana; Barbez, Elke; Kozubíková, Hana; Pospíšil, Tomáš; Wierzbicka, Roksana; Kleine-Vehn, Jürgen; Fránek, Milan; Strnad, Miroslav; Robert, Stéphanie

    2016-01-01

    The herbicide 2,4-D exhibits an auxinic activity and therefore can be used as a synthetic and traceable analog to study auxin-related responses. Here we identified that not only exogenous 2,4-D but also its amide-linked metabolite 2,4-D-Glu displayed an inhibitory effect on plant growth via the TIR1/AFB auxin-mediated signaling pathway. To further investigate 2,4-D metabolite conversion, identity and activity, we have developed a novel purification procedure based on the combination of ion exchange and immuno-specific sorbents combined with a sensitive liquid chromatography-mass spectrometry method. In 2,4-D treated samples, 2,4-D-Glu and 2,4-D-Asp were detected at 100-fold lower concentrations compared to 2,4-D levels, showing that 2,4-D can be metabolized in the plant. Moreover, 2,4-D-Asp and 2,4-D-Glu were identified as reversible forms of 2,4-D homeostasis that can be converted to free 2,4-D. This work paves the way to new studies of auxin action in plant development. PMID:27434212

  14. 2,4-D and IAA Amino Acid Conjugates Show Distinct Metabolism in Arabidopsis.

    PubMed

    Eyer, Luděk; Vain, Thomas; Pařízková, Barbora; Oklestkova, Jana; Barbez, Elke; Kozubíková, Hana; Pospíšil, Tomáš; Wierzbicka, Roksana; Kleine-Vehn, Jürgen; Fránek, Milan; Strnad, Miroslav; Robert, Stéphanie; Novak, Ondrej

    2016-01-01

    The herbicide 2,4-D exhibits an auxinic activity and therefore can be used as a synthetic and traceable analog to study auxin-related responses. Here we identified that not only exogenous 2,4-D but also its amide-linked metabolite 2,4-D-Glu displayed an inhibitory effect on plant growth via the TIR1/AFB auxin-mediated signaling pathway. To further investigate 2,4-D metabolite conversion, identity and activity, we have developed a novel purification procedure based on the combination of ion exchange and immuno-specific sorbents combined with a sensitive liquid chromatography-mass spectrometry method. In 2,4-D treated samples, 2,4-D-Glu and 2,4-D-Asp were detected at 100-fold lower concentrations compared to 2,4-D levels, showing that 2,4-D can be metabolized in the plant. Moreover, 2,4-D-Asp and 2,4-D-Glu were identified as reversible forms of 2,4-D homeostasis that can be converted to free 2,4-D. This work paves the way to new studies of auxin action in plant development. PMID:27434212

  15. The ARF, AUX/IAA and GH3 gene families in citrus: genome-wide identification and expression analysis during fruitlet drop from abscission zone A.

    PubMed

    Xie, Rangjin; Pang, Shaoping; Ma, Yanyan; Deng, Lie; He, Shaolan; Yi, Shilai; Lv, Qiang; Zheng, Yongqiang

    2015-12-01

    Completion of the whole genome sequencing of citrus enabled us to perform genome-wide identification and functional analysis of the gene families involved in agronomic traits and morphological diversity of citrus. In this study, 22 CitARF, 11 CitGH3 and 26 CitAUX/IAA genes were identified in citrus, respectively. Phylogenetic analysis revealed that all the genes of each gene family could be subdivided into three groups and showed strong evolutionary conservation. The GH3 and AUX/IAA gene families shrank and ARF gene family was highly conserved in the citrus genome after speciation from Arabidopsis thaliana. Tissue-specific expression profiles revealed that 54 genes were expressed in at least one tissue while just 5 genes including CitARF07, CitARF20, CitGH3.04, CitAUX/IAA25 and CitAUX/IAA26 with very low expression level in all tissues tested, suggesting that the CitARF, CitGH3 and CitAUX/IAA gene families played important roles in the development of citrus organs. In addition, our data found that the expression of 2 CitARF, 4 CitGH3 and 4 AUX/IAA genes was affected by IAA treatment, and 7 genes including, CitGH3.04, CitGH3.07, CitAUX/IAA03, CitAUX/IAA04, CitAUX/IAA18, CitAUX/IAA19 and CitAUX/IAA23 were related to fruitlet abscission. This study provides a foundation for future studies on elucidating the precise role of citrus ARF, GH3 and AUX/IAA genes in early steps of auxin signal transduction and open up a new opportunity to uncover the molecular mechanism underlying citrus fruitlet abscission.

  16. The ARF, AUX/IAA and GH3 gene families in citrus: genome-wide identification and expression analysis during fruitlet drop from abscission zone A.

    PubMed

    Xie, Rangjin; Pang, Shaoping; Ma, Yanyan; Deng, Lie; He, Shaolan; Yi, Shilai; Lv, Qiang; Zheng, Yongqiang

    2015-12-01

    Completion of the whole genome sequencing of citrus enabled us to perform genome-wide identification and functional analysis of the gene families involved in agronomic traits and morphological diversity of citrus. In this study, 22 CitARF, 11 CitGH3 and 26 CitAUX/IAA genes were identified in citrus, respectively. Phylogenetic analysis revealed that all the genes of each gene family could be subdivided into three groups and showed strong evolutionary conservation. The GH3 and AUX/IAA gene families shrank and ARF gene family was highly conserved in the citrus genome after speciation from Arabidopsis thaliana. Tissue-specific expression profiles revealed that 54 genes were expressed in at least one tissue while just 5 genes including CitARF07, CitARF20, CitGH3.04, CitAUX/IAA25 and CitAUX/IAA26 with very low expression level in all tissues tested, suggesting that the CitARF, CitGH3 and CitAUX/IAA gene families played important roles in the development of citrus organs. In addition, our data found that the expression of 2 CitARF, 4 CitGH3 and 4 AUX/IAA genes was affected by IAA treatment, and 7 genes including, CitGH3.04, CitGH3.07, CitAUX/IAA03, CitAUX/IAA04, CitAUX/IAA18, CitAUX/IAA19 and CitAUX/IAA23 were related to fruitlet abscission. This study provides a foundation for future studies on elucidating the precise role of citrus ARF, GH3 and AUX/IAA genes in early steps of auxin signal transduction and open up a new opportunity to uncover the molecular mechanism underlying citrus fruitlet abscission. PMID:25982744

  17. Biosynthesis of Indoleacetic Acid from Tryptophan-14C in Cell-free Extracts of Pea Shoot Tips 1

    PubMed Central

    Moore, Thomas C.; Shaner, Coralie A.

    1967-01-01

    A 2-step, 1-dimensional thin-layer chromatographic procedure for isolating indoleacetic acid (IAA) was developed and utilized in investigations of the biosynthesis of IAA from tryptophan-14C in cell-free extracts of pea (Pisum sativum L.) shoot tips. Identification of a 14C-product as IAA was by (a) co-chromatography of authentic IAA and 14C-product on thin-layer chromatography, and (b) gas-liquid and thin-layer chromatography of authentic and presumptive IAA methyl esters. Dialysis of enzyme extracts and addition of α-ketoglutaric acid and pyridoxal phosphate to reaction mixtures resulted in approximately 2- to 3-fold increases in net yields of IAA over yields in non-dialyzed reaction mixtures which did not contain additives essential to a transaminase reaction of tryptophan. Addition of thiamine pyrophosphate to reaction mixtures further enhanced net biosynthesis of IAA. It is concluded that the formation of indolepyruvic acid and its subsequent decarboxylation probably are sequential reactions in the major pathway of IAA biosynthesis from tryptophan in cell-free extracts of Pisum shoot tips. Comparison of maximum net IAA biosynthesis in extracts of shoot tips of etiolated and light-grown dwarf and tall pea seedlings revealed an order, on a unit protein N basis, of: light-grown tall > light-grown dwarf > etiolated tall ≅ etiolated dwarf. It is concluded that the different rates of stem elongation among etiolated and light-grown dwarf and tall pea seedlings are correlated, in general, with differences in net IAA biosynthesis and sensitivity of the tissues to IAA. PMID:16656720

  18. Conserved and unique features of the homeologous maize Aux/IAA proteins ROOTLESS WITH UNDETECTABLE MERISTEM 1 and RUM1-like 1

    PubMed Central

    Zhang, Yanxiang; Marcon, Caroline; Tai, Huanhuan; von Behrens, Inga; Ludwig, Yvonne; Hey, Stefan; Berendzen, Kenneth W.; Hochholdinger, Frank

    2016-01-01

    The maize (Zea mays L.) Aux/IAA protein RUM1 (ROOTLESS WITH UNDETECTABLE MERISTEM 1) is a key regulator of lateral and seminal root formation. An ancient maize genome duplication resulted in the emergence of its homeolog rum1-like1 (rul1), which displays 92% amino acid sequence identity with RUM1. Both, RUL1 and RUM1 exhibit the canonical four domain structure of Aux/IAA proteins. Moreover, both are localized to the nucleus, are instable and have similar short half-lives of ~23min. Moreover, RUL1 and RUM1 can be stabilized by specific mutations in the five amino acid degron sequence of domain II. In addition, proteins encoded by both genes interact in vivo with auxin response factors (ARFs) such as ZmARF25 and ZmARF34 in protoplasts. Although it was demonstrated that RUL1 and RUM1 can homo and heterodimerize in vivo, rul1 expression is independent of rum1. Moreover, on average rul1 expression is ~84-fold higher than rum1 in the 12 tested tissues and developmental stages, although the relative expression levels in different root tissues are very similar. While RUM1 and RUL1 display conserved biochemical properties, yeast-two-hybrid in combination with BiFC experiments identified a RUM1-associated protein 1 (RAP1) that specifically interacts with RUM1 but not with RUL1. This suggests that RUM1 and RUL1 are at least in part interwoven into different molecular networks. PMID:26672614

  19. The DefH9-iaaM-containing construct efficiently induces parthenocarpy in cucumber.

    PubMed

    Yin, Zhimin; Malinowski, Robert; Ziółkowska, Agnieszka; Sommer, Hans; Plcader, Wojciech; Malepszy, Stefan

    2006-01-01

    Parthenocarpy (seedless fruits) is a desirable trait that has been achieved in many plant cultivars. We generated parthenocarpic cucumber fruits by introducing the chimeric DefH9-iaaM construct into the cucumber genome using an Agrobacterium tumefaciens-mediated protocol. The construct consists of the DefH9 promoter from Antirrhinum majus and the iaaM coding sequence from Pseudomonas syringae. Transgenic plants were obtained from nine independent transformation events: half of these were tetraploid and did not produce seeds following self-pollination, while the remaining half were capable of displaying parthenocarpy in the subsequent reproductive generation. Of the fruits produced by the transgenic lines, 70-90% were parthenocarpic. The segregation of the marker gene in the transgenic T(1) progeny indicated single gene inheritance. The seed set in the transgenic lines and their F(1) hybrids was lower than in the non-transgenic control plants. Some of the methodological details and the practical significance of the results are discussed. PMID:16847572

  20. Down-regulation of SlIAA15 in tomato altered stem xylem development and production of volatile compounds in leaf exudates.

    PubMed

    Deng, Wei; Yan, Fang; Liu, Minchun; Wang, Xinyu; Li, Zhengguo

    2012-08-01

    The Aux/IAA family genes encode short-lived nuclear proteins that function as transcriptional regulators in auxin signal transduction. Aux/IAA genes have been reported to control many processes of plant development. Our recent study showed that down-regulation of SlIAA15 in tomato reduced apical dominance, altered pattern of axillary shoot development, increased lateral root formation and leaves thickness. The SlIAA15 suppressed lines display strong reduction of trichome density, suggesting that SlIAA15 is involved in trichome formation. Here, we reported that SlIAA15-suppressed transgenic lines display increased number of xylem cells compared to wild-type plants. Moreover, the monoterpene content in trichome exudates are significantly reduced in SlIAA15 down-regulated leaves. The results provide the roles of SlIAA15 in production of volatile compounds in leaf exudates and xylem development, clearly indicating that members of the Aux/IAA gene family can play distinct and specific functions.  PMID:22836503

  1. A genetic screen for mutants defective in IAA1-LUC degradation in Arabidopsis thaliana reveals an important requirement for TOPOISOMERASE6B in auxin physiology

    PubMed Central

    Gilkerson, Jonathan; Callis, Judy

    2014-01-01

    Many plant growth and developmental processes are modulated by the hormone auxin. Auxin-modulated proteolysis of Aux/IAAs, a family of transcriptional repressors, represents a major mode of auxin action. Auxin facilitates the interaction of Aux/IAAs with TIR1/AFB F-box proteins, promoting their ubiquitination by the SCFTIR1/AFB ubiquitin E3 ligase leading to subsequent degradation by the 26S proteasome. To identify new genes regulating Aux/IAA proteolysis in Arabidopsis thaliana, we took a genetic approach, identifying individuals with altered degradation of an IAA1-luciferase fusion protein (IAA1-LUC). A mutant with 2-fold slower IAA1-LUC degradation rate compared with wild-type was isolated. Positional cloning identified the mutant as an allele of TOPOISOMERASE6B, named top6b-7. TOP6B encodes a subunit of a plant and archea-specific enzyme regulating endoreduplication, DNA damage repair and transcription in plants. T-DNA insertion alleles (top6b-8 and top6b-9) were also analyzed. top6b-7 seedlings are less sensitive to exogenous auxin than wild-type siblings in primary root growth assays, and experiments with DR5:GUS. Additionally, top6b-7 seedlings have a 40% reduction in the amount of endogenous IAA. These data suggest that increased IAA1-LUC half-life in top6b-7 probably results from a combination of both lower endogenous IAA levels and reduced sensitivity to auxin. PMID:25482814

  2. Interactions of Indoleacetic Acid and Gibberellic Acid in Leaf Abscission Control

    PubMed Central

    Lewis, Lowell N.; Bakhshi, Jagdish C.

    1968-01-01

    Debladed midribs of citrus leaves showed the typical delay of abscission in response to indoleacetic acid (IAA), and the typical acceleration of abscission in response to gibberellic acid (GA). Interaction experiments with these 2 hormones indicated that the balance of the 2 hormones may be more important in regulating abscission than the quantity of either. The often reported acceleration of abscission with low quantities of IAA did not seem to exist in citrus. IAA did accelerate abscission in this tissue when its application was delayed for at least 24 hours after deblading, which suggests the 2-stage effect is also present in citrus. When abscission was first delayed with IAA and then allowed to continue, the rate of abscission proceeded at a slower rate than was typical for this tissue. This slower rate was also typical of the effect observed when GA overcame the abscission retarding effect of IAA. The phenylurethane, Barban, blocked the GA acceleration of abscission, but it did not affect the rate of abscission of control or IAA treated midribs. Images PMID:16656770

  3. Defining Binding Efficiency and Specificity of Auxins for SCFTIR1/AFB-Aux/IAA Co-receptor Complex Formation

    PubMed Central

    2013-01-01

    Structure–activity profiles for the phytohormone auxin have been collected for over 70 years, and a number of synthetic auxins are used in agriculture. Auxin classification schemes and binding models followed from understanding auxin structures. However, all of the data came from whole plant bioassays, meaning the output was the integral of many different processes. The discovery of Transport Inhibitor-Response 1 (TIR1) and the Auxin F-Box (AFB) proteins as sites of auxin perception and the role of auxin as molecular glue in the assembly of co-receptor complexes has allowed the development of a definitive quantitative structure–activity relationship for TIR1 and AFB5. Factorial analysis of binding activities offered two uncorrelated factors associated with binding efficiency and binding selectivity. The six maximum-likelihood estimators of Efficiency are changes in the overlap matrixes, inferring that Efficiency is related to the volume of the electronic system. Using the subset of compounds that bound strongly, chemometric analyses based on quantum chemical calculations and similarity and self-similarity indices yielded three classes of Specificity that relate to differential binding. Specificity may not be defined by any one specific atom or position and is influenced by coulomb matrixes, suggesting that it is driven by electrostatic forces. These analyses give the first receptor-specific classification of auxins and indicate that AFB5 is the preferred site for a number of auxinic herbicides by allowing interactions with analogues having van der Waals surfaces larger than that of indole-3-acetic acid. The quality factors are also examined in terms of long-standing models for the mechanism of auxin binding. PMID:24313839

  4. IAA Space Terminological Multilingual Data Bank Towards an On- Line Dictionary with Definitions in French and in English

    NASA Astrophysics Data System (ADS)

    Bensaid, R.

    2002-01-01

    It has been emphasized in previous papers that the bilingual "basic list" of the IAA multilingual terminological data bank (MTDB) needed improvement before beginning works on definitions. In this communication, in a first part, we report, on the works (corrections and additions) done to improve the scope of the "basic list" . These works have yet to be done by coordinators for the others twelve languages concerned by the IAA MTBD. In a second part, according to the decision of the IAA MTDB committee to complete the MTDB with definitions in French and in English, we describe the methodology adopted and the problems encountered to elaborate a mock-up of a space dictionary, including in a first step definitions in English and in French, of the English terms and expressions beginning by the letter "A" in the basic list.

  5. Functional evaluation of iodoacetic acid induced photoreceptor degeneration in the cat.

    PubMed

    Nan, Yan; Zhang, Qin; Ren, Chaoran; Huang, Xin; Gao, Jie; Li, Xiaoxin; Pu, Mingliang

    2013-06-01

    Iodoacetic acid (IAA) has been applied to different species to acutely induce photoreceptor degeneration. The purpose of the present study was to use this toxin to thoroughly eliminate photoreceptors and induce complete blindness in the cat. IAA was delivered by single ear vein injection (20 mg kg(-1)). Six months after the IAA treatment, functional evaluations including pupillary light reflex (PLR), electroretinogram (ERG), visual behavior tests were performed. Morphological examinations were carried out after the functional evaluation. The present result shows that, six months after the IAA application, animals lost visual functions and became completely blind. High dose IAA application via ear vein delivery created an acute and reliable complete photoreceptor degeneration model in the cat. This model can be applied to genetic and cellular therapies for visual function restoration. PMID:23657794

  6. Bound Indoleacetic Acid in Avena Coleoptiles 1

    PubMed Central

    Winter, Alan; Thimann, Kenneth V.

    1966-01-01

    When C14 carboxyl indoleacetic acid (IAA) is transported through Avena coleoptile sections a fraction of the activity becomes bound. The nature of this bound IAA has been investigated. Upon extraction with solvents and chromatography a substance having the RF of IAA in 4 solvents was detected. No evidence could be found for the formation of indoleacetyl conjugates. In pea stem sections subjected to a similar experimental regime good evidence was obtained for the occurrence of conjugates. When IAA was supplied exogenously to coleoptile sections floating in solutions the occurrence of conjugates was shown to be dependent on the presence of the primary leaf. In its absence no conjugates could be detected. On grinding coleoptile sections and subsequent centrifugation at 240 × g the radioactivity was found to be in the tissue fraction as opposed to the supernatant. The radioactivity cannot be removed from the tissue by extraction with water, buffer solution or treatment with ribonuclease. It is readily removed by 10% urea, crystalline trypsin and chymotrypsin. It is therefore concluded that IAA becomes bound to a protein. Bound IAA does not appear to be able to cause growth in Avena coleoptile sections. PMID:16656259

  7. The anti-inflammatory and analgesic profile of 6,11-dihydrodibenzo-[b.e.]-thiepin-11-one-3-acetic acid (tiopinac).

    PubMed

    Rooks, W H; Tomolonis, A J; Maloney, P J; Roszkowski, A; Wallach, M B

    1980-06-01

    Tiopinac displayed marked anti-inflammatory activity when given p.o. in rat models of acute and chronic inflammation. It inhibited carrageenan-induced paw edema (40 x phenylbutazone), and cotton-pellet-induced granuloma (0.8 x indomethacin). In an 18-day test, tiopinac prevented the development of adjuvant-induced arthritis (10-15 x naproxen) and had similar activity versus pre-induced arthritis. Tiopinac exhibited antiphlogistic activity in adrenalectomized rats. It did not have corticosteroid activity. Depending upon the type of analgesic test used, the potency of tiopinac varied. When given p.o. it inhibited phenylquinone-induced writhing in the mouse and rat (respectively 16 and 10 x aspirin). In contrast, tiopinac had approximately 10 times the potency of indomethacin in increasing the pain threshold when yeast-inflamed paws were compressed. The pain threshold of the noninflamed paw was not increased. Tiopinac was highly active versus pain induced by flexing the adjuvant arthritic-inflamed paw (greater than or equal to 1000 x aspirin). It was inactive in the mouse hot-plate test in which opiate-like agents are active. Tiopinac, p.o., lowered yeast-induced pyrexia (130 x aspirin). Tiopinac did not have significant cardiovascular or CNS activity. Whereas the Ed50 versus adjuvant arthritis in rats was 0.1 mg/kg/day p.o., rats tolerated up to 20 mg/kg/day p.o. in the 8-day cotton-pellet test. Lack of anorexia and emesis in dogs with up to 30 mg/kg p.o. and mild oral activity in producing gastric erosion in acute and subacute studies in rats suggests that tiopinac may have relatively little gastrointestinal irritating activity. PMID:6967686

  8. Blockage by gibberellic Acid of phytochrome effects on growth, auxin responses, and flavonoid synthesis in etiolated pea internodes.

    PubMed

    Russell, D W; Galston, A W

    1969-09-01

    Red light inhibits the growth of etiolated pea internodes, causes a shift toward higher indoleacetic acid (IAA) concentrations in the IAA dose-response curve of excised sections, and promotes the synthesis in intact internodes of kaempferol-3-triglucoside. Gibberellic acid (GA(3)) prevents all 3 effects, the first effect substantially and the last 2 completely. This suggests GA(3) blockage of an early or basic event initiated by the active form of phytochrome. The red light-induced shift in the IAA dose-response curve of excised sections is consistent with a light-induced increase in the activity of an IAA destruction system, since the magnitude of the red light inhibition varied with IAA concentration. The red light and GA(3) effects on growth and on flavonoid synthesis are consistent with the view that phytochrome may control growth by regulating the synthesis of phenolic compounds which act as cofactors in an IAA-oxidase system. GA(3) reversal of the red light-induced shift in the IAA dose-response curve involves both growth promotion and inhibition by GA(3) at different IAA concentrations and this, together with the GA(3) reversal of light-induced flavonoid synthesis, supports the suggested regulatory role of phenolic compounds in growth. PMID:16657193

  9. The Brain’s Response to an Essential Amino Acid-Deficient Diet and the Circuitous Route to a Better Meal

    PubMed Central

    Gietzen, Dorothy W.; Aja, Susan M.

    2012-01-01

    The essential (indispensable) amino acids (IAA) are neither synthesized nor stored in metazoans, yet they are the building blocks of protein. Survival depends on availability of these protein precursors, which must be obtained in the diet; it follows that food selection is critical for IAA homeostasis. If even one of the IAA is depleted, its tRNA becomes quickly deacylated and the levels of charged tRNA fall, leading to disruption of global protein synthesis. As they have priority in the diet, second only to energy, the missing IAA must be restored promptly or protein catabolism ensues. Animals detect and reject an IAA-deficient meal in 20 min, but how? Here, we review the molecular basis for sensing IAA depletion and repletion in the brain’s IAA chemosensor, the anterior piriform cortex (APC). As animals stop eating an IAA-deficient meal, they display foraging and altered choice behaviors, to improve their chances of encountering a better food. Within 2 h, sensory cues are associated with IAA depletion or repletion, leading to learned aversions and preferences that support better food selection. We show neural projections from the APC to appetitive and consummatory motor control centers, and to hedonic, motivational brain areas that reinforce these adaptive behaviors. PMID:22674217

  10. Transport of stele-associated IAA in gravistimulated roots of maize

    SciTech Connect

    Stinemetz, C.L.; Evans, M.L. )

    1989-04-01

    We tested the redistribution of label from a pulse of {sup 3}H IAA applied to the cut surface of 5 mm apical root segments. We determined the amount of label in the stele, meristematic region (MR), root cap, and cortical tissue on the lower and upper sides of gravistimulated vs control roots. Label entered the stele and moved into the MR prior to accumulating in the elongation zone (EZ). Little label moved into the cap. Gravistimulation did not increase the amount of label moving from the stele, but it increased the amount of label accumulating on the lower side of the EZ. Removal of the cap immediately following gravistimulation rendered the roots insensitive to gravity and prevented gravi-induced asymmetric redistribution of label. The results suggest that a signal originating in the root cap directs auxin redistribution in tissue behind the cap.

  11. Early Fuel Cell Market Deployments: ARRA and Combined (IAA, DLA, ARRA): Quarter 4 2013 Composite Data Products

    SciTech Connect

    Kurtz, J.; Sprik, S.

    2014-06-01

    This report includes the composite data products (CDPs) for early fuel cell market deployments in quarter 4 of 2013. Results are presented for ARRA (projects funded by the American Recovery and Reinvestment Act of 2009 [ARRA]) and Combined (projects funded by DOE Interagency Agreements [IAA], Department of Defense Defense Logistics Agency [DLA], and ARRA).

