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Sample records for bacterial blight xanthomonas

  1. Dominant gene for common bean resistance to common bacterial blight caused by Xanthomonas axonopodis pv. phaseoli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The common bacterial blight pathogen [Xanthomonas axonopodis pv. phaseoli (Xap)] is a limiting factor for common bean (Phaseolus vulgaris L.) production worldwide and resistance to the pathogen in most commercial cultivars is inadequate. Variability in virulence of the bacterial pathogen has been ob...

  2. Surface layers of Xanthomonas malvacearum, the cause of bacterial blight of cotton.

    PubMed

    Verma, J P; Formanek, H

    1981-01-01

    Mureins were isolated from two strains of Xanthomonas malvacearum, a phytopathogenic bacterium causing bacterial blight of cotton. The purity of murein was 70-95 % and the amino acid and amino sugar components (glutamic acid, alanina, meso-disminopimelic acid, muramic acid and glucosamine) were present at the molar ratio of 1:1.9:1:l.12.0.85. The bacterium secreted a copious amount of slime which masked itd surface structure. The slime was composed of densley interwoven network of filamentous material originating from the cell surface and extended into the medium without and discernable boundary. The slime was secreted through surface layers pores by force, giving the effect of a spray or jet. Slime also played a role in chain formatin of baterial cells.

  3. Direct suppression of a rice bacterial blight (Xanthomonas oryzae pv. oryzae) by monoterpene (S)-limonene.

    PubMed

    Lee, Gun Woong; Chung, Moon-Soo; Kang, Mihyung; Chung, Byung Yeoup; Lee, Sungbeom

    2016-05-01

    Rice bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is a severe disease of rice plants. Upon pathogen infection, rice biosynthesizes phytoalexins, including diterpenoids such as momilactones, phytocassanes, and oryzalexins. However, information on headspace volatiles in response to Xoo infection is limited. We have examined headspace volatile terpenes, induced by the infection of Xoo, and investigated their biological roles in the rice plant. Monoterpenes α-thujene, α-pinene, sabinene, myrcene, α-terpene, and (S)-limonene and sesquiterpenes cyclosativene, α-copaene, and β-elemene were detected from 1-week-old Xoo-infected rice seedlings, by solid-phase microextraction-gas chromatography-mass spectrometry. All monoterpenes were constitutively released from rice seedlings before Xoo infection. However, (S)-limonene emission was further elicited after exposure of the seedlings to Xoo in coincidence with upregulation of limonene synthase gene (OsTPS20) transcripts. Only the stereospecific (S)-limonene [and not (R)-limonene or other monoterpenes] severely inhibited Xoo growth, as confirmed by disc diffusion and liquid culture assays. Rice seedlings showed suppressed pathogenic symptoms suggestive of resistance to Xoo infection after foliar treatment with (S)-limonene. Collectively, our findings suggest that (S)-limonene is a volatile phytoanticipin, which plays a significant role in suppressing Xoo growth in rice seedlings.

  4. Inheritance of high levels of resistance to common bacterial blight caused by Xanthomonas Axonopodis pv. Phaseoli in common bean (Phaseolus vulgaris L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Common bacterial blight caused by the pathogen Xanthomonas axonopodis pv. phaseoli (Xap) is an important biotic factor limiting common bean (Phaseolus vulgaris L.) production. A few interspecific bean breeding lines such as VAX 6 exhibit a high level of resistance to a wide range of Xap strains repr...

  5. First report of bacterial blight of carrot in Indiana caused by Xanthomonas hortorum pv. carotae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In summer 2012, bacterial blight symptoms were observed on leaves of carrot plants in 7 out of 70 plots of carrot breeding lines at the Purdue University Meig Horticulture Research Farm, Lafayette, IN. Symptoms included small to large, variably shaped, water soaked to dry, necrotic lesions, with or ...

  6. Antimicrobial peptide melittin against Xanthomonas oryzae pv. oryzae, the bacterial leaf blight pathogen in rice.

    PubMed

    Shi, Wei; Li, Caiyun; Li, Man; Zong, Xicui; Han, Dongju; Chen, Yuqing

    2016-06-01

    Xanthomonas oryzae pv. oryzae is a destructive bacterial disease of rice, and the development of an environmentally safe bactericide is urgently needed. Antimicrobial peptides, as antibacterial sources, may play important roles in bactericide development. In the present study, we found that the antimicrobial peptide melittin had the desired antibacterial activity against X. oryzae pv. oryzae. The antibacterial mechanism was investigated by examining its effects on cell membranes, energy metabolism, and nucleic acid, and protein synthesis. The antibacterial effects arose from its ability to interact with the bacterial cell wall and disrupt the cytoplasmic membrane by making holes and channels, resulting in the leakage of the cytoplasmic content. Additionally, melittin is able to permeabilize bacterial membranes and reach the cytoplasm, indicating that there are multiple mechanisms of antimicrobial action. DNA/RNA binding assay suggests that melittin may inhibit macromolecular biosynthesis by binding intracellular targets, such as DNA or RNA, and that those two modes eventually lead to bacterial cell death. Melittin can inhibit X. oryzae pv. oryzae from spreading, alleviating the disease symptoms, which indicated that melittin may have potential applications in plant protection.

  7. Testing the model for a dominant resistance gene expresed on leaves of Phaseolus vulgaris F2 (0313-58 X Rosada Nativa) to the common bacterial blight pathogen, Xanthomonas axonopodis pv. Phaseoli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The common bean bacterial blight pathogen, Xanthomonas axonopodis pv. phaseoli, is a limiting factor for bean, Phaseolus vulgaris, production worldwide and resistance to the pathogen in commercial varieties is inadequate. To test the hypothesis of the presence of strain specific genes for resistance...

  8. Analyses of genetic diversity of bacterial blight pathogen, Xanthomonas oryzae pv. oryzae using IS1112 in Bangladesh.

    PubMed

    Islam, Md Rashidul; Alam, Md Samiul; Khan, Ashik Iqbal; Hossain, Ismail; Adam, Lorne R; Daayf, Fouad

    2016-01-01

    Bacterial blight (BB) is caused by Xanthomonas oryzae pv. oryzae (Xoo), a most destructive disease of rice, mostly in Asia, including Bangladesh. Altogether 96 isolates of Xoo were collected from 19 rice-growing districts of Bangladesh in both the rain-fed and irrigated seasons of 2014 to assess their pathotypic and genetic variation. Pathotypic analyses were carried out on a set of 12 Near Isogenic Lines (NILs) of rice containing a single resistance gene and two check varieties IR24 and TN1 by the leaf clipping inoculation method. A total of 24 pathotypes were identified based on their virulence patterns on the NILs tested. Among these, pathotypes VII, XII and XIV, considered as major, containing a maximum number of isolates (9.38% each), are frequently distributed in seven northern to mid-eastern districts of Bangladesh. The most virulent pathotype I was recorded in the Habiganj and Brahmanbaria districts. The molecular analysis of variability among the isolates was carried out through PCR analysis using multi-locus primers Jel1 and Jel2 (based on the repetitive element IS1112 in the Xoo genome). Using the genotypic data, a dendrogram was constructed with 17 clusters along with 17 molecular haplotypes at the 65% similarity index. Cluster I was composed of 46 isolates considered as major, whereas clusters X, XI, XII and XVII were represented by a single isolate. A phenogram was constructed based on virulence to interpret the relationship between the pathotypes and the molecular haplotypes. At the 50% similarity level, among 10 clusters, cluster I, considered as major, consisted of a maximum of 10 pathotypes out of 24. In case of haplotypes, a maximum of 7 haplotypes were obtained from pathotype XII, whereas pathotypes IX, X, XV, XXII and XXIV were represented by a single haplotype. However, the present study revealed that different isolates belonging to the same pathotypes belonged to different haplotypes. Conversely, genetically similar haplotypes were also

  9. The RpfB-Dependent Quorum Sensing Signal Turnover System Is Required for Adaptation and Virulence in Rice Bacterial Blight Pathogen Xanthomonas oryzae pv. oryzae.

    PubMed

    Wang, Xing-Yu; Zhou, Lian; Yang, Jun; Ji, Guang-Hai; He, Ya-Wen

    2016-03-01

    Xanthomonas oryzae pv. oryzae, the bacterial blight pathogen of rice, produces diffusible signal factor (DSF) family quorum sensing signals to regulate virulence. The biosynthesis and perception of DSF family signals require components of the rpf (regulation of pathogenicity factors) cluster. In this study, we report that RpfB plays an essential role in DSF family signal turnover in X. oryzae pv. oryzae PXO99A. The production of DSF family signals was boosted by deletion of the rpfB gene and was abolished by its overexpression. The RpfC/RpfG-mediated DSF signaling system negatively regulates rpfB expression via the global transcription regulator Clp, whose activity is reversible in the presence of cyclic diguanylate monophosphate. These findings indicate that the DSF family signal turnover system in PXO99A is generally consistent with that in Xanthomonas campestris pv. campestris. Moreover, this study has revealed several specific roles of RpfB in PXO99A. First, the rpfB deletion mutant produced high levels of DSF family signals but reduced extracellular polysaccharide production, extracellular amylase activity, and attenuated pathogenicity. Second, the rpfB/rpfC double-deletion mutant was partially deficient in xanthomonadin production. Taken together, the RpfB-dependent DSF family signal turnover system is a conserved and naturally presenting signal turnover system in Xanthomonas spp., which plays unique roles in X. oryzae pv. oryzae adaptation and pathogenesis.

  10. Niclosamide inhibits leaf blight caused by Xanthomonas oryzae in rice

    PubMed Central

    Kim, Sung-Il; Song, Jong Tae; Jeong, Jin-Yong; Seo, Hak Soo

    2016-01-01

    Rice leaf blight, which is caused by the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo), results in huge losses in grain yield. Here, we show that Xoo-induced rice leaf blight is effectively controlled by niclosamide, an oral antihelminthic drug and molluscicide, which also functions as an anti-tumor agent. Niclosamide directly inhibited the growth of the three Xoo strains PXO99, 10208 and K3a. Niclosamide moved long distances from the site of local application to distant rice tissues. Niclosamide also increased the levels of salicylate and induced the expression of defense-related genes such as OsPR1 and OsWRKY45, which suppressed Xoo-induced leaf wilting. Niclosamide had no detrimental effects on vegetative/reproductive growth and yield. These combined results indicate that niclosamide can be used to block bacterial leaf blight in rice with no negative side effects. PMID:26879887

  11. SCREENING OF TRANSGENIC ANTHURIUMS FOR BACTERIAL BLIGHT AND NEMATODE RESISTANCE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anthuriums exhibit limited resistance to bacterial blight caused by Xanthomonas axonopodis pv. dieffenbachiae and to the nematodes Radopholus simile and Meloidogyne javanica. Agrobacterium tumefaciens transformation of embryogenic calli with strains LBA4404, EHA105, and AGLO resulted in transgenic p...

  12. Genome sequencing and comparative analysis of the carrot bacterial blight pathogen, Xanthomonas hortorum pv. carotae M081, for insights into pathogenicity and applications in molecular diagnostics.

    PubMed

    Kimbrel, Jeffrey A; Givan, Scott A; Temple, Todd N; Johnson, Kenneth B; Chang, Jeff H

    2011-08-01

    Xanthomonas hortorum pv. carotae (Xhc) is an economically important pathogen of carrots. Its ability to epiphytically colonize foliar surfaces and infect seeds can result in bacterial blight of carrots when grown in warm and humid regions. We used high-throughput sequencing to determine the genome sequence of isolate M081 of Xhc. The short reads were de novo assembled and the resulting contigs were ordered using a syntenic reference genome sequence from X. campestris pv. campestris ATCC 33913. The improved, high-quality draft genome sequence of Xhc M081 is the first for its species. Despite its distance from other sequenced xanthomonads, Xhc M081 still shared a large inventory of orthologous genes, including many clusters of virulence genes common to other foliar pathogenic species of Xanthomonas. We also mined the genome sequence and identified at least 21 candidate type III effector genes. Two were members of the avrBs2 and xopQ families that demonstrably elicit effector-triggered immunity. We showed that expression in planta of these two type III effectors from Xhc M081 was sufficient to elicit resistance gene-mediated hypersensitive responses in heterologous plants, indicating a possibility for resistance gene-mediated control of Xhc. Finally, we identified regions unique to the Xhc M081 genome sequence, and demonstrated their potential in the design of molecular diagnostics for this pathogen.

  13. ERIC-PCR-generated genomic fingerprints and their relationship with pathogenic variability of Xanthomonas campestris pv. punicae, the incitant of bacterial blight of pomegranate.

    PubMed

    Mondal, Kalyan K; Mani, C

    2009-12-01

    Bacterial blight caused by Xanthomonas campestris pv. punicae (Xcp) has emerged as a potential threat in pomegranate (Punica granatum) cultivation in India. Here, we report the genomic fingerprints and their correlation with virulence pattern of Xcp isolates from Maharashtra and Delhi. The genomic fingerprints of Xcp isolates were generated using enterobacterial repetitive intergenic consensus (ERIC) sequence-based primers, and virulence level was based on their reaction upon infiltration to susceptible pomegranate cultivar. Maharashtra isolate PGM1 showed only 50% similarity with Delhi isolate PGD8 forming a distinct genotype, whereas the Delhi isolates PGD5 and PGD6 form a cluster with Maharashtra isolates PGM2 and PGM4. The isolates PGM2, PGM4, PGD5, and PGD6 showing mean disease score of 7.47 were marked as group A or highly virulent. The moderately virulent or group B isolates PGM3 and PGD7 produced mean disease score of 4.19, whereas less virulent or group C isolates PGD8 and PGM1 gave mean disease intensity of 1.91. A correlation between genotypic groups based on ERIC fingerprints and pathogenicity of the isolates was established. The highly virulent isolates PGM2, PGM4, PGD5, and PGD6 formed a single cluster. A unique 900 bp amplicon present in all highly virulent isolates has been identified that can be used as genetic marker to screen isolates for virulence. The less virulent isolates PGD8 and PGM1 formed single cluster at 50% similarity coefficient. This seems to be the first report to establish a correlation between ERIC-PCR fingerprints and their corresponding virulence pattern of the pomegranate bacterial blight pathogen.

  14. The broad bacterial blight resistance of rice line CBB23 is triggered by a novel transcription activator-like (TAL) effector of Xanthomonas oryzae pv. oryzae.

    PubMed

    Wang, Chun-Lian; Qin, Teng-Fei; Yu, Hong-Man; Zhang, Xiao-Ping; Che, Jin-Ying; Gao, Ying; Zheng, Chong-Ke; Yang, Bing; Zhao, Kai-Jun

    2014-05-01

    Bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is not only a disease devastating rice production worldwide, but also an ideal model system for the study of the interaction between plants and their bacterial pathogens. The rice near-isogenic line (NIL) CBB23, derived from a cross between a wild rice Oryza rufipogon accession (RBB16) and a susceptible indica rice variety (Jingang 30), is highly resistant to all field Xoo strains tested so far. Although the BB resistance of CBB23 has been widely used in rice breeding programmes, the mechanism of its extremely broad-spectrum resistance remains unknown. Here, we report the molecular cloning of an avirulence gene, designated as avrXa23, from Xoo strain PXO99(A) . We validate that AvrXa23, a novel transcription activator-like effector, specifically triggers the broad-spectrum BB resistance in CBB23. The prevalence of avrXa23 in all 38 Xoo strains surveyed may explain the broad-spectrum feature of BB resistance in CBB23. The results will significantly facilitate the molecular cloning of the corresponding resistance (R) gene in the host, and provide new insights into our understanding of the molecular mechanism for broad-spectrum disease resistance in plants.

  15. The structure of the lipooligosaccharide from Xanthomonas oryzae pv. Oryzae: the causal agent of the bacterial leaf blight in rice.

    PubMed

    Di Lorenzo, Flaviana; Palmigiano, Angelo; Silipo, Alba; Desaki, Yoshitake; Garozzo, Domenico; Lanzetta, Rosa; Shibuya, Naoto; Molinaro, Antonio

    2016-06-02

    The structure of the lipooligosaccharide (LOS) from the rice pathogen Xanthomonas oryzae pv. oryzae has been elucidated. The characterization of the core oligosaccharide structure was obtained by the employment of two chemical degradation protocols and by analysis of the products via NMR spectroscopy. The structure of the lipid A portion was achieved by MALDI mass spectrometry analysis on purified lipid A. The LOS from Xanthomonas oryzae pv. oryzae revealed to possess the same core structure of Xanthomonas campestris pv. campestris and interesting novel features on its lipid A domain. The evaluation of the biological activity of both LOS and isolated lipid A was also executed.

  16. Diversity of bacteriophages infecting Xanthomonas oryzae pv. oryzae in paddy fields and its potential to control bacterial leaf blight of rice.

    PubMed

    Chae, Jong-Chan; Hung, Nguyen Bao; Yu, Sang-Mi; Lee, Ha Kyung; Lee, Yong Hoon

    2014-06-28

    Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a very serious disease in rice-growing regions of the world. In spite of their economic importance, there are no effective ways of protecting rice plants from this disease. Bacteriophages infecting Xoo affect the population dynamics of the pathogen and consequently the occurrence of the disease. In this study, we investigated the diversity, host range, and infectivity of Xoo phages, and their use as a bicontrol agent on BLB was tested. Among the 34 phages that were isolated from floodwater in paddy fields, 29 belonged to the Myoviridae family, which suggests that the dominant phage in the ecosystem was Myoviridae. The isolated phages were classified into two groups based on plaque size produced on the lawn of Xoo. In general, there was a negative relationship between plaque size and host range, and interestingly the phages having a narrow host range had low efficiency of infectivity. The deduced protein sequence analysis of htf genes indicated that the gene was not a determinant of host specificity. Although the difference in host range and infectivity depending on morphotype needs to be addressed, the results revealed deeper understanding of the interaction between the phages and Xoo strains in floodwater and damp soil environments. The phage mixtures reduced the occurrence of BLB when they were treated with skim milk. The results indicate that the Xoo phages could be used as an alternative control method to increase the control efficacy and reduce the use of agrochemicals.

  17. Development of bioformulation and delivery system of Pseudomonas fluorescens against bacterial leaf blight of rice (Xanthomonas oryzae pv. oryzae).

    PubMed

    Jambhulkar, P P; Sharma, P

    2014-09-01

    Antagonistic potential of Pseudomonas fluorescens isolate RRb-11 has been evaluated against bacterial leaf blight (BLB) pathogen of rice in vitro, in vivo, microplot and field tests. RRb-11 isolate mass multiplied in substrates like talc and kaolinite powder and bran of barley, soybean and wheat to prepare suitable bioformulation. The maximum shelf life of P. fluorescens was recorded in talc based bioformulation up to 150 days after storage. In rhizosphere competence study, the root rhizosphere of talc, kaolinite and barley based bioformulation treated plants showed good survivability and competence even up to 90 days after treatment. In field study, the talc based bioformulation was applied and the best results were obtained when talc based bioformulation of P. fluorescens RRb-11 was applied as seed treatment, seedling root dip and soil application in combination which reduced the disease by 92.3 and 88.5% over control in the year 2009 and 2010, respectively. This treatment also produced maximum yield of 3.88 t ha(-1) i.e., 61% greater than control.