  12. Early Fuel Cell Market Deployments: ARRA and Combined (IAA, DLA, ARRA); Quarter 3 2012 Composite Data Products

    SciTech Connect

    Kurtz, J.; Wipke, K.; Sprik, S.; Ramsden, T.; Ainscough, C.; Saur, G.; Post, M.

    2013-01-01

    This report from the U.S. Department of Energy's National Renewable Energy Laboratory includes early fuel cell market composite data products for the third quarter of 2012 for American Recovery and Reinvestment Act (ARRA) and combined (IAA, DLA, ARRA) deployment projects.

  13. Brassinosteroids regulate the differential growth of Arabidopsis hypocotyls through auxin signaling components IAA19 and ARF7.

    PubMed

    Zhou, Xiao-Yi; Song, Li; Xue, Hong-Wei

    2013-05-01

    Brassinosteroids (BRs) are an important class of phytohormones which regulates a wide range of physiological processes. Genetic and physiological studies have revealed that BR responses usually depend on an intact auxin signaling pathway. Here, we demonstrate that high BR concentration or enhanced BR signaling induce the differential growth of etiolated hypocotyls and result in the morphological changes, while auxin-resistant mutants, msg2 (dominant mutant of IAA19) and arf7, are insensitive to the BR effect and can partially suppress the phenotype of bzr1-D (dominant mutant of BZR1 with enhanced BR signaling). Interestingly, BZR1 protein can directly bind to the promoter regions of both IAA19 and ARF7, indicating that IAA19 and ARF7 mediate the BR-induced differential growth by serving as direct targets of BZR1. Systemic microarray analysis revealed that a number of BR-responsive genes showed reduced BR response in msg2, confirming that BR employs auxin signaling components IAA19 and ARF7 to modulate the specific downstream processes. These results provide informative clues on the crosstalk of BR-auxin signaling and the mechanisms of BR-auxin effects in regulating differential growth.

  14. Amino acid profiles and digestible indispensable amino acid scores of proteins from the prioritized key foods in Bangladesh.

    PubMed

    Shaheen, Nazma; Islam, Saiful; Munmun, Sarah; Mohiduzzaman, Md; Longvah, Thingnganing

    2016-12-15

    Concentrations of standard amino acids were determined in the composite samples (representing 30 agro-ecological zones of Bangladesh) of six prioritized key dietary protein sources: Oryza sativa (rice), Triticum aestivum (wheat flour), Lens culinaris (lentils), Pangusius pangusius (pangas), Labeo rohita (rohu) and Oreochromis mossambicus (tilapia). Digestible indispensable amino acid scores (DIAAS) was calculated using published data on amino acids' digestibility to evaluate the protein quality of these foods. Indispensable amino acid (IAA) contents (mg IAA/g protein), found to be highest in pangas (430) and lowest in wheat (336), of all these analyzed foods exceeded the FAO recommended daily allowance (277mg IAA/g protein) and contributed on average 40% to total amino acid contents. Untruncated DIAAS values ranged from 51% (lysine) in wheat to 106% (histidine) in pangas and distinguished pangas, rohu, and tilapia containing 'excellent quality' protein (DIAAS>100%) with potential to complement lower quality protein of cereals, fruits, and vegetables. PMID:27451158

  15. WITHDRAWN: Erythrodiol-3-acetate isolated from Styrax japonica elicits the inhibition of UV-induced gelatinases B in cultured human keratinocyte cells.

    PubMed

    Moon, Hyungin; Jung, Jae-Chul

    2007-02-26

    Methanol and aqueous extracts of Styrax japonica Sieb. et Zucc used traditionally for the treatments of skin elastic materials were screened in vitro for the gelatinases B inhibitor actions. Erythrodiol-3-acetate (E) from the stem barks of S. japonica showed significant gelatinase B inhibition in human keratinocyte cells caused by ultraviolet irradiation. Here we investigated the effect of E, which was isolated from S. japonica on UV-induced premature skin aging. We studied the effect of E on UV-induced gelatinase B expression in an immortalized human keratinocyte cell line, in vitro. Acute UV irradiation induced gelatinase B expression at the protein levels and E suppressed this UV-induced gelatinase B expression in a dose-dependent manner. Taken together, these results show that E can prevent the harmful effects of UV that lead to skin aging or skin cancer. Therefore, we suggest that E should be viewed as a potential therapeutic agent for preventing and/or treating premature skin aging. PMID:17329089

  16. Patterns of auxin and abscisic acid movement in the tips of gravistimulated primary roots of maize.

    PubMed

    Young, L M; Evans, M L

    1996-01-01

    Because both abscisic acid (ABA) and auxin (IAA) have been suggested as possible chemical mediators of differential growth during root gravitropism, we compared with redistribution of label from applied 3H-IAA and 3H-ABA during maize root gravitropism and examined the relative basipetal movement of 3H-IAA and 3H-ABA applied to the caps of vertical roots. Lateral movement of 3H-ABA across the tips of vertical roots was non-polar and about 2-fold greater than lateral movement of 3H-IAA (also non-polar). The greater movement of ABA was not due to enhanced uptake since the uptake of 3H-IAA was greater than that of 3H-ABA. Basipetal movement of label from 3H-IAA or 3H-ABA applied to the root cap was determined by measuring radioactivity in successive 1 mm sections behind the tip 90 minutes after application. ABA remained largely in the first mm (point of application) whereas IAA was concentrated in the region 2-4 mm from the tip with substantial levels found 7-8 mm from the tip. Pretreatment with inhibitors of polar auxin transport decreased both gravicurvature and the basipetal movement of IAA. When roots were placed horizontally, the movement of 3H-IAA from top to bottom across the cap was enhanced relative to movement from bottom to top whereas the pattern of movement of label from 3H-ABA was unaffected. These results are consistent with the hypothesis that IAA plays a role in root gravitropism but contrary to the idea that gravi-induced asymmetric distribution of ABA contributes to the response. PMID:11540494

  17. Patterns of auxin and abscisic acid movement in the tips of gravistimulated primary roots of maize

    NASA Technical Reports Server (NTRS)

    Young, L. M.; Evans, M. L.

    1996-01-01

    Because both abscisic acid (ABA) and auxin (IAA) have been suggested as possible chemical mediators of differential growth during root gravitropism, we compared with redistribution of label from applied 3H-IAA and 3H-ABA during maize root gravitropism and examined the relative basipetal movement of 3H-IAA and 3H-ABA applied to the caps of vertical roots. Lateral movement of 3H-ABA across the tips of vertical roots was non-polar and about 2-fold greater than lateral movement of 3H-IAA (also non-polar). The greater movement of ABA was not due to enhanced uptake since the uptake of 3H-IAA was greater than that of 3H-ABA. Basipetal movement of label from 3H-IAA or 3H-ABA applied to the root cap was determined by measuring radioactivity in successive 1 mm sections behind the tip 90 minutes after application. ABA remained largely in the first mm (point of application) whereas IAA was concentrated in the region 2-4 mm from the tip with substantial levels found 7-8 mm from the tip. Pretreatment with inhibitors of polar auxin transport decreased both gravicurvature and the basipetal movement of IAA. When roots were placed horizontally, the movement of 3H-IAA from top to bottom across the cap was enhanced relative to movement from bottom to top whereas the pattern of movement of label from 3H-ABA was unaffected. These results are consistent with the hypothesis that IAA plays a role in root gravitropism but contrary to the idea that gravi-induced asymmetric distribution of ABA contributes to the response.

  18. Saturable uptake of indol-3yl-acetic Acid by maize roots.

    PubMed

    Martin, H V; Pilet, P E

    1986-07-01

    The uptake of 5-[(3)H]indol-3yl-acetic acid (IAA(*)) by segments of Zea mays L. roots was measured in the presence of nonradioactive indol-3yl-acetic acid (IAA degrees ) at different concentrations. IAA uptake was found to have a nonsaturable component and a saturable part with (at pH 5.0) an apparent K(m) of 0.285 micromolar and apparent V(max) 55.0 picomoles per gram fresh mass per minute. These results are consistent with those which might be expected for a saturable carrier capable of regulating IAA levels. High performance liquid chromatography analyses showed that very little metabolism of IAA(*) took place during 4 minute uptake experiments. Whereas nonsaturable uptake was similar for all 2 millimeter long segments prepared within the 2 to 10 millimeter region, saturable uptake was greatest for the 2 to 4 millimeter region. High levels of uptake by stelar (as compared with cortical) segments are partly attributable to the saturable carrier, and also to a high level of uptake by nonsaturable processes. The carrier may play an essential role in controlling IAA levels in maize roots, especially the accumulation of IAA in the apical region. The increase in saturable uptake toward the root tip may also contribute to the acropetal polarity of auxin transport.

  19. Contribution of microbial amino acids to amino acid homeostasis of the host.

    PubMed

    Metges, C C

    2000-07-01

    Among the reasons suggested for the discrepancy between N balance and tracer-derived indispensable amino acid (IAA) requirement estimates is the possibility that the metabolic requirement is met not only by the diet but also by IAA synthesized de novo by the gastrointestinal microflora, which are then absorbed. It is therefore crucial to better understand and quantify the microbial biosynthesis of amino acids in the human gastrointestinal tract and its potential role in providing IAA to meet human amino acid requirement. Here, the available evidence on the contribution of microbial amino acids to the host's amino acid homeostasis, applying the (15)N labeling paradigm, is summarized. Between 1 and 20% of circulating plasma lysine, urinary lysine and body protein lysine of the host, respectively, is derived from intestinal microbial sources and corresponds to a gross microbial lysine contribution of 11-68 mg. kg(-1). d(-1) in adult humans with an adequate protein intake when fecal or ileal microbial lysine enrichment is used as precursor. Factors affecting estimates of net microbial IAA contribution are discussed. It appears that the small intestine is responsible for a large part of microbial lysine uptake, although some absorption from the large intestine cannot be excluded. Nonoxidative lysine losses from the human gastrointestinal tract, which were found to be between 3.9 to 8.5 mg. kg(-1). d(-1), are necessary to estimate the net contribution of microbial IAA. It is reasonable to assume that microbial amino acid synthesis in the human gastrointestinal tract utilizes a mixture of various nitrogen sources, i.e., endogenous amino acids, urea and ammonia. Microbes in the small intestine may rely more on endogenous amino acids. Deprivation of nutrients, the intake of certain dietary nonstarch oligosaccharides, lipids, as well as protein intake level and source and level of consumption of certain amino acids can affect the composition and metabolic activity of the

  20. Space Weather Research at IAA/NOA: Solar Energetic Particle Investigations

    NASA Astrophysics Data System (ADS)

    Malandraki, O.; Tylka, A. J.; Ng, C. K.; Marsden, R. G.; Tranquille, C.; Klein, K. L.; Patterson, J. D.; Armstrong, T. P.; Lanzerotti, L. J.; Papaioannou, A.; Marhavilas, P. K.; Tziotziou, K.; Crosby, N.; Vainio, R.

    2012-01-01

    During an eleven year cycle the Sun goes from quiet conditions at minimum to levels of high activity at maximum. In the latter case, energetic phenomena such as coronal mass ejections (CMEs) and solar flares (SFs) accompanied by explosive releases of mass, magnetic flux and solar energetic particles (SEPs) are common. Damaging effects, as a result of these phenomena, have been recorded on satellites, on-board detectors and in extreme cases on ground based systems (e.g. oil and natural gas pipelines, communication systems, aircraft electronics, power-grids). Furthermore, the intense SEP radiation can damage human DNA and cause cell replications. To this end, ensuring the safety of astronauts working in the extreme conditions of space, especially the energetic particle environments, is a key goal for both ESA and NASA. The analysis, the risk assessment and management and the possible forecasting of such events constitutes the scientific field of Space Weather. The Institute of Astronomy and Astrophysics (IAA) of the National Observatory of Athens (NOA) is currently strongly involved in two collaborative projects funded by the seventh framework program of the European Union, namely: 'SEPServer' and 'COMESEP'. 'SEPServer' focuses on the implementation of a comprehensive and up to date SEP analysis service including scientific data driven analysis both for 1 AU and for > 1 AU using data from the SOHO/ ERNE, SOHO/EPHIN, ACE/EPAM, ACE/SIS, WIND/3DP, Ulysses/HISCALE, Ulysses/COSPIN/LET and Ulysses/COSPIN/KET experiments. SEPServer will also provide for the first time the release of the HELIOS data set in a reasonable format and in full time resolution, thus making available data also for orbits inside 1 AU (down to 0.3 AU). Observational data-driven analysis methods such as: onset determination, velocity dispersion, and/or time-shifting analysis, direct comparison of observed SEP fluxes, spectra and abundance ratios with the associated electromagnetic emission data will be

  1. The IAA cosmic dust laboratory: Experimental scattering matrices of clay particles

    NASA Astrophysics Data System (ADS)

    Muñoz, O.; Moreno, F.; Guirado, D.; Ramos, J. L.; Volten, H.; Hovenier, J. W.

    2011-01-01

    We present the first results of measurements on solid particles performed at the Instituto de Astrofı´sica de Andalucı´a (IAA) cosmic dust laboratory located in Granada, Spain. The laboratory apparatus measures the complete scattering matrix as a function of the scattering angle of aerosol particles. The measurements can be performed at a wavelength ( λ) of 483, 488, 520, 568, or 647 nm in the scattering angle range from 3° to 177°. Results of special test experiments are presented which show that our experimental results for scattering matrices are not significantly contaminated by multiple scattering and that the sizes/shapes of the particles do not change during the measurements. Moreover, the measured scattering matrix for a sample of green clay particles is compared with measurements previously performed in the Amsterdam light scattering setup for the same sample. New measurements on a white clay sample at 488 and 647 nm are also presented. The apparatus is devoted to experimentally studying the angle dependence of scattering matrices of dust samples of astrophysical interest. Moreover, there is a great interest in similar studies of aerosols that can affect the radiative balance of the atmosphere of the Earth and other planets such as silicates, desert dust, volcanic ashes, and carbon soot particles.

  2. Validation of MIPAS IMK/IAA V5R_O3_224 ozone profiles

    NASA Astrophysics Data System (ADS)

    Laeng, A.; Grabowski, U.; von Clarmann, T.; Stiller, G.; Glatthor, N.; Höpfner, M.; Kellmann, S.; Kiefer, M.; Linden, A.; Lossow, S.; Sofieva, V.; Petropavlovskikh, I.; Hubert, D.; Bathgate, T.; Bernath, P.; Boone, C. D.; Clerbaux, C.; Coheur, P.; Damadeo, R.; Degenstein, D.; Frith, S.; Froidevaux, L.; Gille, J.; Hoppel, K.; McHugh, M.; Kasai, Y.; Lumpe, J.; Rapoe, N.; Toon, G.; Sano, T.; Suzuki, M.; Tamminen, J.; Urban, J.; Walker, K.; Weber, M.; Zawodny, J.

    2014-04-01

    We present the results of an extensive validation program of the most recent version of ozone vertical profiles retrieved with the IMK/IAA MIPAS research level 2 processor from version 5 spectral Level 1 data. The time period covered corresponds to the reduced spectral resolution period of the MIPAS instrument, i.e. January 2005-April 2012. The comparison with satellite instruments includes all post-2005 satellite limb and occultation sensors having measured the vertical profiles of tropospheric and stratospheric ozone: ACE-FTS, GOMOS, HALOE, HIRDLS, MLS, OSIRIS, POAM, SAGE II, SCIAMACHY, SMILES, and SMR. In addition, balloon-borne MkIV solar occultation measurements and groundbased Umkehr measurements have been included, as well as two nadir sensors: IASI and SBUV. For each reference dataset, bias determination and precision assessment are performed. Better agreement with reference instruments than for the previous data version, V5R_O3_220 (Laeng et al., 2013), is found: the known high bias around the ozone vmr peak is significantly reduced and the vertical resolution at 35 km has been improved. The agreement with limb and solar occultation reference instruments that have a known small bias vs. ozone sondes is within 7% in the lower and middle stratosphere and 5% in the upper troposphere. Around the ozone vmr peak, the agreement with most of satellite reference instruments is within 5%; this bias is as low as 3% for ACE-FTS, MLS, OSIRIS, POAM and SBUV.

  3. Effects of IAA, IBA, NAA, and GA3 on Rooting and Morphological Features of Melissa officinalis L. Stem Cuttings

    PubMed Central

    Guney, Kerim

    2013-01-01

    This study analyzed the potential of producing Melissa officinalis L. using stem cuttings. Four different hormones (IAA, IBA, NAA, and GA3) were applied to the cuttings, with and without buds, in two doses (1000 mg/L and 5000 mg/L), and after 60 days, 10 morphological characteristics of newly generated plants were detected, and a statistical analysis was carried out. The results of the study show that the cuttings with at least one bud must be used in order to produce M. officinalis using stem cuttings. Even though the auxin group hormones (IAA, IBA, and NAA) do not have an apparent effect on rooting percentage, these hormones were detected to affect the morphological characteristics of the newly generated plants, especially root generation. GA3 application has a considerable effect on stem height. PMID:23818834

  4. Effects of IAA, IBA, NAA, and GA3 on rooting and morphological features of Melissa officinalis L. stem cuttings.

    PubMed

    Sevik, Hakan; Guney, Kerim

    2013-01-01

    This study analyzed the potential of producing Melissa officinalis L. using stem cuttings. Four different hormones (IAA, IBA, NAA, and GA3) were applied to the cuttings, with and without buds, in two doses (1000 mg/L and 5000 mg/L), and after 60 days, 10 morphological characteristics of newly generated plants were detected, and a statistical analysis was carried out. The results of the study show that the cuttings with at least one bud must be used in order to produce M. officinalis using stem cuttings. Even though the auxin group hormones (IAA, IBA, and NAA) do not have an apparent effect on rooting percentage, these hormones were detected to affect the morphological characteristics of the newly generated plants, especially root generation. GA3 application has a considerable effect on stem height. PMID:23818834

  5. Effects of IAA, IBA, NAA, and GA3 on rooting and morphological features of Melissa officinalis L. stem cuttings.

    PubMed

    Sevik, Hakan; Guney, Kerim

    2013-01-01

    This study analyzed the potential of producing Melissa officinalis L. using stem cuttings. Four different hormones (IAA, IBA, NAA, and GA3) were applied to the cuttings, with and without buds, in two doses (1000 mg/L and 5000 mg/L), and after 60 days, 10 morphological characteristics of newly generated plants were detected, and a statistical analysis was carried out. The results of the study show that the cuttings with at least one bud must be used in order to produce M. officinalis using stem cuttings. Even though the auxin group hormones (IAA, IBA, and NAA) do not have an apparent effect on rooting percentage, these hormones were detected to affect the morphological characteristics of the newly generated plants, especially root generation. GA3 application has a considerable effect on stem height.

  6. Bacteria isolated from roots and rhizosphere of Vitis vinifera retard water losses, induce abscisic acid accumulation and synthesis of defense-related terpenes in in vitro cultured grapevine.

    PubMed

    Salomon, María Victoria; Bottini, Rubén; de Souza Filho, Gonçalo Apolinário; Cohen, Ana Carmen; Moreno, Daniela; Gil, Mariana; Piccoli, Patricia

    2014-08-01

    Eleven bacterial strains were isolated at different soil depths from roots and rhizosphere of grapevines from a commercial vineyard. By 16S rRNA gene sequencing 10 different genera and 8 possible at species level were identified. From them, Bacillus licheniformis Rt4M10 and Pseudomonas fluorescens Rt6M10 were selected according to their characteristics as plant growth promoting rhizobacteria (PGPR). Both produced abscisic acid (ABA), indole-3-acetic acid (IAA) and the gibberellins A1 and A3 in chemically-defined medium. They also colonized roots of in vitro grown Vitis vinifera cv. Malbec plants. As result of bacterization ABA levels in 45 days-old in vitro plants were increased 76-fold by B. licheniformis and 40-fold by P. fluorescens as compared to controls. Both bacteria diminished plant water loss rate in correlation with increments of ABA. Twenty and 30 days post bacterization the plants incremented terpenes. The monoterpenes α-pinene, terpinolene, 4-carene, limonene, eucalyptol and lilac aldehyde A, and the sesquiterpenes α-bergamotene, α-farnesene, nerolidol and farnesol were assessed by gas chromatography-electron impact mass spectrometry analysis. α-Pinene and nerolidol were the most abundant (µg per g of tissue in plants bacterized with P. fluorescens). Only α-pinene, eucalyptol and farnesol were identified at low concentration in non-bacterized plants treated with ABA, while no terpenes were detected in controls. The results obtained along with others from literature suggest that B. licheniformis and P. fluorescens act as stress alleviators by inducing ABA synthesis so diminishing water losses. These bacteria also elicit synthesis of compounds of plant defense via an ABA independent mechanism.

  7. Detection of iso-α-acids to confirm beer consumption in postmortem specimens.

    PubMed

    Rodda, Luke N; Gerostamoulos, Dimitri; Drummer, Olaf H

    2015-01-01

    Iso-α-acids (IAAs) can be used as markers for the consumption of beer. Postmortem specimens from a range of coronial cases were analyzed for IAAs in order to determine the prevalence of beer consumption and any correlation to blood alcohol concentrations (BAC). A total of 130 cases were included in this study including those where beer was mentioned in the case circumstances, cases where beer was not mentioned specifically but alcohol was detected, and cases where neither beer was mentioned nor a positive BAC was present. Available blood, serum, vitreous humour and urine specimens were analyzed. Of the 50 cases where beer was mentioned, 86% had one or more IAAs detected. In cases that only had a positive BAC (n = 60), 57% of these cases also showed the presence of these beer markers. IAAs were detected in specimens obtained from traumatized, burnt, and decomposed cases with a mention of beer consumption or where BAC was positive in blood. No IAAs were detected in cases where BAC was negative. There was little or no correlation between blood IAA concentrations and BAC. This study demonstrates the possible detection of IAAs as a marker for beer consumption.

  8. Pharmacokinetics of iso-α-acids in volunteers following the consumption of beer.

    PubMed

    Rodda, Luke N; Gerostamoulos, Dimitri; Drummer, Olaf H

    2014-01-01

    Hop-derived iso-α-acid (IAA) ingredient congeners are specific to beer. Concentrations of IAAs were determined in blood of five volunteers over 6 h following the consumption of small volumes of beer containing relatively high (Pale Ale beer) or low (wheat beer) concentrations of IAAs. IAAs were quickly absorbed with peak trans-IAA concentrations at 0.5 h followed by a drop of generally 10-fold at 2 h and low or not detectable trans-IAA levels at 6 h. However, the qualitative monitoring showed that the cis-IAAs were detected at all time-points. Preliminary pharmacokinetics of these compounds in humans shows relatively small interindividual differences and an estimated short half-life of ∼30 min. Comparison of 0.5 and 2 h blood specimens demonstrated that the trans isomers were eliminated faster than the cis counterparts. Preliminary urine analysis showed only unmodified 'co' analytes detectable throughout the 6 h. In authentic forensic casework where typically large amounts of conventionally hopped beer are consumed, this approach may provide a novel method to target ingredient congeners consistent with beer ingestion.

  9. Uptake and incorporation of labeled tryptophan isomers into IAA in the jsR sub 1 mutant of Lemna gibba

    SciTech Connect

    Baldi, B.G.; Maher, B.R.; Cohen, J.D. )

    1989-04-01

    Analyses of the IAA-overproducing mutant of Lemna have been initiated in order to study in vivo biosynthesis of IAA. Using radiolabelled tryptophan isomers prepared from commercial sources of {sup 14}C-D,L tryptophan by chiral separation kinetics of uptake of L and D tryptophan were determined for sterile cultures of individual jsR{sub 1} four-frond colonies. Over a 24 h period, about 50% of the radioactivity from {sup 14}C-L-TRP in media, or about 25% from {sup 14}C-D-TRP, was found in the plant tissue. Maximal rates of uptake were seen in the first six hors for both isomers. Endogenous levels of tryptophan determined in jsR{sub 1} as measures of pool sizes in vivo show 5 to 10 ug/g FW total tryptophan with less than 1% in the D isomer form. Information on uptake and endogenous pool sizes of tryptophan isomers is being used for feeding of stable isotope labeled tryptophan ({sup 13}C, {sup 14}N) to jsR{sub 1} at physiological levels. Analyses of incorporation of label into IAA using GC-MS and high resolution mass spectrometry are currently underway.

  10. Biosynthetic pathway of the phytohormone auxin in insects and screening of its inhibitors.

    PubMed

    Suzuki, Hiroyoshi; Yokokura, Junpei; Ito, Tsukasa; Arai, Ryoma; Yokoyama, Chiaki; Toshima, Hiroaki; Nagata, Shinji; Asami, Tadao; Suzuki, Yoshihito

    2014-10-01

    Insect galls are abnormal plant tissues induced by galling insects. The galls are used for food and habitation, and the phytohormone auxin, produced by the insects, may be involved in their formation. We found that the silkworm, a non-galling insect, also produces an active form of auxin, indole-3-acetic acid (IAA), by de novo synthesis from tryptophan (Trp). A detailed metabolic analysis of IAA using IAA synthetic enzymes from silkworms indicated an IAA biosynthetic pathway composed of a three-step conversion: Trp → indole-3-acetaldoxime → indole-3-acetaldehyde (IAAld) → IAA, of which the first step is limiting IAA production. This pathway was shown to also operate in gall-inducing sawfly. Screening of a chemical library identified two compounds that showed strong inhibitory activities on the conversion step IAAld → IAA. The inhibitors can be efficiently used to demonstrate the importance of insect-synthesized auxin in gall formation in the future.

  11. Perturbation of Auxin Homeostasis by Overexpression of Wild-Type IAA15 Results in Impaired Stem Cell Differentiation and Gravitropism in Roots

    PubMed Central

    Yan, Da-Wei; Wang, Jing; Yuan, Ting-Ting; Hong, Li-Wei; Gao, Xiang; Lu, Ying-Tang

    2013-01-01

    Aux/IAAs interact with auxin response factors (ARFs) to repress their transcriptional activity in the auxin signaling pathway. Previous studies have focused on gain-of-function mutations of domain II and little is known about whether the expression level of wild-type Aux/IAAs can modulate auxin homeostasis. Here we examined the perturbation of auxin homeostasis by ectopic expression of wild-type IAA15. Root gravitropism and stem cell differentiation were also analyzed. The transgenic lines were less sensitive to exogenous auxin and exhibited low-auxin phenotypes including failures in gravity response and defects in stem cell differentiation. Overexpression lines also showed an increase in auxin concentration and reduced polar auxin transport. These results demonstrate that an alteration in the expression of wild-type IAA15 can disrupt auxin homeostasis. PMID:23472140

  12. Validation of MIPAS IMK/IAA V5R_O3_224 ozone profiles

    NASA Astrophysics Data System (ADS)

    Laeng, A.; Grabowski, U.; von Clarmann, T.; Stiller, G.; Glatthor, N.; Höpfner, M.; Kellmann, S.; Kiefer, M.; Linden, A.; Lossow, S.; Sofieva, V.; Petropavlovskikh, I.; Hubert, D.; Bathgate, T.; Bernath, P.; Boone, C. D.; Clerbaux, C.; Coheur, P.; Damadeo, R.; Degenstein, D.; Frith, S.; Froidevaux, L.; Gille, J.; Hoppel, K.; McHugh, M.; Kasai, Y.; Lumpe, J.; Rahpoe, N.; Toon, G.; Sano, T.; Suzuki, M.; Tamminen, J.; Urban, J.; Walker, K.; Weber, M.; Zawodny, J.

    2014-11-01

    We present the results of an extensive validation program of the most recent version of ozone vertical profiles retrieved with the IMK/IAA (Institute for Meteorology and Climate Research/Instituto de Astrofísica de Andalucía) MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) research level 2 processor from version 5 spectral level 1 data. The time period covered corresponds to the reduced spectral resolution period of the MIPAS instrument, i.e., January 2005-April 2012. The comparison with satellite instruments includes all post-2005 satellite limb and occultation sensors that have measured the vertical profiles of tropospheric and stratospheric ozone: ACE-FTS, GOMOS, HALOE, HIRDLS, MLS, OSIRIS, POAM, SAGE II, SCIAMACHY, SMILES, and SMR. In addition, balloon-borne MkIV solar occultation measurements and ground-based Umkehr measurements have been included, as well as two nadir sensors: IASI and SBUV. For each reference data set, bias determination and precision assessment are performed. Better agreement with reference instruments than for the previous data version, V5R_O3_220 (Laeng et al., 2014), is found: the known high bias around the ozone vmr (volume mixing ratio) peak is significantly reduced and the vertical resolution at 35 km has been improved. The agreement with limb and solar occultation reference instruments that have a known small bias vs. ozonesondes is within 7% in the lower and middle stratosphere and 5% in the upper troposphere. Around the ozone vmr peak, the agreement with most of the satellite reference instruments is within 5%; this bias is as low as 3% for ACE-FTS, MLS, OSIRIS, POAM and SBUV.

  13. Transport of indoleacetic acid in intact corn coleoptiles. [Zea mays L

    SciTech Connect

    Parker, K.E.; Briggs, W.R. )

    1990-10-01

    We have characterized the transport of ({sup 3}H)indoleacetic acid (IAA) in intact corn (Zea mays L.) coleoptiles. We have used a wide range of concentrations of added IAA (28 femtomoles to 100 picomoles taken up over 60 minutes). The shape of the transport curve varies with the concentration of added IAA, although the rate of movement of the observed front of tracer is invariant with concentration. At the lowest concentration of tracer used, the labeled IAA in the transport stream is not detectably metabolized or immobilized, curvature does not develop as a result of tracer application, and normal phototropic and gravitropic responsiveness are not affected. Therefore we believe we are observing the transport of true tracer quantities of labeled auxin at this lowest concentration.

  14. The Swedish Interplanetary Society (1950-1969) and the formation of IAF and IAA

    NASA Astrophysics Data System (ADS)

    Ingemar Skoog, A.

    2011-06-01

    With a growing interest for rocket technology and space travel after WW II a number of new "space societies" were formed in the period 1948-1951 in addition to the ones already existing in Germany, the UK and the US since before WW II. Soon came the need for a common international platform for exchange of information and experience, and the concept of an international federation of astronautical societies emerged. Sweden was one of the 8 countries to sign the original declaration to create an International Astronautical Federation on October 2, 1950 in Paris at the 1st International Astronautical Congress. The Swedish Society for Space Research (Svenska Sällskapet för Rymdforskning) was formed a few days after the historical event in Paris. The name was soon to be changed to the Swedish Interplanetary Society (Svenska Interplanetariska Sällskapet, SIS). Sweden was one of the 10 countries to sign the IAF foundation in 1951 in London and in the following year the first Constitution of IAF in Stuttgart. The SIS quickly grow to a membership of several hundred persons and its membership in IAF promoted an intensive exchange of journals, and the annual participation at the IAC gave growth to start study projects on spacecraft and sounding rockets, and the publication of astronautical journals in Swedish. In 1957 the first Swede was elected vice-president of IAF. Not too long after the IAF foundation the idea of an international body of distinguished individuals emerged, in addition to the body of "member societies" (IAF). Upon the initiative of Theodor von Karman, Eugen Sänger and Andrew Haley the IAF council approval of an International Academy of Astronautical was given on August 15, 1960 during the 11th IAC in Stockholm. This IAC in Stockholm gave a large publicity to space research and astronautics in Sweden, and put the activities of the SIS in the focus of the general public. This paper presents the Swedish involvement in the foundation of IAF and IAA. It also

  15. Altered growth response to exogenous auxin and gibberellic acid by gravistimulation in pulvini of Avena sativa

    NASA Technical Reports Server (NTRS)

    Brock, T. G.; Kaufman, P. B.

    1988-01-01

    Pulvini of excised segments from oats (Avena sativa L. cv Victory) were treated unilaterally with indoleacetic acid (IAA) or gibberellic acid (GA3) with or without gravistimulation to assess the effect of gravistimulation on hormone action. Optimum pulvinus elongation growth (millimeters) and segment curvature (degrees) over 24 hours were produced by 100 micromolar IAA in vertical segments. The curvature response to IAA at levels greater than 100 micromolar, applied to the lower sides of gravistimulated (90 degrees) pulvini, was significantly less than the response to identical levels in vertical segments. Furthermore, the bending response of pulvini to 100 micromolar IAA did not vary significantly over a range of presentation angles between 0 and 90 degrees. In contrast, the response to IAA at levels less than 10 micromolar, with gravistimulation, was approximately the sum of the responses to gravistimulation alone and to IAA without gravistimulation. This was observed over a range of presentation angles. Also, GA3 (0.3-30 micromolar) applied to the lower sides of horizontal segments significantly enhanced pulvinus growth and segment curvature, although exogenous GA3 over a range of concentrations had no effect on pulvinus elongation growth or segment curvature in vertical segments. The response to GA3 (10 micromolar) plus IAA (1.0 or 100 micromolar) was additive for either vertical or horizontal segments. These results indicate that gravistimulation produces changes in pulvinus responsiveness to both IAA and GA3 and that the changes are unique for each growth regulator. It is suggested that the changes in responsiveness may result from processes at the cellular level other than changes in hormonal sensitivity.

  16. [Interaction of Cucurbit[8]uril with β-Indoleacetic Acid and Methylviologen].

    PubMed

    Song, Gui-xian; Tang, Qing; Huang, Ying; Zhang, Jian-xin; Tao, Zhu; Xue, Sai-feng; Zhu, Qian-jiang; Wei, Gang

    2015-11-01

    The interaction between Q[8] with β-indoleacetic acid and the methylviologen was studied in aqueous solution with electronic absorption spectroscopy (UV-Vis), fluorescence spectroscopy, 1H NMR spectroscopy and isothermal titration calorimetry (ITC) in details. The authors explored the mode of action, action site and thermodynamic properties of the host-guest system. The electronic absorption and fluorescence spectroscopy data showed that the Q[8]/IAA system and Q[8]/MV²⁺ system informed 1:1 inclusion complexes in aqueous solution. ITC results showed that the changes of Gibbs free energy and enthalpy are all negative, it suggested that complex formation was spontaneous and exothermic reaction. Moreover, ITC results for the Q [8] and IAA with MV²⁺ indicate that the association constants of the Q[8]-IAA and Q[8]-MV²⁺ complexes were (3.22 ± 0.96) x 10⁵ L · mol⁻¹ and (3.90 ± 0.91) x 10⁶ L · mol⁻¹, respectively. Therefore, the interaction between Q[8] and IAA with the MV²⁺ was a competitive process. This likely occurs because the MV²⁺ and IAA molecules attempt to occupy the Q[8] cavity, which reduces the fluorescence and absorption spectra intensity of Q[8]-IAA because of the formation of a new inclusion complex between Q[8] and IAA with MV²⁺. In addition, with the addition of MV²⁺ to a Q[8]/IAA complex, 1H NMR results showed that the indole moieties of β-indoleacetic acid and bipyridyl group of methylviologen can be incorporated into Q[8] cavities because of electronic transfer MV²⁺ with PQ in a Q[8] cavity with ternary complexes. These results provides the potential applications for the supramolecular self-assembly in cucurbit[n]urils field. PMID:26978923

  17. Enzymic synthesis of indole-3-acetyl-1-O-beta-d-glucose. II. Metabolic characteristics of the enzyme

    NASA Technical Reports Server (NTRS)

    Leznicki, A. J.; Bandurski, R. S.

    1988-01-01

    The synthesis of indole-3-acetyl-1-O-beta-D-glucose from indole-3-acetic acid (IAA) and uridine diphosphoglucose (UDPG) has been shown to be a reversible reaction with the equilibrium away from ester formation and toward formation of IAA. The enzyme occurs primarily in the liquid endosperm of the corn kernel but some activity occurs in the embryo. It is relatively specific showing no glucose ester formation with oxindole-3-acetic acid or 7-hydroxy-oxindole-3-acetic acid, and low activity with phenylpropene acids, such as rho-coumaric acid. The enzyme is also specific for the nucleotide sugar showing no activity with UDPGalactose or UDPXylose. The enzyme is inhibited by inorganic pyrophosphate, by phosphate esters and by phospholipids, particularly phosphatidyl ethanolamine. The enzyme is inhibited by zeatin, by 2,4-dichlorophenoxy-acetic acid, by IAA-myo-inositol and IAA-glucan, but not by zeatin riboside, and only weakly by gibberellic acid, abscisic acid and kinetin. The reaction is slightly stimulated by both calcium and calmodulin and, in some cases, by thiol compounds. The role of this enzyme in the homeostatic control of indole-3-acetic acid levels in Zea mays is discussed.

  18. Draft Genome Sequence of Endophytic Bacterium Enterobacter asburiae PDA134, Isolated from Date Palm (Phoenix dactylifera L.) Roots.

    PubMed

    Yaish, Mahmoud W

    2016-01-01

    In this report, a draft of the Enterobacter asburiae strain PDA134 genome was sequenced. This bacterial strain was isolated from the root tissue of a date palm, where it has the ability to produce 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and indole-3-acetic acid (IAA) under salinity stress. PMID:27540071

  19. Draft Genome Sequence of Endophytic Bacterium Enterobacter asburiae PDA134, Isolated from Date Palm (Phoenix dactylifera L.) Roots

    PubMed Central

    2016-01-01

    In this report, a draft of the Enterobacter asburiae strain PDA134 genome was sequenced. This bacterial strain was isolated from the root tissue of a date palm, where it has the ability to produce 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and indole-3-acetic acid (IAA) under salinity stress. PMID:27540071

  20. Defining binding efficiency and specificity of auxins for SCF(TIR1/AFB)-Aux/IAA co-receptor complex formation.

    PubMed

    Lee, Sarah; Sundaram, Shanthy; Armitage, Lynne; Evans, John P; Hawkes, Tim; Kepinski, Stefan; Ferro, Noel; Napier, Richard M

    2014-03-21

    Structure-activity profiles for the phytohormone auxin have been collected for over 70 years, and a number of synthetic auxins are used in agriculture. Auxin classification schemes and binding models followed from understanding auxin structures. However, all of the data came from whole plant bioassays, meaning the output was the integral of many different processes. The discovery of Transport Inhibitor-Response 1 (TIR1) and the Auxin F-Box (AFB) proteins as sites of auxin perception and the role of auxin as molecular glue in the assembly of co-receptor complexes has allowed the development of a definitive quantitative structure-activity relationship for TIR1 and AFB5. Factorial analysis of binding activities offered two uncorrelated factors associated with binding efficiency and binding selectivity. The six maximum-likelihood estimators of Efficiency are changes in the overlap matrixes, inferring that Efficiency is related to the volume of the electronic system. Using the subset of compounds that bound strongly, chemometric analyses based on quantum chemical calculations and similarity and self-similarity indices yielded three classes of Specificity that relate to differential binding. Specificity may not be defined by any one specific atom or position and is influenced by coulomb matrixes, suggesting that it is driven by electrostatic forces. These analyses give the first receptor-specific classification of auxins and indicate that AFB5 is the preferred site for a number of auxinic herbicides by allowing interactions with analogues having van der Waals surfaces larger than that of indole-3-acetic acid. The quality factors are also examined in terms of long-standing models for the mechanism of auxin binding.

  1. Pharmacokinetics of reduced iso-α-acids in volunteers following clear bottled beer consumption.

    PubMed

    Rodda, Luke N; Gerostamoulos, Dimitri; Drummer, Olaf H

    2015-05-01

    Reduced iso-α-acids (reduced IAA) consisting of the rho-, tetrahydro- and hexahydro-IAA groups (RIAA, TIAA and HIAA, respectively) are ingredient congeners specific to beer and generally found in clear and also occasionally green bottled beer. Concentrations of reduced IAA were determined in the blood and urine of five volunteers over 6h following the consumption of small volumes of beer containing each of the reduced IAA. The reduced IAA were absorbed and bioavailable with peak concentrations at 0.5h followed by a drop of generally fivefold by 2h. Preliminary pharmacokinetics of these compounds in humans shows relatively small inter-individual differences and an estimated short half-life varying between ∼38 and 46min for the three groups. Comparison of RIAA analyte ratios within the group indicate that some analytes eliminate relatively faster than others and the formation of metabolite products was observed. Preliminary urine analysis showed only unmodified RIAA analytes were detectable throughout 6h and suggests extensive phase I metabolism of TIAA and HIAA analytes. In authentic forensic casework where clear or green bottled beers are consumed, the identification of reduced IAA groups may provide a novel method to target ingredient congeners consistent with beer ingestion and suggest the type of beer consumed.

  2. Current aspects of auxin biosynthesis in plants.

    PubMed

    Kasahara, Hiroyuki

    2015-01-01

    Auxin is an important plant hormone essential for many aspects of plant growth and development. Indole-3-acetic acid (IAA) is the most studied auxin in plants, and its biosynthesis pathway has been investigated for over 70 years. Although the complete picture of auxin biosynthesis remains to be elucidated, remarkable progress has been made recently in understanding the mechanism of IAA biosynthesis. Genetic and biochemical studies demonstrate that IAA is mainly synthesized from l-tryptophan (Trp) via indole-3-pyruvate by two-step reactions in Arabidopsis. While IAA is also produced from Trp via indole-3-acetaldoxime in Arabidopsis, this pathway likely plays an auxiliary role in plants of the family Brassicaceae. Recent studies suggest that the Trp-independent pathway is not a major route for IAA biosynthesis, but they reveal an important role for a cytosolic indole synthase in this pathway. In this review, I summarize current views and future prospects of IAA biosynthesis research in plants.

  3. Patterns of auxin distribution during gravitational induction of reaction wood in poplar and pine.

    PubMed

    Hellgren, Jenny M; Olofsson, Kjell; Sundberg, Björn

    2004-05-01

    Gravistimulation of tree stems affects wood development by unilaterally inducing wood with modified properties, called reaction wood. Commonly, it also stimulates cambial growth on the reaction wood side. Numerous experiments involving applications of indole-3-acetic acid (IAA) or IAA-transport inhibitors have suggested that reaction wood is induced by a redistribution of IAA around the stem. However, in planta proof for this model is lacking. Therefore, we have mapped endogenous IAA distribution across the cambial region tissues in both aspen (Populus tremula, denoted poplar) and Scots pine (Pinus sylvestris) trees forming reaction wood, using tangential cryosectioning combined with sensitive gas chromatography-mass spectrometry analysis. Moreover, we have documented the kinetics of IAA during reaction wood induction in these species. Our analysis of endogenous IAA demonstrates that reaction wood is formed without any obvious alterations in IAA balance. This is in contrast to gravitropic responses in roots and shoots where a redistribution of IAA has been documented. It is also of interest that cambial growth on the tension wood side was stimulated without an increase in IAA. Taken together, our results suggest a role for signals other than IAA in the reaction wood response, or that the gravitational stimulus interacts with the IAA signal transduction pathway. PMID:15122024

  4. The Impact of Reclassification from Division II to DI-AA and from Division I-AA to I-A on NCAA Member Institutions from 1993 to 2003

    ERIC Educational Resources Information Center

    Frieder, Laura L., Comp.; Fulks, Daniel L., Comp.

    2007-01-01

    Recent years have seen a number of National Collegiate Athletic Association (NCAA) Division II institutions seeking reclassification to Division I-AA and Division I-AA institutions moving to Division I-A. Yet, other schools that seem like natural candidates to reclassify have resisted. The purpose of this study is to investigate the impact of the…

  5. Rapid construction of multiple sgRNA vectors and knockout of the Arabidopsis IAA2 gene using the CRISPR/Cas9 genomic editing technology.

    PubMed

    Dingyuan, Liu; Ting, Qiu; Xiaohui, Ding; Miaomiao, Li; Muyuan, Zhu; Junhui, Wang

    2016-08-01

    IAA2 is a member of the Aux/IAA auxin responsive gene family in Arabidopsis thaliana. No iaa2 mutant has been reported until now, thus hindering its further mechanistic investigations. The normal genomic editing technology of CRISPR/Cas9 (Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) uses only a single guide RNA (sgRNA) to target one site in a specific gene, and the gene knockout efficiency is not high. Instead, multiple sgRNAs can target multiple sites; therefore, the efficiency may be improved. In the present investigation, we used the golden-gate cloning strategy and two rounds of PCR reactions to combine three sgRNAs in the same entry vector. The final expression vector was obtained by LR reactions with the destination vector containing the Cas9 expression cassette. Four out of the six sgRNAs were effective, and we also obtained a lot of insertion and deletion mutations. Compared with one sgRNA approach, multiple sgRNAs displayed higher gene-knockout efficiency and produced more germ-line mutants. Thus, we established a more rapid and efficient method and generated five mutants for further studies of IAA2 functions.

  6. Rapid construction of multiple sgRNA vectors and knockout of the Arabidopsis IAA2 gene using the CRISPR/Cas9 genomic editing technology.

    PubMed

    Dingyuan, Liu; Ting, Qiu; Xiaohui, Ding; Miaomiao, Li; Muyuan, Zhu; Junhui, Wang

    2016-08-01

    IAA2 is a member of the Aux/IAA auxin responsive gene family in Arabidopsis thaliana. No iaa2 mutant has been reported until now, thus hindering its further mechanistic investigations. The normal genomic editing technology of CRISPR/Cas9 (Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) uses only a single guide RNA (sgRNA) to target one site in a specific gene, and the gene knockout efficiency is not high. Instead, multiple sgRNAs can target multiple sites; therefore, the efficiency may be improved. In the present investigation, we used the golden-gate cloning strategy and two rounds of PCR reactions to combine three sgRNAs in the same entry vector. The final expression vector was obtained by LR reactions with the destination vector containing the Cas9 expression cassette. Four out of the six sgRNAs were effective, and we also obtained a lot of insertion and deletion mutations. Compared with one sgRNA approach, multiple sgRNAs displayed higher gene-knockout efficiency and produced more germ-line mutants. Thus, we established a more rapid and efficient method and generated five mutants for further studies of IAA2 functions. PMID:27531614

  7. DAO1 catalyzes temporal and tissue-specific oxidative inactivation of auxin in Arabidopsis thaliana.

    PubMed

    Zhang, Jun; Lin, Jinshan Ella; Harris, Chinchu; Campos Mastrotti Pereira, Fernanda; Wu, Fan; Blakeslee, Joshua J; Peer, Wendy Ann

    2016-09-27

    Tight homeostatic regulation of the phytohormone auxin [indole-3-acetic acid (IAA)] is essential to plant growth. Auxin biosynthetic pathways and the processes that inactivate auxin by conjugation to amino acids and sugars have been thoroughly characterized. However, the enzyme that catalyzes oxidation of IAA to its primary catabolite 2-oxindole-3-acetic acid (oxIAA) remains uncharacterized. Here, we show that DIOXYGENASE FOR AUXIN OXIDATION 1 (DAO1) catalyzes formation of oxIAA in vitro and in vivo and that this mechanism regulates auxin homeostasis and plant growth. Null dao1-1 mutants contain 95% less oxIAA compared with wild type, and complementation of dao1 restores wild-type oxIAA levels, indicating that DAO1 is the primary IAA oxidase in seedlings. Furthermore, dao1 loss of function plants have altered morphology, including larger cotyledons, increased lateral root density, delayed sepal opening, elongated pistils, and reduced fertility in the primary inflorescence stem. These phenotypes are tightly correlated with DAO1 spatiotemporal expression patterns as shown by DAO1pro:β-glucuronidase (GUS) activity and DAO1pro:YFP-DAO1 signals, and transformation with DAO1pro:YFP-DAO1 complemented the mutant phenotypes. The dominant dao1-2D mutant has increased oxIAA levels and decreased stature with shorter leaves and inflorescence stems, thus supporting DAO1 IAA oxidase function in vivo. A second isoform, DAO2, is very weakly expressed in seedling root apices. Together, these data confirm that IAA oxidation by DAO1 is the principal auxin catabolic process in Arabidopsis and that localized IAA oxidation plays a role in plant morphogenesis. PMID:27651492

  8. DAO1 catalyzes temporal and tissue-specific oxidative inactivation of auxin in Arabidopsis thaliana.

    PubMed

    Zhang, Jun; Lin, Jinshan Ella; Harris, Chinchu; Campos Mastrotti Pereira, Fernanda; Wu, Fan; Blakeslee, Joshua J; Peer, Wendy Ann

    2016-09-27

    Tight homeostatic regulation of the phytohormone auxin [indole-3-acetic acid (IAA)] is essential to plant growth. Auxin biosynthetic pathways and the processes that inactivate auxin by conjugation to amino acids and sugars have been thoroughly characterized. However, the enzyme that catalyzes oxidation of IAA to its primary catabolite 2-oxindole-3-acetic acid (oxIAA) remains uncharacterized. Here, we show that DIOXYGENASE FOR AUXIN OXIDATION 1 (DAO1) catalyzes formation of oxIAA in vitro and in vivo and that this mechanism regulates auxin homeostasis and plant growth. Null dao1-1 mutants contain 95% less oxIAA compared with wild type, and complementation of dao1 restores wild-type oxIAA levels, indicating that DAO1 is the primary IAA oxidase in seedlings. Furthermore, dao1 loss of function plants have altered morphology, including larger cotyledons, increased lateral root density, delayed sepal opening, elongated pistils, and reduced fertility in the primary inflorescence stem. These phenotypes are tightly correlated with DAO1 spatiotemporal expression patterns as shown by DAO1pro:β-glucuronidase (GUS) activity and DAO1pro:YFP-DAO1 signals, and transformation with DAO1pro:YFP-DAO1 complemented the mutant phenotypes. The dominant dao1-2D mutant has increased oxIAA levels and decreased stature with shorter leaves and inflorescence stems, thus supporting DAO1 IAA oxidase function in vivo. A second isoform, DAO2, is very weakly expressed in seedling root apices. Together, these data confirm that IAA oxidation by DAO1 is the principal auxin catabolic process in Arabidopsis and that localized IAA oxidation plays a role in plant morphogenesis.