  18. Occurrence of Xanthomonas axonopodis pv. phaseoli, the causal agent of common bacterial blight disease, on seeds of common bean (Phaseolus vulgaris L.) in upper Egypt.

    PubMed

    Abd-Alla, M H; Bashandy, S R; Schnell, S

    2010-01-01

    Common bean seed lots collected from different seed dealers and Malawii agriculture station were screened for the presence of Xanthomonas axonopodis pv. phaseoli. In the laboratory the pathogen was isolated following the routine laboratory assay method, i.e. direct plating method using yeast extract-dextrose-calcium carbonate agar medium (YDC). Yellow, convex, mucoid colonies of Xanthomonas were consistently isolated on YDC from seed samples. The presumptive pathogen was confirmed by isolation on semiselective medium, such as mTBM and MD5A. Further, the pathogen was confirmed by biochemical, physiological and, finally, the pathogenicity tests. Five samples out of seven were positive for Xanthomonas. The isolates were found to cause common blight of 3-week-old common bean plants by 7 d after inoculation. Bacteria with the same characteristics as those inoculated were re-isolated from the infected plants.

  19. TAL effector-mediated susceptibility to bacterial blight of cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial blight of cotton (BBC) caused by Xanthomonas campestris pv. malvacearum (Xcm) is a destructive disease that has recently re-emerged in the U.S. Xcm injects transcription activator-like (TAL) effectors that directly induce the expression of host susceptibility (S) or resistance (R) genes. ...

  20. New multilocus variable-number tandem-repeat analysis tool for surveillance and local epidemiology of bacterial leaf blight and bacterial leaf streak of rice caused by Xanthomonas oryzae.

    PubMed

    Poulin, L; Grygiel, P; Magne, M; Gagnevin, L; Rodriguez-R, L M; Forero Serna, N; Zhao, S; El Rafii, M; Dao, S; Tekete, C; Wonni, I; Koita, O; Pruvost, O; Verdier, V; Vernière, C; Koebnik, R

    2015-01-01

    Multilocus variable-number tandem-repeat analysis (MLVA) is efficient for routine typing and for investigating the genetic structures of natural microbial populations. Two distinct pathovars of Xanthomonas oryzae can cause significant crop losses in tropical and temperate rice-growing countries. Bacterial leaf streak is caused by X. oryzae pv. oryzicola, and bacterial leaf blight is caused by X. oryzae pv. oryzae. For the latter, two genetic lineages have been described in the literature. We developed a universal MLVA typing tool both for the identification of the three X. oryzae genetic lineages and for epidemiological analyses. Sixteen candidate variable-number tandem-repeat (VNTR) loci were selected according to their presence and polymorphism in 10 draft or complete genome sequences of the three X. oryzae lineages and by VNTR sequencing of a subset of loci of interest in 20 strains per lineage. The MLVA-16 scheme was then applied to 338 strains of X. oryzae representing different pathovars and geographical locations. Linkage disequilibrium between MLVA loci was calculated by index association on different scales, and the 16 loci showed linear Mantel correlation with MLSA data on 56 X. oryzae strains, suggesting that they provide a good phylogenetic signal. Furthermore, analyses of sets of strains for different lineages indicated the possibility of using the scheme for deeper epidemiological investigation on small spatial scales.

  1. In vitro antibacterial activity of sphaeropsidins and chemical derivatives toward Xanthomonas oryzae pv. oryzae, the causal agent of rice bacterial blight.

    PubMed

    Evidente, Antonio; Venturi, Vittorio; Masi, Marco; Degrassi, Giuliano; Cimmino, Alessio; Maddau, Lucia; Andolfi, Anna

    2011-12-27

    Sphaeropsidin A, the main phytotoxin produced by Diplodia cupressi, as well as the two natural analogues sphaeropsidins B and C and 14 derivatives obtained by chemical modifications were assayed for antibacterial activity against Xanthomonas oryzae pv. oryzae, Pseudomonas fuscovaginae, and Burkholderia glumae, the causal agents of severe bacterial rice diseases. The results showed a strong and specific activity of sphaeropsidin A against X. oryzae pv. oryzae, while no activity was observed against the other two pathogens. The results of structure-activity relationship studies showed that structural features important to impart this antibacterial activity are the presence of the C-7 carbonyl group and the hemiketalic lactone functionality. The C-13 vinyl group, the double bond of ring C, and/or the tertiary C-9 hydroxy group, as well as the pimarane arrangement of the tricylic carbon skeleton, were also important for the antibacterial activity. These findings may be useful in designing novel compounds for practical applications in agriculture.

  2. Inoculation and virulence assay for bacterial blight and bacterial leaf streak of rice.

    PubMed

    Yang, Bing; Bogdanove, Adam

    2013-01-01

    Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) cause bacterial blight and bacterial leaf streak in rice, respectively. Despite being very closely related, the pathogens colonize different tissues and cause distinct diseases. The diseases are economically important and also serve as model systems for studying plant-bacterial interactions. Here we describe protocols for Xoo and Xoc inoculation and disease scoring methods that are appropriate to their different modes of infection. These methods are routinely used to evaluate pathogen virulence or host responses under controlled environmental conditions.

  3. Draft Genome Sequences of Four Xanthomonas arboricola pv. juglandis Strains Associated with Walnut Blight in Chile

    PubMed Central

    Higuera, Gastón; González-Escalona, Narjol; Véliz, Camila; Vera, Francisca

    2015-01-01

    Xanthomonas arboricola pv. juglandis is an important pathogen responsible for walnut blight outbreaks globally. Here, we report four draft genome sequences of X. arboricola pv. juglandis strains isolated from Chilean walnut trees. PMID:26450732

  4. Microarray analysis of the semi-compatible pathogenic response and recovery of leafy spurge inoculated with the Cassava bacterial blight pathogen Xanthomonas axonopodis pv. manihotis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infection by Xanthomonas axonopodis pv. manihotis (Xam)of the model perennial range land weed leafy spurge was tested to see if Xam might serve a potential biological control agent for this invasive weed. Although leafy spurge was susceptible to Xam infection, it recovered with 21 days after inocula...

  5. Draft genome sequence of XANTHOMONAS ARBORICOLA strain 3004, causal agent of bacterial disease on barley

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report here the annotated genome sequence of XANTHOMONAS ARBORICOLA str. 3004, a Gram-negative phytopathogenic bacteria that includes several pathovars characterized by virulence specificity. Strain 3004 was isolated from barley leaves with symptoms of streak (bacterial blight) and also can infec...

  6. Development of candidate gene markers associated to common bacterial blight resistance in common bean

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Common bacterial blight (CBB), caused by Xanthomonas axonopodis pv. phaseoli (Xap), is a major yield-limiting factor of common bean (Phaseolus vulgaris L.) production around the world. Two major CBB-resistant quantitative trait loci (QTL), linked to the sequence characterized amplified region marker...

  7. Controlling rice bacterial blight in Africa: needs and prospects.

    PubMed

    Verdier, Valérie; Vera Cruz, Casiana; Leach, Jan E

    2012-06-30

    Rice cultivation has drastically increased in Africa over the last decade. During this time, the region has also seen a rise in the incidence of rice bacterial blight caused by the pathogen Xanthomonas oryzae pv. oryzae. The disease is expanding to new rice production areas and threatens food security in the region. Yield losses caused by X. oryzae pv. oryzae range from 20 to 30% and can be as high as 50% in some areas. Employing resistant cultivars is the most economical and effective way to control this disease. To facilitate development and strategic deployment of rice cultivars with resistance to bacterial blight, biotechnology tools and approaches, including marker-assisted breeding, gene combinations for disease control, and multiplex-PCR for pathogen diagnosis, have been developed. Although these technologies are routinely used elsewhere, their application in Africa remains limited, usually due to high cost and advanced technical skills required. To combat this problem, developers of the technologies at research institutions need to work with farmers from an early stage to create and promote the integration of successful, low cost applications of research biotech products. Here, we review the current knowledge and biotechnologies available to improve bacterial blight control. We will also discuss how to facilitate their application in Africa and delivery to the field.

  8. Pyramiding transgenic resistance in elite indica rice cultivars against the sheath blight and bacterial blight.

    PubMed

    Maruthasalam, S; Kalpana, K; Kumar, K K; Loganathan, M; Poovannan, K; Raja, J A J; Kokiladevi, E; Samiyappan, R; Sudhakar, D; Balasubramanian, P

    2007-06-01

    Elite indica rice cultivars were cotransformed with genes expressing a rice chitinase (chi11) and a thaumatin-like protein (tlp) conferring resistance to fungal pathogens and a serine-threonine kinase (Xa21) conferring bacterial blight resistance, through particle bombardment, with a view to pyramiding sheath blight and bacterial blight resistance. Molecular analyses of putative transgenic lines by polymerase chain reaction, Southern Blot hybridization, and Western Blotting revealed stable integration and expression of the transgenes in a few independent transgenic lines. Progeny analyses showed the stable inheritance of transgenes to their progeny. Coexpression of chitinase and thaumatin-like protein in the progenies of a transgenic Pusa Basmati1 line revealed an enhanced resistance to the sheath blight pathogen, Rhizoctonia solani, as compared to that in the lines expressing the individual genes. A transgenic Pusa Basmati1 line pyramided with chi11, tlp, and Xa21 showed an enhanced resistance to both sheath blight and bacterial blight.

  9. Screening Rice Cultivars for Resistance to Bacterial Leaf Blight.

    PubMed

    Fred, Agaba Kayihura; Kiswara, Gilang; Yi, Gihwan; Kim, Kyung-Min

    2016-05-28

    Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most serious threats to rice production. In this study, screening of rice for resistance to BLB was carried out at two different times and locations; that is, in a greenhouse during winter and in an open field during summer. The pathogenicity of Xoo race K1 was tested on 32 Korean rice cultivars. Inoculation was conducted at the maximum tillering stage, and the lesion length was measured after 14 days of inoculation. Five cultivars, Hanareum, Namcheon, Samgdeok, Samgang, and Yangjo, were found to be resistant in both the greenhouse and open-field screenings. Expression of the plant defense-related genes JAmyb, OsNPR1, OsPR1a, OsWRKY45, and OsPR10b was observed in resistant and susceptible cultivars by qRT-PCR. Among the five genes tested, only OsPR10b showed coherent expression with the phenotypes. Screening of resistance to Xoo in rice was more accurate when conducted in open fields in the summer cultivation period than in greenhouses in winter. The expression of plant defenserelated genes after bacterial inoculation could give another perspective in elucidating defense mechanisms by using both resistant and susceptible individuals.

  10. Screening and identification of antimicrobial compounds from Streptomyces bottropensis suppressing rice bacterial blight.

    PubMed

    Park, Sait Byul; Lee, In Ae; Suh, Joo-Won; Kim, Jeong-Gu; Lee, Choong Hwan

    2011-12-01

    Xanthomonas oryzae pv. oryzae (Xoo) is the most devastating pathogen to Oryza sativa and has been shown to cause bacterial blight. Two bioactive compounds showing antimicrobial activities against Xoo strain KACC 10331 were isolated from a Streptomyces bottropensis strain. The ethyl acetate extract was fractionated on a Sephadex LH-20 column, and then purified by preparative HPLC. The purified compounds were identified as bottromycin A2 and dunaimycin D3S by HR/MS and 1H NMR analyses. The MIC value against Xoo and the lowest concentration still capable of suppressing rice bacterial blight were 2 microgram/ml and 16 microgram/ml for bottromycin A2, and 64 microgram/ml and 0.06 microgram/ml for dunaimycin D3S, respectively. These two compounds were shown to exert different bioactivities in vitro and in rice leaf explants.

  11. Biological control of Xanthomonas Oryzae pv. Oryzae causing rice bacterial blight disease by Streptomyces toxytricini VN08-A-12, isolated from soil and leaf-litter samples in Vietnam.

    PubMed

    Van Hop, Duong; Phuong Hoa, Phan Thi; Quang, Nguyen Duc; Ton, Phan Huu; Ha, Trinh Hoang; Van Hung, Nguyen; Van, Nguyen Thi; Van Hai, Tong; Kim Quy, Nguyen Thi; Anh Dao, Nguyen Thi; Thi Thom, Vu

    2014-01-01

    A total of 2690 actinomycete strains were screened as potential biological control agents in controlling rice bacterial blight (BB) in Vietnam. From these microorganisms, seventeen actinomycete strains were found to be capable of inhibiting all 10 major Xoo races isolated from Xoo-infected rice leaves. One strain, namely VN08-A-12, contained effective characteristics in selectively inhibiting all 10 races in vitro, but did not inhibit most of the other tested microorganisms. Therefore, VN08-A-12 was subsequently selected for rice field trials for two seasons on two rice cultivars SS1 and KD18. Results showed VN08-A-12 was not only able to reduce Xoo lesion lengths in the two rice cultivars (lesion length reduction of up to 38.3%), but it also significantly reduced Xoo-related yield loss in infected rice cultivars from the field (yield loss reduction of up to 43.2%). Interestingly, the culture of this strain also increased the rice yield in healthy rice cultivars (from 2.66% to 16.98% for SS1 and from 3.11% to 5.94% for KD18 cultivar). The strain VN08-A-12 was shown to be identical to Streptomyces toxytricini. To our knowledge, this is the first study reporting S. toxytricini as a beneficial biological agent for the control of BB in rice.

  12. DgcA, a diguanylate cyclase from Xanthomonas oryzae pv. oryzae regulates bacterial pathogenicity on rice.

    PubMed

    Su, Jianmei; Zou, Xia; Huang, Liangbo; Bai, Tenglong; Liu, Shu; Yuan, Meng; Chou, Shan-Ho; He, Ya-Wen; Wang, Haihong; He, Jin

    2016-05-19

    Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of rice blight disease as well as a serious phytopathogen worldwide. It is also one of the model organisms for studying bacteria-plant interactions. Current progress in bacterial signal transduction pathways has identified cyclic di-GMP as a major second messenger molecule in controlling Xanthomonas pathogenicity. However, it still remains largely unclear how c-di-GMP regulates the secretion of bacterial virulence factors in Xoo. In this study, we focused on the important roles played by DgcA (XOO3988), one of our previously identified diguanylate cyclases in Xoo, through further investigating the phenotypes of several dgcA-related mutants, namely, the dgcA-knockout mutant ΔdgcA, the dgcA overexpression strain OdgcA, the dgcA complemented strain CdgcA and the wild-type strain. The results showed that dgcA negatively affected virulence, EPS production, bacterial autoaggregation and motility, but positively triggered biofilm formation via modulating the intracellular c-di-GMP levels. RNA-seq data further identified 349 differentially expressed genes controlled by DgcA, providing a foundation for a more solid understanding of the signal transduction pathways in Xoo. Collectively, the present study highlights DgcA as a major regulator of Xoo virulence, and can serve as a potential target for preventing rice blight diseases.

  13. DgcA, a diguanylate cyclase from Xanthomonas oryzae pv. oryzae regulates bacterial pathogenicity on rice

    PubMed Central

    Su, Jianmei; Zou, Xia; Huang, Liangbo; Bai, Tenglong; Liu, Shu; Yuan, Meng; Chou, Shan-Ho; He, Ya-Wen; Wang, Haihong; He, Jin

    2016-01-01

    Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of rice blight disease as well as a serious phytopathogen worldwide. It is also one of the model organisms for studying bacteria-plant interactions. Current progress in bacterial signal transduction pathways has identified cyclic di-GMP as a major second messenger molecule in controlling Xanthomonas pathogenicity. However, it still remains largely unclear how c-di-GMP regulates the secretion of bacterial virulence factors in Xoo. In this study, we focused on the important roles played by DgcA (XOO3988), one of our previously identified diguanylate cyclases in Xoo, through further investigating the phenotypes of several dgcA-related mutants, namely, the dgcA-knockout mutant ΔdgcA, the dgcA overexpression strain OdgcA, the dgcA complemented strain CdgcA and the wild-type strain. The results showed that dgcA negatively affected virulence, EPS production, bacterial autoaggregation and motility, but positively triggered biofilm formation via modulating the intracellular c-di-GMP levels. RNA-seq data further identified 349 differentially expressed genes controlled by DgcA, providing a foundation for a more solid understanding of the signal transduction pathways in Xoo. Collectively, the present study highlights DgcA as a major regulator of Xoo virulence, and can serve as a potential target for preventing rice blight diseases. PMID:27193392

  14. XopN-T3SS effector of Xanthomonas axonopodis pv. punicae localizes to the plasma membrane and modulates ROS accumulation events during blight pathogenesis in pomegranate.

    PubMed

    Kumar, Rishikesh; Soni, Madhvi; Mondal, Kalyan K

    2016-12-01

    Bacterial blight caused by Xanthomonas axonopodis pv. punicae (Xap) is a major disease of pomegranate. Xap secretes effector proteins via type III secretion system (T3SS) to suppress pathogen-associated molecular pattern (PAMP)-triggered plant immunity (PTI). Previously we reported that XopN, a conserved effector of Xap, modulate in planta bacterial growth, and blight disease. In continuation to that here we report the deletion of XopN from Xap caused higher accumulation of reactive oxygen species (ROS) including H2O2 and O2(-). We quantitatively assessed the higher accumulation of H2O2 in pomegranate leaves infiltrated with Xap ΔxopN compared to Xap wild-type. We analysed that 1.5 to 3.3 fold increase in transcript expression of ROS and flg22-inducible genes, namely FRK1, GST1, WRKY29, PR1, PR2 and PR5 in Arabidopsis when challenged with Xap ΔxopN; contrary, the up-regulation of all the genes were compromised when challenged with either Xap wild-type or Xap ΔxopN+xopN. Further, we demonstrated the plasma-membrane based localization of XopN protein both in its natural and experimental hosts. All together, the present study suggested that XopN-T3SS effector of Xap gets localized in the plasma membrane and suppresses ROS-mediated early defense responses during blight pathogenesis in pomegranate.

  15. Genome-wide association analysis identifies resistance loci for bacterial blight in a diverse collection of indica rice germplasm.

    PubMed

    Zhang, Fan; Wu, Zhi-Chao; Wang, Ming-Ming; Zhang, Fan; Dingkuhn, Michael; Xu, Jian-Long; Zhou, Yong-Li; Li, Zhi-Kang

    2017-01-01

    Bacterial blight, which is caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating rice diseases worldwide. The development and use of disease-resistant cultivars have been the most effective strategy to control bacterial blight. Identifying the genes mediating bacterial blight resistance is a prerequisite for breeding cultivars with broad-spectrum and durable resistance. We herein describe a genome-wide association study involving 172 diverse Oryza sativa ssp. indica accessions to identify loci influencing the resistance to representative strains of six Xoo races. Twelve resistance loci containing 121 significantly associated signals were identified using 317,894 single nucleotide polymorphisms, which explained 13.3-59.9% of the variability in lesion length caused by Xoo races P1, P6, and P9a. Two hotspot regions (L11 and L12) were located within or nearby two cloned R genes (xa25 and Xa26) and one fine-mapped R gene (Xa4). Our results confirmed the relatively high resolution of genome-wide association studies. Moreover, we detected novel significant associations on chromosomes 2, 3, and 6-10. Haplotype analyses of xa25, the Xa26 paralog (MRKc; LOC_Os11g47290), and a Xa4 candidate gene (LOC_11g46870) revealed differences in bacterial blight resistance among indica subgroups. These differences were responsible for the observed variations in lesion lengths resulting from infections by Xoo races P1 and P9a. Our findings may be relevant for future studies involving bacterial blight resistance gene cloning, and provide insights into the genetic basis for bacterial blight resistance in indica rice, which may be useful for knowledge-based crop improvement.