  9. DAO1 catalyzes temporal and tissue-specific oxidative inactivation of auxin in Arabidopsis thaliana

    PubMed Central

    Zhang, Jun; Lin, Jinshan Ella; Harris, Chinchu; Campos Mastrotti Pereira, Fernanda; Wu, Fan; Blakeslee, Joshua J.; Peer, Wendy Ann

    2016-01-01

    Tight homeostatic regulation of the phytohormone auxin [indole-3-acetic acid (IAA)] is essential to plant growth. Auxin biosynthetic pathways and the processes that inactivate auxin by conjugation to amino acids and sugars have been thoroughly characterized. However, the enzyme that catalyzes oxidation of IAA to its primary catabolite 2-oxindole-3-acetic acid (oxIAA) remains uncharacterized. Here, we show that DIOXYGENASE FOR AUXIN OXIDATION 1 (DAO1) catalyzes formation of oxIAA in vitro and in vivo and that this mechanism regulates auxin homeostasis and plant growth. Null dao1-1 mutants contain 95% less oxIAA compared with wild type, and complementation of dao1 restores wild-type oxIAA levels, indicating that DAO1 is the primary IAA oxidase in seedlings. Furthermore, dao1 loss of function plants have altered morphology, including larger cotyledons, increased lateral root density, delayed sepal opening, elongated pistils, and reduced fertility in the primary inflorescence stem. These phenotypes are tightly correlated with DAO1 spatiotemporal expression patterns as shown by DAO1pro:β-glucuronidase (GUS) activity and DAO1pro:YFP-DAO1 signals, and transformation with DAO1pro:YFP-DAO1 complemented the mutant phenotypes. The dominant dao1-2D mutant has increased oxIAA levels and decreased stature with shorter leaves and inflorescence stems, thus supporting DAO1 IAA oxidase function in vivo. A second isoform, DAO2, is very weakly expressed in seedling root apices. Together, these data confirm that IAA oxidation by DAO1 is the principal auxin catabolic process in Arabidopsis and that localized IAA oxidation plays a role in plant morphogenesis. PMID:27651492

  10. Genome-wide analysis of the auxin-responsive transcriptome downstream of iaa1 and its expression analysis reveal the diversity and complexity of auxin-regulated gene expression.

    PubMed

    Lee, Dong Ju; Park, Jong Wha; Lee, Han Woo; Kim, Jungmook

    2009-01-01

    The AUXIN RESPONSE FACTORs (ARFs) and the Aux/IAA proteins regulate various auxin responses through auxin perception mediated by the F-box proteins TIR1/AFBs. ARFs are transcription factors that modulate expression of auxin response genes and are negatively regulated by the Aux/IAA proteins. To gain insight into the regulatory mechanisms of Aux/IAA-ARF action at the genome level, the transcriptome regulated downstream of iaa1, a stabilized IAA1 mutant protein, was identified using dexamethasone (DEX)-controlled nuclear translocation of iaa1 during the auxin response. The expression of the iaa1-regulated auxin-responsive genes selected from microarray data was analysed with RNA-gel blot analysis and it was shown that auxin-regulated expression of these genes was significantly inhibited by DEX treatment. While cycloheximide-inducible expression of a majority of these genes was also DEX-suppressible, expression of some genes could not be suppressed by treatment with DEX. Expression analysis in a variety of arf mutant backgrounds suggested that all iaa1-regulated auxin-response genes examined are controlled by ARFs to different extents and that the same ARF protein can regulate the expression of these genes in response to auxin in a positive or a negative manner. However, arf mutations did not affect auxin-mediated down-regulation, indicating that ARFs might not play a critical role in down-regulation. The decrease in auxin-responsive gene expression in arf7 arf19 mutants was more severe than that of tir1/afb quadruple mutants. These results show the diversity and complexity of mechanisms of Aux/IAA-ARF- and auxin-regulated gene expression. These data also provide the opportunity for functional analysis of genes mediating the auxin-response downstream of Aux/IAA-ARFs.

  11. An attempt to localize and identify the gravity sensing mechanism of plants

    NASA Technical Reports Server (NTRS)

    Bandurski, R. S.; Schulze, A.; Reinecke, D.

    1985-01-01

    The oxidation and transport of indole-3-acetic acid (IAA) in Zea mays is examined towards an understanding of the gravity-influenced promotion of growth in plants. An enzyme that oxidizes IAA to a nongrowth-promoting species has been partially purified, and determined to be stimulated by a lipoidal factor. Data suggest that the upward transport of IAA in the stele and outward movement from the stele into the mesophyll cortex is metabolically mediated, and possibly affected by the gravitational stimulus. It is postulated that hormone assymmetries can arise by 'potential-gating' of the transport channels between the various plant tissues.

  12. Transcriptome analysis of the rhizosphere bacterium Azospirillum brasilense reveals an extensive auxin response.

    PubMed

    Van Puyvelde, Sandra; Cloots, Lore; Engelen, Kristof; Das, Frederik; Marchal, Kathleen; Vanderleyden, Jos; Spaepen, Stijn

    2011-05-01

    The rhizosphere bacterium Azospirillum brasilense produces the auxin indole-3-acetic acid (IAA) through the indole-3-pyruvate pathway. As we previously demonstrated that transcription of the indole-3-pyruvate decarboxylase (ipdC) gene is positively regulated by IAA, produced by A. brasilense itself or added exogenously, we performed a microarray analysis to study the overall effects of IAA on the transcriptome of A. brasilense. The transcriptomes of A. brasilense wild-type and the ipdC knockout mutant, both cultured in the absence and presence of exogenously added IAA, were compared.Interfering with the IAA biosynthesis/homeostasis in A. brasilense through inactivation of the ipdC gene or IAA addition results in much broader transcriptional changes than anticipated. Based on the multitude of changes observed by comparing the different transcriptomes, we can conclude that IAA is a signaling molecule in A. brasilense. It appears that the bacterium, when exposed to IAA, adapts itself to the plant rhizosphere, by changing its arsenal of transport proteins and cell surface proteins. A striking example of adaptation to IAA exposure, as happens in the rhizosphere, is the upregulation of a type VI secretion system (T6SS) in the presence of IAA. The T6SS is described as specifically involved in bacterium-eukaryotic host interactions. Additionally, many transcription factors show an altered regulation as well, indicating that the regulatory machinery of the bacterium is changing.

  13. vProtein: Identifying Optimal Amino Acid Complements from Plant-Based Foods

    PubMed Central

    Woolf, Peter J.; Fu, Leeann L.; Basu, Avik

    2011-01-01

    Background Indispensible amino acids (IAAs) are used by the body in different proportions. Most animal-based foods provide these IAAs in roughly the needed proportions, but many plant-based foods provide different proportions of IAAs. To explore how these plant-based foods can be better used in human nutrition, we have created the computational tool vProtein to identify optimal food complements to satisfy human protein needs. Methods vProtein uses 1251 plant-based foods listed in the United States Department of Agriculture standard release 22 database to determine the quantity of each food or pair of foods required to satisfy human IAA needs as determined by the 2005 daily recommended intake. The quantity of food in a pair is found using a linear programming approach that minimizes total calories, total excess IAAs, or the total weight of the combination. Results For single foods, vProtein identifies foods with particularly balanced IAA patterns such as wheat germ, quinoa, and cauliflower. vProtein also identifies foods with particularly unbalanced IAA patterns such as macadamia nuts, degermed corn products, and wakame seaweed. Although less useful alone, some unbalanced foods provide unusually good complements, such as Brazil nuts to legumes. Interestingly, vProtein finds no statistically significant bias toward grain/legume pairings for protein complementation. These analyses suggest that pairings of plant-based foods should be based on the individual foods themselves instead of based on broader food group-food group pairings. Overall, the most efficient pairings include sweet corn/tomatoes, apple/coconut, and sweet corn/cherry. The top pairings also highlight the utility of less common protein sources such as the seaweeds laver and spirulina, pumpkin leaves, and lambsquarters. From a public health perspective, many of the food pairings represent novel, low cost food sources to combat malnutrition. Full analysis results are available online at http

  14. Bacterial endophyte Sphingomonas sp. LK11 produces gibberellins and IAA and promotes tomato plant growth.

    PubMed

    Khan, Abdul Latif; Waqas, Muhammad; Kang, Sang-Mo; Al-Harrasi, Ahmed; Hussain, Javid; Al-Rawahi, Ahmed; Al-Khiziri, Salima; Ullah, Ihsan; Ali, Liaqat; Jung, Hee-Young; Lee, In-Jung

    2014-08-01

    Plant growth promoting endophytic bacteria have been identified as potential growth regulators of crops. Endophytic bacterium, Sphingomonas sp. LK11, was isolated from the leaves of Tephrosia apollinea. The pure culture of Sphingomonas sp. LK11 was subjected to advance chromatographic and spectroscopic techniques to extract and isolate gibberellins (GAs). Deuterated standards of [17, 17-(2)H2]-GA4, [17, 17-(2)H2]-GA9 and [17, 17-(2)H2]-GA20 were used to quantify the bacterial GAs. The analysis of the culture broth of Sphingomonas sp. LK11 revealed the existence of physiologically active gibberellins (GA4: 2.97 ± 0.11 ng/ml) and inactive GA9 (0.98 ± 0.15 ng/ml) and GA20 (2.41 ± 0.23). The endophyte also produced indole acetic acid (11.23 ± 0.93 μM/ml). Tomato plants inoculated with endophytic Sphingomonas sp. LK11 showed significantly increased growth attributes (shoot length, chlorophyll contents, shoot, and root dry weights) compared to the control. This indicated that such phyto-hormones-producing strains could help in increasing crop growth. PMID:24994010

  15. Tobacco mosaic virus-directed reprogramming of auxin/indole acetic acid protein transcriptional responses enhances virus phloem loading.

    PubMed

    Collum, Tamara D; Padmanabhan, Meenu S; Hsieh, Yi-Cheng; Culver, James N

    2016-05-10

    Vascular phloem loading has long been recognized as an essential step in the establishment of a systemic virus infection. In this study, an interaction between the replication protein of tobacco mosaic virus (TMV) and phloem-specific auxin/indole acetic acid (Aux/IAA) transcriptional regulators was found to modulate virus phloem loading in an age-dependent manner. Promoter expression studies show that in mature tissues TMV 126/183-kDa-interacting Aux/IAAs predominantly express and accumulate within the nuclei of phloem companion cells (CCs). Furthermore, CC Aux/IAA nuclear localization is disrupted upon infection with an interacting virus. In situ analysis of virus spread shows that the inability to disrupt Aux/IAA CC nuclear localization correlates with a reduced ability to load into the vascular tissue. Subsequent systemic movement assays also demonstrate that a virus capable of disrupting Aux/IAA localization is significantly more competitive at moving out of older plant tissues than a noninteracting virus. Similarly, CC expression and overaccumulation of a degradation-resistant Aux/IAA-interacting protein was found to inhibit TMV accumulation and phloem loading selectively in flowering plants. Transcriptional expression studies demonstrate a role for Aux/IAA-interacting proteins in the regulation of salicylic and jasmonic acid host defense responses as well as virus-specific movement factors, including pectin methylesterase, that are involved in regulating plasmodesmata size-exclusion limits and promoting virus cell-to-cell movement. Combined, these findings indicate that TMV directs the reprogramming of auxin-regulated gene expression within the vascular phloem of mature tissues as a means to enhance phloem loading and systemic spread. PMID:27118842

  16. [Immunocytological localization of IAA in the parenchyma cell and vascular elements in the graft union of Cucurbita pepo/Cucurbita moschata at the early developmental stage].

    PubMed

    Wang, Y Q; Han, J; Jia, W S; Du, Z

    2000-06-01

    Immuno-gold localization of IAA in cells of the graft union in the explant internode graft of Cucurbita pepo/Cucurbita moschata were investigated with electron microscopy. In parenchyma cells near the graft union, the gold particles were mainly accumulated in nucleus, plastid and endoplasmic reticulum, while no gold particles was detected in Golgi body, mitochondrion, cell wall and vacuoles. In the differentiating xylem element, the gold particles were labeled in secondary wall and cytoplasm. In the sieve element gold particles were found in the sieve plate, sieve pore and cytoplasm. There was a dense label of the gold particles in the companion cell. The role of IAA in the differentiation of the vascular elements was discussed.

  17. Indole acetic acid production by fluorescent Pseudomonas spp. from the rhizosphere of Plectranthus amboinicus (Lour.) Spreng. and their variation in extragenic repetitive DNA sequences.

    PubMed

    Sethia, Bedhya; Mustafa, Mariam; Manohar, Sneha; Patil, Savita V; Jayamohan, Nellickal Subramanian; Kumudini, Belur Satyan

    2015-06-01

    Fluorescent Pseudomonas (FP) is a heterogenous group of growth promoting rhizobacteria that regulate plant growth by releasing secondary metabolic compounds viz., indole acetic acid (IAA), siderophores, ammonia and hydrogen cyanide. In the present study, IAA producing FPs from the rhizosphere of Plectranthus amboinicus were characterized morphologically, biochemically and at the molecular level. Molecular identification of the isolates were carried out using Pseudomonas specific primers. The effect of varying time (24, 48, 72 and 96 h), Trp concentrations (100, 200, 300, 400 and 500 μg x ml(-1)), temperature (10, 26, 37 and 50 ± 2 degrees C) and pH (6, 7 and 8) on IAA production by 10 best isolates were studied. Results showed higher IAA production at 72 h incubation, at 300 μg x ml(-1) Trp concentration, temperature 26 ± 2 degrees C and pH 7. TLC with acidified ethyl acetate extract showed that the IAA produced has a similar Rf value to that of the standard IAA. Results of TLC were confirmed by HPLC analysis. Genetic diversity of the isolates was also studied using 40 RAPD and 4 Rep primers. Genetic diversity parameters such as dominance, Shannon index and Simpson index were calculated. Out of 40 RAPD primers tested, 9 (2 OP-D series and 7 OP-E series) were shortlisted for further analysis. Studies using RAPD, ERIC, BOX, REP and GTG5 primers revealed that isolates exhibit significant diversity in repetitive DNA sequences irrespective of the rhizosphere. PMID:26155673

  18. Response to gravity by Zea mays seedlings. I. Time course of the response

    NASA Technical Reports Server (NTRS)

    Bandurski, R. S.; Schulze, A.; Dayanandan, P.; Kaufman, P. B.

    1984-01-01

    Gravistimulation induces an asymmetric distribution of free indole-3-acetic acid (IAA) in the cortex-epidermis of the Zea mays L. cv 'Stowells Evergreen' mesocotyl within 15 minutes, the shortest time tested. IAA was measured by an isotope dilution method as the pentaflurobenzyl ester. The per cent IAA in the lower half of the mescotyl cortex was 56 to 57% at 15, 30, and 90 minutes after stimulus initiation. Curvature is detectable in the mescotyl within 3 minutes after beginning gravitropic stimulation. The rate of curvature of the mesocotyl increases during the first 60 minutes to maximum of about 30 degrees per hour. Thus, the growth asymmetry continues to increase for 45 minutes after hormone asymmetry is established. Free IAA occurs predominantly in the stele of the mesocotyl whereas esterified IAA is mainly in the mesocotyl cortex-epidermis. This compartmentation may permit determining in which tissue the hormone asymmetry arises. Current data suggest the asymmetry originated in the stele.

  19. Space traffic management: The new comprehensive approach for regulating the use of outer space—Results from the 2006 IAA cosmic study

    NASA Astrophysics Data System (ADS)

    Schrogl, Kai-Uwe

    2008-01-01

    October 2007 held two anniversaries: 50 years ago, Sputnik was launched and 40 years ago, the Outer Space Treaty entered into force. The first satellite and the foundation of the legal regime governing outer space mark the two decisive points for the use of outer space and its international regulation. During the past decades, space activities have taken a tremendous development in quantity and scope. Regulation has, however, not been able to keep pace with technology, so that today the legal environment shows more and more shortcomings. This paper argues that the growing problems of space law cannot be solved by "piecemeal engineering" any more but can only be overcome through a "big bang" comprehensive approach for regulating space activities: Space traffic management (STM). The debate on this issue has recently been strongly invigorated by the publication of the IAA Cosmic Study on STM. [IAA "Cosmic Study on Space Traffic Management", Paris 2006, in: edited by C. Contant-Jorgensen (Secretary of the Study Group), P. Lala, K.-U. Schrogl (Coordinators of the Study Group) (Eds.), The Study Group consisted of 16 contributors from numerous countries covering engineering, policy and legal aspects. Download at iaa/Studies/spacetraffic.pdf>[1].

  20. Auxin Is Rapidly Induced by Herbivore Attack and Regulates a Subset of Systemic, Jasmonate-Dependent Defenses1[OPEN

    PubMed Central

    Machado, Ricardo A. R.; Robert, Christelle A. M.; Arce, Carla C. M.; Ferrieri, Abigail P.; Jimenez-Aleman, Guillermo H.

    2016-01-01

    Plant responses to herbivore attack are regulated by phytohormonal networks. To date, the role of the auxin indole-3-acetic acid (IAA) in this context is not well understood. We quantified and manipulated the spatiotemporal patterns of IAA accumulation in herbivore-attacked Nicotiana attenuata plants to unravel its role in the regulation of plant secondary metabolism. We found that IAA is strongly, rapidly, and specifically induced by herbivore attack. IAA is elicited by herbivore oral secretions and fatty acid conjugate elicitors and is accompanied by a rapid transcriptional increase of auxin biosynthetic YUCCA-like genes. IAA accumulation starts 30 to 60 s after local induction and peaks within 5 min after induction, thereby preceding the jasmonate (JA) burst. IAA accumulation does not require JA signaling and spreads rapidly from the wound site to systemic tissues. Complementation and transport inhibition experiments reveal that IAA is required for the herbivore-specific, JA-dependent accumulation of anthocyanins and phenolamides in the stems. In contrast, IAA does not affect the accumulation of nicotine or 7-hydroxygeranyllinalool diterpene glycosides in the same tissue. Taken together, our results uncover IAA as a rapid and specific signal that regulates a subset of systemic, JA-dependent secondary metabolites in herbivore-attacked plants. PMID:27485882

  1. Auxin Is Rapidly Induced by Herbivore Attack and Regulates a Subset of Systemic, Jasmonate-Dependent Defenses.

    PubMed

    Machado, Ricardo A R; Robert, Christelle A M; Arce, Carla C M; Ferrieri, Abigail P; Xu, Shuqing; Jimenez-Aleman, Guillermo H; Baldwin, Ian T; Erb, Matthias

    2016-09-01

    Plant responses to herbivore attack are regulated by phytohormonal networks. To date, the role of the auxin indole-3-acetic acid (IAA) in this context is not well understood. We quantified and manipulated the spatiotemporal patterns of IAA accumulation in herbivore-attacked Nicotiana attenuata plants to unravel its role in the regulation of plant secondary metabolism. We found that IAA is strongly, rapidly, and specifically induced by herbivore attack. IAA is elicited by herbivore oral secretions and fatty acid conjugate elicitors and is accompanied by a rapid transcriptional increase of auxin biosynthetic YUCCA-like genes. IAA accumulation starts 30 to 60 s after local induction and peaks within 5 min after induction, thereby preceding the jasmonate (JA) burst. IAA accumulation does not require JA signaling and spreads rapidly from the wound site to systemic tissues. Complementation and transport inhibition experiments reveal that IAA is required for the herbivore-specific, JA-dependent accumulation of anthocyanins and phenolamides in the stems. In contrast, IAA does not affect the accumulation of nicotine or 7-hydroxygeranyllinalool diterpene glycosides in the same tissue. Taken together, our results uncover IAA as a rapid and specific signal that regulates a subset of systemic, JA-dependent secondary metabolites in herbivore-attacked plants. PMID:27485882

  2. Effects of essential amino acid deficiency: down-regulation of KCC2 and the GABAA receptor; disinhibition in the anterior piriform cortex.

    PubMed

    Sharp, James W; Ross-Inta, Catherine M; Baccelli, Irène; Payne, John A; Rudell, John B; Gietzen, Dorothy W

    2013-11-01

    The anterior piriform cortex (APC) is activated by, and is the brain area most sensitive to, essential (indispensable) amino acid (IAA) deficiency. The APC is required for the rapid (20 min) behavioral rejection of IAA deficient diets and increased foraging, both crucial adaptive functions supporting IAA homeostasis in omnivores. The biochemical mechanisms signaling IAA deficiency in the APC block initiation of translation in protein synthesis via uncharged tRNA and the general amino acid control kinase, general control nonderepressing kinase 2. Yet, how inhibition of protein synthesis activates the APC is unknown. The neuronal K(+) Cl(-) cotransporter, neural potassium chloride co-transporter (KCC2), and GABAA receptors are essential inhibitory elements in the APC with short plasmalemmal half-lives that maintain control in this highly excitable circuitry. After a single IAA deficient meal both proteins were reduced (vs. basal diet controls) in western blots of APC (but not neocortex or cerebellum) and in immunohistochemistry of APC. Furthermore, electrophysiological analyses support loss of inhibitory elements such as the GABAA receptor in this model. As the crucial inhibitory function of the GABAA receptor depends on KCC2 and the Cl(-) transmembrane gradient it establishes, these results suggest that loss of such inhibitory elements contributes to disinhibition of the APC in IAA deficiency. The circuitry of the anterior piriform cortex (APC) is finely balanced between excitatory (glutamate, +) and inhibitory (GABA, -) transmission. GABAA receptors use Cl(-), requiring the neural potassium chloride co-transporter (KCC2). Both are rapidly turning-over proteins, dependent on protein synthesis for repletion. In IAA (indispensable amino acid) deficiency, within 20 min, blockade of protein synthesis prevents restoration of these inhibitors; they are diminished; disinhibition ensues. GCN2 = general control non-derepressing kinase 2, eIF2α = α-subunit of the eukaryotic

  3. Ultrastructure of Sheep Primordial Follicles Cultured in the Presence of Indol Acetic Acid, EGF, and FSH

    PubMed Central

    Andrade, Evelyn Rabelo; Maddox-Hyttel, Poul; Landim-Alvarenga, Fernanda Da Cruz; Viana Silva, José Roberto; Alfieri, Amauri Alcindo; Seneda, Marcelo Marcondes; Figueiredo, José Ricardo; Toniolli, Ricardo

    2011-01-01

    The aim of this study was to investigate the ultrastructural characteristics of primordial follicles after culturing of sheep ovarian cortical slices in the presence of indol acetic acid (IAA), Epidermal Growth Factor (EGF), and FSH. To evaluate ultrastructure of primordial follicles cultured in MEM (control) or in MEM containing IAA, EGF, and FSH, fragments of cultured tissue were processes for transmission electron microscopy. Except in the control, primordial follicles cultured in supplemented media for 6 d were ultrastructurally normal. They had oocyte with intact nucleus and the cytoplasm contained heterogeneous-sized lipid droplets and numerous round or elongated mitochondria with intact parallel cristae were observed. Rough endoplasmic reticulum (RER) was rarely found. The granulosa cells cytoplasm contained a great number of mitochondria and abundant RER. In conclusion, the presence of IAA, EGF, and FSH helped to maintain ultrastructural integrity of sheep primordial follicles cultured in vitro. PMID:21188166

  4. Nordihydroguaiaretic Acid Attenuates the Oxidative Stress-Induced Decrease of CD33 Expression in Human Monocytes

    PubMed Central

    Guzmán-Beltrán, Silvia; Pedraza-Chaverri, José; Gonzalez-Reyes, Susana; Juarez-Figueroa, Ulises E.; Gonzalez, Yolanda

    2013-01-01

    Nordihydroguaiaretic acid (NDGA) is a natural lignan with recognized antioxidant and beneficial properties that is isolated from Larrea tridentata. In this study, we evaluated the effect of NDGA on the downregulation of oxidant stress-induced CD33 in human monocytes (MNs). Oxidative stress was induced by iodoacetate (IAA) or hydrogen peroxide (H2O2) and was evaluated using reactive oxygen species (ROS) production, and cell viability. NDGA attenuates toxicity, ROS production and the oxidative stress-induced decrease of CD33 expression secondary to IAA or H2O2 in human MNs. It was also shown that NDGA (20 μM) attenuates cell death in the THP-1 cell line that is caused by treatment with either IAA or H2O2. These results suggest that NDGA has a protective effect on CD33 expression, which is associated with its antioxidant activity in human MNs. PMID:23533689

  5. Auxin Input Pathway Disruptions Are Mitigated by Changes in Auxin Biosynthetic Gene Expression in Arabidopsis1[W][OPEN

    PubMed Central

    Spiess, Gretchen M.; Hausman, Amanda; Yu, Peng; Cohen, Jerry D.; Rampey, Rebekah A.; Zolman, Bethany K.

    2014-01-01

    Auxin is a phytohormone involved in cell elongation and division. Levels of indole-3-acetic acid (IAA), the primary auxin, are tightly regulated through biosynthesis, degradation, sequestration, and transport. IAA is sequestered in reversible processes by adding amino acids, polyol or simple alcohols, or sugars, forming IAA conjugates, or through a two-carbon elongation forming indole-3-butyric acid. These sequestered forms of IAA alter hormone activity. To gain a better understanding of how auxin homeostasis is maintained, we have generated Arabidopsis (Arabidopsis thaliana) mutants that combine disruptions in the pathways, converting IAA conjugates and indole-3-butyric acid to free IAA. These mutants show phenotypes indicative of low auxin levels, including delayed germination, abnormal vein patterning, and decreased apical dominance. Root phenotypes include changes in root length, root branching, and root hair growth. IAA levels are reduced in the cotyledon tissue but not meristems or hypocotyls. In the combination mutants, auxin biosynthetic gene expression is increased, particularly in the YUCCA/Tryptophan Aminotransferase of Arabidopsis1 pathway, providing a feedback mechanism that allows the plant to compensate for changes in IAA input pathways and maintain cellular homeostasis. PMID:24891612

  6. Indoleacetic Acid and the Synthesis of Glucanases and Pectic Enzymes

    PubMed Central

    Datko, Anne Harmon; Maclachlan, G. A.