  16. Genome-wide association analysis identifies resistance loci for bacterial blight in a diverse collection of indica rice germplasm

    PubMed Central

    Wang, Ming-Ming; Zhang, Fan; Dingkuhn, Michael; Xu, Jian-Long; Zhou, Yong-Li; Li, Zhi-Kang

    2017-01-01

    Bacterial blight, which is caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating rice diseases worldwide. The development and use of disease-resistant cultivars have been the most effective strategy to control bacterial blight. Identifying the genes mediating bacterial blight resistance is a prerequisite for breeding cultivars with broad-spectrum and durable resistance. We herein describe a genome-wide association study involving 172 diverse Oryza sativa ssp. indica accessions to identify loci influencing the resistance to representative strains of six Xoo races. Twelve resistance loci containing 121 significantly associated signals were identified using 317,894 single nucleotide polymorphisms, which explained 13.3–59.9% of the variability in lesion length caused by Xoo races P1, P6, and P9a. Two hotspot regions (L11 and L12) were located within or nearby two cloned R genes (xa25 and Xa26) and one fine-mapped R gene (Xa4). Our results confirmed the relatively high resolution of genome-wide association studies. Moreover, we detected novel significant associations on chromosomes 2, 3, and 6–10. Haplotype analyses of xa25, the Xa26 paralog (MRKc; LOC_Os11g47290), and a Xa4 candidate gene (LOC_11g46870) revealed differences in bacterial blight resistance among indica subgroups. These differences were responsible for the observed variations in lesion lengths resulting from infections by Xoo races P1 and P9a. Our findings may be relevant for future studies involving bacterial blight resistance gene cloning, and provide insights into the genetic basis for bacterial blight resistance in indica rice, which may be useful for knowledge-based crop improvement. PMID:28355306

  17. Development of an engineered bioluminescent reporter phage for detection of bacterial blight of crucifers.

    PubMed

    Schofield, David A; Bull, Carolee T; Rubio, Isael; Wechter, W Patrick; Westwater, Caroline; Molineux, Ian J

    2012-05-01

    Bacterial blight, caused by the phytopathogen Pseudomonas cannabina pv. alisalensis, is an emerging disease afflicting important members of the Brassicaceae family. The disease is often misdiagnosed as pepper spot, a much less severe disease caused by the related pathogen Pseudomonas syringae pv. maculicola. We have developed a phage-based diagnostic that can both identify and detect the causative agent of bacterial blight and differentiate the two pathogens. A recombinant "light"-tagged reporter phage was generated by integrating bacterial luxAB genes encoding luciferase into the genome of P. cannabina pv. alisalensis phage PBSPCA1. The PBSPCA1::luxAB reporter phage is viable and stable and retains properties similar to those of the wild-type phage. PBSPCA1::luxAB rapidly and sensitively detects P. cannabina pv. alisalensis by conferring a bioluminescent signal response to cultured cells. Detection is dependent on cell viability. Other bacterial pathogens of Brassica species such as P. syringae pv. maculicola, Pseudomonas marginalis, Pectobacterium carotovorum, Xanthomonas campestris pv. campestris, and X. campestris pv. raphani either do not produce a response or produce significantly attenuated signals with the reporter phage. Importantly, the reporter phage detects P. cannabina pv. alisalensis on diseased plant specimens, indicating its potential for disease diagnosis.

  18. Design, synthesis, and antibacterial activity against rice bacterial leaf blight and leaf streak of 2,5-substituted-1,3,4-oxadiazole/thiadiazole sulfone derivative.

    PubMed

    Li, Pei; Shi, Li; Yang, Xia; Yang, Lei; Chen, Xue-Wen; Wu, Fang; Shi, Qing-Cai; Xu, Wei-Ming; He, Ming; Hu, De-Yu; Song, Bao-An

    2014-04-01

    A series of 2,5-substituted-1,3,4-oxadiazole/thiadiazole sulfone derivatives were synthesized and evaluated for their antibacterial activities against rice bacterial leaf blight and leaf streak caused by Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicolaby via the turbidimeter test in vitro. Antibacterial bioassay results indicated that most compounds demonstrated good inhibitory effect antibacterial bioactivities against rice bacterial leaf blight and leaf streak. Among the title compounds, compound 6c demonstrated the best inhibitory effect against rice bacterial leaf blight and leaf streak with half-maximal effective concentration (EC50) values of 1.07 and 7.14 μg/mL, respectively, which were even better than those of commercial agents such as Bismerthiazol and Thiediazole Copper. In vivo antibacterial activities tests at greenhouse conditions demonstrated that the controlling effect of compounds 6c (43.5%) and 6g (42.4%) against rice bacterial leaf blight were better than those of Bismerthiazol (25.5%) and Thiediazole Copper (37.5%).

  19. Decision tools for bacterial blight resistance gene deployment in rice-based agricultural ecosystems

    PubMed Central

    Dossa, Gerbert S.; Sparks, Adam; Cruz, Casiana Vera; Oliva, Ricardo

    2015-01-01

    Attempting to achieve long-lasting and stable resistance using uniformly deployed rice varieties is not a sustainable approach. The real situation appears to be much more complex and dynamic, one in which pathogens quickly adapt to resistant varieties. To prevent disease epidemics, deployment should be customized and this decision will require interdisciplinary actions. This perspective article aims to highlight the current progress on disease resistance deployment to control bacterial blight in rice. Although the model system rice-Xanthomonas oryzae pv. oryzae has distinctive features that underpin the need for a case-by-case analysis, strategies to integrate those elements into a unique decision tool could be easily extended to other crops. PMID:25999970

  20. Decision tools for bacterial blight resistance gene deployment in rice-based agricultural ecosystems.

    PubMed

    Dossa, Gerbert S; Sparks, Adam; Cruz, Casiana Vera; Oliva, Ricardo

    2015-01-01

    Attempting to achieve long-lasting and stable resistance using uniformly deployed rice varieties is not a sustainable approach. The real situation appears to be much more complex and dynamic, one in which pathogens quickly adapt to resistant varieties. To prevent disease epidemics, deployment should be customized and this decision will require interdisciplinary actions. This perspective article aims to highlight the current progress on disease resistance deployment to control bacterial blight in rice. Although the model system rice-Xanthomonas oryzae pv. oryzae has distinctive features that underpin the need for a case-by-case analysis, strategies to integrate those elements into a unique decision tool could be easily extended to other crops.

  1. Rice Xa21 primed genes and pathways that are critical for combating bacterial blight infection.

    PubMed

    Peng, Hai; Chen, Zheng; Fang, Zhiwei; Zhou, Junfei; Xia, Zhihui; Gao, Lifen; Chen, Lihong; Li, Lili; Li, Tiantian; Zhai, Wenxue; Zhang, Weixiong

    2015-07-17

    Rice bacterial blight (BB) is a devastating rice disease. The Xa21 gene confers a broad and persistent resistance against BB. We introduced Xa21 into Oryza sativa L ssp indica (rice 9311), through multi-generation backcrossing, and generated a nearly isogenic, blight-resistant 9311/Xa21 rice. Using next-generation sequencing, we profiled the transcriptomes of both varieties before and within four days after infection of bacterium Xanthomonas oryzae pv. oryzae. The identified differentially expressed (DE) genes and signaling pathways revealed insights into the functions of Xa21. Surprisingly, before infection 1,889 genes on 135 of the 316 signaling pathways were DE between the 9311/Xa21 and 9311 plants. These Xa21-mediated basal pathways included mainly those related to the basic material and energy metabolisms and many related to phytohormones such as cytokinin, suggesting that Xa21 triggered redistribution of energy, phytohormones and resources among essential cellular activities before invasion. Counter-intuitively, after infection, the DE genes between the two plants were only one third of that before the infection; other than a few stress-related pathways, the affected pathways after infection constituted a small subset of the Xa21-mediated basal pathways. These results suggested that Xa21 primed critically important genes and signaling pathways, enhancing its resistance against bacterial infection.

  2. Identification of an emergent bacterial blight of garlic in Brazil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Outbreaks of a bacterial blight disease occurred on garlic (Allium sativum) cultivars Roxo Caxiense, Quiteria and Cacador in Southern Brazil, and threatened the main production regions of Rio Grande do Sul State. Symptoms were characterized by watersoaked reddish streaks along the leaf midrib, follo...

  3. Detection of bacterial blight resistance genes in basmati rice landraces.

    PubMed

    Ullah, I; Jamil, S; Iqbal, M Z; Shaheen, H L; Hasni, S M; Jabeen, S; Mehmood, A; Akhter, M

    2012-07-20

    Aromatic basmati rice is vulnerable to bacterial blight disease. Genes conferring resistance to bacterial blight have been identified in coarse rice; however, their incorporation into basmati varieties compromises the prized basmati aroma. We identified bacterial blight resistance genes Xa4, xa5, Xa7, and xa13 in 52 basmati landraces and five basmati cultivars using PCR markers. The Xa7 gene was found to be the most prevalent among the cultivars and landraces. The cultivars Basmati-385 and Basmati-2000 also contained the Xa4 gene; however, xa5 and xa13 were confined to landraces only. Ten landraces were found to have multiple resistance genes. Landraces Basmati-106, Basmati-189 and Basmati-208 contained Xa4 and Xa7 genes. Whereas, landraces Basmati-122, Basmati-427, Basmati-433 were observed to have xa5 and Xa7 genes. Landraces Basmati-48, Basmati-51A, Basmati-334, and Basmati-370A possessed Xa7 and xa13 genes. The use of landraces containing recessive genes xa5 and xa13 as donor parents in hybridization with cultivars Basmati-385 and Basmati-2000, which contain the genes Xa4 and Xa7, will expedite efforts to develop bacterial blight-resistant basmati rice cultivars through marker assisted selection, based on a pyramiding approach, without compromising aroma and grain quality.

  4. Antibacterial activities against rice bacterial leaf blight and tomato bacterial wilt of 2-mercapto-5-substituted-1,3,4-oxadiazole/thiadiazole derivatives.

    PubMed

    Li, Pei; Shi, Li; Gao, Man-Ni; Yang, Xia; Xue, Wei; Jin, Lin-Hong; Hu, De-Yu; Song, Bao-An

    2015-02-01

    In this study, a series of 2-mercapto-5-substituted-1,3,4-oxadiazole/thiadiazole derivatives were synthesized and evaluated for their antibacterial activities against rice bacterial leaf blight and tomato bacterial wilt caused by Xanthomonas oryzae pv. oryzae (Xoo) and Ralstonia solanacearum (R. solanacearum) via the turbidimeter test in vitro. Antibacterial bioassays indicated that most compounds demonstrated appreciable antibacterial bioactivities against Xoo and R. solanacearum. Among the title compounds, compound 4i demonstrated the best inhibitory effect against Xoo and R. solanacearum with half-maximal effective concentration (EC50) values of 14.69 and 15.14μg/mL, respectively, which were even better than those of commercial agents Bismerthiazol and Thiodiazole Copper. In vivo antibacterial activities tests under greenhouse conditions revealed that the control efficiency of compound 4i against rice bacterial leaf blight and tobacco bacterial wilt were better than those of Bismerthiazol and Thiodiazole Copper. Meanwhile, field trials also indicated that compound 4i demonstrated appreciable control efficiency against rice bacterial leaf blight and tomato bacterial wilt.

  5. Data set from a comprehensive phosphoproteomic analysis of rice variety IRBB5 in response to bacterial blight.

    PubMed

    Hou, Yuxuan; Tong, Xiaohong; Wang, Yifeng; Qiu, Jiehua; Li, Zhiyong; Zhang, Wen; Huang, Shiwen; Zhang, Jian

    2016-03-01

    Bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo) has become one of the most devastating diseases for rice, a major food source for over half of the world populations. To investigate the roles of protein phosphorylation in rice bacterial blight resistance, a quantitative phosphoproteomic study was conducted in rice variety IRBB5 at 0 h and 24 h after Xoo infection. 2367 and 2223 phosphosites on 1334 and 1297 representative proteins were identified in 0 h and 24 h after Xoo infection, respectively, out of which 762 proteins were found to be differentially phosphorylated. In associated with the published article "A comprehensive quantitative phosphoproteome analysis of rice in response to bacterial blight" in BMC Plant Biology (Hou et al., 2015) [1], this dataset article provided the detailed information of experimental designing, methods, features as well as the raw data of mass spectrometry (MS) identification. The MS proteomics data could be fully accessed from the ProteomeXchange Consortium with the dataset identifier PXD002222.

  6. Genomic Survey of Pathogenicity Determinants and VNTR Markers in the Cassava Bacterial Pathogen Xanthomonas axonopodis pv. Manihotis Strain CIO151

    PubMed Central

    Arrieta-Ortiz, Mario L.; Rodríguez-R, Luis M.; Pérez-Quintero, Álvaro L.; Poulin, Lucie; Díaz, Ana C.; Arias Rojas, Nathalia; Trujillo, Cesar; Restrepo Benavides, Mariana; Bart, Rebecca; Boch, Jens; Boureau, Tristan; Darrasse, Armelle; David, Perrine; Dugé de Bernonville, Thomas; Fontanilla, Paula; Gagnevin, Lionel; Guérin, Fabien; Jacques, Marie-Agnès; Lauber, Emmanuelle; Lefeuvre, Pierre; Medina, Cesar; Medina, Edgar; Montenegro, Nathaly; Muñoz Bodnar, Alejandra; Noël, Laurent D.; Ortiz Quiñones, Juan F.; Osorio, Daniela; Pardo, Carolina; Patil, Prabhu B.; Poussier, Stéphane; Pruvost, Olivier; Robène-Soustrade, Isabelle; Ryan, Robert P.; Tabima, Javier; Urrego Morales, Oscar G.; Vernière, Christian; Carrere, Sébastien; Verdier, Valérie; Szurek, Boris; Restrepo, Silvia; López, Camilo

    2013-01-01

    Xanthomonas axonopodis pv. manihotis (Xam) is the causal agent of bacterial blight of cassava, which is among the main components of human diet in Africa and South America. Current information about the molecular pathogenicity factors involved in the infection process of this organism is limited. Previous studies in other bacteria in this genus suggest that advanced draft genome sequences are valuable resources for molecular studies on their interaction with plants and could provide valuable tools for diagnostics and detection. Here we have generated the first manually annotated high-quality draft genome sequence of Xam strain CIO151. Its genomic structure is similar to that of other xanthomonads, especially Xanthomonas euvesicatoria and Xanthomonas citri pv. citri species. Several putative pathogenicity factors were identified, including type III effectors, cell wall-degrading enzymes and clusters encoding protein secretion systems. Specific characteristics in this genome include changes in the xanthomonadin cluster that could explain the lack of typical yellow color in all strains of this pathovar and the presence of 50 regions in the genome with atypical nucleotide composition. The genome sequence was used to predict and evaluate 22 variable number of tandem repeat (VNTR) loci that were subsequently demonstrated as polymorphic in representative Xam strains. Our results demonstrate that Xanthomonas axonopodis pv. manihotis strain CIO151 possesses ten clusters of pathogenicity factors conserved within the genus Xanthomonas. We report 126 genes that are potentially unique to Xam, as well as potential horizontal transfer events in the history of the genome. The relation of these regions with virulence and pathogenicity could explain several aspects of the biology of this pathogen, including its ability to colonize both vascular and non-vascular tissues of cassava plants. A set of 16 robust, polymorphic VNTR loci will be useful to develop a multi-locus VNTR analysis

  7. Genomic survey of pathogenicity determinants and VNTR markers in the cassava bacterial pathogen Xanthomonas axonopodis pv. Manihotis strain CIO151.

    PubMed

    Arrieta-Ortiz, Mario L; Rodríguez-R, Luis M; Pérez-Quintero, Álvaro L; Poulin, Lucie; Díaz, Ana C; Arias Rojas, Nathalia; Trujillo, Cesar; Restrepo Benavides, Mariana; Bart, Rebecca; Boch, Jens; Boureau, Tristan; Darrasse, Armelle; David, Perrine; Dugé de Bernonville, Thomas; Fontanilla, Paula; Gagnevin, Lionel; Guérin, Fabien; Jacques, Marie-Agnès; Lauber, Emmanuelle; Lefeuvre, Pierre; Medina, Cesar; Medina, Edgar; Montenegro, Nathaly; Muñoz Bodnar, Alejandra; Noël, Laurent D; Ortiz Quiñones, Juan F; Osorio, Daniela; Pardo, Carolina; Patil, Prabhu B; Poussier, Stéphane; Pruvost, Olivier; Robène-Soustrade, Isabelle; Ryan, Robert P; Tabima, Javier; Urrego Morales, Oscar G; Vernière, Christian; Carrere, Sébastien; Verdier, Valérie; Szurek, Boris; Restrepo, Silvia; López, Camilo; Koebnik, Ralf; Bernal, Adriana

    2013-01-01

    Xanthomonas axonopodis pv. manihotis (Xam) is the causal agent of bacterial blight of cassava, which is among the main components of human diet in Africa and South America. Current information about the molecular pathogenicity factors involved in the infection process of this organism is limited. Previous studies in other bacteria in this genus suggest that advanced draft genome sequences are valuable resources for molecular studies on their interaction with plants and could provide valuable tools for diagnostics and detection. Here we have generated the first manually annotated high-quality draft genome sequence of Xam strain CIO151. Its genomic structure is similar to that of other xanthomonads, especially Xanthomonas euvesicatoria and Xanthomonas citri pv. citri species. Several putative pathogenicity factors were identified, including type III effectors, cell wall-degrading enzymes and clusters encoding protein secretion systems. Specific characteristics in this genome include changes in the xanthomonadin cluster that could explain the lack of typical yellow color in all strains of this pathovar and the presence of 50 regions in the genome with atypical nucleotide composition. The genome sequence was used to predict and evaluate 22 variable number of tandem repeat (VNTR) loci that were subsequently demonstrated as polymorphic in representative Xam strains. Our results demonstrate that Xanthomonas axonopodis pv. manihotis strain CIO151 possesses ten clusters of pathogenicity factors conserved within the genus Xanthomonas. We report 126 genes that are potentially unique to Xam, as well as potential horizontal transfer events in the history of the genome. The relation of these regions with virulence and pathogenicity could explain several aspects of the biology of this pathogen, including its ability to colonize both vascular and non-vascular tissues of cassava plants. A set of 16 robust, polymorphic VNTR loci will be useful to develop a multi-locus VNTR analysis

  8. Pyramiding B genes in cotton achieves broader but not always higher resistance to bacterial blight.

    PubMed

    Essenberg, Margaret; Bayles, Melanie B; Pierce, Margaret L; Verhalen, Laval M

    2014-10-01

    Near-isogenic lines of upland cotton (Gossypium hirsutum) carrying single, race-specific genes B4, BIn, and b7 for resistance to bacterial blight were used to develop a pyramid of lines with all possible combinations of two and three genes to learn whether the pyramid could achieve broad and high resistance approaching that of L. A. Brinkerhoff's exceptional line Im216. Isogenic strains of Xanthomonas axonopodis pv. malvacearum carrying single avirulence (avr) genes were used to identify plants carrying specific resistance (B) genes. Under field conditions in north-central Oklahoma, pyramid lines exhibited broader resistance to individual races and, consequently, higher resistance to a race mixture. It was predicted that lines carrying two or three B genes would also exhibit higher resistance to race 1, which possesses many avr genes. Although some enhancements were observed, they did not approach the level of resistance of Im216. In a growth chamber, bacterial populations attained by race 1 in and on leaves of the pyramid lines decreased significantly with increasing number of B genes in only one of four experiments. The older lines, Im216 and AcHR, exhibited considerably lower bacterial populations than any of the one-, two-, or three-B-gene lines. A spreading collapse of spray-inoculated AcBIn and AcBInb7 leaves appears to be a defense response (conditioned by BIn) that is out of control.

  9. A SNP Haplotype Associated with a gene resistant to Xanthomonas axonopodis pv. malvacearum in Upland Cotton (Gossyium hirsutum L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An F5 population of 285 families with each tracing back to a different F2 plant , derived from a cotton bacterial blight resistant line ‘DeltaOpal’ and a susceptible line ‘DP388’, was artificially inoculated with bacterial blight race 18 (Xanthomonas campestris pv. Malvacearum) to assay their resist...

  10. High-throughput genomic sequencing of cassava bacterial blight strains identifies conserved effectors to target for durable resistance.

    PubMed

    Bart, Rebecca; Cohn, Megan; Kassen, Andrew; McCallum, Emily J; Shybut, Mikel; Petriello, Annalise; Krasileva, Ksenia; Dahlbeck, Douglas; Medina, Cesar; Alicai, Titus; Kumar, Lava; Moreira, Leandro M; Rodrigues Neto, Júlio; Verdier, Valerie; Santana, María Angélica; Kositcharoenkul, Nuttima; Vanderschuren, Hervé; Gruissem, Wilhelm; Bernal, Adriana; Staskawicz, Brian J

    2012-07-10

    Cassava bacterial blight (CBB), incited by Xanthomonas axonopodis pv. manihotis (Xam), is the most important bacterial disease of cassava, a staple food source for millions of people in developing countries. Here we present a widely applicable strategy for elucidating the virulence components of a pathogen population. We report Illumina-based draft genomes for 65 Xam strains and deduce the phylogenetic relatedness of Xam across the areas where cassava is grown. Using an extensive database of effector proteins from animal and plant pathogens, we identify the effector repertoire for each sequenced strain and use a comparative sequence analysis to deduce the least polymorphic of the conserved effectors. These highly conserved effectors have been maintained over 11 countries, three continents, and 70 y of evolution and as such represent ideal targets for developing resistance strategies.

  11. Role of hydroperoxide lyase in white-backed planthopper (Sogatella furcifera Horváth)-induced resistance to bacterial blight in rice, Oryza sativa L.

    PubMed

    Gomi, Kenji; Satoh, Masaru; Ozawa, Rika; Shinonaga, Yumi; Sanada, Sachiyo; Sasaki, Katsutomo; Matsumura, Masaya; Ohashi, Yuko; Kanno, Hiroo; Akimitsu, Kazuya; Takabayashi, Junji

    2010-01-01

    A pre-infestation of the white-backed planthopper (WBPH), Sogatella furcifera Horváth, conferred resistance to bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) in rice (Oryza sativa L.) under both laboratory and field conditions. The infestation of another planthopper species, the brown planthopper (BPH) Nilaparvata lugens Stål, did not significantly reduce the incidence of bacterial blight symptoms. A large-scale screening using a rice DNA microarray and quantitative RT-PCR revealed that WBPH infestation caused the upregulation of more defence-related genes than did BPH infestation. Hydroperoxide lyase 2 (OsHPL2), an enzyme for producing C(6) volatiles, was upregulated by WBPH infestation, but not by BPH infestation. One C(6) volatile, (E)-2-hexenal, accumulated in rice after WBPH infestation, but not after BPH infestation. A direct application of (E)-2-hexenal to a liquid culture of Xoo inhibited the growth of the bacterium. Furthermore, a vapour treatment of rice plants with (E)-2-hexenal induced resistance to bacterial blight. OsHPL2-overexpressing transgenic rice plants exhibited increased resistance to bacterial blight. Based on these data, we conclude that OsHPL2 and its derived (E)-2-hexenal play some role in WBPH-induced resistance in rice.

  12. Mapping EST-derived SSRs and ESTs involved in resistance to bacterial blight in Manihot esculenta.

    PubMed

    López, Camilo E; Quesada-Ocampo, Lina M; Bohórquez, Adriana; Duque, Myriam Cristina; Vargas, Jaime; Tohme, Joe; Verdier, Valérie

    2007-12-01

    Cassava (Manihot esculenta Crantz) is a major root crop widely grown in the tropics. Cassava bacterial blight, caused by Xanthomonas axonopodis pv. manihotis (Xam), is an important disease in Latin America and Africa resulting in significant losses. The preferred control method is the use of resistant genotypes. Mapping expressed sequence tags (ESTs) and determining their co-localization with quantitative trait loci (QTLs) may give additional evidence of the role of the corresponding genes in resistance or defense. Twenty-one EST-derived simple sequence repeats (SSRs) were mapped in 16 linkage groups. ESTs showing similarities with candidate resistance genes or defense genes were also mapped using strategies such as restriction fragment length polymorphisms, cleaved amplified polymorphic sequences, and allele-specific primers. In total, 10 defense-related genes and 2 bacterial artificial chromosomes (BACs) containing resistance gene candidates (RGCs) were mapped in 11 linkage groups. Two new QTLs associated with resistance to Xam strains CIO121 and CIO151 were detected in linkage groups A and U, respectively. The QTL in linkage group U explained 61.6% of the phenotypic variance and was associated with an RGC-containing BAC. No correlation was found between the new EST-derived SSRs or other mapped ESTs and the new or previously reported QTLs.

  13. Epidemiological Study of Hazelnut Bacterial Blight in Central Italy by Using Laboratory Analysis and Geostatistics

    PubMed Central

    Lamichhane, Jay Ram; Fabi, Alfredo; Ridolfi, Roberto; Varvaro, Leonardo

    2013-01-01

    Incidence of Xanthomonas arboricola pv. corylina, the causal agent of hazelnut bacterial blight, was analyzed spatially in relation to the pedoclimatic factors. Hazelnut grown in twelve municipalities situated in the province of Viterbo, central Italy was studied. A consistent number of bacterial isolates were obtained from the infected tissues of hazelnut collected in three years (2010–2012). The isolates, characterized by phenotypic tests, did not show any difference among them. Spatial patterns of pedoclimatic data, analyzed by geostatistics showed a strong positive correlation of disease incidence with higher values of rainfall, thermal shock and soil nitrogen; a weak positive correlation with soil aluminium content and a strong negative correlation with the values of Mg/K ratio. No correlation of the disease incidence was found with soil pH. Disease incidence ranged from very low (<1%) to very high (almost 75%) across the orchards. Young plants (4-year old) were the most affected by the disease confirming a weak negative correlation of the disease incidence with plant age. Plant cultivars did not show any difference in susceptibility to the pathogen. Possible role of climate change on the epidemiology of the disease is discussed. Improved management practices are recommended for effective control of the disease. PMID:23424654

  14. Epidemiological study of hazelnut bacterial blight in central Italy by using laboratory analysis and geostatistics.

    PubMed

    Lamichhane, Jay Ram; Fabi, Alfredo; Ridolfi, Roberto; Varvaro, Leonardo

    2013-01-01

    Incidence of Xanthomonas arboricola pv. corylina, the causal agent of hazelnut bacterial blight, was analyzed spatially in relation to the pedoclimatic factors. Hazelnut grown in twelve municipalities situated in the province of Viterbo, central Italy was studied. A consistent number of bacterial isolates were obtained from the infected tissues of hazelnut collected in three years (2010-2012). The isolates, characterized by phenotypic tests, did not show any difference among them. Spatial patterns of pedoclimatic data, analyzed by geostatistics showed a strong positive correlation of disease incidence with higher values of rainfall, thermal shock and soil nitrogen; a weak positive correlation with soil aluminium content and a strong negative correlation with the values of Mg/K ratio. No correlation of the disease incidence was found with soil pH. Disease incidence ranged from very low (<1%) to very high (almost 75%) across the orchards. Young plants (4-year old) were the most affected by the disease confirming a weak negative correlation of the disease incidence with plant age. Plant cultivars did not show any difference in susceptibility to the pathogen. Possible role of climate change on the epidemiology of the disease is discussed. Improved management practices are recommended for effective control of the disease.

  15. Suppression of bacterial blight on mustard greens with host plant resistance and Acibenzolar-S-Methyl

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial blight, caused by Pseudomonas cannabina pv. alisalensis, attacks the leaves of most brassica vegetables, including mustard greens (Brassica juncea). ‘Carolina Broadleaf,’ a new mustard cultivar, is resistant to bacterial blight. Acibenzolar-S-methyl (trade name Actigard) has been used to m...

  16. Bismerthiazol inhibits Xanthomonas citri subsp. citri growth and induces differential expression of citrus defense-related genes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus canker, caused by Xanthomonas citri ssp. citri (Xcc), is a serious disease and causes substantial economic losses to the citrus industry worldwide. The bactericide, bismerthiazol, has been widely used to control rice bacterial blight (Xanthomonas oryzae pv. oryzae). In this paper, we demonstr...

  17. Characterization of the pigment xanthomonadin in the bacterial genus Xanthomonas using micro- and resonance Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Paret, Mathews L.; Sharma, Shiv K.; Misra, Anupam K.; Acosta, Tayro; deSilva, Asoka S.; Vowell, Tomie; Alvarez, Anne M.

    2012-06-01

    We used micro- and resonance Raman spectroscopy with 785 nm and 514.5 nm laser excitation, respectively, to characterize a plant pathogenic bacteria, Xanthomonas axonopodis pv. dieffenbachiae D150. The bacterial genus Xathomonas is closely related to bacterial genus Stenotrophomonas that causes an infection in humans. This study has identified for the first time the unique Raman spectra of the carotenoid-like pigment xanthomonadin of the Xanthomonas strain. Xanthomonadin is a brominated aryl-polyene pigment molecule similar to carotenoids. Further studies were conducted using resonance Raman spectroscopy with 514.5 nm laser excitation on several strains of the bacterial genus Xanthomonas isolated from numerous plants from various geographical locations. The current study revealed that the Raman bands representing the vibrations (v1, v2, v3) of the polyene chain of xanthomonadin are 1003-1005 (v3), 1135-1138 (v2), and 1530 (v1). Overtone bands representing xanthomonadin were identified as 2264-2275 (2v2), and combinational bands at 2653-2662 (v1+ v2). The findings from this study validate our previous finding that the Raman fingerprints of xanthomonadin are unique for the genus Xanthomonas. This facilitates rapid identification (~5 minutes) of Xanthomonas spp. from bacterial culture plates. The xanthomonadin marker is different from Raman markers of many other bacterial genus including Agrobacterium, Bacillus, Clavibacter, Enterobacter, Erwinia, Microbacterium, Paenibacillus, and Ralstonia. This study also identified Xanthomonas spp. from bacterial strains isolated from a diseased wheat sample on a culture plate.

  18. Plant Growth Promotion and Suppression of Bacterial Leaf Blight in Rice by Inoculated Bacteria.

    PubMed

    Yasmin, Sumera; Zaka, Abha; Imran, Asma; Zahid, Muhammad Awais; Yousaf, Sumaira; Rasul, Ghulam; Arif, Muhammad; Mirza, Muhammad Sajjad

    2016-01-01

    The present study was conducted to evaluate the potential of rice rhizosphere associated antagonistic bacteria for growth promotion and disease suppression of bacterial leaf blight (BLB). A total of 811 rhizospheric bacteria were isolated and screened against 3 prevalent strains of BLB pathogen Xanthomonas oryzae pv. oryzae (Xoo) of which five antagonistic bacteria, i.e., Pseudomonas spp. E227, E233, Rh323, Serratia sp. Rh269 and Bacillus sp. Rh219 showed antagonistic potential (zone of inhibition 1-19 mm). Production of siderophores was found to be the common biocontrol determinant and all the strains solubilized inorganic phosphate (82-116 μg mL-1) and produced indole acetic acid (0.48-1.85 mg L-1) in vitro. All antagonistic bacteria were non-pathogenic to rice, and their co-inoculation significantly improved plant health in terms of reduced diseased leaf area (80%), improved shoot length (31%), root length (41%) and plant dry weight (60%) as compared to infected control plants. Furthermore, under pathogen pressure, bacterial inoculation resulted in increased activity of defense related enzymes including phenylalanine ammonia-lyase and polyphenol oxidase, along with 86% increase in peroxidase and 53% increase in catalase enzyme activities in plants inoculated with Pseudomonas sp. Rh323 as well as co-inoculated plants. Bacterial strains showed good colonization potential in the rice rhizosphere up to 21 days after seed inoculation. Application of bacterial consortia in the field resulted in an increase of 31% in grain yield and 10% in straw yield over non-inoculated plots. Although, yield increase was statistically non-significant but was accomplished with overall saving of 20% chemical fertilizers. The study showed that Pseudomonas sp. Rh323 can be used to develop dual-purpose inoculum which can serve not only to suppress BLB but also to promote plant growth in rice.

  19. Plant Growth Promotion and Suppression of Bacterial Leaf Blight in Rice by Inoculated Bacteria

    PubMed Central

    Zaka, Abha; Imran, Asma; Zahid, Muhammad Awais; Yousaf, Sumaira; Rasul, Ghulam; Arif, Muhammad; Mirza, Muhammad Sajjad

    2016-01-01

    The present study was conducted to evaluate the potential of rice rhizosphere associated antagonistic bacteria for growth promotion and disease suppression of bacterial leaf blight (BLB). A total of 811 rhizospheric bacteria were isolated and screened against 3 prevalent strains of BLB pathogen Xanthomonas oryzae pv. oryzae (Xoo) of which five antagonistic bacteria, i.e., Pseudomonas spp. E227, E233, Rh323, Serratia sp. Rh269 and Bacillus sp. Rh219 showed antagonistic potential (zone of inhibition 1–19 mm). Production of siderophores was found to be the common biocontrol determinant and all the strains solubilized inorganic phosphate (82–116 μg mL-1) and produced indole acetic acid (0.48–1.85 mg L-1) in vitro. All antagonistic bacteria were non-pathogenic to rice, and their co-inoculation significantly improved plant health in terms of reduced diseased leaf area (80%), improved shoot length (31%), root length (41%) and plant dry weight (60%) as compared to infected control plants. Furthermore, under pathogen pressure, bacterial inoculation resulted in increased activity of defense related enzymes including phenylalanine ammonia-lyase and polyphenol oxidase, along with 86% increase in peroxidase and 53% increase in catalase enzyme activities in plants inoculated with Pseudomonas sp. Rh323 as well as co-inoculated plants. Bacterial strains showed good colonization potential in the rice rhizosphere up to 21 days after seed inoculation. Application of bacterial consortia in the field resulted in an increase of 31% in grain yield and 10% in straw yield over non-inoculated plots. Although, yield increase was statistically non-significant but was accomplished with overall saving of 20% chemical fertilizers. The study showed that Pseudomonas sp. Rh323 can be used to develop dual-purpose inoculum which can serve not only to suppress BLB but also to promote plant growth in rice. PMID:27532545

  20. Bean common bacterial blight: pathogen epiphytic life and effect of irrigation practices.

    PubMed

    Akhavan, Alireza; Bahar, Masoud; Askarian, Homa; Lak, Mohammad Reza; Nazemi, Abolfazl; Zamani, Zahra

    2013-12-01

    In recent years, bean common bacterial blight (CBB) caused by Xanthomonas axonopodis pv. phaseoli (Xap) has caused serious yield losses in several countries. CBB is considered mainly a foliar disease in which symptoms initially appear as small water-soaked spots that then enlarge and become necrotic and usually bordered by a chlorotic zone. Xap epiphytic population community has a critical role in the development of the disease and subsequent epidemics. The epiphytic population of Xap in the field has two major parts; solitary cells (potentially planktonic) and biofilms which are sources for providing and refreshing the solitary cell components. Irrigation type has a significant effect on epiphytic population of Xap. The mean epiphytic population size in the field with an overhead sprinkler irrigation system is significantly higher than populations under furrow irrigation. A significant positive correlation between the epiphytic population size of Xap and disease severity has been reported in both the overhead irrigated (r=0.64) and the furrow irrigated (r= 0.44) fields.

  1. Incorporation of Bacterial Blight Resistance Genes Into Lowland Rice Cultivar Through Marker-Assisted Backcross Breeding.

    PubMed

    Pradhan, Sharat Kumar; Nayak, Deepak Kumar; Pandit, Elssa; Behera, Lambodar; Anandan, Annamalai; Mukherjee, Arup Kumar; Lenka, Srikanta; Barik, Durga Prasad

    2016-07-01

    Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae is a major disease of rice in many rice growing countries. Pyramided lines carrying two BB resistance gene combinations (Xa21+xa13 and Xa21+xa5) were developed in a lowland cultivar Jalmagna background through backcross breeding by integrating molecular markers. In each backcross generation, markers closely linked to the disease resistance genes were used to select plants possessing the target genes. Background selection was continued in those plants carrying resistant genes until BC(3) generation. Plants having the maximum contribution from the recurrent parent genome were selected in each generation and hybridized with the recipient parent. The BB-pyramided line having the maximum recipient parent genome recovery of 95% was selected among BC3F1 plants and selfed to isolate homozygous BC(3)F(2) plants with different combinations of BB resistance genes. Twenty pyramided lines with two resistance gene combinations exhibited high levels of tolerance against the BB pathogen. In order to confirm the resistance, the pyramided lines were inoculated with different X. oryzae pv. oryzae strains of Odisha for bioassay. The genotypes with combination of two BB resistance genes conferred high levels of resistance to the predominant X. oryzae pv. oryzae isolates prevalent in the region. The pyramided lines showed similarity with the recipient parent with respect to major agro-morphologic traits.

  2. Code-Assisted Discovery of TAL Effector Targets in Bacterial Leaf Streak of Rice Reveals Contrast with Bacterial Blight and a Novel Susceptibility Gene

    PubMed Central

    Cernadas, Raul A.; Doyle, Erin L.; Niño-Liu, David O.; Wilkins, Katherine E.; Bancroft, Timothy; Wang, Li; Schmidt, Clarice L.; Caldo, Rico; Yang, Bing; White, Frank F.; Nettleton, Dan; Wise, Roger P.; Bogdanove, Adam J.