    1968-01-01

    Indoleacetic acid (IAA) and/or inhibitors of DNA, RNA or protein synthesis were added to the apex of decapitated seedlings of Pisum sativum L. var. Alaska. At various times up to 4 days, enzymic protein was extracted from a segment of epicotyl immediately below the apex and assayed for its ability to hydrolyse polysaccharides or their derivatives. With the exception of amylase, the total amounts per segment of all of the tested enzymes increased due to IAA treatment. The development of β-1,4-glucanase (cellulase) activity per unit of protein or fresh weight proceeded according to a typical sigmoid induction curve. Pectinase was formed for about 2 days in control segments and IAA treatment resulted in continued synthesis for at least another 2 days provided cell division took place. β-1,3-glucanase and pectinesterase activities were only enhanced by IAA to the extent that total protein levels increased. Reaction mechanisms for these effects and functions for the enzymes during growth are discussed. PMID:16656834

  7. Protocol: High-throughput and quantitative assays of auxin and auxin precursors from minute tissue samples

    PubMed Central

    2012-01-01

    Background The plant hormone auxin, indole-3-acetic acid (IAA), plays important roles in plant growth and development. The signaling response to IAA is largely dependent on the local concentration of IAA, and this concentration is regulated by multiple mechanisms in plants. Therefore, the precise quantification of local IAA concentration provides insights into the regulation of IAA and its biological roles. Meanwhile, pathways and genes involved in IAA biosynthesis are not fully understood, so it is necessary to analyze the production of IAA at the metabolite level for unbiased studies of IAA biosynthesis. Results We have developed high-throughput methods to quantify plant endogenous IAA and its biosynthetic precursors including indole, tryptophan, indole-3-pyruvic acid (IPyA), and indole-3-butyric acid (IBA). The protocol starts with homogenizing plant tissues with stable-labeled internal standards added, followed by analyte purification using solid phase extraction (SPE) tips and analyte derivatization. The derivatized analytes are finally analyzed by selected reaction monitoring on a gas chromatograph-mass spectrometer (GC-MS/MS) to determine the precise abundance of analytes. The amount of plant tissue required for the assay is small (typically 2–10 mg fresh weight), and the use of SPE tips is simple and convenient, which allows preparation of large sets of samples within reasonable time periods. Conclusions The SPE tips and GC-MS/MS based method enables high-throughput and accurate quantification of IAA and its biosynthetic precursors from minute plant tissue samples. The protocol can be used for measurement of these endogenous compounds using isotope dilution, and it can also be applied to analyze IAA biosynthesis and biosynthetic pathways using stable isotope labeling. The method will potentially advance knowledge of the role and regulation of IAA. PMID:22883136

  8. Translation Start Sequences Affect the Efficiency of Silencing of Agrobacterium tumefaciens T-DNA Oncogenes1

    PubMed Central

    Lee, Hyewon; Humann, Jodi L.; Pitrak, Jennifer S.; Cuperus, Josh T.; Parks, T. Dawn; Whistler, Cheryl A.; Mok, Machteld C.; Ream, L. Walt

    2003-01-01

    Agrobacterium tumefaciens oncogenes cause transformed plant cells to overproduce auxin and cytokinin. Two oncogenes encode enzymes that convert tryptophan to indole-3-acetic acid (auxin): iaaM (tryptophan mono-oxygenase) and iaaH (indole-3-acetamide hydrolase). A third oncogene (ipt) encodes AMP isopentenyl transferase, which produces cytokinin (isopentenyl-AMP). Inactivation of ipt and iaaM (or iaaH) abolishes tumorigenesis. Because adequate means do not exist to control crown gall, we created resistant plants by introducing transgenes designed to elicit posttranscriptional gene silencing (PTGS) of iaaM and ipt. Transgenes that elicit silencing trigger sequence-specific destruction of the inducing RNA and messenger RNAs with related sequences. Although PTGS has proven effective against a variety of target genes, we found that a much higher percentage of transgenic lines silenced iaaM than ipt, suggesting that transgene sequences influenced the effectiveness of PTGS. Sequences required for oncogene silencing included a translation start site. A transgene encoding a translatable sense-strand RNA from the 5′ end of iaaM silenced the iaaM oncogene, but deletion of the translation start site abolished the ability of the transgene to silence iaaM. Silencing A. tumefaciens T-DNA oncogenes is a new and effective method to produce plants resistant to crown gall disease. PMID:12972655

  9. IAA Space Exploration Conference

    NASA Technical Reports Server (NTRS)

    Davis, Jeffrey R.; Richard Elizabeth E.

    2014-01-01

    The NASA Human Health and Performance Center (NHHPC) was established in October 2010 to facilitate development of partnerships and collaborative projects in human health and performance with a focus on Earthspace benefits. The membership, which now stands at over 135 members from around the world, was developed to span the government, academic, industry and non-profit sectors, making the NHHPC a global convener in human health and performance. International members include organizations from Germany, the United Kingdom, Spain, Japan, South Africa, and India. The virtual center facilitates sharing of best practices and development of collaborative opportunities through a variety of vehicles, including annual in-person workshops, Innovation Lecture Series and Member to Member Connect webcasts, quarterly electronic newsletters, web postings, and electronic member announcements. The NHHPC has conducted four workshops leading to several collaborative projects between members, with the most recent workshop held focusing on new organizational business models for accelerating innovation. This short paper will discuss how the NHHPC facilitates partnerships and the collaborative research and technology developments projects with applications to both the NASA mission and life on Earth.

  10. Investigating organic molecules responsible of auxin-like activity of humic acid fraction extracted from vermicompost.

    PubMed

    Scaglia, Barbara; Nunes, Ramom Rachide; Rezende, Maria Olímpia Oliveira; Tambone, Fulvia; Adani, Fabrizio

    2016-08-15

    This work studied the auxin-like activity of humic acids (HA) obtained from vermicomposts produced using leather wastes plus cattle dung at different maturation stages (fresh, stable and mature). Bioassays were performed by testing HA concentrations in the range of 100-6000mgcarbonL(-1). (13)C CPMAS-NMR and GC-MS instrumental methods were used to assess the effect of biological processes and starting organic mixtures on HA composition. Not all HAs showed IAA-like activity and in general, IAA-like activity increased with the length of the vermicomposting process. The presence of leather wastes was not necessary to produce the auxin-like activity of HA, since HA extracted from a mix of cattle manure and sawdust, where no leather waste was added, showed IAA-like activity as well. CPMAS (13)CNMR revealed that HAs were similar independently of the mix used and that the humification process involved the increasing concentration of pre-existing alkali soluble fractions in the biomass. GC/MS allowed the identification of the molecules involved in IAA-like effects: carboxylic acids and amino acids. The concentration of active molecules, rather than their simple presence in HA, determined the bio-stimulating effect, and a good linear regression between auxin-like activity and active stimulating molecules concentration was found (R(2)=-0.85; p<0.01, n=6). PMID:27100009

  11. Investigating organic molecules responsible of auxin-like activity of humic acid fraction extracted from vermicompost.

    PubMed

    Scaglia, Barbara; Nunes, Ramom Rachide; Rezende, Maria Olímpia Oliveira; Tambone, Fulvia; Adani, Fabrizio

    2016-08-15

    This work studied the auxin-like activity of humic acids (HA) obtained from vermicomposts produced using leather wastes plus cattle dung at different maturation stages (fresh, stable and mature). Bioassays were performed by testing HA concentrations in the range of 100-6000mgcarbonL(-1). (13)C CPMAS-NMR and GC-MS instrumental methods were used to assess the effect of biological processes and starting organic mixtures on HA composition. Not all HAs showed IAA-like activity and in general, IAA-like activity increased with the length of the vermicomposting process. The presence of leather wastes was not necessary to produce the auxin-like activity of HA, since HA extracted from a mix of cattle manure and sawdust, where no leather waste was added, showed IAA-like activity as well. CPMAS (13)CNMR revealed that HAs were similar independently of the mix used and that the humification process involved the increasing concentration of pre-existing alkali soluble fractions in the biomass. GC/MS allowed the identification of the molecules involved in IAA-like effects: carboxylic acids and amino acids. The concentration of active molecules, rather than their simple presence in HA, determined the bio-stimulating effect, and a good linear regression between auxin-like activity and active stimulating molecules concentration was found (R(2)=-0.85; p<0.01, n=6).

  12. A comparison of gamma-aminobutyric acid and the semi-rigid analogues 4-aminotetrolic acid, 4-aminocrotonic acid and imidazole-4-acetic acid on the isolated superior cervical ganglion of the rat.

    PubMed Central

    Bowery, N G; Jones, G P

    1976-01-01

    1 The rat superior cervical ganglion possesses receptors for gamma-aminobutyric acid (GABA). This can be demonstrated in vitro by recording the changes in ganglionic surface potential which occur after the addition of GABA to the bathing solution. 2 The action of three conformationally-restricted analogues of GABA namely 4-aminotetrolic acid (4-ATA), trans 4-aminocrotonic acid (4-ACA) and imidazole-4-acetic acid (IAA) have been examined for activity at this peripheral receptor. 3 All three analogues depolarized the ganglion in a manner similar to GABA. Their actions were transient and were 'occluded' by GABA; also the dose-response curve in each case was parallel to that of GABA. Molar potencies relative to GABA (= 1) were 4-ACA = 1.48, IAA = 0.100, 4-ATA = 0.0028. 4 The action of each analogue could be blocked by the GABA antagonists bicuculline and tetramethylenedisulphotetramine at doses which had relatively little effect on responses to the cholinomimetic carbachol. 5 4-ACA and IAA (1 mM) significantly reduced the ganglionic accumulation of [3H]-GABA (0.2 muM) by 88% and 58% respectively whereas 4-ATA (1 mM), caused no significant reduction in [3H]-GABA accumulation. PMID:1260178

  13. Retention, Molecular Evolution, and Expression Divergence of the Auxin/Indole Acetic Acid and Auxin Response Factor Gene Families in Brassica Rapa Shed Light on Their Evolution Patterns in Plants.

    PubMed

    Huang, Zhinan; Duan, Weike; Song, Xiaoming; Tang, Jun; Wu, Peng; Zhang, Bei; Hou, Xilin

    2016-02-01

    Auxin/indole acetic acids (Aux/IAAs) and auxin response factors (ARFs), major components of the Aux signaling network, are involved in many developmental processes in plants. Investigating their evolution will provide new sight on the relationship between the molecular evolution of these genes and the increasing morphotypes of plants. We constructed comparative analyses of the retention, structure, expansion, and expression patterns of Aux/IAAs and ARFs in Brassica rapa and their evolution in eight other plant species, including algae, bryophytes, lycophytes, and angiosperms. All 33 of the ARFs, including 1 ARF-like (AL) (a type of ARF-like protein) and 53 Aux/IAAs, were identified in the B. rapa genome. The genes mainly diverged approximately 13 Ma. After the split, no Aux/IAA was completely lost, and they were more preferentially retained than ARFs. In land plants, compared with ARFs, which increased in stability, Aux/IAAs expanded more rapidly and were under more relaxed selective pressure. Moreover, BraIAAs were expressed in a more tissue-specific fashion than BraARFs and demonstrated functional diversification during gene duplication under different treatments, which enhanced the cooperative interaction of homologs to help plants adapt to complex environments. In addition, ALs existed widely and had a closer relationship with ARFs, suggesting that ALs might be the initial structure of ARFs. Our results suggest that the rapid expansion and preferential retention of Aux/IAAs are likely paralleled by the increasingly complex morphotypes in Brassicas and even in land plants. Meanwhile, the data support the hypothesis that the PB1 domain plays a key role in the origin of both Aux/IAAs and ARFs. PMID:26721260

  14. Retention, Molecular Evolution, and Expression Divergence of the Auxin/Indole Acetic Acid and Auxin Response Factor Gene Families in Brassica Rapa Shed Light on Their Evolution Patterns in Plants.

    PubMed

    Huang, Zhinan; Duan, Weike; Song, Xiaoming; Tang, Jun; Wu, Peng; Zhang, Bei; Hou, Xilin

    2016-02-01

    Auxin/indole acetic acids (Aux/IAAs) and auxin response factors (ARFs), major components of the Aux signaling network, are involved in many developmental processes in plants. Investigating their evolution will provide new sight on the relationship between the molecular evolution of these genes and the increasing morphotypes of plants. We constructed comparative analyses of the retention, structure, expansion, and expression patterns of Aux/IAAs and ARFs in Brassica rapa and their evolution in eight other plant species, including algae, bryophytes, lycophytes, and angiosperms. All 33 of the ARFs, including 1 ARF-like (AL) (a type of ARF-like protein) and 53 Aux/IAAs, were identified in the B. rapa genome. The genes mainly diverged approximately 13 Ma. After the split, no Aux/IAA was completely lost, and they were more preferentially retained than ARFs. In land plants, compared with ARFs, which increased in stability, Aux/IAAs expanded more rapidly and were under more relaxed selective pressure. Moreover, BraIAAs were expressed in a more tissue-specific fashion than BraARFs and demonstrated functional diversification during gene duplication under different treatments, which enhanced the cooperative interaction of homologs to help plants adapt to complex environments. In addition, ALs existed widely and had a closer relationship with ARFs, suggesting that ALs might be the initial structure of ARFs. Our results suggest that the rapid expansion and preferential retention of Aux/IAAs are likely paralleled by the increasingly complex morphotypes in Brassicas and even in land plants. Meanwhile, the data support the hypothesis that the PB1 domain plays a key role in the origin of both Aux/IAAs and ARFs.

  15. Retention, Molecular Evolution, and Expression Divergence of the Auxin/Indole Acetic Acid and Auxin Response Factor Gene Families in Brassica Rapa Shed Light on Their Evolution Patterns in Plants

    PubMed Central

    Huang, Zhinan; Duan, Weike; Song, Xiaoming; Tang, Jun; Wu, Peng; Zhang, Bei; Hou, Xilin

    2016-01-01

    Auxin/indole acetic acids (Aux/IAAs) and auxin response factors (ARFs), major components of the Aux signaling network, are involved in many developmental processes in plants. Investigating their evolution will provide new sight on the relationship between the molecular evolution of these genes and the increasing morphotypes of plants. We constructed comparative analyses of the retention, structure, expansion, and expression patterns of Aux/IAAs and ARFs in Brassica rapa and their evolution in eight other plant species, including algae, bryophytes, lycophytes, and angiosperms. All 33 of the ARFs, including 1 ARF-like (AL) (a type of ARF-like protein) and 53 Aux/IAAs, were identified in the B. rapa genome. The genes mainly diverged approximately 13 Ma. After the split, no Aux/IAA was completely lost, and they were more preferentially retained than ARFs. In land plants, compared with ARFs, which increased in stability, Aux/IAAs expanded more rapidly and were under more relaxed selective pressure. Moreover, BraIAAs were expressed in a more tissue-specific fashion than BraARFs and demonstrated functional diversification during gene duplication under different treatments, which enhanced the cooperative interaction of homologs to help plants adapt to complex environments. In addition, ALs existed widely and had a closer relationship with ARFs, suggesting that ALs might be the initial structure of ARFs. Our results suggest that the rapid expansion and preferential retention of Aux/IAAs are likely paralleled by the increasingly complex morphotypes in Brassicas and even in land plants. Meanwhile, the data support the hypothesis that the PB1 domain plays a key role in the origin of both Aux/IAAs and ARFs. PMID:26721260

  16. Validation of MIPAS IMK-IAA Temperature, Water Vapor, and Ozone Profiles with MOHAVE-2009 Campaign Measurements

    NASA Technical Reports Server (NTRS)

    Stiller, Gabrielle; Kiefer, M.; Eckert, E.; von Clarmann, T.; Kellmann, S.; Garcia-Comas, M.; Funke, B.; Leblanc, T.; Fetzer, E.; Froidevaux, L.; Gomez, M.; Hall, E.; Hurst, D.; Jordan, A.; Kampfer, N.; Lambert, A.; McDermid, I. S.; McGee, T.; Miloshevich, L.; Nedoluha, G.; Read, W.; Schneider, M.; Schwartz, M.; Straub, C.; Toon, G.; Twigg, L. W.; Walker, K.; Whiteman, D. N.

    2012-01-01

    MIPAS observations of temperature, water vapor, and ozone in October 2009 as derived with the scientific level-2 processor run by Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK) and CSIC, Instituto de Astrofisica de Andalucia (IAA) and retrieved from version 4.67 level-1b data have been compared to co-located field campaign observations obtained during the MOHAVE-2009 campaign at the Table Mountain Facility near Pasadena, California in October 2009. The MIPAS measurements were validated regarding any potential biases of the profiles, and with respect to their precision estimates. The MOHAVE-2009 measurement campaign provided measurements of atmospheric profiles of temperature, water vapor/relative humidity, and ozone from the ground to the mesosphere by a suite of instruments including radiosondes, ozonesondes, frost point hygrometers, lidars, microwave radiometers and Fourier transform infrared (FTIR) spectrometers. For MIPAS temperatures (version V4O_T_204), no significant bias was detected in the middle stratosphere; between 22 km and the tropopause MIPAS temperatures were found to be biased low by up to 2 K, while below the tropopause, they were found to be too high by the same amount. These findings confirm earlier comparisons of MIPAS temperatures to ECMWF data which revealed similar differences. Above 12 km up to 45 km, MIPAS water vapor (version V4O_H2O_203) is well within 10% of the data of all correlative instruments. The well-known dry bias of MIPAS water vapor above 50 km due to neglect of non-LTE effects in the current retrievals has been confirmed. Some instruments indicate that MIPAS water vapor might be biased high by 20 to 40% around 10 km (or 5 km below the tropopause), but a consistent picture from all comparisons could not be derived. MIPAS ozone (version V4O_O3_202) has a high bias of up to +0.9 ppmv around 37 km which is due to a non-identified continuum like radiance contribution. No further

  17. Auxin responsiveness of the MONOPTEROS-BODENLOS module in primary root initiation critically depends on the nuclear import kinetics of the Aux/IAA inhibitor BODENLOS.

    PubMed

    Herud, Ole; Weijers, Dolf; Lau, Steffen; Jürgens, Gerd

    2016-01-01

    Primary root formation in early embryogenesis of Arabidopsis thaliana is initiated with the specification of a single cell called hypophysis. This initial step requires the auxin-dependent release of the transcription factor MONOPTEROS (MP, also known as ARF5) from its inhibition by the Aux/IAA protein BODENLOS (BDL, also known as IAA12). Auxin-insensitive bdl mutant embryos and mp loss-of-function embryos fail to specify the hypophysis, giving rise to rootless seedlings. A suppressor screen of rootless bdl mutant seedlings yielded a mutation in the nuclear import receptor IMPORTIN-ALPHA 6 (IMPα6) that promoted primary root formation through rescue of the embryonic hypophysis defects, without causing additional phenotypic changes. Aux/IAA proteins are continually synthesized and degraded, which is essential for rapid transcriptional responses to changing auxin concentrations. Nuclear translocation of bdl:3×GFP was slowed down in impα6 mutants as measured by fluorescence recovery after photobleaching (FRAP) analysis, which correlated with the reduced inhibition of MP by bdl in transient expression assays in impα6 knock-down protoplasts. The MP-BDL module acts like an auxin-triggered genetic switch because MP activates its own expression as well as the expression of its inhibitor BDL. Using an established simulation model, we determined that the reduced nuclear translocation rate of BDL in impα6 mutant embryos rendered the auxin-triggered switch unstable, impairing the fast response to changes in auxin concentration. Our results suggest that the instability of the inhibitor BDL necessitates a fast nuclear uptake in order to reach the critical threshold level required for auxin responsiveness of the MP-BDL module in primary root initiation.

  18. Structures and functions of insect arylalkylamine N-acetyltransferase (iaaNAT); a key enzyme for physiological and behavioral switch in arthropods

    PubMed Central

    Hiragaki, Susumu; Suzuki, Takeshi; Mohamed, Ahmed A. M.; Takeda, Makio

    2015-01-01

    The evolution of N-acetyltransfeases (NATs) seems complex. Vertebrate arylalkylamine N-acetyltransferase (aaNAT) has been extensively studied since it leads to the synthesis of melatonin, a multifunctional neurohormone prevalent in photoreceptor cells, and is known as a chemical token of the night. Melatonin also serves as a scavenger for reactive oxygen species. This is also true with invertebrates. NAT therefore has distinct functional implications in circadian function, as timezymes (aaNAT), and also xenobiotic reactions (arylamine NAT or simply NAT). NATs belong to a broader enzyme group, the GCN5-related N-acetyltransferase superfamily. Due to low sequence homology and a seemingly fast rate of structural differentiation, the nomenclature for NATs can be confusing. The advent of bioinformatics, however, has helped to classify this group of enzymes; vertebrates have two distinct subgroups, the timezyme type and the xenobiotic type, which has a wider substrate range including imidazolamine, pharmacological drugs, environmental toxicants and even histone. Insect aaNAT (iaaNAT) form their own clade in the phylogeny, distinct from vertebrate aaNATs. Arthropods are unique, since the phylum has exoskeleton in which quinones derived from N-acetylated monoamines function in coupling chitin and arthropodins. Monoamine oxidase (MAO) activity is limited in insects, but NAT-mediated degradation prevails. However, unexpectedly iaaNAT occurs not only among arthropods but also among basal deuterostomia, and is therefore more apomorphic. Our analyses illustrate that iaaNATs has unique physiological roles but at the same time it plays a role in a timezyme function, at least in photoperiodism. Photoperiodism has been considered as a function of circadian system but the detailed molecular mechanism is not well understood. We propose a molecular hypothesis for photoperiodism in Antheraea pernyi based on the transcription regulation of NAT interlocked by the circadian system

  19. Early embryo development in Fucus distichus is auxin sensitive

    NASA Technical Reports Server (NTRS)

    Basu, Swati; Sun, Haiguo; Brian, Leigh; Quatrano, Ralph L.; Muday, Gloria K.

    2002-01-01

    Auxin and polar auxin transport have been implicated in controlling embryo development in land plants. The goal of these studies was to determine if auxin and auxin transport are also important during the earliest stages of development in embryos of the brown alga Fucus distichus. Indole-3-acetic acid (IAA) was identified in F. distichus embryos and mature tissues by gas chromatography-mass spectroscopy. F. distichus embryos accumulate [(3)H]IAA and an inhibitor of IAA efflux, naphthylphthalamic acid (NPA), elevates IAA accumulation, suggesting the presence of an auxin efflux protein complex similar to that found in land plants. F. distichus embryos normally develop with a single unbranched rhizoid, but growth on IAA leads to formation of multiple rhizoids and growth on NPA leads to formation of embryos with branched rhizoids, at concentrations that are active in auxin accumulation assays. The effects of IAA and NPA are complete before 6 h after fertilization (AF), which is before rhizoid germination and cell division. The maximal effects of IAA and NPA are between 3.5 and 5 h AF and 4 and 5.5 h AF, respectively. Although, the location of the planes of cell division was significantly altered in NPA- and IAA-treated embryos, these abnormal divisions occurred after abnormal rhizoid initiation and branching was observed. The results of this study suggest that auxin acts in the formation of apical basal patterns in F. distichus embryo development.

  20. Early Embryo Development in Fucus distichus Is Auxin Sensitive1

    PubMed Central

    Basu, Swati; Sun, Haiguo; Brian, Leigh; Quatrano, Ralph L.; Muday, Gloria K.

    2002-01-01

    Auxin and polar auxin transport have been implicated in controlling embryo development in land plants. The goal of these studies was to determine if auxin and auxin transport are also important during the earliest stages of development in embryos of the brown alga Fucus distichus. Indole-3-acetic acid (IAA) was identified in F. distichus embryos and mature tissues by gas chromatography-mass spectroscopy. F. distichus embryos accumulate [3H]IAA and an inhibitor of IAA efflux, naphthylphthalamic acid (NPA), elevates IAA accumulation, suggesting the presence of an auxin efflux protein complex similar to that found in land plants. F. distichus embryos normally develop with a single unbranched rhizoid, but growth on IAA leads to formation of multiple rhizoids and growth on NPA leads to formation of embryos with branched rhizoids, at concentrations that are active in auxin accumulation assays. The effects of IAA and NPA are complete before 6 h after fertilization (AF), which is before rhizoid germination and cell division. The maximal effects of IAA and NPA are between 3.5 and 5 h AF and 4 and 5.5 h AF, respectively. Although, the location of the planes of cell division was significantly altered in NPA- and IAA-treated embryos, these abnormal divisions occurred after abnormal rhizoid initiation and branching was observed. The results of this study suggest that auxin acts in the formation of apical basal patterns in F. distichus embryo development. PMID:12226509

  1. The auxin concentration in sixteen Chinese marine algae

    NASA Astrophysics Data System (ADS)

    Han, Lijun

    2006-09-01

    The author determined the occurrence of indole-3-acetic acid in sixteen Chinese marine algae collected from the east coast of China with fluorescence spectrophotometry (FS) and wheat coleoptile bioanalysis methods (WCB). The concentration of indole-3-acetic acid (IAA) presented was from 1.1 46.9 ng/g Fw (fresh weight) with FS and 5.3 110.2 ng/g Fw with WCB. The results by the two methods were in the orders of 10-3 103 ng/g Fw reported previously from multiple references.