    2014-01-01

    Bacterial leaf streak of rice, caused by Xanthomonas oryzae pv. oryzicola (Xoc) is an increasingly important yield constraint in this staple crop. A mesophyll colonizer, Xoc differs from X. oryzae pv. oryzae (Xoo), which invades xylem to cause bacterial blight of rice. Both produce multiple distinct TAL effectors, type III-delivered proteins that transactivate effector-specific host genes. A TAL effector finds its target(s) via a partially degenerate code whereby the modular effector amino acid sequence identifies nucleotide sequences to which the protein binds. Virulence contributions of some Xoo TAL effectors have been shown, and their relevant targets, susceptibility (S) genes, identified, but the role of TAL effectors in leaf streak is uncharacterized. We used host transcript profiling to compare leaf streak to blight and to probe functions of Xoc TAL effectors. We found that Xoc and Xoo induce almost completely different host transcriptional changes. Roughly one in three genes upregulated by the pathogens is preceded by a candidate TAL effector binding element. Experimental analysis of the 44 such genes predicted to be Xoc TAL effector targets verified nearly half, and identified most others as false predictions. None of the Xoc targets is a known bacterial blight S gene. Mutational analysis revealed that Tal2g, which activates two genes, contributes to lesion expansion and bacterial exudation. Use of designer TAL effectors discriminated a sulfate transporter gene as the S gene. Across all targets, basal expression tended to be higher than genome-average, and induction moderate. Finally, machine learning applied to real vs. falsely predicted targets yielded a classifier that recalled 92% of the real targets with 88% precision, providing a tool for better target prediction in the future. Our study expands the number of known TAL effector targets, identifies a new class of S gene, and improves our ability to predict functional targeting. PMID:24586171

  3. Code-assisted discovery of TAL effector targets in bacterial leaf streak of rice reveals contrast with bacterial blight and a novel susceptibility gene.

    PubMed

    Cernadas, Raul A; Doyle, Erin L; Niño-Liu, David O; Wilkins, Katherine E; Bancroft, Timothy; Wang, Li; Schmidt, Clarice L; Caldo, Rico; Yang, Bing; White, Frank F; Nettleton, Dan; Wise, Roger P; Bogdanove, Adam J

    2014-02-01

    Bacterial leaf streak of rice, caused by Xanthomonas oryzae pv. oryzicola (Xoc) is an increasingly important yield constraint in this staple crop. A mesophyll colonizer, Xoc differs from X. oryzae pv. oryzae (Xoo), which invades xylem to cause bacterial blight of rice. Both produce multiple distinct TAL effectors, type III-delivered proteins that transactivate effector-specific host genes. A TAL effector finds its target(s) via a partially degenerate code whereby the modular effector amino acid sequence identifies nucleotide sequences to which the protein binds. Virulence contributions of some Xoo TAL effectors have been shown, and their relevant targets, susceptibility (S) genes, identified, but the role of TAL effectors in leaf streak is uncharacterized. We used host transcript profiling to compare leaf streak to blight and to probe functions of Xoc TAL effectors. We found that Xoc and Xoo induce almost completely different host transcriptional changes. Roughly one in three genes upregulated by the pathogens is preceded by a candidate TAL effector binding element. Experimental analysis of the 44 such genes predicted to be Xoc TAL effector targets verified nearly half, and identified most others as false predictions. None of the Xoc targets is a known bacterial blight S gene. Mutational analysis revealed that Tal2g, which activates two genes, contributes to lesion expansion and bacterial exudation. Use of designer TAL effectors discriminated a sulfate transporter gene as the S gene. Across all targets, basal expression tended to be higher than genome-average, and induction moderate. Finally, machine learning applied to real vs. falsely predicted targets yielded a classifier that recalled 92% of the real targets with 88% precision, providing a tool for better target prediction in the future. Our study expands the number of known TAL effector targets, identifies a new class of S gene, and improves our ability to predict functional targeting.

  4. Isolation and characterization of bacteriophages infecting Xanthomonas arboricola pv. juglandis, the causal agent of walnut blight disease.

    PubMed

    Romero-Suarez, Sandra; Jordan, Brian; Heinemann, Jack A

    2012-05-01

    Walnut orchards suffer from a blight caused by the bacteria Xanthomonas arboricola pv. juglandis. These bacteria can be infected by viral bacteriophages and this study was carried out to isolate and characterize bacteriophages from walnut orchards located throughout the South Island of New Zealand. Twenty six X. arboricola phages were isolated from three hundred and twenty six samples of plant material representing phyllosphere and rhizosphere ecosystems. The phage isolates were characterized by host-range, plaque and particle morphology, restriction digest and phylogenetic analysis and stability under various storage conditions. From capsid and tail dimensions the bacteriophages were considered to belong to the double-stranded DNA families Podoviridae and Siphoviridae. Of the twenty six bacteriophages, sixteen belonged to Podoviridae and were found both in the phyllosphere and rhizosphere. In contrast, Siphoviridae were present only in the rhizosphere isolates. Phage genome sizes ranged from 38.0 to 52.0 kb from a Hind III restriction digestion and had in common a 400 kb fragment that was identical at the DNA level. Despite the similar restriction patterns, maximum parsimony bootstrap analysis showed that the phage were members of different groups. Finally, we hypothesise that these phage might have use in a biocontrol strategy and therefore storage stability and efficacy was tested. Titres declined more than 50% over a 12-months storage period. Deep-freezing temperatures (-34°C) increased while chloroform decreased the stability.

  5. High-resolution genetic mapping of rice bacterial blight resistance gene Xa23.

    PubMed

    Wang, Chunlian; Fan, Yinglun; Zheng, Chongke; Qin, Tengfei; Zhang, Xiaoping; Zhao, Kaijun

    2014-10-01

    Bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is the most devastating bacterial disease of rice (Oryza sativa L.), a staple food crop that feeds half of the world's population. In management of this disease, the most economical and effective approach is cultivating resistant varieties. Due to rapid change of pathogenicity in the pathogen, it is necessary to identify and characterize more host resistance genes for breeding new resistant varieties. We have previously identified the BB resistance (R) gene Xa23 that confers the broadest resistance to Xoo strains isolated from different rice-growing regions and preliminarily mapped the gene within a 1.7 cm region on the long arm of rice chromosome 11. Here, we report fine genetic mapping and in silico analysis of putative candidate genes of Xa23. Based on F2 mapping populations derived from crosses between Xa23-containing rice line CBB23 and susceptible varieties JG30 or IR24, six new STS markers Lj36, Lj46, Lj138, Lj74, A83B4, and Lj13 were developed. Linkage analysis revealed that the new markers were co-segregated with or closely linked to the Xa23 locus. Consequently, the Xa23 gene was mapped within a 0.4 cm region between markers Lj138 and A83B4, in which the co-segregating marker Lj74 was identified. The corresponding physical distance between Lj138 and A83B4 on Nipponbare genome is 49.8 kb. Six Xa23 candidate genes have been annotated, including four candidate genes encoding hypothetical proteins and the other two encoding a putative ADP-ribosylation factor protein and a putative PPR protein. These results will facilitate marker-assisted selection of Xa23 in rice breeding and molecular cloning of this valuable R gene.

  6. Induction of Xa10-like genes in rice cultivar Nipponbare confers disease resistance to rice bacterial blight.

    PubMed

    Wang, Jun; Tian, Dongsheng; Gu, Keyu; Yang, Xiaobei; Wang, Lanlan; Zeng, Xuan; Yin, Zhongchao

    2017-03-17

    Bacterial blight of rice, caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive bacterial diseases throughout the major rice growing regions in the world. The rice disease resistance (R) genes Xa10 confers race-specific disease resistance to X. oryzae pv. oryzae strains that deliver the corresponding transcription activator-like (TAL) effectors AvrXa10. Upon bacterial infection, AvrXa10 binds specifically to the effector binding element (EBE) in the promoter of the R gene and activates its expression. Xa10 encodes an executor R protein that triggers hypersensitive response and activates disease resistance. Rice cultivar Nipponbare carries two Xa10-like genes in its genome, of which one is the susceptible allele of the Xa23 gene, a Xa10-like TAL effector-dependent executor R gene isolated recently from rice cultivar CBB23. However, the function of the two Xa10-like genes in disease resistance to X. oryzae pv. oryzae strains has not been investigated. Here we designated the two Xa10-like genes as Xa10-Ni and Xa23-Ni and characterized their function for disease resistance to rice bacterial blight. Both Xa10-Ni and Xa23-Ni provided disease resistance to X. oryzae pv. oryzae strains that deliver the matching artificially designed TAL effectors (dTALEs). Transgenic rice plants containing Xa10-Ni and Xa23-Ni under the Xa10 promoter provided specific disease resistance to X. oryzae pv. oryzae strains that deliver AvrXa10. Xa10-Ni and Xa23-Ni knock-out mutants abolished dTALE-dependent disease resistance to X. oryzae pv. oryzae. Heterologous expression of Xa10-Ni and Xa23-Ni in Nicotiana benthamiana triggered cell death. The 19-amino acid residues at the N-terminal regions of XA10 or XA10-Ni are dispensable for their function in inducing cell death in N. benthamiana and the C-terminal regions of XA10, XA10-Ni and XA23-Ni are interchangeable among each other without affecting their function. Like XA10, both XA10-Ni and XA23-Ni locate to the endoplasmic

  7. Breeding Common Bean for resistance to Common Blight: A review

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Common blight {caused by Xanthomonas campestris pv. phaseoli Smith (Dye) is a major bacterial disease causing >40% seed yield and quality losses in common bean (Phaseolus vulgaris L.) worldwide. Use of resistant cultivars is crucial for its effective, economical, and environment friendly integarated...

  8. Biological Control Activities of Rice-Associated Bacillus sp. Strains against Sheath Blight and Bacterial Panicle Blight of Rice.

    PubMed

    Shrestha, Bishnu K; Karki, Hari Sharan; Groth, Donald E; Jungkhun, Nootjarin; Ham, Jong Hyun

    2016-01-01

    Potential biological control agents for two major rice diseases, sheath blight and bacterial panicle blight, were isolated from rice plants in this study. Rice-associated bacteria (RABs) isolated from rice plants grown in the field were tested for their antagonistic activities against the rice pathogens, Rhizoctonia solani and Burkholderia glumae, which cause sheath blight and bacterial panicle blight, respectively. Twenty-nine RABs were initially screened based on their antagonistic activities against both R. solani and B. glumae. In follow-up retests, 26 RABs of the 29 RABs were confirmed to have antimicrobial activities, but the rest three RABs did not reproduce any observable antagonistic activity against R. solani or B. glumae. According to16S rDNA sequence identity, 12 of the 26 antagonistic RABs were closest to Bacillus amyloliquefaciens, while seven RABs were to B. methylotrophicus and B, subtilis, respectively. The 16S rDNA sequences of the three non-antagonistic RABs were closest to Lysinibacillus sphaericus (RAB1 and RAB12) and Lysinibacillus macroides (RAB5). The five selected RABs showing highest antimicrobial activities (RAB6, RAB9, RAB16, RAB17S, and RAB18) were closest to B. amyloliquefaciens in DNA sequence of 16S rDNA and gyrB, but to B. subtilis in that of recA. These RABs were observed to inhibit the sclerotial germination of R. solani on potato dextrose agar and the lesion development on detached rice leaves by artificial inoculation of R. solani. These antagonistic RABs also significantly suppressed the disease development of sheath blight and bacterial panicle blight in a field condition, suggesting that they can be potential biological control agents for these rice diseases. However, these antagonistic RABs showed diminished disease suppression activities in the repeated field trial conducted in the following year probably due to their reduced antagonistic activities to the pathogens during the long-term storage in -70C, suggesting that

  9. Biological Control Activities of Rice-Associated Bacillus sp. Strains against Sheath Blight and Bacterial Panicle Blight of Rice

    PubMed Central

    Shrestha, Bishnu K.; Karki, Hari Sharan; Groth, Donald E.; Jungkhun, Nootjarin; Ham, Jong Hyun

    2016-01-01

    Potential biological control agents for two major rice diseases, sheath blight and bacterial panicle blight, were isolated from rice plants in this study. Rice-associated bacteria (RABs) isolated from rice plants grown in the field were tested for their antagonistic activities against the rice pathogens, Rhizoctonia solani and Burkholderia glumae, which cause sheath blight and bacterial panicle blight, respectively. Twenty-nine RABs were initially screened based on their antagonistic activities against both R. solani and B. glumae. In follow-up retests, 26 RABs of the 29 RABs were confirmed to have antimicrobial activities, but the rest three RABs did not reproduce any observable antagonistic activity against R. solani or B. glumae. According to16S rDNA sequence identity, 12 of the 26 antagonistic RABs were closest to Bacillus amyloliquefaciens, while seven RABs were to B. methylotrophicus and B, subtilis, respectively. The 16S rDNA sequences of the three non-antagonistic RABs were closest to Lysinibacillus sphaericus (RAB1 and RAB12) and Lysinibacillus macroides (RAB5). The five selected RABs showing highest antimicrobial activities (RAB6, RAB9, RAB16, RAB17S, and RAB18) were closest to B. amyloliquefaciens in DNA sequence of 16S rDNA and gyrB, but to B. subtilis in that of recA. These RABs were observed to inhibit the sclerotial germination of R. solani on potato dextrose agar and the lesion development on detached rice leaves by artificial inoculation of R. solani. These antagonistic RABs also significantly suppressed the disease development of sheath blight and bacterial panicle blight in a field condition, suggesting that they can be potential biological control agents for these rice diseases. However, these antagonistic RABs showed diminished disease suppression activities in the repeated field trial conducted in the following year probably due to their reduced antagonistic activities to the pathogens during the long-term storage in -70C, suggesting that

  10. Interaction of common bacterial blight bacteria with disease resistance quantitative trait loci in common bean.

    PubMed

    Duncan, Robert W; Singh, Shree P; Gilbertson, Robert L

    2011-04-01

    Common bacterial blight (CBB) of common bean (Phaseolus vulgaris L.) is caused by Xanthomonas campestris pv. phaseoli and X. fuscans subsp. fuscans, and is the most important bacterial disease of this crop in many regions of the world. In 2005 and 2006, dark red kidney bean fields in a major bean-growing region in central Wisconsin were surveyed for CBB incidence and representative symptomatic leaves collected. Xanthomonad-like bacteria were isolated from these leaves and characterized based upon phenotypic (colony) characteristics, pathogenicity on common bean, polymerase chain reaction (PCR) with X. campestris pv. phaseoli- and X. fuscans subsp. fuscans-specific primers, and repetitive-element PCR (rep-PCR) and 16S-28S ribosomal RNA spacer region sequence analyses. Of 348 isolates that were characterized, 293 were identified as common blight bacteria (i.e., pathogenic on common bean and positive in PCR tests with the X. campestris pv. phaseoli- and X. fuscans subsp. fuscans-specific primers), whereas the other isolates were nonpathogenic xanthomonads. Most (98%) of the pathogenic xanthomonads were X. campestris pv. phaseoli, consistent with the association of this bacterium with CBB in large-seeded bean cultivars of the Andean gene pool. Two types of X. campestris pv. phaseoli were involved with CBB in this region: typical X. campestris pv. phaseoli (P) isolates with yellow mucoid colonies, no brown pigment production, and a typical X. campestris pv. phaseoli rep-PCR fingerprint (60% of strains); and a new phenotype and genotype (Px) with an X. campestris pv. phaseoli-type fingerprint and less mucoid colonies that produced brown pigment (40% of strains). In addition, a small number of X. fuscans subsp. fuscans strains, representing a new genotype (FH), were isolated from two fields in 2005. Representative P and Px X. campestris pv. phaseoli strains, an FH X. fuscans subsp. fuscans strain, plus five previously characterized X. campestris pv. phaseoli and X

  11. Mapping quantitative trait loci associated with resistance to bacterial spot (Xanthomonas arboricola pv. pruni) in peach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial spot, caused by Xanthomonas arboricola pv. pruni (Xap), is a serious disease that can affect peach fruit quality and production worldwide. This disease causes severe defoliation and blemishing of fruit, particularly in areas with high rainfall, strong winds, high humidity, and sandy soil. ...

  12. A novel Xanthomonas sp. causes bacterial spot of rose (Rosa spp.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A severe bacterial spot of rose (Rosa spp.) caused by a xanthomonad was observed in Florida and Texas. A total of 11 strains were collected from the two states. Multilocus sequence typing and analysis (MLST/MLSA) and pathogenicity tests were conducted to characterize the Xanthomonas strains. The MLS...

  13. Molecular characterization of Xanthomonas strains responsible for bacterial leaf spot of tomato in Ethiopia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial spot of tomato (BST) is a major constraint to tomato production in Ethiopia and many other countries leading to significant crop losses. In the present study, using pathogenicity tests, sensitivity to copper and streptomycin, and multilocus sequence analysis, a diverse group of Xanthomonas...

  14. Addition of transcription activator-like effector binding sites to a pathogen strain-specific rice bacterial blight resistance gene makes it effective against additional strains and against bacterial leaf streak.

    PubMed

    Hummel, Aaron W; Doyle, Erin L; Bogdanove, Adam J

    2012-09-01

    Xanthomonas transcription activator-like (TAL) effectors promote disease in plants by binding to and activating host susceptibility genes. Plants counter with TAL effector-activated executor resistance genes, which cause host cell death and block disease progression. We asked whether the functional specificity of an executor gene could be broadened by adding different TAL effector binding elements (EBEs) to it. We added six EBEs to the rice Xa27 gene, which confers resistance to strains of the bacterial blight pathogen Xanthomonas oryzae pv. oryzae (Xoo) that deliver the TAL effector AvrXa27. The EBEs correspond to three other effectors from Xoo strain PXO99(A) and three from strain BLS256 of the bacterial leaf streak pathogen Xanthomonas oryzae pv. oryzicola (Xoc). Stable integration into rice produced healthy lines exhibiting gene activation by each TAL effector, and resistance to PXO99(A) , a PXO99(A) derivative lacking AvrXa27, and BLS256, as well as two other Xoo and 10 Xoc strains virulent toward wildtype Xa27 plants. Transcripts initiated primarily at a common site. Sequences in the EBEs were found to occur nonrandomly in rice promoters, suggesting an overlap with endogenous regulatory sequences. Thus, executor gene specificity can be broadened by adding EBEs, but caution is warranted because of the possible coincident introduction of endogenous regulatory elements.

  15. Characterization of a disease susceptibility locus for exploring an efficient way to improve rice resistance against bacterial blight.

    PubMed

    Cheng, Qi; Mao, Weihua; Xie, Wenya; Liu, Qinsong; Cao, Jianbo; Yuan, Meng; Zhang, Qinglu; Li, Xianghua; Wang, Shiping

    2017-03-01

    Bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is the most harmful bacterial disease of rice worldwide. Previously, we characterized major disease resistance (MR) gene xa25, which confers race-specific resistance to Xoo strain PXO339. The xa25 is a recessive allele of the SWEET13 locus, but SWEET13's interaction with PXO339 and how efficiently using this locus for rice breeding still need to be defined. Here we show that the SWEET13 allele from rice Zhenshan 97 is a susceptibility gene to PXO339. Using this allele's promoter to regulate xa25 resulted in disease, suggesting that the promoter is a key determinant in SWEET13 caused disease in Zhanshan 97 after PXO339 infection. PXO339 transcriptionally induces SWEET13 to cause disease. Partial suppressing SWEET13 expression leads to a high level of resistance to PXO339. Thus, the transcriptionally suppressed SWEET13 functions as xa25 in resistance to PXO339. Hybrid rice is widely grown in many countries. However, recessive MR genes have not been efficiently used for disease resistance breeding in hybrid rice production for both parents of the hybrid have to carry the same recessive gene. However, the suppressed SWEET13 functions dominantly, which will have advantage to improve the resistance of hybrid rice to xa25-incomptible Xoo.

  16. Ectopic activation of the rice NLR heteropair RGA4/RGA5 confers resistance to bacterial blight and bacterial leaf streak diseases.

    PubMed

    Hutin, Mathilde; Césari, Stella; Chalvon, Véronique; Michel, Corinne; Tran, Tuan Tu; Boch, Jens; Koebnik, Ralf; Szurek, Boris; Kroj, Thomas

    2016-10-01

    Bacterial blight (BB) and bacterial leaf streak (BLS) are important diseases in Oryza sativa caused by Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc), respectively. In both bacteria, transcription activator-like (TAL) effectors are major virulence determinants that act by transactivating host genes downstream of effector-binding elements (EBEs) bound in a sequence-specific manner. Resistance to Xoo is mostly related to the action of TAL effectors, either by polymorphisms that prevent the induction of susceptibility (S) genes or by executor (R) genes with EBEs embedded in their promoter, and that induce cell death and resistance. For Xoc, no resistance sources are known in rice. Here, we investigated whether the recognition of effectors by nucleotide binding and leucine-rich repeat domain immune receptors (NLRs), the most widespread resistance mechanism in plants, is also able to stop BB and BLS. In one instance, transgenic rice lines harboring the AVR1-CO39 effector gene from the rice blast fungus Magnaporthe oryzae, under the control of an inducible promoter, were challenged with transgenic Xoo and Xoc strains carrying a TAL effector designed to transactivate the inducible promoter. This induced AVR1-CO39 expression and triggered BB and BLS resistance when the corresponding Pi-CO39 resistance locus was present. In a second example, the transactivation of an auto-active NLR by Xoo-delivered designer TAL effectors resulted in BB resistance, demonstrating that NLR-triggered immune responses efficiently control Xoo. This forms the foundation for future BB and BLS disease control strategies, whereupon endogenous TAL effectors will target synthetic promoter regions of Avr or NLR executor genes.

  17. Development of candidate gene markers associated to common bacterial blight resistance in common bean.

    PubMed

    Shi, Chun; Yu, Kangfu; Xie, Weilong; Perry, Gregory; Navabi, Alireza; Pauls, K Peter; Miklas, Phillip N; Fourie, Deidré

    2012-11-01

    Common bacterial blight (CBB), caused by Xanthomonas axonopodis pv. phaseoli (Xap), is a major yield-limiting factor of common bean (Phaseolus vulgaris L.) production around the world. Two major CBB-resistant quantitative trait loci (QTL), linked to the sequence characterized amplified region markers BC420 and SU91, are located at chromosomes 6 and 8, respectively. Using map-based cloning approach, four bacterial artificial chromosome (BAC) clones from the BC420-QTL locus and one BAC clone containing SU91 were sequenced by Roche 454 technique and subsequently assembled using merged assemblies from three different programs. Based on the quality of the assembly, only the sequences of BAC 32H6 and 4K7 were used for candidate gene marker (CGM) development and candidate gene (CG) selection. For the BC420-QTL locus, 21 novel genes were predicted in silico by FGENESH using Medicago gene model, whereas 16 genes were identified in the SU91-QTL locus. For each putative gene, one or more primer pairs were designed and tested in the contrasting near isogenic lines. Overall, six and nine polymorphic markers were found in the SU91- and BC420-QTL loci, respectively. Afterwards, association mapping was conducted in a breeding population of 395 dry bean lines to discover marker-trait associations. Two CGMs per each locus showed better association with CBB resistance than the BC420 and SU91 markers, which include BC420-CG10B and BC420-CG14 for BC420_QTL locus, and SU91-CG10 and SU91-CG11 for SU91_QTL locus. The strong associations between CBB resistance and the CGs 10 and 14 from BC420_QTL locus and the CGs 10 and 11 from SU91_QTL locus indicate that the genes 10 and 14 from the BC420 locus are potential CGs underlying the BC420_QTL locus, whereas the genes 10 and 11 from the SU91 locus are potential CGs underlying the SU91_QTL locus. The superiority of SU91-CG11 was further validated in a recombinant inbred line population Sanilac × OAC 09-3. Thus, co-dominant CGMs, BC420-CG14 and

  18. Jasmonate induction of the monoterpene linalool confers resistance to rice bacterial blight and its biosynthesis is regulated by JAZ protein in rice.

    PubMed

    Taniguchi, Shiduku; Hosokawa-Shinonaga, Yumi; Tamaoki, Daisuke; Yamada, Shoko; Akimitsu, Kazuya; Gomi, Kenji

    2014-02-01

    Jasmonic acid (JA) is involved in the regulation of host immunity in plants. Recently, we demonstrated that JA signalling has an important role in resistance to rice bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) in rice. Here, we report that many volatile compounds accumulate in response to exogenous application of JA, including the monoterpene linalool. Expression of linalool synthase was up-regulated by JA. Vapour treatment with linalool induced resistance to Xoo, and transgenic rice plants overexpressing linalool synthase were more resistance to Xoo, presumably due to the up-regulation of defence-related genes in the absence of any treatment. JA-induced accumulation of linalool was regulated by OsJAZ8, a rice jasmonate ZIM-domain protein involving the JA signalling pathway at the transcriptional level, suggesting that linalool plays an important role in JA-induced resistance to Xoo in rice.

  19. Integrated Control of Fire Blight with Bacterial Antagonists and Oxytetracycline

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the Pacific Northwest of the United States, the antibiotic streptomycin provided excellent control of fire blight until resistant isolates of Erwinia amylovora were prevalent. Oxytetracycline (Mycoshield) is now sprayed as an alternative antibiotic. We found that the duration of inhibitory acti...

  20. Association mapping of common bacterial blight resistance QTL in Ontario bean breeding populations

    PubMed Central

    2011-01-01

    Background Common bacterial blight (CBB), incited by Xanthomonas axonopodis pv. phaseoli (Xap), is a major yield-limiting factor of common bean (Phaseolus vulgaris L.) production around the world. Host resistance is practically the most effective and environmentally-sound approach to control CBB. Unlike conventional QTL discovery strategies, in which bi-parental populations (F2, RIL, or DH) need to be developed, association mapping-based strategies can use plant breeding populations to synchronize QTL discovery and cultivar development. Results A population of 469 dry bean lines of different market classes representing plant materials routinely developed in a bean breeding program were used. Of them, 395 lines were evaluated for CBB resistance at 14 and 21 DAI (Days After Inoculation) in the summer of 2009 in an artificially inoculated CBB nursery in south-western Ontario. All lines were genotyped using 132 SNPs (Single Nucleotide Polymorphisms) evenly distributed across the genome. Of the 132 SNPs, 26 SNPs had more than 20% missing data, 12 SNPs were monomorphic, and 17 SNPs had a MAF (Minor Allelic Frequency) of less than 0.20, therefore only 75 SNPs were used for association study, based on one SNP per locus. The best possible population structure was to assign 36% and 64% of the lines into Andean and Mesoamerican subgroups, respectively. Kinship analysis also revealed complex familial relationships among all lines, which corresponds with the known pedigree history. MLM (Mixed Linear Model) analysis, including population structure and kinship, was used to discover marker-trait associations. Eighteen and 22 markers were significantly associated with CBB rating at 14 and 21 DAI, respectively. Fourteen markers were significant for both dates and the markers UBC420, SU91, g321, g471, and g796 were highly significant (p ≤ 0.001). Furthermore, 12 significant SNP markers were co-localized with or close to the CBB-QTLs identified previously in bi-parental QTL mapping

  1. Antibacterial Activity and Mechanism of Action of Sulfone Derivatives Containing 1,3,4-Oxadiazole Moieties on Rice Bacterial Leaf Blight.

    PubMed

    Shi, Li; Li, Pei; Wang, Wenli; Gao, Manni; Wu, Zengxue; Song, Xianpeng; Hu, Deyu

    2015-06-24

    In this study, sulfone derivatives containing 1,3,4-oxadiazole moieties indicated good antibacterial activities against rice bacterial leaf blight caused by the pathogen Xanthomonas oryzaepv. pv. oryzae (Xoo). In particular, 2-(methylsulfonyl)-5-(4-fluorobenzyl)-1,3,4-oxadiazole revealed the best antibacterial activity against Xoo, with a half-maximal effective concentration (EC50) of 9.89 μg/mL, which was better than those of the commercial agents of bismerthiazole (92.61 μg/mL) and thiodiazole copper (121.82 μg/mL). In vivo antibacterial activity tests under greenhouse conditions and field trials demonstrated that 2-(methylsulfonyl)-5-(4-fluorophenyl)-1,3,4-oxadiazole was effective in reducing rice bacterial leaf blight. Meanwhile, 2-(methylsulfonyl)-5-(4-fluorophenyl)-1,3,4-oxadiazole stimulate the increase in superoxide dismutase (SOD) and peroxidase (POD) activities in rice, causing marked enhancement of plant resistance against rice bacterial leaf blight. It could also improve the chlorophyll content and restrain the increase in the malondialdehyde (MDA) content in rice to considerably reduce the amount of damage caused by Xoo. Moreover, 2-(methylsulfonyl)-5-(4-fluorophenyl)-1,3,4-oxadiazole, at a concentration of 20 μg/mL, could inhibit the production of extracellular polysaccharide (EPS) with an inhibition ratio of 94.52%, and reduce the gene expression levels of gumB, gumG, gumM, and xanA, with inhibition ratios of 94.88%, 68.14%, 86.76%, and 79.21%, respectively.

  2. Rice xa13 recessive resistance to bacterial blight is defeated by induction of the disease susceptibility gene Os-11N3.

    PubMed

    Antony, Ginny; Zhou, Junhui; Huang, Sheng; Li, Ting; Liu, Bo; White, Frank; Yang, Bing

    2010-11-01

    The rice (Oryza sativa) gene xa13 is a recessive resistance allele of Os-8N3, a member of the NODULIN3 (N3) gene family, located on rice chromosome 8. Os-8N3 is a susceptibility (S) gene for Xanthomonas oryzae pv oryzae, the causal agent of bacterial blight, and the recessive allele is defeated by strains of the pathogen producing any one of the type III effectors AvrXa7, PthXo2, or PthXo3, which are all members of the transcription activator-like (TAL) effector family. Both AvrXa7 and PthXo3 induce the expression of a second member of the N3 gene family, here named Os-11N3. Insertional mutagenesis or RNA-mediated silencing of Os-11N3 resulted in plants with loss of susceptibility specifically to strains of X. oryzae pv oryzae dependent on AvrXa7 or PthXo3 for virulence. We further show that AvrXa7 drives expression of Os-11N3 and that AvrXa7 interacts and binds specifically to an effector binding element within the Os-11N3 promoter, lending support to the predictive models for TAL effector binding specificity. The result indicates that variations in the TAL effector repetitive domains are driven by selection to overcome both dominant and recessive forms of resistance to bacterial blight in rice. The finding that Os-8N3 and Os-11N3 encode closely related proteins also provides evidence that N3 proteins have a specific function in facilitating bacterial blight disease.

  3. Monitoring bacterial panicle blight disease of rice and germplasm evaluation for resistance in Arkansas in 2015

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice is a major cereal crop that contributes significantly to the global food security. Rice production is challenged by both abiotic and biotic stresses. Rice bacterial panicle blight (BPB) has been recognized as one of the major biotic factors that can cause severe yield loss in Southern rice stat...

  4. Registration of common bacterial blight resistant cranberry dry bean germplasm line USCR-CBB-20

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Common bacterial blight is a serious disease of dry edible beans in warm humid climates. The disease is most prominent east of the continental divide in the U.S. Large seeded dry beans from the Andean gene pool, such as those in the cranberry bean market class are very susceptible to this disease. ...

  5. Factors influencing efficacy of plastic shelters for control of bacterial blight of lilac

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plastic shelters are thought to manage bacterial blight by protecting plants from rain and/or frost. In February to April 2008 and 2009, we studied the contribution of frost protection to efficacy of this cultural control practice. Lilacs in 1-gallon pots were exposed to four treatments: 1) plants...

  6. Suppression of the Bacterial Spot Pathogen Xanthomonas euvesicatoria on Tomato Leaves by an Attenuated Mutant of Xanthomonas perforans▿

    PubMed Central

    Hert, A. P.; Marutani, M.; Momol, M. T.; Roberts, P. D.; Olson, S. M.; Jones, J. B.

    2009-01-01

    A bacteriocin-producing strain of the bacterial spot of tomato plant pathogen, Xanthomonas perforans, with attenuated pathogenicity was deployed for biocontrol of a bacteriocin-sensitive strain of the genetically closely related bacterial spot of tomato plant pathogen, X. euvesicatoria. The attenuated mutant (91-118ΔopgHΔbcnB) of X. perforans was tested in leaf tissue and shown to significantly inhibit internal populations of the wild-type X. euvesicatoria strain although significantly less than the wild-type 91-118 strain, whereas in a phyllosphere inhibition assay, the mutant strain reduced epiphytic populations comparably to 91-118. Thus, the attenuated mutant limited the sensitive bacterium more efficiently on the leaf surface than inside the leaf. In field experiments, weekly application of 91-118ΔopgHΔbcnB significantly reduced X. euvesicatoria populations compared to the growers’ standard control (copper hydroxide and mancozeb applied weekly and acibenzolar-S-methyl applied every 2 weeks). The biological control agent, 91-118ΔopgHΔbcnB, applied every 2 weeks also significantly reduced X. euvesicatoria populations in one season but was not significantly different from the growers’ standard control. Potentially, attenuated pathogenic strains could be deployed as biological control agents in order to improve disease control of foliar plant pathogens. PMID:19286785

  7. Gene targeting by the TAL effector PthXo2 reveals cryptic resistance gene for bacterial blight of rice.

    PubMed

    Zhou, Junhui; Peng, Zhao; Long, Juying; Sosso, Davide; Liu, Bo; Eom, Joon-Seob; Huang, Sheng; Liu, Sanzhen; Vera Cruz, Casiana; Frommer, Wolf B; White, Frank F; Yang, Bing

    2015-05-01

    Bacterial blight of rice is caused by the γ-proteobacterium Xanthomonas oryzae pv. oryzae, which utilizes a group of type III TAL (transcription activator-like) effectors to induce host gene expression and condition host susceptibility. Five SWEET genes are functionally redundant to support bacterial disease, but only two were experimentally proven targets of natural TAL effectors. Here, we report the identification of the sucrose transporter gene OsSWEET13 as the disease-susceptibility gene for PthXo2 and the existence of cryptic recessive resistance to PthXo2-dependent X. oryzae pv. oryzae due to promoter variations of OsSWEET13 in japonica rice. PthXo2-containing strains induce OsSWEET13 in indica rice IR24 due to the presence of an unpredicted and undescribed effector binding site not present in the alleles in japonica rice Nipponbare and Kitaake. The specificity of effector-associated gene induction and disease susceptibility is attributable to a single nucleotide polymorphism (SNP), which is also found in a polymorphic allele of OsSWEET13 known as the recessive resistance gene xa25 from the rice cultivar Minghui 63. The mutation of OsSWEET13 with CRISPR/Cas9 technology further corroborates the requirement of OsSWEET13 expression for the state of PthXo2-dependent disease susceptibility to X. oryzae pv. oryzae. Gene profiling of a collection of 104 strains revealed OsSWEET13 induction by 42 isolates of X. oryzae pv. oryzae. Heterologous expression of OsSWEET13 in Nicotiana benthamiana leaf cells elevates sucrose concentrations in the apoplasm. The results corroborate a model whereby X. oryzae pv. oryzae enhances the release of sucrose from host cells in order to exploit the host resources.

  8. Complete Genome Sequences of Six Copper-Resistant Xanthomonas Strains Causing Bacterial Spot of Solaneous Plants, Belonging to X. gardneri, X. euvesicatoria, and X. vesicatoria, Using Long-Read Technology

    PubMed Central

    Richard, Damien; Boyer, Claudine; Lefeuvre, Pierre; Canteros, Blanca I.; Beni-Madhu, Shyam; Portier, Perrine

    2017-01-01

    ABSTRACT Xanthomonas vesicatoria, Xanthomonas euvesicatoria, and Xanthomonas gardneri cause bacterial spot disease. Copper has been applied since the 1920s as part of integrated management programs. The first copper-resistant strains were reported some decades later. Here, we fully sequenced six Xanthomonas strains pathogenic to tomato and/or pepper and having a copper-resistant phenotype. PMID:28232425

  9. Differential response of tomato genotypes to Xanthomonas-specific pathogen-associated molecular patterns and correlation with bacterial spot (Xanthomonas perforans) resistance

    PubMed Central

    Bhattarai, Krishna; Louws, Frank J; Williamson, John D; Panthee, Dilip R

    2016-01-01

    Plants depend on innate immune responses to retard the initial spread of pathogens entering through stomata, hydathodes or injuries. These responses are triggered by conserved patterns in pathogen-encoded molecules known as pathogen-associated molecular patterns (PAMPs). Production of reactive oxygen species (ROS) is one of the first responses, and the resulting ‘oxidative burst’ is considered to be a first line of defense. In this study, we conducted association analyses between ROS production and bacterial spot (BS; Xanthomonas spp.) resistance in 63 genotypes of tomato (Solanum lycopersicum L.). A luminol-based assay was performed on leaf tissues that had been treated with a flagellin 22 (flg22), flagellin 28 and a Xanthomonas-specific flg22 (flg22-Xac) peptide, to measure PAMP-induced ROS production in each genotype. These genotypes were also assessed for BS disease response by inoculation with Xanthomonas perforans, race T4. Although there was no consistent relationship between peptides used and host response to the BS, there was a significant negative correlation (r=−0.25, P<0.05) between foliar disease severity and ROS production, when flg22-Xac was used. This response could potentially be used to identify the Xanthomonas-specific PRR allele in tomato, and eventually PAMP-triggered immunity loci could be mapped in a segregating population. This has potential significance in tomato improvement. PMID:27555919

  10. Improvement of Basmati rice varieties for resistance to blast and bacterial blight diseases using marker assisted backcross breeding.

    PubMed

    Ellur, Ranjith K; Khanna, Apurva; Yadav, Ashutosh; Pathania, Sandeep; Rajashekara, H; Singh, Vikas K; Gopala Krishnan, S; Bhowmick, Prolay K; Nagarajan, M; Vinod, K K; Prakash, G; Mondal, Kalyan K; Singh, Nagendra K; Vinod Prabhu, K; Singh, Ashok K

    2016-01-01

    Marker assisted backcross breeding was employed to incorporate the blast resistance genes, Pi2 and Pi54 and bacterial blight (BB) resistance genes xa13 and Xa21 into the genetic background of Pusa Basmati 1121 (PB1121) and Pusa Basmati 6. Foreground selection for target gene(s) was followed by arduous phenotypic and background selection which fast-tracked the recovery of recurrent parent genome (RPG) to an extent of 95.8% in one of the near-isogenic lines (NILs) namely, Pusa 1728-23-33-31-56, which also showed high degree of resemblance to recurrent parent, PB6 in phenotype. The phenotypic selection prior to background selection provided an additional opportunity for identifying the novel recombinants viz., Pusa 1884-9-12-14 and Pusa 1884-3-9-175, superior to parental lines in terms of early maturity, higher yield and improved quality parameters. There was no significant difference between the RPG recovery estimated based on SSR or SNP markers, however, the panel of SNPs markers was considered as the better choice for background selection as it provided better genome coverage and included SNPs in the genic regions. Multi-location evaluation of NILs depicted their stable and high mean performance in comparison to the respective recurrent parents. The Pi2+Pi54 carrying NILs were effective in combating a pan-India panel of Magnaporthe oryzae isolates with high level of field resistance in northern, eastern and southern parts of India. Alongside, the PB1121-NILs and PB6-NILs carrying BB resistance genes xa13+Xa21 were resistant against Xanthomonas oryzae pv. oryzae races of north-western, southern and eastern parts of the country. Three of NILs developed in this study, have been promoted to final stage of testing during the ​Kharif 2015 in the Indian National Basmati Trial.