  2. Red light-regulated growth. I. Changes in the abundance of indoleacetic acid and a 22-kilodalton auxin-binding protein in the maize mesocotyl

    NASA Technical Reports Server (NTRS)

    Jones, A. M.; Cochran, D. S.; Lamerson, P. M.; Evans, M. L.; Cohen, J. D.

    1991-01-01

    We examined the changes in the levels of indoleacetic acid (IAA), IAA esters, and a 22-kilodalton subunit auxin-binding protein (ABP1) in apical mesocotyl tissue of maize (Zea mays L.) during continuous red light (R) irradiation. These changes were compared with the kinetics of R-induced growth inhibition in the same tissue. Upon the onset of continuous irradiation, growth decreased in a continuous manner following a brief lag period. The decrease in growth continued for 5 hours, then remained constant at 25% of the dark rate. The abundance of ABP1 and the level of free IAA both decreased in the mesocotyl. Only the kinetics of the decrease in IAA within the apical mesocotyl correlated with the initial change in growth, although growth continued to decrease even after IAA content reached its final level, 50% of the dark control. This decrease in IAA within the mesocotyl probably occurs primarily by a change in its transport within the shoot since auxin applied as a pulse move basipetally in R-irradiated tissue at the same rate but with half the area as dark control tissue. In situ localization of auxin in etiolated maize shoots revealed that R-irradiated shoots contained less auxin in the epidermis than the dark controls. Irradiated mesocotyl grew 50% less than the dark controls even when incubated in an optimal level of auxin. However, irradiated and dark tissue contained essentially the same amount of radioactivity after incubation in [14C]IAA indicating that the light treatment does not affect the uptake into the tissue through the cut end, although it is possible that a small subset of cells within the mesocotyl is affected. These observations support the hypothesis that R causes a decrease in the level of auxin in epidermal cells of the mesocotyl, consequently constraining the growth of the entire mesocotyl.

  3. Effects of N(6)-benzylaminopurine and Indole Acetic Acid on In Vitro Shoot Multiplication, Nodule-like Meristem Proliferation and Plant Regeneration of Malaysian Bananas (Musa spp.).

    PubMed

    Sipen, Philip; Davey, Michael R

    2012-12-01

    Different concentrations of N(6)-benzylaminopurine (BAP) and indole acetic acid (IAA) in Murashige and Skoog based medium were assessed for their effects on shoot multiplication, nodule-like meristem proliferation and plant regeneration of the Malaysian banana cultivars Pisang Mas, Pisang Nangka, Pisang Berangan and Pisang Awak. BAP at 1-14 mg L(-1) with or without 0.2 mg L(-1) IAA, or BAP at 7-14 mg L(-1) with the same concentration of IAA, was evaluated for shoot multiplication from shoot tips and the proliferation of nodule-like meristems from scalps, respectively. Plant regeneration from scalps was assessed using 1 mg L(-1) BAP and 0.2 mg L(-1) IAA separately, or a combination of these two growth regulators. Data on shoot multiplication, the proliferation of nodule-like meristems with associated plant regeneration were recorded after 30 days of culture. A maximum of 5 shoots per original shoot tip was achieved on medium supplemented with BAP at 5 mg L(-1) (Pisang Nangka), 6 mg L(-1) (Pisang Mas and Pisang Berangan), or 7 mg L(-1) (Pisang Awak), with 0.2 mg L(-1) IAA. BAP at 11 mg L(-1) with 0.2 mg L(-1) IAA induced the most highly proliferating nodule-like meristems in the four banana cultivars. Plant regeneration from scalps was optimum in all cases on medium containing 1 mg L(-1) BAP and 0.2 mg L(-1) IAA. This is the first report on the successful induction of highly proliferating nodule-like meristems and plant regeneration from scalps of the Malaysian banana cultivars Pisang Mas, Pisang Nangka, Pisang Berangan and Pisang Awak.

  4. LATERAL ROOT PRIMORDIA 1 of maize acts as a transcriptional activator in auxin signalling downstream of the Aux/IAA gene rootless with undetectable meristem 1.

    PubMed

    Zhang, Yanxiang; von Behrens, Inga; Zimmermann, Roman; Ludwig, Yvonne; Hey, Stefan; Hochholdinger, Frank

    2015-07-01

    Only little is known about target genes of auxin signalling downstream of the Aux/IAA-ARF module. In the present study, it has been demonstrated that maize lateral root primordia 1 (lrp1) encodes a transcriptional activator that is directly regulated by the Aux/IAA protein ROOTLESS WITH UNDETECTABLE MERISTEM 1 (RUM1). Expression of lrp1 is confined to early root primordia and meristems and is auxin-inducible. Based on its primary protein structure, LRP1 is predicted to be a transcription factor. This notion is supported by exclusive LRP1 localization in the nucleus and its ability to activate downstream gene activity. Based on the observation that lrp1 transcription is completely repressed in the semi-dominant gain of function mutant rum1, it was demonstrated that the lrp1 promoter is a direct target of RUM1 proteins. Subsequently, promoter activation assays indicated that RUM1 represses the expression of a GFP reporter fused to the native promoter of lrp1. Constitutive repression of lrp1 in rum1 mutants is a consequence of the stability of mutated rum1 proteins which cannot be degraded by the proteasome and thus constitutively bind to the lrp1 promoter and repress transcription. Taken together, the repression of the transcriptional activator lrp1 by direct binding of RUM1 to its promoter, together with specific expression of lrp1 in root meristems, suggests a function in maize root development via the RUM1-dependent auxin signalling pathway. PMID:25911745

  5. Rapid auxin-mediated changes in the proteome of the epidermal cells in rye coleoptiles: Implications for the initiation of growth

    PubMed Central

    Deng, Z.; Xu, S.; Chalkley, R. J.; Oses-Prieto, J. A.; Burlingame, A. L.; Wang, Z.-Y.; Kutschera, U.

    2011-01-01

    In axial organs of juvenile plants, the phytohormone auxin (indole-3-acetic acid, IAA) rapidly allows cell wall loosening and hence promotes turgor-driven elongation. In this study, we used rye (Secale cereale) coleoptile sections to investigate possible effects of IAA on the proteome of cells. In a first set of experiments, we document that IAA causes organ elongation via promotion of expansion of the rigid outer wall of the outer epidermis. A quantitative comparison of the proteome (membrane-associated proteins), using two-dimensional difference gel electrophoresis (2-D DIGE), revealed that, within 2 h of auxin treatment, at least 16 protein spots were up- or down-regulated by IAA. These proteins were identified using reverse-phase liquid chromatography electrospray tandem mass spectrometry. Four of these proteins were detected in the growth-controlling outer epidermis and were further analysed. One epidermal polypeptide, a small Ras-related GTP-binding protein, was rapidly down-regulated by IAA (after 0.5 h of incubation) by −35% compared to the control. Concomitantly, a subunit of the 26S proteasome was up-regulated by IAA (+30% within 1 h). In addition, this protein displayed IAA-mediated post-translational modification. The implications of these rapid auxin effects with respect to signal transduction and IAA-mediated secretion of glycoproteins (osmiophilic nano-particles) into the growth-controlling outer epidermal wall are discussed. PMID:22117532

  6. The mechanism by which an asymmetric distribution of plant growth hormone is attained

    NASA Astrophysics Data System (ADS)

    Bandurski, Robert S.; Schulze, Aga; Jensen, Philip; Desrosiers, Mark; Epel, Bernard; Kowalczyk, Stanley

    Zea mays (sweet corn) seedlings attain an asymmetric distribution of the growth hormone indole-3-acetic acid (IAA) within 3 minutes following a gravity stimulus. Both free and esterified IAA (that is total IAA) accumulate to a greater extent in the lower half of the mesocotyl cortex of a horizontally placed seedling than in the upper half. Thus, changes in the ratio of free IAA to ester IAA cannot account for the asymmetric distribution. Our studies demonstrate there is no de novo synthesis of IAA in young seedlings. We conclude that asymmetric IAA distribution is attained by a gravity-induced, potential-regulated gating of the movement of IAA from kernel to shoot and from stele to cortex. As a working theory, which we call the Potential Gating Theory, we propose that perturbation of the plant's bioelectric field, induced by gravity, causes opening and closing of transport channels in the plasmodesmata connecting the vascular stele to the surrounding cortical tissues. This results in asymmetric growth hormone distribution which results in the asymmetric growth characteristic of the gravitropic response.

  7. Auxin production by the plant trypanosomatid Phytomonas serpens and auxin homoeostasis in infected tomato fruits.

    PubMed

    Ienne, Susan; Freschi, Luciano; Vidotto, Vanessa F; De Souza, Tiago A; Purgatto, Eduardo; Zingales, Bianca

    2014-09-01

    Previously we have characterized the complete gene encoding a pyruvate decarboxylase (PDC)/indolepyruvate decarboxylase (IPDC) of Phytomonas serpens, a trypanosomatid highly abundant in tomato fruits. Phylogenetic analyses indicated that the clade that contains the trypanosomatid protein behaves as a sister group of IPDCs of γ-proteobacteria. Since IPDCs are key enzymes in the biosynthesis of the plant hormone indole-3-acetic acid (IAA), the ability for IAA production by P. serpens was investigated. Similar to many microorganisms, the production of IAA and related indolic compounds, quantified by high performance liquid chromatography, increased in P. serpens media in response to amounts of tryptophan. The auxin functionality was confirmed in the hypocotyl elongation assay. In tomato fruits inoculated with P. serpens the concentration of free IAA had no significant variation, whereas increased levels of IAA-amide and IAA-ester conjugates were observed. The data suggest that the auxin produced by the flagellate is converted to IAA conjugates, keeping unaltered the concentration of free IAA. Ethanol also accumulated in P. serpens-conditioned media, as the result of a PDC activity. In the article we discuss the hypothesis of the bifunctionality of P. serpens PDC/IPDC and provide a three-dimensional model of the enzyme.

  8. Hydrolases of the ILR1-like family of Arabidopsis thaliana modulate auxin response by regulating auxin homeostasis in the endoplasmic reticulum.

    PubMed

    Sanchez Carranza, Ana Paula; Singh, Aparajita; Steinberger, Karoline; Panigrahi, Kishore; Palme, Klaus; Dovzhenko, Alexander; Dal Bosco, Cristina

    2016-01-01

    Amide-linked conjugates of indole-3-acetic acid (IAA) have been identified in most plant species. They function in storage, inactivation or inhibition of the growth regulator auxin. We investigated how the major known endogenous amide-linked IAA conjugates with auxin-like activity act in auxin signaling and what role ILR1-like proteins play in this process in Arabidopsis. We used a genetically encoded auxin sensor to show that IAA-Leu, IAA-Ala and IAA-Phe act through the TIR1-dependent signaling pathway. Furthermore, by using the sensor as a free IAA reporter, we followed conjugate hydrolysis mediated by ILR1, ILL2 and IAR3 in plant cells and correlated the activity of the hydrolases with a modulation of auxin response. The conjugate preferences that we observed are in agreement with available in vitro data for ILR1. Moreover, we identified IAA-Leu as an additional substrate for IAR3 and showed that ILL2 has a more moderate kinetic performance than observed in vitro. Finally, we proved that IAR3, ILL2 and ILR1 reside in the endoplasmic reticulum, indicating that in this compartment the hydrolases regulate the rates of amido-IAA hydrolysis which results in activation of auxin signaling. PMID:27063913

  9. Hydrolases of the ILR1-like family of Arabidopsis thaliana modulate auxin response by regulating auxin homeostasis in the endoplasmic reticulum

    PubMed Central

    Sanchez Carranza, Ana Paula; Singh, Aparajita; Steinberger, Karoline; Panigrahi, Kishore; Palme, Klaus; Dovzhenko, Alexander; Dal Bosco, Cristina

    2016-01-01

    Amide-linked conjugates of indole-3-acetic acid (IAA) have been identified in most plant species. They function in storage, inactivation or inhibition of the growth regulator auxin. We investigated how the major known endogenous amide-linked IAA conjugates with auxin-like activity act in auxin signaling and what role ILR1-like proteins play in this process in Arabidopsis. We used a genetically encoded auxin sensor to show that IAA-Leu, IAA-Ala and IAA-Phe act through the TIR1-dependent signaling pathway. Furthermore, by using the sensor as a free IAA reporter, we followed conjugate hydrolysis mediated by ILR1, ILL2 and IAR3 in plant cells and correlated the activity of the hydrolases with a modulation of auxin response. The conjugate preferences that we observed are in agreement with available in vitro data for ILR1. Moreover, we identified IAA-Leu as an additional substrate for IAR3 and showed that ILL2 has a more moderate kinetic performance than observed in vitro. Finally, we proved that IAR3, ILL2 and ILR1 reside in the endoplasmic reticulum, indicating that in this compartment the hydrolases regulate the rates of amido-IAA hydrolysis which results in activation of auxin signaling. PMID:27063913

  10. The branching gene RAMOSUS1 mediates interactions among two novel signals and auxin in pea.

    PubMed

    Foo, Eloise; Bullier, Erika; Goussot, Magali; Foucher, Fabrice; Rameau, Catherine; Beveridge, Christine Anne

    2005-02-01

    In Pisum sativum, the RAMOSUS genes RMS1, RMS2, and RMS5 regulate shoot branching via physiologically defined mobile signals. RMS1 is most likely a carotenoid cleavage enzyme and acts with RMS5 to control levels of an as yet unidentified mobile branching inhibitor required for auxin inhibition of branching. Our work provides molecular, genetic, and physiological evidence that RMS1 plays a central role in a shoot-to-root-to-shoot feedback system that regulates shoot branching in pea. Indole-3-acetic acid (IAA) positively regulates RMS1 transcript level, a potentially important mechanism for regulation of shoot branching by IAA. In addition, RMS1 transcript levels are dramatically elevated in rms3, rms4, and rms5 plants, which do not contain elevated IAA levels. This degree of upregulation of RMS1 expression cannot be achieved in wild-type plants by exogenous IAA application. Grafting studies indicate that an IAA-independent mobile feedback signal contributes to the elevated RMS1 transcript levels in rms4 plants. Therefore, the long-distance signaling network controlling branching in pea involves IAA, the RMS1 inhibitor, and an IAA-independent feedback signal. Consistent with physiological studies that predict an interaction between RMS2 and RMS1, rms2 mutations appear to disrupt this IAA-independent regulation of RMS1 expression. PMID:15659639

  11. Evidence that the mature leaves contribute auxin to the immature tissues of pea (Pisum sativum L.).

    PubMed

    Jager, Corinne E; Symons, Gregory M; Glancy, Naomi E; Reid, James B; Ross, John J

    2007-07-01

    In plants such as the garden pea (Pisum sativum L.), it is widely thought that the auxin indole-3-acetic acid (IAA) is synthesised mainly in the immature tissues of the apical bud and then transported basipetally to other parts of the plant. Consistent with this belief are results showing that removal of the apical bud markedly reduces the IAA content in the stem. However, it has also been suggested that the mature leaves may synthesise substantial amounts of IAA, which enters the basipetal transport stream after being transported to the shoot apex in the phloem (Cambridge and Morris in Planta 99:583-588, 1996). To examine this theory, we defoliated pea plants and measured the effect on IAA content in the remaining shoot tissues. IAA levels were reduced in the internodes, and to a lesser extent in the apical bud, after defoliation, suggesting that mature leaves are indeed an important source of auxin for the shoot. Consistent with this idea, we have demonstrated that mature, fully expanded leaves are capable of de novo IAA synthesis. Furthermore, we report evidence for the presence of IAA in the phloem sap of pea. Together these results support those of Cambridge and Morris, suggesting that mature leaves are a source of the IAA in the basipetal transport stream. PMID:17308928

  12. Novel use of positively charged nylon transfer membranes for trapping indoleacetic acid or other small anions during efflux from plant tissues

    NASA Technical Reports Server (NTRS)

    Evans, M. L.; Hangarter, R. P.

    1993-01-01

    Positively charged nylon blotting membranes were used as an anion binding medium to trap [14C]indoleactic acid (IAA) as it exited cells at the basal ends of Coleus blumei L. stem and Zea mays L. coleoptile segments. Autoradiography was used to visualize where the [14C] that moved out of the cut ends was localized on the nylon membrane. Diffusion of [14C]IAA from the initial point of contact with the nylon membrane was minimal. Comparison of the autoradiograms with anatomical tissue prints of the cut ends of the segments was used to determine what tissues participate in IAA movement. The results of these initial studies were consistent with other reports suggesting that [14C]IAA movement was primarily associated with vascular tissues in both C. blumei stems and corn coleoptiles, but the resolution was not sufficient to identify which vascular tissues were involved in IAA transport. With further refinements, this technique could also be used for studying the movement of other small charged molecules through plant tissues.

  13. Novel use of positively charged nylon transfer membranes for trapping indoleacetic acid or other small anions during efflux from plant tissues.

    PubMed

    Cha M-R; Evans, M L; Hangarter, R P

    1993-01-01

    Positively charged nylon blotting membranes were used as an anion binding medium to trap [14C]indoleactic acid (IAA) as it exited cells at the basal ends of Coleus blumei L. stem and Zea mays L. coleoptile segments. Autoradiography was used to visualize where the [14C] that moved out of the cut ends was localized on the nylon membrane. Diffusion of [14C]IAA from the initial point of contact with the nylon membrane was minimal. Comparison of the autoradiograms with anatomical tissue prints of the cut ends of the segments was used to determine what tissues participate in IAA movement. The results of these initial studies were consistent with other reports suggesting that [14C]IAA movement was primarily associated with vascular tissues in both C. blumei stems and corn coleoptiles, but the resolution was not sufficient to identify which vascular tissues were involved in IAA transport. With further refinements, this technique could also be used for studying the movement of other small charged molecules through plant tissues. PMID:11538208

  14. Characterization of a tryptophan 2-monooxygenase gene from Puccinia graminis f. sp. tritici involved in auxin biosynthesis and rust pathogenicity.

    PubMed

    Yin, Chuntao; Park, Jeong-Jin; Gang, David R; Hulbert, Scot H

    2014-03-01

    The plant hormone indole-3-acetic acid (IAA) is best known as a regulator of plant growth and development but its production can also affect plant-microbe interactions. Microorganisms, including numerous plant-associated bacteria and several fungi, are also capable of producing IAA. The stem rust fungus Puccinia graminis f. sp. tritici induced wheat plants to accumulate auxin in infected leaf tissue. A gene (Pgt-IaaM) encoding a putative tryptophan 2-monooxygenase, which makes the auxin precursor indole-3-acetamide (IAM), was identified in the P. graminis f. sp. tritici genome and found to be expressed in haustoria cells in infected plant tissue. Transient silencing of the gene in infected wheat plants indicated that it was required for full pathogenicity. Expression of Pgt-IaaM in Arabidopsis caused a typical auxin expression phenotype and promoted susceptibility to the bacterial pathogen Pseudomonas syringae pv. tomato DC3000.

  15. Enzymic synthesis of indole-3-acetyl-1-O-beta-d-glucose. I. Partial purification and characterization of the enzyme from Zea mays

    NASA Technical Reports Server (NTRS)

    Leznicki, A. J.; Bandurski, R. S.

    1988-01-01

    The first enzyme-catalyzed reaction leading from indole-3-acetic acid (IAA) to the myo-inositol esters of IAA is the synthesis of indole-3-acetyl-1-O-beta-D-glucose from uridine-5'-diphosphoglucose (UDPG) and IAA. The reaction is catalyzed by the enzyme, UDPG-indol-3-ylacetyl glucosyl transferase (IAA-glucose-synthase). This work reports methods for the assay of the enzyme and for the extraction and partial purification of the enzyme from kernels of Zea mays sweet corn. The enzyme has an apparent molecular weight of 46,500 an isoelectric point of 5.5, and its pH optimum lies between 7.3 and 7.6. The enzyme is stable to storage at zero degrees but loses activity during column chromatographic procedures which can be restored only fractionally by addition of column eluates. The data suggest either multiple unknown cofactors or conformational changes leading to activity loss.

  16. Gravitational effects on plant growth hormone concentration

    NASA Technical Reports Server (NTRS)

    Bandurski, R. S.; Schulze, A.

    1983-01-01

    Dolk's (1936) finding that more growth hormone diffuses from the lower side of a gravity-stimulated plant shoot than from the upper side is presently confirmed by means of both an isotope dilution assay and selected ion monitoring-gas chromatography-mass spectrometry, and it is established that the asymmetrically distributed hormone is indole-3-acetic acid (IAA). This is the first physicochemical demonstration that there is more IAA on the lower sides of a geostimulated plant shoot. It is also found that free IAA primarily occurs in the conductive vascular tissues of the shoot, while IAA esters predominate in the growing cortical cells. A highly sensitive gas chromatographic isotope dilution assay shows that the hormone asymmetry also occurs in the nonvascular tissue.

  17. Basipetal auxin transport is required for gravitropism in roots of Arabidopsis

    NASA Technical Reports Server (NTRS)

    Rashotte, A. M.; Brady, S. R.; Reed, R. C.; Ante, S. J.; Muday, G. K.; Davies, E. (Principal Investigator)

    2000-01-01

    Auxin transport has been reported to occur in two distinct polarities, acropetally and basipetally, in two different root tissues. The goals of this study were to determine whether both polarities of indole-3-acetic acid (IAA) transport occur in roots of Arabidopsis and to determine which polarity controls the gravity response. Global application of the auxin transport inhibitor naphthylphthalamic acid (NPA) to roots blocked the gravity response, root waving, and root elongation. Immediately after the application of NPA, the root gravity response was completely blocked, as measured by an automated video digitizer. Basipetal [(3)H]IAA transport in Arabidopsis roots was inhibited by NPA, whereas the movement of [(14)C]benzoic acid was not affected. Inhibition of basipetal IAA transport by local application of NPA blocked the gravity response. Inhibition of acropetal IAA transport by application of NPA at the root-shoot junction only partially reduced the gravity response at high NPA concentrations. Excised root tips, which do not receive auxin from the shoot, exhibited a normal response to gravity. The Arabidopsis mutant eir1, which has agravitropic roots, exhibited reduced basipetal IAA transport but wild-type levels of acropetal IAA transport. These results support the hypothesis that basipetally transported IAA controls root gravitropism in Arabidopsis.

  18. Changes in starch and inositol 1,4,5-trisphosphate levels and auxin transport are interrelated in graviresponding oat (Avena sativa) shoots.

    PubMed

    Yun, Hye Sup; Joo, Se-Hwan; Kaufman, Peter B; Kim, Tae-Wuk; Kirakosyan, Ara; Philosoph-Hadas, Sonia; Kim, Seong-Ki; Chang, Soo Chul

    2006-11-01

    This study was conducted to unravel a mechanism for the gravitropic curvature response in oat (Avena sativa) shoot pulvini. For this purpose, we examined the downward movement of starch-filled chloroplast gravisensors, differential changes in inositol 1,4,5-trisphosphate (IP(3)) levels, transport of indole-3-acetic acid (IAA) and gravitropic curvature. Upon gravistimulation, the ratio for IAA levels in lower halves versus those in upper halves (L/U) increased from 1.0 at 0 h and reached a maximum value of 1.45 at 8 h. When shoots were grown in the dark for 10 d, to deplete starch in the chloroplast, the gravity-induced L/U of IAA was reduced to 1.0. N-naphthylphthalamic acid (NPA) and 2,3,5-triiodobenzoic acid (TIBA), both auxin transport inhibitors, significantly reduced the amount of gravitropic curvature and gravity-induced lateral IAA transport, but did not reduce the gravity-induced late change in the L/U ratio of IP(3) levels. U73122, a specific phospholipase C (PLC) inhibitor, decreased gravity-induced curvature. Because U73122 reduced the ratio of L/U of IAA imposed by gravistimulation, it is clear that IAA transport is correlated with changes in IP(3) levels upon gravistimulation. These results indicate that gravistimulation-induced differential lateral IAA transport may result from the onset of graviperception in the chloroplast gravisensors coupled with gravity-induced asymmetric changes in IP(3) levels in oat shoot pulvini.

  19. Development of a semipurified test diet for determining amino acid requirements of Florida pompano Trachinotus carolinus reared under low-salinity conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two trials were conducted to develop a semipurified test diet for determining indispensable amino acid (IAA) requirements for Florida pompano Trachinotus carolinus. The objective of the first trial was to evaluate casein and corn gluten meal as principal intact protein sources, and the ability of F...

  20. Auxin and Tryptophan Homeostasis Are Facilitated by the ISS1/VAS1 Aromatic Aminotransferase in Arabidopsis

    PubMed Central

    Pieck, Michael; Yuan, Youxi; Godfrey, Jason; Fisher, Christopher; Zolj, Sanda; Vaughan, Dylan; Thomas, Nicholas; Wu, Connie; Ramos, Julian; Lee, Norman; Normanly, Jennifer; Celenza, John L.