  11. High-resolution genetic mapping of Xa27(t), a new bacterial blight resistance gene in rice, Oryza sativa L.

    PubMed

    Gu, K; Tian, D; Yang, F; Wu, L; Sreekala, C; Wang, D; Wang, G-L; Yin, Z

    2004-03-01

    Bacterial blight of rice, caused by Xanthomonas oryzae pv. oryzae ( Xoo) (Ishyama) Dye, is one of the serious diseases prevalent throughout Asia. In a previous study, a resistance ( R) locus was transferred from the tetraploid wild rice Oryza minuta to the cultivated rice species, Oryza sativa L. Here, we report the fine genetic mapping of the R locus, tentatively designated as Xa27(t). We performed disease evaluation with an Xa27(t) near-isogenic line, IRBB27, testing 35 Xoo strains collected from 11 countries. The Xa27(t) locus conferred a high level of resistance to 27 strains and moderate resistance to three strains. Resistance of the Xa27(t) gene was developmentally regulated in IRBB27 and showed semi-dominant or a dosage effect in the cv. CO39 genetic background. As a prelude to cloning Xa27(t), a molecular mapping strategy was employed with a large mapping population consisting of 3,875 gametes. Three molecular markers, M336, M1081, and M1059, closely linked to Xa27(t), were identified to facilitate the mapping of Xa27(t) to the long arm of chromosome 6. The Xa27(t) locus was confirmed by chromosome landing of M1081 and M1095 markers on the rice genome. Markers derived from the genomic sequence of O. sativa cv. Nipponbare were used to further saturate the Xa27(t) genomic region. Xa27(t) was finally located within a genetic interval of 0.052 cM, flanked by markers M964 and M1197, and co-segregated with markers M631, M1230, and M449.

  12. Bacterial blight of soybean: Regulation of a pathogen gene determining host cultivar specificity

    SciTech Connect

    Huynh, T.V.; Dahlbeck, D.; Staskawicz, B.J. )

    1989-09-22

    Soybean cultivars resistant to Pseudomonas syringae pathovar glycinea (Psg), the causal agent of bacterial blight, exhibit a hypersensitive (necrosis) reaction (HR) to infection. Psg strains carrying the avrB gene elicit the HR in soybean cultivars carrying the resistance gene Rpg1. Psg expressing avrB at a high level and capable of eliciting the HR in the absence of de novo bacterial RNA synthesis have been obtained in in vitro culture. Nutritional signals and regions within the Psg hrp gene cluster, an approximately 20-kilobase genomic region also necessary for pathogenicity, control avrB transcription.

  13. The rsmA-like gene rsmA(Xoo) of Xanthomonas oryzae pv. oryzae regulates bacterial virulence and production of diffusible signal factor.

    PubMed

    Zhu, Pei-Liang; Zhao, Shuai; Tang, Ji-Liang; Feng, Jia-Xun

    2011-04-01

    The plant-pathogenic prokaryote Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight, one of the most destructive diseases of rice. A nonpolar mutant of the rsmA-like gene rsmA(Xoo) of the Xoo Chinese strain 13751 was constructed by homologous integration with a suicide plasmid. Virulence tests on a host plant, namely the hybrid rice cultivar Teyou 63, showed that the mutant had lost its virulence almost completely, whereas tests on a nonhost, namely castor-oil plant (Ricinus communis), showed that the mutant had also lost the ability to induce a hypersensitive response in the nonhost. In addition, the rsmA(Xoo) mutant produced significantly smaller amounts of the diffusible signal factor, extracellular endoglucanase, amylase and extracellular polysaccharide, but showed significantly higher glycogen accumulation, bacterial aggregation and cell adhesion. The expression of most hrp genes, genes encoding AvrBs3/PthA family members, rpfB, xrvA, glgA, eglXoB and XOO0175 (encoding an α-amylase) was down-regulated in the rsmA(Xoo) mutant. All phenotypes and expression levels of the tested genes in the rsmA(Xoo) mutant were restored to their levels in the wild-type by the presence of rsmA(Xoo) in trans. These results indicate that rsmA(Xoo) is essential for the virulence of Xoo.

  14. Molecular phylogeny, homology modeling, and molecular dynamics simulation of race-specific bacterial blight disease resistance protein (xa5) of rice: a comparative agriproteomics approach.

    PubMed

    Dehury, Budheswar; Sahu, Mousumi; Sarma, Kishore; Sahu, Jagajjit; Sen, Priyabrata; Modi, Mahendra Kumar; Sharma, Gauri Dutta; Choudhury, Manabendra Dutta; Barooah, Madhumita

    2013-08-01

    Rice (Oryza sativa L.), a model plant belonging to the family Poaceae, is a staple food for a majority of the people worldwide. Grown in the tropical and subtropical regions of the world, this important cereal crop is under constant and serious threat from both biotic and abiotic stresses. Among the biotic threats, Xanthomonas oryzae pv. oryzae, causing the damaging bacterial blight disease in rice, is a prominent pathogen. The xa5 gene in the host plant rice confers race-specific resistance to this pathogen. This recessive gene belongs to the Xa gene family of rice and encodes a gamma subunit of transcription factor IIA (TFIIAγ). In view of the importance of this gene in conferring resistance to the devastating disease, we reconstructed the phylogenetic relationship of this gene, developed a three-dimensional protein model, followed by long-term molecular dynamics simulation studies to gain a better understanding of the evolution, structure, and function of xa5. The modeled structure was found to fit well with the small subunit of TFIIA from human, suggesting that it may also act as a small subunit of TFIIA in rice. The model had a stable conformation in response to the atomic flexibility and interaction, when subjected to MD simulation at 20 nano second in aqueous solution. Further structural analysis of xa5 indicated that the protein retained its basic transcription factor function, suggesting that it might govern a novel pathway responsible for bacterial blight resistance. Future molecular docking studies of xa5 underway with its corresponding avirulence gene is expected to shed more direct light into plant-pathogen interactions at the molecular level and thus pave the way for richer agriproteomic insights.

  15. Mapping quantitative trait loci associated with resistance to bacterial spot (Xanthomonas arboricola pv. pruni)in peach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial spot, caused by Xanthomonas arboricola pv. pruni (Xap), is a serious disease that can affect peach fruit quality and production worldwide. This disease causes severe defoliation and blemishing of fruit, particularly in areas with high rainfall, strong winds, high humidity, and sandy soil. ...

  16. Evaluation of triticale accessions for resistance to wheat bacterial leaf streak caused by Xanthomonas translucens pv. undulosa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The bacterium Xanthomonas translucens pv. undulosa (Xtu) causes bacterial leaf streak (BLS) on wheat and other small grains. Several triticale accessions were reported to possess high levels of resistance to wheat Xtu strains. In this study, we evaluated a worldwide collection of 502 triticale acces...

  17. The inheritance of resistance to bacterial leaf spot of lettuce caused by Xanthomonas campestris pv. vitians in three lettuce cultivars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lettuce yields can be reduced by the disease bacterial leaf spot (BLS) caused by the pathogen Xanthomonas campestris pv. vitians (Xcv) and host resistance is the most feasible method to reduce disease losses. The cultivars La Brillante, Pavane, and Little Gem express an incompatible host-pathogen in...

  18. Baby leaf lettuce germplasm enhancement: developing diverse populations with resistance to bacterial leaf spot caused by Xanthomonas campestris pv. vitians

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Baby leaf lettuce cultivars with resistance to bacterial leaf spot (BLS) caused by Xanthomonas campestris pv. vitians (Xcv) are needed to reduce crop losses. The objectives of this research were to assess the genetic diversity for BLS resistance in baby leaf lettuce cultivars and to select early gen...

  19. Genetic Diversity of Lettuce (Lactuca sativa) for Resistance to Bacterial Leaf Spot Caused by Xanthomonas campestris pv. vitians.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lettuce plants were artificially inoculated with three isolates of Xanthomonas campestris pv. vitians in field and greenhouse evaluations for genetic variation in resistance to bacterial leaf spot. The cultivar Little Gem had the least amount of disease, whether evaluated for disease severity or dis...

  20. Role of rpfF in Virulence and Exoenzyme Production of Xanthomonas axonopodis pathovar glycines, the Causal Agent of Bacterial Pustule of Soybean

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ten strains of Xanthomonas axonopodis pv. glycines, the causal agent of bacterial pustule of soybean, obtained from various soybean growing regions of Thailand produced an extracellular diffusible factor (DSF) related to a well-characterized quorum sensing molecule produced by other Xanthomonas spp....

  1. Oscyp71Z2 involves diterpenoid phytoalexin biosynthesis that contributes to bacterial blight resistance in rice.

    PubMed

    Li, Wenqi; Shao, Min; Yang, Jie; Zhong, Weigong; Okada, Kazunori; Yamane, Hisakazu; Qian, Guoliang; Liu, Fengquan

    2013-06-01

    Bacterial blight is one of the most destructive rice diseases, which caused by Xoo, and results in yield losses, endangering worldwide food security. Diterpenoid phytoalexins, a type of antimicrobials produced in rice, are critical for resistance to fungal and bacterial pathogens. This article reports the characterization of the cytochrome P450 gene Oscyp71Z2, which belongs to the CYP71Z subfamily. Overexpression of Oscyp71Z2 in rice enhanced resistance to Xoo at the booting stage. The accumulation of phytoalexins was rapidly and strongly induced in Oscyp71Z2-overexpressing plants, and the transcript levels of genes related to the phytoalexin biosynthesis pathway were elevated. The H₂O₂ concentration in Oscyp71Z2-overexpressing plants was reduced in accordance with the increase in ROS-scavenging ability due to the induction of SOD as well as POD and CAT activation. We also showed that suppression of Oscyp71Z2 had no significantly effect on disease resistance to Xoo in rice. These results demonstrated that Oscyp71Z2 plays an important role in bacterial blight resistance by regulating the diterpenoid phytoalexin biosynthesis and H₂O₂ generation.

  2. [Polyvalence of bacteriophages isolated from fruit trees, affected by bacterial fire blight].

    PubMed

    Tovkach, F I; Moroz, S N; Korol', N A; Faĭdiuk, Iu V; Kushkina, A I

    2013-01-01

    Phage populations appearing as a result of a pathogenic process caused by Erwinia amylovora have been discovered and described. They accompany bacterial fire blight development in the process of quince, pear and apple trees vegetation in Zakarpattya region of Ukraine. Phage isolates of the affected pear and quince include polyvalent virulent phages able to develop on bacterial strains associated with plants--E. amylovora. E. "horticola" and Pantoea agglomerans. E. amylovora isolated from the plant tissues affected by the fire blight and detected at the same time as phages proved to be resistant to the viral infection. It is hard to explain now this characteristic however it was noticed that resistance to phages can change drastically in case of dissociation, lysogenization and mutagenesis of erwinia in laboratory conditions. Phage population study shows that they are heterogeneous and can obviously include not only polyvalent but also specific viruses. Further studies of biology and molecular genetics of pure lines of isolated phages will help to get closer to understanding the place and role of bacteriophages in the complicated network of relations between bacterial pathogens and plants.

  3. A knowledge-based molecular screen uncovers a broad-spectrum OsSWEET14 resistance allele to bacterial blight from wild rice.

    PubMed

    Hutin, Mathilde; Sabot, François; Ghesquière, Alain; Koebnik, Ralf; Szurek, Boris

    2015-11-01

    Transcription activator-like (TAL) effectors are type III-delivered transcription factors that enhance the virulence of plant pathogenic Xanthomonas species through the activation of host susceptibility (S) genes. TAL effectors recognize their DNA target(s) via a partially degenerate code, whereby modular repeats in the TAL effector bind to nucleotide sequences in the host promoter. Although this knowledge has greatly facilitated our power to identify new S genes, it can also be easily used to screen plant genomes for variations in TAL effector target sequences and to predict for loss-of-function gene candidates in silico. In a proof-of-principle experiment, we screened a germplasm of 169 rice accessions for polymorphism in the promoter of the major bacterial blight susceptibility S gene OsSWEET14, which encodes a sugar transporter targeted by numerous strains of Xanthomonas oryzae pv. oryzae. We identified a single allele with a deletion of 18 bp overlapping with the binding sites targeted by several TAL effectors known to activate the gene. We show that this allele, which we call xa41(t), confers resistance against half of the tested Xoo strains, representative of various geographic origins and genetic lineages, highlighting the selective pressure on the pathogen to accommodate OsSWEET14 polymorphism, and reciprocally the apparent limited possibilities for the host to create variability at this particular S gene. Analysis of xa41(t) conservation across the Oryza genus enabled us to hypothesize scenarios as to its evolutionary history, prior to and during domestication. Our findings demonstrate that resistance through TAL effector-dependent loss of S-gene expression can be greatly fostered upon knowledge-based molecular screening of a large collection of host plants.

  4. Identification and linkage analysis of a new rice bacterial blight resistance gene from XM14, a mutant line from IR24

    PubMed Central

    Busungu, Constantine; Taura, Satoru; Sakagami, Jun-Ichi; Ichitani, Katsuyuki

    2016-01-01

    Bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is a chief factor limiting rice productivity worldwide. XM14, a rice mutant line resistant to Xoo, has been obtained by treating IR24, which is susceptible to six Philippine Xoo races and six Japanese Xoo races, with N-methyl-N-nitrosourea. XM14 showed resistance to six Japanese Xoo races. The F2 population from XM14 × IR24 clearly showed 1 resistant : 3 susceptible segregation, suggesting control of resistance by a recessive gene. The approximate chromosomal location of the resistance gene was determined using 10 plants with shortest lesion length in the F2 population from XM14 × Koshihikari, which is susceptible to Japanese Xoo races. DNA marker-assisted analysis revealed that the gene was located on chromosome 3. IAS16 line carries IR24 genetic background with a Japonica cultivar Asominori segment of chromosome 3, on which the resistance gene locus was thought to be located. The F2 population from IAS16 × XM14 showed a discrete distribution. Linkage analysis indicated that the gene is located around the centromeric region. The resistance gene in XM14 was a new gene, named XA42. This gene is expected to be useful for resistance breeding programs and for genetic analysis of Xoo resistance. PMID:27795689

  5. The broadly effective recessive resistance gene xa5 of rice is a virulence effector-dependent quantitative trait for bacterial blight.

    PubMed

    Huang, Sheng; Antony, Ginny; Li, Ting; Liu, Bo; Obasa, Ken; Yang, Bing; White, Frank F

    2016-04-01

    Mutations in disease susceptibility (S) genes, here referred to as recessive resistance genes, have promise for providing broad durable resistance in crop species. However, few recessive disease resistance genes have been characterized. Here, we show that the broadly effective resistance gene xa5,for resistance to bacterial blight of rice (Oryza sativa), is dependent on the effector genes present in the pathogen. Specifically, the effectiveness of xa5 in preventing disease by strains of Xanthomonas oryzae pv. oryzae is dependent on major transcription activation-like (TAL) effector genes, and correlates with reduced expression of the cognate S genes. xa5 is ineffective in preventing disease by strains containing the TAL effector gene pthXo1, which directs robust expression of the S gene OsSWEET11, a member of sucrose transporter gene family. Incompatibility is associated with major TAL effectors that target the known alternative S genes OsSWEET14 and OsSWEET13. Incompatibility is defeated by transfer of pthXo1 to otherwise xa5-incompatible strains or by engineering a synthetic designer TAL effector to boost SWEET gene expression. In either case, compatible or incompatible, target gene expression and lesion formation are reduced in the presence of xa5. The results indicate that xa5 functions as a quantitative trait locus, dampening effector function, and, regardless of compatibility, target gene expression. Resistance is hypothesized to occur when S gene expression, and, by inference, sucrose leakage, falls below a threshold level.

  6. Analysis of nucleotide diversity among alleles of the major bacterial blight resistance gene Xa27 in cultivars of rice (Oryza sativa) and its wild relatives.

    PubMed

    Bimolata, Waikhom; Kumar, Anirudh; Sundaram, Raman Meenakshi; Laha, Gouri Shankar; Qureshi, Insaf Ahmed; Reddy, Gajjala Ashok; Ghazi, Irfan Ahmad

    2013-08-01

    Xa27 is one of the important R-genes, effective against bacterial blight disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo). Using natural population of Oryza, we analyzed the sequence variation in the functionally important domains of Xa27 across the Oryza species. DNA sequences of Xa27 alleles from 27 rice accessions revealed higher nucleotide diversity among the reported R-genes of rice. Sequence polymorphism analysis revealed synonymous and non-synonymous mutations in addition to a number of InDels in non-coding regions of the gene. High sequence variation was observed in the promoter region including the 5'UTR with 'π' value 0.00916 and 'θ w ' = 0.01785. Comparative analysis of the identified Xa27 alleles with that of IRBB27 and IR24 indicated the operation of both positive selection (Ka/Ks > 1) and neutral selection (Ka/Ks ≈ 0). The genetic distances of alleles of the gene from Oryza nivara were nearer to IRBB27 as compared to IR24. We also found the presence of conserved and null UPT (upregulated by transcriptional activator) box in the isolated alleles. Considerable amino acid polymorphism was localized in the trans-membrane domain for which the functional significance is yet to be elucidated. However, the absence of functional UPT box in all the alleles except IRBB27 suggests the maintenance of single resistant allele throughout the natural population.

  7. Overexpression of OsMYC2 Results in the Up-Regulation of Early JA-Rresponsive Genes and Bacterial Blight Resistance in Rice.

    PubMed

    Uji, Yuya; Taniguchi, Shiduku; Tamaoki, Daisuke; Shishido, Hodaka; Akimitsu, Kazuya; Gomi, Kenji

    2016-09-01

    JASMONATE ZIM-domain (JAZ) proteins act as transcriptional repressors of jasmonic acid (JA) responses and play a crucial role in the regulation of host immunity in plants. Here, we report that OsMYC2, a JAZ-interacting transcription factor in rice (Oryza sativa L.), plays an important role in the resistance response against rice bacterial blight, which is one of the most serious diseases in rice, caused by Xanthomonas oryzae pv. oryzae (Xoo). The results showed that OsMYC2 interacted with some OsJAZ proteins in a JAZ-interacting domain (JID)-dependent manner. The up-regulation of OsMYC2 in response to JA was regulated by OsJAZ8. Transgenic rice plants overexpressing OsMYC2 exhibited a JA-hypersensitive phenotype and were more resistant to Xoo. A large-scale microarray analysis revealed that OsMYC2 up-regulated OsJAZ10 as well as many other defense-related genes. OsMYC2 selectively bound to the G-box-like motif of the OsJAZ10 promoter in vivo and regulated the expression of early JA-responsive genes, but not of late JA-responsive genes. The nuclear localization of OsMYC2 depended on a nuclear localization signal within JID. Overall, we conclude that OsMYC2 acts as a positive regulator of early JA signals in the JA-induced resistance against Xoo in rice.

  8. Identification and linkage analysis of a new rice bacterial blight resistance gene from XM14, a mutant line from IR24.