    2015-01-01

    Indole-3-acetic acid (IAA) plays a critical role in regulating numerous aspects of plant growth and development. While there is much genetic support for tryptophan-dependent (Trp-D) IAA synthesis pathways, there is little genetic evidence for tryptophan-independent (Trp-I) IAA synthesis pathways. Using Arabidopsis, we identified two mutant alleles of ISS1 (Indole Severe Sensitive) that display indole-dependent IAA overproduction phenotypes including leaf epinasty and adventitious rooting. Stable isotope labeling showed that iss1, but not WT, uses primarily Trp-I IAA synthesis when grown on indole-supplemented medium. In contrast, both iss1 and WT use primarily Trp-D IAA synthesis when grown on unsupplemented medium. iss1 seedlings produce 8-fold higher levels of IAA when grown on indole and surprisingly have a 174-fold increase in Trp. These findings indicate that the iss1 mutant’s increase in Trp-I IAA synthesis is due to a loss of Trp catabolism. ISS1 was identified as At1g80360, a predicted aromatic aminotransferase, and in vitro and in vivo analysis confirmed this activity. At1g80360 was previously shown to primarily carry out the conversion of indole-3-pyruvic acid to Trp as an IAA homeostatic mechanism in young seedlings. Our results suggest that in addition to this activity, in more mature plants ISS1 has a role in Trp catabolism and possibly in the metabolism of other aromatic amino acids. We postulate that this loss of Trp catabolism impacts the use of Trp-D and/or Trp-I IAA synthesis pathways. PMID:26163189

  1. Gravitational effects on plant growth hormone concentration

    NASA Astrophysics Data System (ADS)

    Bandurski, Robert S.; Schulze, Aga

    Numerous studies, particularly those of H. Dolk in the 1930's, established by means of bio-assay, that more growth hormone diffused from the lower, than from the upper side of a gravity-stimulated plant shoot. Now, using an isotope dilution assay, with 4,5,6,7 tetradeutero indole-3-acetic acid as internal standard, and selected ion monitoring-gas chromatography-mass spectrometry as the method of determination, we have confirmed Dolk's finding and established that the asymmetrically distributed hormone is, in fact, indole-3-acetic acid (IAA). This is the first physico-chemical demonstration that there is more free IAA on the lower sides of a geo-stimulated plant shoot. We have also shown that free IAA occurs primarily in the conductive vascular tissues of the shoot, whereas IAA esters predominate in the growing cortical cells. Now, using an especially sensitive gas chromatographic isotope dilution assay we have found that the hormone asymmetry also occurs in the non-vascular tissue. Currently, efforts are directed to developing isotope dilution assays, with picogram sensitivity, to determine how this asymmetry of IAA distribution is attained so as to better understand how the plant perceives the geo-stimulus.

  2. Auxin-induced leaf blade expansion in Arabidopsis requires both wounding and detachment.

    PubMed

    Keller, Christopher P; Grundstad, Morgan L; Evanoff, Michael A; Keith, Jeremy D; Lentz, Derek S; Wagner, Samuel L; Culler, Angela H; Cohen, Jerry D

    2011-12-01

    Elevation of leaf auxin (indole-3-acetic acid; IAA) levels in intact plants has been consistently found to inhibit leaf expansion whereas excised leaf strips grow faster when treated with IAA. Here we test two hypothetical explanations for this difference in growth sensitivity to IAA by expanding leaf tissues in vivo versus in vitro. We asked if, in Arabidopsis, IAA-induced growth of excised leaf strips results from the wounding required to excise tissue and/or results from detachment from the plant and thus loss of some shoot or root derived growth controlling factors. We tested the effect of a range of exogenous IAA concentrations on the growth of intact attached, wounded attached, detached intact, detached wounded as well as excised leaf strips. After 24 h, the growth of intact attached, wounded attached, and detached intact leaves was inhibited by IAA concentrations as little as 1 µM in some experiments. Growth of detached wounded leaves and leaf strips was induced by IAA concentrations as low as 10 µM. Stress, in the form of high light, increased the growth response to IAA by leaf strips and reduced growth inhibition response by intact detached leaves. Endogenous free IAA content of intact attached leaves and excised leaf strips was found not to change over the course of 24 h. Together these results indicate growth induction of Arabidopsis leaf blade tissue by IAA requires both substantial wounding as well as detachment from the plant and suggests in vivo that IAA induces parallel pathways leading to growth inhibition.

  3. Localize and identify the gravity sensing mechanism of plants

    NASA Technical Reports Server (NTRS)

    Bandurski, Robert S.

    1990-01-01

    The machinery by which a plant transduces the gravity stimulus into a growth response is localized and identified at the cellular level. The fact that a plant grows unequally on the lower side of a horizontally placed stem implies that there must be an asymmetric distribution of some of the chemical substances involved in the growth response. The three most likely chemicals to cause this growth were determined to be potassium, calcium, or the growth hormone, indole-3-acetic acid (IAA). IAA was chosen for this study and the results present a fairly complete understanding of the transduction of the gravity stimulus.

  4. Insights into Auxin Signaling in Plant–Pathogen Interactions

    PubMed Central

    Fu, Jing; Wang, Shiping

    2011-01-01

    The phytohormone auxin has been known to be a regulator of plant growth and development ever since its discovery. Recent studies on plant–pathogen interactions identify auxin as a key character in pathogenesis and plant defense. Like plants, diverse pathogens possess the capacity to synthesize indole-3-acetic acid (IAA), the major form of auxin in plants. The emerging knowledge on auxin-signaling components, auxin metabolic processes, and indole-derived phytoalexins in plant responses to pathogen invasion has provided putative mechanisms of IAA in plant susceptibility and resistance to non-gall- or tumor-inducing pathogens. PMID:22639609

  5. Detailed Quantitative Analysis of Architectural Traits of Basal Roots of Young Seedlings of Bean in Response to Auxin and Ethylene1[W

    PubMed Central

    Basu, Paramita; Brown, Kathleen M.; Pal, Anupam

    2011-01-01

    Vertical placement of roots within the soil determines their efficiency of acquisition of heterogeneous belowground resources. This study quantifies the architectural traits of seedling basal roots of bean (Phaseolus vulgaris), and shows that the distribution of root tips at different depths results from a combined effect of both basal root growth angle (BRGA) and root length. Based on emergence locations, the basal roots are classified in three zones, upper, middle, and lower, with each zone having distinct architectural traits. The genotypes characterized as shallow on BRGA alone produced basal roots with higher BRGA, greater length, and more vertically distributed roots than deep genotypes, thereby establishing root depth as a robust measure of root architecture. Although endogenous indole-3-acetic acid (IAA) levels were similar in all genotypes, IAA and 1-N-naphthylphthalamic acid treatments showed different root growth responses to auxin because shallow and deep genotypes tended to have optimal and supraoptimal auxin levels, respectively, for root growth in controls. While IAA increased ethylene production, ethylene also increased IAA content. Although differences in acropetal IAA transport to roots of different zones can account for some of the differences in auxin responsiveness among roots of different emergence positions, this study shows that mutually dependent ethylene-auxin interplay regulates BRGA and root growth differently in different genotypes. Root length inhibition by auxin was reversed by an ethylene synthesis inhibitor. However, IAA caused smaller BRGA in deep genotypes, but not in shallow genotypes, which only responded to IAA in the presence of an ethylene inhibitor. PMID:21311033

  6. Polar Transport Related to Mobilization of Plant Constituents

    PubMed Central

    Zaerr, J. B.; Mitchell, J. W.

    1967-01-01

    Indole-3-acetic acid (IAA), 2-methoxy-3,6-dichlorobenzoic acid (dicamba), sucrose, and mannitol, were tested for polar transport through 5-mm hypocotyl segments of bean (Phaseolus vulgaris var. Pinto) seedlings. All 4 compounds were transported in a polar direction. Autoradiographs of segments through which 14C-labeled compounds were transported indicated areas of 14C concentration near the morphological base of segments. There was a direct correlation of IAA transport with the ability to initiate roots as well as with the degree of 14C accumulation in the morphological base of segments. Unlabeled IAA in lanolin applied to segments appeared to reduce transport of IAA-14C through those segments when measured by the accumulation of 14C in a receiver-block of agar, caused an increase in 14C accumulation in the region to which the unlabeled IAA was applied, and also caused a decrease in accumulation of 14C at the morphological base of upright segments. Histological studies showed that IAA accelerated cell division and the formation of root primordia particularly at the basal ends, and that these responses sometimes occurred at the expense of cell proliferation at the apical ends of segments. The data presented support the hypothesis that polar movement of IAA, and other endogenous and exogenous substances, in isolated stem segments was controlled by mobilization and utilization of plant constituents at the growth centers. Images PMID:16656584

  7. The role of hormone transport and metabolism in apical dominance in oats

    NASA Technical Reports Server (NTRS)

    Harrison, M. A.; Kaufman, P. B.

    1984-01-01

    14C-benzyladenine (BA) and 14C-indole-3-acetic acid (IAA) were used to study hormone transport to the tiller bud and hormone catabolism in excised oat stem segments. Acropetal BA transport was greatest from upright stem segments to tiller buds suppressed by apical dominance. IAA, abscisic acid (ABA), and C2H4 inhibited BA transport to the tiller bud. IAA transport to the tiller bud site was inhibited by BA, C2H4, or after gravistimulation, which affected BA transport to a lesser extent than IAA transport. Multiple peaks of radioactivity were observed in 14C-BA- or 14C-IAA-treated stem segments after 9 h of transport. IAA, ABA, and C2H4 promoted BA catabolism. Auxin, ABA, and C2H4 may inhibit tiller bud release by inhibiting cytokinin transport to the tiller bud and by promoting cytokinin catabolism. Gravistimulation may promote tiller release by inhibiting IAA transport to the tiller bud and allowing cytokinins to accumulate there preferentially.

  8. Local auxin metabolism regulates environment-induced hypocotyl elongation.

    PubMed

    Zheng, Zuyu; Guo, Yongxia; Novák, Ondřej; Chen, William; Ljung, Karin; Noel, Joseph P; Chory, Joanne

    2016-01-01

    A hallmark of plants is their adaptability of size and form in response to widely fluctuating environments. The metabolism and redistribution of the phytohormone auxin play pivotal roles in establishing active auxin gradients and resulting cellular differentiation. In Arabidopsis thaliana, cotyledons and leaves synthesize indole-3-acetic acid (IAA) from tryptophan through indole-3-pyruvic acid (3-IPA) in response to vegetational shade. This newly synthesized auxin moves to the hypocotyl where it induces elongation of hypocotyl cells. Here we show that loss of function of VAS2 (IAA-amido synthetase Gretchen Hagen 3 (GH3).17) leads to increases in free IAA at the expense of IAA-Glu (IAA-glutamate) in the hypocotyl epidermis. This active IAA elicits shade- and high temperature-induced hypocotyl elongation largely independently of 3-IPA-mediated IAA biosynthesis in cotyledons. Our results reveal an unexpected capacity of local auxin metabolism to modulate the homeostasis and spatial distribution of free auxin in specialized organs such as hypocotyls in response to shade and high temperature. PMID:27249562

  9. Local auxin metabolism regulates environment-induced hypocotyl elongation

    PubMed Central

    Zheng, Zuyu; Guo, Yongxia; Novák, Ondřej; Chen, William; Ljung, Karin; Noel, Joseph P.; Chory, Joanne

    2016-01-01

    A hallmark of plants is their adaptability of size and form in response to widely fluctuating environments. The metabolism and redistribution of the phytohormone auxin play pivotal roles in establishing active auxin gradients and resulting cellular differentiation. In Arabidopsis thaliana, cotyledons and leaves synthesize indole-3-acetic acid (IAA) from tryptophan through indole-3-pyruvic acid (3-IPA) in response to vegetational shade. This newly synthesized auxin moves to the hypocotyl where it induces elongation of hypocotyl cells. Here we show that loss of function of VAS2 (IAA-amido synthetase Gretchen Hagen 3 (GH3).17) leads to increases in free IAA at the expense of IAA-Glu (IAA-glutamate) in the hypocotyl epidermis. This active IAA elicits shade- and high temperature-induced hypocotyl elongation largely independently of 3-IPA-mediated IAA biosynthesis in cotyledons. Our results reveal an unexpected capacity of local auxin metabolism to modulate the homeostasis and spatial distribution of free auxin in specialized organs such as hypocotyls in response to shade and high temperature. PMID:27249562

  10. Enhancing polysaccharide-mediated delivery of nucleic acids through functionalization with secondary and tertiary amines.

    PubMed

    Ghosn, Bilal; Kasturi, Sudhir Pai; Roy, Krishnendu

    2008-01-01

    Chitosan is a polysaccharide that has generated significant interest as a non-viral gene delivery vehicle due to its cationic and biocompatible characteristics. However, transfection efficiency of chitosan is significantly lower compared to other cationic gene delivery agents, e.g. polyethyleneimine (PEI), dendrimers or cationic lipids. This is primarily attributed to its minimal solubility and low buffering capacity at physiological pH leading to poor endosomal escape of the gene carrier and inefficient cytoplasmic decoupling of the complexed nucleic acid. Here we have developed an imidazole acetic acid (IAA)-modified chitosan to introduce secondary and tertiary amines to the polymer in order to improve its endosomal buffering and solubility. The modified polymer was characterized by ninhydrin and (1)H NMR assays for degree of modification, while buffering and solubility were analyzed by acid titration. Nanocomplex formation, studied at various polymer-nucleic acid ratios, showed an increase in particle zeta potential for chitosan-IAA, as well as an increase in the effective diameter. Up to 100-fold increase in transfection efficiency of pDNA was seen for chitosan-IAA as compared to native chitosan, nearly matching that of PEI. In addition, transfection of siRNA by the modified polymers showed efficient gene knockdown equivalent to commercially available siPORT Amines. Collectively, these results demonstrate the potential of the imidazole-grafted chitosan as a biocompatible and effective delivery vehicle for both pDNA and siRNA.

  11. Differential downward stream of auxin synthesized at the tip has a key role in gravitropic curvature via TIR1/AFBs-mediated auxin signaling pathways.

    PubMed

    Nishimura, Takeshi; Nakano, Hitomi; Hayashi, Ken-ichiro; Niwa, Chiharu; Koshiba, Tomokazu

    2009-11-01

    Since the early days of Darwin, monocot coleoptiles have been used to investigate indole-3-acetic acid (IAA) production, polar transport and tropisms. Here, using maize coleoptiles, we first showed that polar transport of IAA synthesized at the tip region is regulated by ZmPIN(s). Then, the TIR/AFBs-mediated auxin signaling pathway corresponds to the asymmetric IAA flow after gravi-stimulus, which results in tropic curvature. When [(13)C(11)(15)N(2)]Trp was applied to coleoptile tips, substantial amounts of the stable isotope were incorporated into IAA at the tip region, and the labeled IAA was transported in a polar manner at approximately 7 mm h(-1). Immunohistochemical analyses revealed that ZmPIN1(s) was present in almost all cells. ZmPIN1(s) showed a relatively non-polar distribution at the tip, but a basal cellular localization at lower regions. Application of the IAA transport inhibitors 1-N-naphthylphthalamic acid (NPA) and brefeldin A (BFA) at the very tip region almost completely inhibited IAA movement from the tip. These inhibitors also severely suppressed gravitropic bending. PEO-IAA, an auxin antagonist that binds to TIR1/AFBs, suppressed not only the expression of an auxin-responsive ZmSAUR2 gene, but also gravitropic curvature. Expression of ZmSAUR2 was up-regulated on the lower side and down-regulated on the upper side of the coleoptile elongation zone, corresponding to the asymmetric IAA distribution. These results indicate that the asymmetric downward streams of IAA control the differential growth rate of the cells by attenuating TIR1/AFBs-mediated auxin response genes, including ZmSAUR2, and therefore result in tropic curvature. PMID:19897572

  12. Complete Genome Sequence of the Rhizobacterium Pseudomonas trivialis Strain IHBB745 with Multiple Plant Growth-Promoting Activities and Tolerance to Desiccation and Alkalinity

    PubMed Central

    Swarnkar, Mohit Kumar; Vyas, Pratibha; Rahi, Praveen; Thakur, Rishu; Thakur, Namika; Singh, Anil Kumar

    2015-01-01

    The complete genome sequence of 6.45 Mb is reported here for Pseudomonas trivialis strain IHBB745 (MTCC 5336), which is an efficient, stress-tolerant, and broad-spectrum plant growth-promoting rhizobacterium. The gene-coding clusters predicted the genes for phosphate solubilization, siderophore production, 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity, indole-3-acetic acid (IAA) production, and stress response. PMID:26337878

  13. Complete Genome Sequence of the Rhizobacterium Pseudomonas trivialis Strain IHBB745 with Multiple Plant Growth-Promoting Activities and Tolerance to Desiccation and Alkalinity.

    PubMed

    Gulati, Arvind; Swarnkar, Mohit Kumar; Vyas, Pratibha; Rahi, Praveen; Thakur, Rishu; Thakur, Namika; Singh, Anil Kumar

    2015-01-01

    The complete genome sequence of 6.45 Mb is reported here for Pseudomonas trivialis strain IHBB745 (MTCC 5336), which is an efficient, stress-tolerant, and broad-spectrum plant growth-promoting rhizobacterium. The gene-coding clusters predicted the genes for phosphate solubilization, siderophore production, 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity, indole-3-acetic acid (IAA) production, and stress response. PMID:26337878

  14. Dynamics of auxin movement in the gravistimulated leaf-sheath pulvinus of oat (Avena sativa)

    NASA Technical Reports Server (NTRS)

    Brock, Thomas C.; Kapen, E. H.; Ghosheh, Najati S.; Kaufman, Peter B.

    1991-01-01

    The role of auxin redistribution in the graviresponse of the leaf-sheath pulvinus of oat was evaluated using H-3-indole-3-acetic acid (H-3-IAA) preloaded into isolated pulvini. Results obtained reveal that, while lateral transport of auxin occurs following gravistimulation, it is not necessary for a graviresponse. Localized changes in tissue responsiveness or the conversion of conjugated hormone to free hormone may suffice to drive the graviresponse.

  15. Monohaloacetic acid drinking water disinfection by-products inhibit follicle growth and steroidogenesis in mouse ovarian antral follicles in vitro.

    PubMed

    Jeong, Clara H; Gao, Liying; Dettro, Tyler; Wagner, Elizabeth D; Ricke, William A; Plewa, Michael J; Flaws, Jodi A

    2016-07-01

    Water disinfection greatly reduced the incidence of waterborne diseases, but the reaction between disinfectants and natural organic matter in water leads to the formation of drinking water disinfection by-products (DBPs). DBPs have been shown to be toxic, but their effects on the ovary are not well defined. This study tested the hypothesis that monohalogenated DBPs (chloroacetic acid, CAA; bromoacetic acid, BAA; iodoacetic acid, IAA) inhibit antral follicle growth and steroidogenesis in mouse ovarian follicles. Antral follicles were isolated and cultured with either vehicle or DBPs (0.25-1.00mM of CAA; 2-15μM of BAA or IAA) for 48 and 96h. Follicle growth was measured every 24h and the media were analyzed for estradiol levels at 96h. Exposure to DBPs significantly inhibited antral follicle growth and reduced estradiol levels compared to controls. These data demonstrate that DBP exposure caused ovarian toxicity in vitro. PMID:27151372

  16. Comparative effects of auxin and abscisic acid on growth, hydrogen ion efflux and gravitropism in primary roots of maize

    NASA Technical Reports Server (NTRS)

    Evans, M. L.; Mulkey, T. J.

    1984-01-01

    In order to test the idea that auxin action on root growth may be mediated by H(+) movement, the correlation of auxin action on growth and H(+) movement in roots was examined along with changes in H(+) efflux patterns associated with the asymmetric growth which occurs during gravitropism. The effects of indoleacetic acid (IAA) and abscisic acid (AbA) on growth, H(+) secretion, and gravitropism in roots were compared. Results show a close correlation existent between H(+) efflux and growth in maize roots. In intact roots there is strong H(+) efflux from the elongation zone. Growth-promoting concentrations of IAA stimulate H(+) efflux. During gravitropism the H(+) efflux from the elongation zone becomes asymmetric; the evidence indicates that auxin redistribution contributes to the development of acid efflux asymmetry. That AbA stimulates root growth is reflected in its ability to stimulate H(+) efflux from apical root segments.

  17. The manipulation of auxin in the abscission zone cells of Arabidopsis flowers reveals that indoleacetic acid signaling is a prerequisite for organ shedding.

    PubMed

    Basu, Manojit M; González-Carranza, Zinnia H; Azam-Ali, Sayed; Tang, Shouya; Shahid, Ahmad Ali; Roberts, Jeremy A

    2013-05-01

    A number of novel strategies were employed to examine the role of indoleacetic acid (IAA) in regulating floral organ abscission in Arabidopsis (Arabidopsis thaliana). Analysis of auxin influx facilitator expression in β-glucuronidase reporter plants revealed that AUXIN RESISTANT1, LIKE AUX1, and LAX3 were specifically up-regulated at the site of floral organ shedding. Flowers from mutants where individual family members were down-regulated exhibited a reduction in the force necessary to bring about petal separation; however, the effect was not additive in double or quadruple mutants. Using the promoter of a polygalacturonase (At2g41850), active primarily in cells undergoing separation, to drive expression of the bacterial genes iaaL and iaaM, we have shown that it is possible to manipulate auxin activity specifically within the floral organ abscission zone (AZ). Analysis of petal breakstrength reveals that if IAA AZ levels are reduced, shedding takes place prematurely, while if they are enhanced, organ loss is delayed. The At2g41850 promoter was also used to transactivate the gain-of-function AXR3-1 gene in order to disrupt auxin signaling specifically within the floral organ AZ cells. Flowers from transactivated lines failed to shed their sepals, petals, and anthers during pod expansion and maturity, and these organs frequently remained attached to the plant even after silique desiccation and dehiscence had taken place. These observations support a key role for IAA in the regulation of abscission in planta and reveal, to our knowledge for the first time, a requirement for a functional IAA signaling pathway in AZ cells for organ shedding to take place.

  18. Endogenous Auxin and Ethylene in the Lichen Ramalina duriaei1

    PubMed Central

    Epstein, Ephraim; Sagee, Oded; Cohen, Jerry D.; Garty, Jacob

    1986-01-01

    Indole-3-acetic acid (IAA) levels and ethylene evolution rates were measured in a fruticose lichen Ramalina duriaei collected from carob trees growing in northeast Israel. IAA levels were estimated by gas liquid chromatography with electron capture detection of the pentafluorobenzyl ester and also by enzyme-linked immunosorbent assay following methylation. The identity of the isolated IAA was confirmed by gas chromatography-mass spectrometry of both the methyl and the pentafluorobenzyl ester. IAA levels in lichens 1 year after transplanting to an air-polluted urban site were found to be lower than in the control thalli left at a nonpolluted, rural site. The material from the latter contained about 2.5 micrograms per gram fresh weight free IAA and 0.5 microgram per gram fresh weight conjugated IAA, while the urban material contained 0.3 microgram per gram each of free and conjugated IAA. Ethylene production rate was 1.0 nanoliter per gram fresh weight per hour in the material from the rural site and 1.5 nanoliters per gram fresh weight per hour in material from the urban site. PMID:16665145

  19. Root cap-dependent gravitropic U-turn of maize root requires light-induced auxin biosynthesis via the YUC pathway in the root apex

    PubMed Central

    Suzuki, Hiromi; Yokawa, Ken; Nakano, Sayuri; Yoshida, Yuriko; Fabrissin, Isabelle; Okamoto, Takashi; Baluška, František; Koshiba, Tomokazu

    2016-01-01

    Gravitropism refers to the growth or movement of plants that is influenced by gravity. Roots exhibit positive gravitropism, and the root cap is thought to be the gravity-sensing site. In some plants, the root cap requires light irradiation for positive gravitropic responses. However, the mechanisms regulating this phenomenon are unknown. We herein report that maize roots exposed to white light continuously for ≥1–2h show increased indole-3-acetic acid (IAA) levels in the root tips, especially in the transition zone (1–3mm from the tip). Treatment with IAA biosynthesis inhibitors yucasin and l-kynurenine prevented any increases in IAA content and root curvature under light conditions. Analyses of the incorporation of a stable isotope label from tryptophan into IAA revealed that some of the IAA in roots was synthesized in the root apex. Furthermore, Zmvt2 and Zmyuc gene transcripts were detected in the root apex. One of the Zmyuc genes (ZM2G141383) was up-regulated by light irradiation in the 0–1mm tip region. Our findings suggest that IAA accumulation in the transition zone is due to light-induced activation of Zmyuc gene expression in the 0–1mm root apex region. Light-induced changes in IAA levels and distributions mediate the maize root gravitropic U-turn. PMID:27307546

  20. Auxin and Cell Wall Invertase Related Signaling during Rice Grain Development

    PubMed Central

    Russell French, Sarah; Abu-Zaitoon, Yousef; Uddin, Md. Myn; Bennett, Karina; Nonhebel, Heather M.

    2014-01-01

    Indole-3-acetic acid (IAA) synthesis is required for grain-fill in maize and appears to be regulated by cell-wall invertase (CWIN) activity. OsYUC12 is one of three IAA biosynthesis genes we previously reported as expressed during early rice grain development, correlating with a large increase in IAA content of the grain. This work aimed to investigate further the role of OsYUC12 and its relationship to CWIN activity and invertase inhibitors (INVINH). The analysis shows a brief peak of OsYUC12 expression early in endosperm development. Meta-analysis of microarray data, confirmed by quantitative expression analysis, revealed that OsYUC12 is coexpressed with OsIAA29, which encodes an unusual AUX/IAA transcription factor previously reported as poorly expressed. Maximum expression of OsYUC12 and OsIAA29 coincided with maximum CWIN activity, but also with a peak in INVINH expression. Unlike ZmYUC1, OsYUC12 expression is not reduced in the rice CWIN mutant, gif1. Several reports have investigated CWIN expression in rice grains but none has reported on expression of INVINH in this species. We show that rice has 54 genes encoding putative invertase/pectin methylesterase inhibitors, seven of which are expressed exclusively during grain development. Our results suggest a more complex relationship between IAA, CWIN, and INVINH than previously proposed. PMID:27135493

  1. Root cap-dependent gravitropic U-turn of maize root requires light-induced auxin biosynthesis via the YUC pathway in the root apex.

    PubMed

    Suzuki, Hiromi; Yokawa, Ken; Nakano, Sayuri; Yoshida, Yuriko; Fabrissin, Isabelle; Okamoto, Takashi; Baluška, František; Koshiba, Tomokazu

    2016-08-01

    Gravitropism refers to the growth or movement of plants that is influenced by gravity. Roots exhibit positive gravitropism, and the root cap is thought to be the gravity-sensing site. In some plants, the root cap requires light irradiation for positive gravitropic responses. However, the mechanisms regulating this phenomenon are unknown. We herein report that maize roots exposed to white light continuously for ≥1-2h show increased indole-3-acetic acid (IAA) levels in the root tips, especially in the transition zone (1-3mm from the tip). Treatment with IAA biosynthesis inhibitors yucasin and l-kynurenine prevented any increases in IAA content and root curvature under light conditions. Analyses of the incorporation of a stable isotope label from tryptophan into IAA revealed that some of the IAA in roots was synthesized in the root apex. Furthermore, Zmvt2 and Zmyuc gene transcripts were detected in the root apex. One of the Zmyuc genes (ZM2G141383) was up-regulated by light irradiation in the 0-1mm tip region. Our findings suggest that IAA accumulation in the transition zone is due to light-induced activation of Zmyuc gene expression in the 0-1mm root apex region. Light-induced changes in IAA levels and distributions mediate the maize root gravitropic U-turn. PMID:27307546

  2. Mechanism of specific inhibition of phototropism by phenylacetic acid in corn seedling

    SciTech Connect

    Vierstra, R.D.; Poff, K.L.

    1981-05-01

    Using geotropism as a control for phototropism, compounds similar to phenylacetic acid that phototreact with flavins and/or have auxin-like activity were examined for their ability to specifically inhibit phototropism in corn seedlings using geotropism as a control. Results using indole-3-acetic acid, napthalene-1-acetic acid, naphthalene-2-acetic acid, phenylacetic acid, and ..beta..-phenylpyruvic acid suggest that such compounds will specifically inhibit phototropism primarily because of their photoreactivity with flavins and not their auxin activity. In addition, the in vivo concentration of phenylacetic acid required to induce specificity was well below that required to stimulate coleoptile growth. Estimates of the percentage of photoreceptor pigment inactivated by phenylacetic acid (>10%) suggest that phenylacetic acid could be used to photoaffinity label the flavoprotein involved in corn seedling phototropism.

  3. Effects of bisphenol A, an environmental endocrine disruptor, on the endogenous hormones of plants.

    PubMed

    Wang, Shengman; Wang, Lihong; Hua, Weiqi; Zhou, Min; Wang, Qingqing; Zhou, Qing; Huang, Xiaohua

    2015-11-01

    Bisphenol A (BPA) is a ubiquitous endocrine-disrupting chemical in the environment that exerts potential harm to plants. Phytohormones play important roles both in regulating multiple aspects of plant growth and in plants' responses to environmental stresses. But how BPA affects plant growth by regulating endogenous hormones remains poorly understood. Here, we found that treatment with 1.5 mg L(-1) BPA improved the growth of soybean seedlings, companied by increases in the contents of indole-3-acetic acid (IAA) and zeatin (ZT), and decreases in the ratios of abscisic acid (ABA)/IAA, ABA/gibberellic acid (GA), ABA/ZT, ethylene (ETH)/GA, ETH/IAA, and ETH/ZT. Treatment with higher concentrations of BPA (from 3 to 96 mg L(-1)) inhibited the growth of soybean seedlings, meanwhile, decreased the contents of IAA, GA, ZT, and ETH, and increased the content of ABA and the ratios of ABA/IAA, ABA/GA, ABA/ZT, ETH/GA, ETH/IAA, and ETH/ZT. The increases in the ratios of growth and stress hormones were correlated with the increase in the BPA content of the roots. Thus, BPA could affect plant growth through changing the levels of single endogenous hormone and the ratios of growth and stress hormones in the roots because of BPA absorption by the roots.

  4. Effects of bisphenol A, an environmental endocrine disruptor, on the endogenous hormones of plants.

    PubMed

    Wang, Shengman; Wang, Lihong; Hua, Weiqi; Zhou, Min; Wang, Qingqing; Zhou, Qing; Huang, Xiaohua

    2015-11-01

    Bisphenol A (BPA) is a ubiquitous endocrine-disrupting chemical in the environment that exerts potential harm to plants. Phytohormones play important roles both in regulating multiple aspects of plant growth and in plants' responses to environmental stresses. But how BPA affects plant growth by regulating endogenous hormones remains poorly understood. Here, we found that treatment with 1.5 mg L(-1) BPA improved the growth of soybean seedlings, companied by increases in the contents of indole-3-acetic acid (IAA) and zeatin (ZT), and decreases in the ratios of abscisic acid (ABA)/IAA, ABA/gibberellic acid (GA), ABA/ZT, ethylene (ETH)/GA, ETH/IAA, and ETH/ZT. Treatment with higher concentrations of BPA (from 3 to 96 mg L(-1)) inhibited the growth of soybean seedlings, meanwhile, decreased the contents of IAA, GA, ZT, and ETH, and increased the content of ABA and the ratios of ABA/IAA, ABA/GA, ABA/ZT, ETH/GA, ETH/IAA, and ETH/ZT. The increases in the ratios of growth and stress hormones were correlated with the increase in the BPA content of the roots. Thus, BPA could affect plant growth through changing the levels of single endogenous hormone and the ratios of growth and stress hormones in the roots because of BPA absorption by the roots. PMID:26150296

  5. Ectomycorrhizal fungi and exogenous auxins influence root and mycorrhiza formation of Scots pine hypocotyl cuttings in vitro.

    PubMed

    Niemi, K; Vuorinen, T; Ernstsen, A; Häggman, H

    2002-12-01

    We studied the ability of the ectomycorrhizal (ECM) fungi, Pisolithus tinctorius (Pers.) Coker and Couch and Paxillus involutus (Batsch) Fr. (Strain H), to produce indole-3-acetic acid (IAA) and to affect the formation and growth of roots on Scots pine (Pinus sylvestris L.) hypocotyl cuttings in vitro. Effects of indole-3-butyric acid (IBA) and the auxin transport inhibitor, 2,3,5-triiodobenzoic acid (TIBA), on rooting and the cutting-fungus interaction were also studied. Both fungi produced IAA in the absence of exogenous tryptophan, but the mycelium and culture filtrate of Pisolithus tinctorius contained higher concentrations of free and conjugated IAA than the mycelium and culture filtrate of Paxillus involutus. Inoculation with either fungus or short-term application of culture filtrate of either fungus to the base of hypocotyl cuttings enhanced root formation. Inoculation with either fungus was even more effective in enhancing root formation than treatment of the hypocotyl bases with IBA. Fungal IAA production was not directly correlated with root formation, because rooting was enhanced more by Paxillus involutus than by Pisolithus tinctorius. This suggests that, in addition to IAA, other fungal components play an important role in root formation. Treatment with 5 microM TIBA increased the rooting percentage of non-inoculated cuttings, as well as of cuttings inoculated with Pisolithus tinctorius, perhaps as a result of accumulation of IAA at the cutting base. However, the marked reduction in growth of Pisolithus tinctorius in the presence of TIBA suggests that the effects of TIBA on rooting are complicated and not solely related to IAA metabolism. The high IAA-producer, Pisolithus tinctorius, formed mycorrhizas, and the IBA treatment increased mycorrhizal frequency in this species, whereas TIBA decreased it. Paxillus involutus did not form mycorrhizas, indicating that a low concentration of IAA together with other fungal components were sufficient to stimulate

  6. Negative phototropism is seen in Arabidopsis inflorescences when auxin signaling is reduced to a minimal level by an Aux/IAA dominant mutation, axr2.

    PubMed

    Sato, Atsuko; Sasaki, Shu; Matsuzaki, Jun; Yamamoto, Kotaro T

    2015-01-01

    Inflorescences of a dominant mutant of Arabidopsis Aux/IAA7, axr2, showed negative phototropism with a similar fluence response curve to the positive phototropism of wild-type stems. Application of a synthetic auxin, NAA, and an inhibitor of polar auxin transport, NPA, increased and decreased respectively the magnitude of the phototropic response in the wild type, while in axr2 application of NAA reduced the negative phototropic response and NPA had no effect. Decapitation of the apex induced a small negative phototropism in wild-type stems, and had no effect in axr2 plants. Inflorescences of the double mutants of auxin transporters, pgp1 pgp19, showed no phototropic response, while decapitation resulted in a negative phototropic response. These results suggest that negative phototropism can occur when the level of auxin or of auxin signaling is reduced to a minimal level, and that in plant axial organs the default phototropic response to unilateral blue light may be negative. Expression of axr2 protein by an endodermis-specific promoter resulted in agravitropism of inflorescences in a similar way to that of axr2, but phototropism was normal, confirming that the endodermis does not play a critical role in phototropism.

  7. Identification of the cells involved in auxin transport in maize mesocotyl

    SciTech Connect

    Jones, A.M. )

    1989-04-01

    A study was undertaken to identify by a direct method the cells involved in auxin transport through maize mesocotyl tissue. The auxin photoaffinity labeling agent, 7-({sup 3}H), 5-azidoindole 3-acetic acid (N{sub 3}IAA), was loaded into excised stem tissue from a cut end. Polar transport of this analog was demonstrated over 4 hours by comparing uptake into tissue loaded with N{sub 3}IAA from the apical vs. the basal end. Triiodobenzoic acid, an auxin transport inhibitor, inhibited N{sub 3}IAA uptake into tissue. Tissue which had taken up the photoaffinity labeling agent was photolyzed to covalently fix the radioisotope within cells. This tissue was sectioned and subjected to in situ autoradiography. The outermost cell of epidermal tissue and certain files of cells in vascular tissue were densely labeled indicating that on a per cell basis these two cell types are most actively transporting auxin.

  8. Hormone crosstalk in wound stress response: wound-inducible amidohydrolases can simultaneously regulate jasmonate and auxin homeostasis in Arabidopsis thaliana.

    PubMed

    Zhang, Tong; Poudel, Arati N; Jewell, Jeremy B; Kitaoka, Naoki; Staswick, Paul; Matsuura, Hideyuki; Koo, Abraham J

    2016-03-01

    Jasmonate (JA) and auxin are essential hormones in plant development and stress responses. While the two govern distinct physiological processes, their signaling pathways interact at various levels. Recently, members of the Arabidopsis indole-3-acetic acid (IAA) amidohydrolase (IAH) family were reported to metabolize jasmonoyl-isoleucine (JA-Ile), a bioactive form of JA. Here, we characterized three IAH members, ILR1, ILL6, and IAR3, for their function in JA and IAA metabolism and signaling. Expression of all three genes in leaves was up-regulated by wounding or JA, but not by IAA. Purified recombinant proteins showed overlapping but distinct substrate specificities for diverse amino acid conjugates of JA and IAA. Perturbed patterns of the endogenous JA profile in plants overexpressing or knocked-out for the three genes were consistent with ILL6 and IAR3, but not ILR1, being the JA amidohydrolases. Increased turnover of JA-Ile in the ILL6- and IAR3-overexpressing plants created symptoms of JA deficiency whereas increased free IAA by overexpression of ILR1 and IAR3 made plants hypersensitive to exogenous IAA conjugates. Surprisingly, ILL6 overexpression rendered plants highly resistant to exogenous IAA conjugates, indicating its interference with IAA conjugate hydrolysis. Fluorescent protein-tagged IAR3 and ILL6 co-localized with the endoplasmic reticulum-localized JA-Ile 12-hydroxylase, CYP94B3. Together, these results demonstrate that in wounded leaves JA-inducible amidohydrolases contribute to regulate active IAA and JA-Ile levels, promoting auxin signaling while attenuating JA signaling. This mechanism represents an example of a metabolic-level crosstalk between the auxin and JA signaling pathways.

  9. Auxin-Growth Relationships in Maize Coleoptiles and Pea Internodes and Control by Auxin of the Tissue Sensitivity to Auxin

    PubMed Central

    Haga, Ken; Iino, Moritoshi

    1998-01-01

    Growth of a zone of maize (Zea mays L.) coleoptiles and pea (Pisum sativum L.) internodes was greatly suppressed when the organ was decapitated or ringed at an upper position with the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA) mixed with lanolin. The transport of apically applied 3H-labeled indole-3-acetic acid (IAA) was similarly inhibited by NPA. The growth suppressed by NPA or decapitation was restored by the IAA mixed with lanolin and applied directly to the zone, and the maximal capacity to respond to IAA did not change after NPA treatment, although it declined slightly after decapitation. The growth rate at IAA saturation was greater than the rate in intact, nontreated plants. It was concluded that growth is limited and controlled by auxin supplied from the apical region. In maize coleoptiles the sensitivity to IAA increased more than 3 times when the auxin level was reduced over a few hours with NPA treatment. This result, together with our previous result that the maximal capacity to respond to IAA declines in pea internodes when the IAA level is enhanced for a few hours, indicates that the IAA concentration-response relationship is subject to relatively slow adaptive regulation by IAA itself. The spontaneous growth recovery observed in decapitated maize coleoptiles was prevented by an NPA ring placed at an upper position of the stump, supporting the view that recovery is due to regenerated auxin-producing activity. The sensitivity increase also appeared to participate in an early recovery phase, causing a growth rate greater than in intact plants. PMID:9701602

  10. Hormone crosstalk in wound stress response: wound-inducible amidohydrolases can simultaneously regulate jasmonate and auxin homeostasis in Arabidopsis thaliana

    PubMed Central

    Zhang, Tong; Poudel, Arati N.; Jewell, Jeremy B.; Kitaoka, Naoki; Staswick, Paul; Matsuura, Hideyuki; Koo, Abraham J.

    2016-01-01

    Jasmonate (JA) and auxin are essential hormones in plant development and stress responses. While the two govern distinct physiological processes, their signaling pathways interact at various levels. Recently, members of the Arabidopsis indole-3-acetic acid (IAA) amidohydrolase (IAH) family were reported to metabolize jasmonoyl-isoleucine (JA-Ile), a bioactive form of JA. Here, we characterized three IAH members, ILR1, ILL6, and IAR3, for their function in JA and IAA metabolism and signaling. Expression of all three genes in leaves was up-regulated by wounding or JA, but not by IAA. Purified recombinant proteins showed overlapping but distinct substrate specificities for diverse amino acid conjugates of JA and IAA. Perturbed patterns of the endogenous JA profile in plants overexpressing or knocked-out for the three genes were consistent with ILL6 and IAR3, but not ILR1, being the JA amidohydrolases. Increased turnover of JA-Ile in the ILL6- and IAR3-overexpressing plants created symptoms of JA deficiency whereas increased free IAA by overexpression of ILR1 and IAR3 made plants hypersensitive to exogenous IAA conjugates. Surprisingly, ILL6 overexpression rendered plants highly resistant to exogenous IAA conjugates, indicating its interference with IAA conjugate hydrolysis. Fluorescent protein-tagged IAR3 and ILL6 co-localized with the endoplasmic reticulum-localized JA-Ile 12-hydroxylase, CYP94B3. Together, these results demonstrate that in wounded leaves JA-inducible amidohydrolases contribute to regulate active IAA and JA-Ile levels, promoting auxin signaling while attenuating JA signaling. This mechanism represents an example of a metabolic-level crosstalk between the auxin and JA signaling pathways. PMID:26672615

  11. Comparative effects of wild type Stenotrophomonas maltophilia and its indole acetic acid-deficient mutants on wheat.

    PubMed

    Hassan, T U; Bano, A

    2016-09-01

    The present investigation evaluated the role of Stenotrophomonas maltophilia and its IAA-deficient mutant on soil health and plant growth under salinity stress in the presence of tryptophan. In the first phase, S. maltophilia isolated from roots of the halo- phytic herb, Cenchrus ciliaris was used as bio-inoculant on wheat grown in saline sodic soil. A field experiment was conducted at Soil Salinity Research Institute during 2010-2011. Treatments included seed inoculation with S. maltophilia with or without tryptophan; uninoculated untreated plants were taken as control. An aqueous solution of tryptophan was added to rhizosphere soil at 1 μg l(_1) after seed germination. Inoculation with S. maltophilia significantly increased soil organic matter, enhanced (20-30%) availability of P, K, Ca and NO3 -N and decreased Na content and electrical conductivity of rhizosphere soil. Plant height, fresh weight, proline and phytohormone content of leaves were increased 30-40% over the control. Activities of superoxide dismutase (SOD) and peroxidase (POD) were 40-50% higher than control. Addition of tryptophan further augmented (10-15%) growth parameters, whereas NO3 -N, P, K and Ca content, proline content and SOD and POD increased 20-30%. In a second phase, indoleacetic acid (IAA)-deficient mutants of S. maltophilia were constructed and evaluated for conversion of tryptophan to IAA at the University of Calgary, Canada, during 2013-2014. About 1800 trans-conjugants were constructed that were unable to produce IAA in the presence of tryptophan. The results suggest that tryptophan assisted S. maltophilia in the amelioration of salt stress, and that IAA played positive role in induction of salt tolerance. PMID:27263526

  12. Apoplastic H2 O2 plays a critical role in axillary bud outgrowth by altering auxin and cytokinin homeostasis in tomato plants.

    PubMed

    Chen, Xiao-Juan; Xia, Xiao-Jian; Guo, Xie; Zhou, Yan-Hong; Shi, Kai; Zhou, Jie; Yu, Jing-Quan

    2016-09-01

    Although phytohormones such as indole-3-acetic acid (IAA), cytokinin (CK) and strigolactone are important modulators of plant architecture, it remains unclear whether reactive oxygen species are involved in the regulation of phytohormone-dependent axillary bud outgrowth in plants. We used diverse techniques, including transcriptional suppression, HPLC-MS, biochemical methodologies and gene transcript analysis to investigate the signaling pathway for apoplastic hydrogen peroxide (H2 O2 )-induced axillary bud outgrowth. Silencing of tomato RESPIRATORY BURST OXIDASE HOMOLOG 1 (RBOH1) and WHITEFLY INDUCED 1 (WFI1), two important genes involved in H2 O2 production in the apoplast, enhanced bud outgrowth, decreased transcript of FZY - a rate-limiting gene in IAA biosynthesis and IAA accumulation in the apex - and increased the transcript of IPT2 involved in CK biosynthesis and CK accumulation in the stem node. These effects were fully abolished by the application of exogenous H2 O2 . Both decapitation and the silencing of FZY promoted bud outgrowth, and downregulated and upregulated the transcripts for IAA3 and IAA15, and IPT2, respectively. However, these effects were not blocked by treatment with exogenous H2 O2 but by napthaleneacetic acid (NAA) treatment. These results suggest that RBOHs-dependent apoplastic H2 O2 promotes IAA biosynthesis in the apex, which, in turn, inhibits CK biosynthesis and subsequent bud outgrowth in tomato plants. PMID:27240824

  13. Auxin Production by Plant-Pathogenic Pseudomonads and Xanthomonads

    PubMed Central

    Fett, William F.; Osman, Stanley F.; Dunn, Michael F.

    1987-01-01

    Pathogenic strains of Xanthomonas campestris pv. glycines which cause hypertrophy of leaf cells of susceptible soybean cultivars and nonpathogenic strains which do not cause hypertrophy were compared for their ability to produce indole compounds, including the plant hormone indole-3-acetic acid (IAA) in liquid media with or without supplementation with l-tryptophan. Several additional strains of plant-pathogenic xanthomonads and pseudomonads were also tested for IAA production to determine whether in vitro production of IAA is related to the ability to induce hypertrophic growth of host tissues. Indoles present in culture filtrates were identified by thin-layer chromatography, high-performance liquid chromatography, UV spectroscopy, mass spectroscopy, and gas chromatography-mass spectrometry and were quantitated by high-performance liquid chromatography. All strains examined produced IAA when liquid media were supplemented with l-tryptophan. The highest levels of IAA were found in culture filtrates from the common bean pathogen Pseudomonas syringae pv. syringae, and this was the only bacterium tested which produced IAA without addition of tryptophan to the medium. Additional indoles identified in culture filtrates of the various strains included indole-3-lactic acid, indole-3-aldehyde, indole-3-acetamide, and N-acetyltryptophan. Pseudomonads and xanthomonads could be distinguished by the presence of N-acetyltryptophan, which was found only in xanthomonad culture filtrates. PMID:16347409

  14. The bHLH Transcription Factor bHLH104 Interacts with IAA-LEUCINE RESISTANT3 and Modulates Iron Homeostasis in Arabidopsis

    PubMed Central

    Zhang, Jie; Liu, Bing; Li, Mengshu; Feng, Dongru; Jin, Honglei; Wang, Peng; Liu, Jun; Xiong, Feng; Wang, Jinfa; Wang, Hong-Bin

    2015-01-01

    Iron (Fe) is an indispensable micronutrient for plant growth and development. The regulation of Fe homeostasis in plants is complex and involves a number of transcription factors. Here, we demonstrate that a basic helix-loop-helix (bHLH) transcription factor, bHLH104, belonging to the IVc subgroup of bHLH family, acts as a key component positively regulating Fe deficiency responses. Knockout of bHLH104 in Arabidopsis thaliana greatly reduced tolerance to Fe deficiency, whereas overexpression of bHLH104 had the opposite effect and led to accumulation of excess Fe in soil-grown conditions. The activation of Fe deficiency-inducible genes was substantially suppressed by loss of bHLH104. Further investigation showed that bHLH104 interacted with another IVc subgroup bHLH protein, IAA-LEUCINE RESISTANT3 (ILR3), which also plays an important role in Fe homeostasis. Moreover, bHLH104 and ILR3 could bind directly to the promoters of Ib subgroup bHLH genes and POPEYE (PYE) functioning in the regulation of Fe deficiency responses. Interestingly, genetic analysis showed that loss of bHLH104 could decrease the tolerance to Fe deficiency conferred by the lesion of BRUTUS, which encodes an E3 ligase and interacts with bHLH104. Collectively, our data support that bHLH104 and ILR3 play pivotal roles in the regulation of Fe deficiency responses via targeting Ib subgroup bHLH genes and PYE expression. PMID:25794933

  15. The Aux/IAA gene rum1 involved in seminal and lateral root formation controls vascular patterning in maize (Zea mays L.) primary roots.

    PubMed

    Zhang, Yanxiang; Paschold, Anja; Marcon, Caroline; Liu, Sanzhen; Tai, Huanhuan; Nestler, Josefine; Yeh, Cheng-Ting; Opitz, Nina; Lanz, Christa; Schnable, Patrick S; Hochholdinger, Frank

    2014-09-01

    The maize (Zea mays L.) Aux/IAA protein RUM1 (ROOTLESS WITH UNDETECTABLE MERISTEMS 1) controls seminal and lateral root initiation. To identify RUM1-dependent gene expression patterns, RNA-Seq of the differentiation zone of primary roots of rum1 mutants and the wild type was performed in four biological replicates. In total, 2 801 high-confidence maize genes displayed differential gene expression with Fc ≥2 and FDR ≤1%. The auxin signalling-related genes rum1, like-auxin1 (lax1), lax2, (nam ataf cuc 1 nac1), the plethora genes plt1 (plethora 1), bbm1 (baby boom 1), and hscf1 (heat shock complementing factor 1) and the auxin response factors arf8 and arf37 were down-regulated in the mutant rum1. All of these genes except nac1 were auxin-inducible. The maize arf8 and arf37 genes are orthologues of Arabidopsis MP/ARF5 (MONOPTEROS/ARF5), which controls the differentiation of vascular cells. Histological analyses of mutant rum1 roots revealed defects in xylem organization and the differentiation of pith cells around the xylem. Moreover, histochemical staining of enlarged pith cells surrounding late metaxylem elements demonstrated that their thickened cell walls displayed excessive lignin deposition. In line with this phenotype, rum1-dependent mis-expression of several lignin biosynthesis genes was observed. In summary, RNA-Seq of RUM1-dependent gene expression in maize primary roots, in combination with histological and histochemical analyses, revealed t