    PubMed

    Busungu, Constantine; Taura, Satoru; Sakagami, Jun-Ichi; Ichitani, Katsuyuki

    2016-09-01

    Bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is a chief factor limiting rice productivity worldwide. XM14, a rice mutant line resistant to Xoo, has been obtained by treating IR24, which is susceptible to six Philippine Xoo races and six Japanese Xoo races, with N-methyl-N-nitrosourea. XM14 showed resistance to six Japanese Xoo races. The F2 population from XM14 × IR24 clearly showed 1 resistant : 3 susceptible segregation, suggesting control of resistance by a recessive gene. The approximate chromosomal location of the resistance gene was determined using 10 plants with shortest lesion length in the F2 population from XM14 × Koshihikari, which is susceptible to Japanese Xoo races. DNA marker-assisted analysis revealed that the gene was located on chromosome 3. IAS16 line carries IR24 genetic background with a Japonica cultivar Asominori segment of chromosome 3, on which the resistance gene locus was thought to be located. The F2 population from IAS16 × XM14 showed a discrete distribution. Linkage analysis indicated that the gene is located around the centromeric region. The resistance gene in XM14 was a new gene, named XA42. This gene is expected to be useful for resistance breeding programs and for genetic analysis of Xoo resistance.

  9. Genetic diversity of the conserved motifs of six bacterial leaf blight resistance genes in a set of rice landraces

    PubMed Central

    2014-01-01

    Background Bacterial leaf blight (BLB) caused by the vascular pathogen Xanthomonas oryzae pv. oryzae (Xoo) is one of the most serious diseases leading to crop failure in rice growing countries. A total of 37 resistance genes against Xoo has been identified in rice. Of these, ten BLB resistance genes have been mapped on rice chromosomes, while 6 have been cloned, sequenced and characterized. Diversity analysis at the resistance gene level of this disease is scanty, and the landraces from West Bengal and North Eastern states of India have received little attention so far. The objective of this study was to assess the genetic diversity at conserved domains of 6 BLB resistance genes in a set of 22 rice accessions including landraces and check genotypes collected from the states of Assam, Nagaland, Mizoram and West Bengal. Results In this study 34 pairs of primers were designed from conserved domains of 6 BLB resistance genes; Xa1, xa5, Xa21, Xa21(A1), Xa26 and Xa27. The designed primer pairs were used to generate PCR based polymorphic DNA profiles to detect and elucidate the genetic diversity of the six genes in the 22 diverse rice accessions of known disease phenotype. A total of 140 alleles were identified including 41 rare and 26 null alleles. The average polymorphism information content (PIC) value was 0.56/primer pair. The DNA profiles identified each of the rice landraces unequivocally. The amplified polymorphic DNA bands were used to calculate genetic similarity of the rice landraces in all possible pair combinations. The similarity among the rice accessions ranged from 18% to 89% and the dendrogram produced from the similarity values was divided into 2 major clusters. The conserved domains identified within the sequenced rare alleles include Leucine-Rich Repeat, BED-type zinc finger domain, sugar transferase domain and the domain of the carbohydrate esterase 4 superfamily. Conclusions This study revealed high genetic diversity at conserved domains of six BLB

  10. Code-assisted discovery of TAL effector targets in bacterial leaf streak of rice reveals contrast with bacterial blight and a novel susceptibility gene

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Transcription activator-like (TAL) effectors found in Xanthomonas spp. promote bacterial growth and plant susceptibility by binding specific DNA sequences or, effector-binding elements (EBEs), and inducing host gene expression. In this study, we have found substantially different transcriptional pro...

  11. Development of an engineered ‘bioluminescent’ reporter phage for the detection of bacterial blight of crucifers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial blight, caused by the phytopathogen Pseudomonas cannabina pv. alisalensis, is an emerging disease afflicting important members of the Brassica family. The disease is often misdiagnosed as peppery leaf spot, a much less severe disease caused by the closely related pathogen Pseudomonas syrin...

  12. First report of bacterial blight of cabbage (Brassica oleracea var. capitata L.) caused by Pseudomonas cannabina pv. alisalensis in California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A novel bacterial leaf blight was seen in field grown cabbage (Brassica oleracea var. capitata L.) in Monterey County, California in 2006. Koch’s postulates were completed and etiology of the pathogen was determined. Physiological and molecular characterization showed that the pathogen was Pseudomon...

  13. Effervescent fast-disintegrating bacterial formulation for biological control of rice sheath blight.

    PubMed

    Wiwattanapatapee, R; Chumthong, A; Pengnoo, A; Kanjanamaneesathian, M

    2007-06-04

    A lack of effective, easily applied and stable formulation has been a major obstacle to widespread use of biocontrol agents for control of rice sheath blight. In this study, effervescent fast-disintegrating granules containing endospores of Bacillus megaterium were developed for use either by broadcast or spray application. The formulation composed of lactose, polyvinyl pyrrolidone K-30 (PVP, K-30) and effervescent base (citric acid, tartaric acid and sodium bicarbonate). The number of living bacteria in effervescent granules that performed mycelial growth inhibition was in the range of 10(9) CFU/g after 12 months storage at room temperature. The number of viable bacteria after applying into the water and spraying on the rice seedling for 7 days in the greenhouse tests were also satisfactory high (10(9) CFU/g of granules and 10(6) CFU/g of plant, respectively). The scanning electron microscope (SEM) was used to observe bacterial antagonist on the surface of leaf sheath and leaf blade after spraying with formulation. Effervescent formulation applied either broadcasting or spraying reduced incidence of sheath blight disease in the greenhouse experiments.

  14. STUDIES ON THE BACTERIAL LEAF BLIGHT OF RICE PLANT. ON THE DISTRIBUTION OF BACTERIUM ORYZAE (UEDA ET ISHIYAMA) NAKATA UPON THE RICE PLANTS (PRELIMINARY REPORT),

    DTIC Science & Technology

    The report contains a study of an outbreak of bacterial leaf blight of rice plants. An investigation of the primary source was made. Knowledge of the...distribution of infective agent on rice plants, when the primary infection occurs and before the appearance of the blight is recognized, was thought

  15. Molecular characterisation of Xanthomonas strains isolated from aroids in Mauritius.

    PubMed

    Khoodoo, M H R; Sahin, F; Donmez, M F; Fakim, Y Jaufeerally

    2005-06-01

    Mauritius is one of the largest world producers of Anthurium cut flowers but outbreaks of bacterial blight have never been reported on the island. This work was about the characterisation and identification of bacterial strains isolated from Anthurium andreanum, Dieffenbachia maculata and Aglaonema simplex in Mauritius. Fifteen strains, that showed the morphological properties of Xanthomonas on conventional media, were tested on two semi-selective media (Esculin-trehalose and cellobiose-starch). ELISA tests using a panel of monoclonal antibodies were carried out and three out of 15 strains reacted with a Xanthomonas-specific monoclonal antibody (MAb XII). Analysis using four sets of ribosomal primers revealed that the same three Mauritius strains shared conserved PCR products with reference xanthomonads including virulent strains of Xanthomonas axonopodis pv. dieffenbachiae (Xad). BIOLOG tests and the Sherlock Microbial Identification system (MIDI) identified these three new strains at the species level as X. axonopodis. The complementary tests that were carried out clearly confirmed that the three strains are xanthomonads and, moreover, a DNA probe which showed specificity to Xad strains suggested that the three Mauritius strains are non-virulent forms of the pathogen causing Anthurium blight.

  16. A new common bacterial blight resistance QTL in VAX 1 common bean and interaction of the new QTL, SAP6 and SU91 with bacterial strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Common bacterial blight (CBB) is a severe disease in common bean. New resistance QTL should facilitate development of cultivars with high levels of resistance. Our objectives were to (i) identify new resistance QTL in VAX 1 and verify presence in VAX 3, (ii) determine interaction of new QTL with exi...

  17. Epidemiology and Control of Strawberry Bacterial Angular Leaf Spot Disease Caused by Xanthomonas fragariae.

    PubMed

    Kim, Da-Ran; Gang, Gun-Hye; Jeon, Chang-Wook; Kang, Nam Jun; Lee, Sang-Woo; Kwak, Youn-Sig

    2016-08-01

    Strawberry bacterial angular leaf spot (ALS) disease, caused by Xanthomonas fragariae has become increasingly problematic in the strawberry agro-industry. ALS causes small angular water-soaked lesions to develop on the abaxial leaf surface. Studies reported optimum temperature conditions for X. fragariae are 20°C and the pathogen suffers mortality above 32°C. However, at the nursery stage, disease symptoms have been observed under high temperature conditions. In the present study, results showed X. fragariae transmission was via infected maternal plants, precipitation, and sprinkler irrigation systems. Systemic infections were detected using X. fragariae specific primers 245A/B and 295A/B, where 300-bp and 615-bp were respectively amplified. During the nursery stage (from May to August), the pathogen was PCR detected only in maternal plants, but not in soil or irrigation water through the nursery stage. During the cultivation period, from September to March, the pathogen was detected in maternal plants, progeny, and soil, but not in water. Additionally, un-infected plants, when planted with infected plants were positive for X. fragariae via PCR at the late cultivation stage. Chemical control for X. fragariae with oxolinic acid showed 87% control effects against the disease during the nursery period, in contrast to validamycin-A, which exhibited increased efficacy against the disease during the cultivation stage (control effect 95%). To our knowledge, this is the first epidemiological study of X. fragariae in Korean strawberry fields.

  18. Epidemiology and Control of Strawberry Bacterial Angular Leaf Spot Disease Caused by Xanthomonas fragariae

    PubMed Central

    Kim, Da-Ran; Gang, Gun-hye; Jeon, Chang-Wook; Kang, Nam Jun; Lee, Sang-woo; Kwak, Youn-Sig

    2016-01-01

    Strawberry bacterial angular leaf spot (ALS) disease, caused by Xanthomonas fragariae has become increasingly problematic in the strawberry agro-industry. ALS causes small angular water-soaked lesions to develop on the abaxial leaf surface. Studies reported optimum temperature conditions for X. fragariae are 20°C and the pathogen suffers mortality above 32°C. However, at the nursery stage, disease symptoms have been observed under high temperature conditions. In the present study, results showed X. fragariae transmission was via infected maternal plants, precipitation, and sprinkler irrigation systems. Systemic infections were detected using X. fragariae specific primers 245A/B and 295A/B, where 300-bp and 615-bp were respectively amplified. During the nursery stage (from May to August), the pathogen was PCR detected only in maternal plants, but not in soil or irrigation water through the nursery stage. During the cultivation period, from September to March, the pathogen was detected in maternal plants, progeny, and soil, but not in water. Additionally, un-infected plants, when planted with infected plants were positive for X. fragariae via PCR at the late cultivation stage. Chemical control for X. fragariae with oxolinic acid showed 87% control effects against the disease during the nursery period, in contrast to validamycin-A, which exhibited increased efficacy against the disease during the cultivation stage (control effect 95%). To our knowledge, this is the first epidemiological study of X. fragariae in Korean strawberry fields. PMID:27493604

  19. TaCPK2-A, a calcium-dependent protein kinase gene that is required for wheat powdery mildew resistance enhances bacterial blight resistance in transgenic rice.

    PubMed

    Geng, Shuaifeng; Li, Aili; Tang, Lichuan; Yin, Lingjie; Wu, Liang; Lei, Cailin; Guo, Xiuping; Zhang, Xin; Jiang, Guanghuai; Zhai, Wenxue; Wei, Yuming; Zheng, Youliang; Lan, Xiujin; Mao, Long

    2013-08-01

    Calcium-dependent protein kinases (CPKs) are important Ca2+ signalling components involved in complex immune and stress signalling networks; but the knowledge of CPK gene functions in the hexaploid wheat is limited. Previously, TaCPK2 was shown to be inducible by powdery mildew (Blumeria graminis tritici, Bgt) infection in wheat. Here, its functions in disease resistance are characterized further. This study shows the presence of defence-response and cold-response cis-elements on the promoters of the A subgenome homoeologue (TaCPK2-A) and D subgenome homoeologue (TaCPK2-D), respectively. Their expression patterns were then confirmed by quantitative real-time PCR (qRT-PCR) using genome-specific primers, where TaCPK2-A was induced by Bgt treatment while TaCPK2-D mainly responded to cold treatment. Downregulation of TaCPK2-A by virus-induced gene silencing (VIGS) causes loss of resistance to Bgt in resistant wheat lines, indicating that TaCPK2-A is required for powdery mildew resistance. Furthermore, overexpression of TaCPK2-A in rice enhanced bacterial blight (Xanthomonas oryzae pv. oryzae, Xoo) resistance. qRT-PCR analysis showed that overexpression of TaCPK2-A in rice promoted the expression of OsWRKY45-1, a transcription factor involved in both fungal and bacterial resistance by regulating jasmonic acid and salicylic acid signalling genes. The opposite effect was found in wheat TaCPK2-A VIGS plants, where the homologue of OsWRKY45-1 was significantly repressed. These data suggest that modulation of WRKY45-1 and associated defence-response genes by CPK2 genes may be the common mechanism for multiple disease resistance in grass species, which may have undergone subfunctionalization in promoters before the formation of hexaploid wheat.

  20. TaCPK2-A, a calcium-dependent protein kinase gene that is required for wheat powdery mildew resistance enhances bacterial blight resistance in transgenic rice

    PubMed Central

    Geng, Shuaifeng; Li, Aili; Tang, Lichuan; Lan, Xiujin; Mao, Long

    2013-01-01

    Calcium-dependent protein kinases (CPKs) are important Ca2+ signalling components involved in complex immune and stress signalling networks; but the knowledge of CPK gene functions in the hexaploid wheat is limited. Previously, TaCPK2 was shown to be inducible by powdery mildew (Blumeria graminis tritici, Bgt) infection in wheat. Here, its functions in disease resistance are characterized further. This study shows the presence of defence-response and cold-response cis-elements on the promoters of the A subgenome homoeologue (TaCPK2-A) and D subgenome homoeologue (TaCPK2-D), respectively. Their expression patterns were then confirmed by quantitative real-time PCR (qRT-PCR) using genome-specific primers, where TaCPK2-A was induced by Bgt treatment while TaCPK2-D mainly responded to cold treatment. Downregulation of TaCPK2-A by virus-induced gene silencing (VIGS) causes loss of resistance to Bgt in resistant wheat lines, indicating that TaCPK2-A is required for powdery mildew resistance. Furthermore, overexpression of TaCPK2-A in rice enhanced bacterial blight (Xanthomonas oryzae pv. oryzae, Xoo) resistance. qRT-PCR analysis showed that overexpression of TaCPK2-A in rice promoted the expression of OsWRKY45-1, a transcription factor involved in both fungal and bacterial resistance by regulating jasmonic acid and salicylic acid signalling genes. The opposite effect was found in wheat TaCPK2-A VIGS plants, where the homologue of OsWRKY45-1 was significantly repressed. These data suggest that modulation of WRKY45-1 and associated defence-response genes by CPK2 genes may be the common mechanism for multiple disease resistance in grass species, which may have undergone subfunctionalization in promoters before the formation of hexaploid wheat. PMID:23918959

  1. Reduction in bacterial ooze formation on immature fruitlets after preventive treatments of Fosethyl-Al against fire blight Erwinia amylovora.

    PubMed

    Deckers, T; Schoofs, H; Verjans, W; De Maeyer, L

    2010-01-01

    Fire blight, caused by the bacterium Erwinia amylovora (Burill Winslow et al.), is a very important bacterial disease on apple and pear orchards with devastating effects in some production area and in some years. Fire blight control consists in a whole strategy of measures that should start with control measures in and around the fruit tree nurseries. Only the use of Vacciplant (Laminarin), an inducer of the self-defence mechanism, is registered in Belgium since 2009. In other European countries Fosethyl-Al has been registered for fire blight control. Recently, research trials have been done at Pcfruit research station for several years on the activity of ALiette (fosethyl-Al) against fire blight. Fosethyl-Al, also a plant defence enhancing molecule, applied preventively 3 times at a dose of 3.75 kg/ha standard orchard (3 x 3000 g a.i./ha standard orchard), showed a reduction in the host susceptibility and decreased the disease development on artificial inoculated flower clusters and shoots. Also a clear reduction in the ooze droplet formation on artificially inoculated immature fruitlets has been observed with this molecule. This reduction in the bacterial ooze formation is considered as a very important factor in the spread of the disease in the orchard.

  2. D-Psicose induces upregulation of defense-related genes and resistance in rice against bacterial blight.

    PubMed

    Kano, Akihito; Hosotani, Kouji; Gomi, Kenji; Yamasaki-Kokudo, Yumiko; Shirakawa, Chikage; Fukumoto, Takeshi; Ohtani, Kouhei; Tajima, Shigeyuki; Izumori, Ken; Tanaka, Keiji; Ishida, Yutaka; Nishizawa, Yoko; Ichimura, Kazuya; Tada, Yasuomi; Akimitsu, Kazuya

    2011-10-15

    We examined rice responses to a rare sugar, d-psicose. Rice growth was inhibited by d-psicose but not by common sugars. Microarray analysis revealed that d-psicose treatment caused an upregulation of many defense-related genes in rice, and dose-dependent upregulation of these genes was confirmed by quantitative reverse-transcription polymerase chain reaction. The level of upregulation of defense-related genes by d-psicose was low compared with that by d-allose, which is another rare sugar known to confer induction of resistance to rice bacterial blight in rice. Treatment with d-psicose conferred resistance to bacterial blight in rice in a dose-dependent manner, and the results indicate that d-psicose might be a candidate plant activator for reducing disease development in rice.

  3. Gene silencing using the recessive rice bacterial blight resistance gene xa13 as a new paradigm in plant breeding.

    PubMed

    Li, Changyan; Wei, Jing; Lin, Yongjun; Chen, Hao

    2012-05-01

    Resistant germplasm resources are valuable for developing resistant varieties in agricultural production. However, recessive resistance genes are usually overlooked in hybrid breeding. Compared with dominant traits, however, they may confer resistance to different pathogenic races or pest biotypes with different mechanisms of action. The recessive rice bacterial blight resistance gene xa13, also involved in pollen development, has been cloned and its resistance mechanism has been recently characterized. This report describes the conversion of bacterial blight resistance mediated by the recessive xa13 gene into a dominant trait to facilitate its use in a breeding program. This was achieved by knockdown of the corresponding dominant allele Xa13 in transgenic rice using recently developed artificial microRNA technology. Tissue-specific promoters were used to exclude most of the expression of artificial microRNA in the anther to ensure that Xa13 functioned normally during pollen development. A battery of highly bacterial blight resistant transgenic plants with normal seed setting rates were acquired, indicating that highly specific gene silencing had been achieved. Our success with xa13 provides a paradigm that can be adapted to other recessive resistance genes.

  4. A comparison of the molecular organization of genomic regions associated with resistance to common bacterial blight in two Phaseolus vulgaris genotypes.

    PubMed

    Perry, Gregory; Dinatale, Claudia; Xie, Weilong; Navabi, Alireza; Reinprecht, Yarmilla; Crosby, William; Yu, Kangfu; Shi, Chun; Pauls, K Peter

    2013-01-01

    Resistance to common bacterial blight, caused by Xanthomonas axonopodis pv. phaseoli, in Phaseolus vulgaris is conditioned by several loci on different chromosomes. Previous studies with OAC-Rex, a CBB-resistant, white bean variety of Mesoamerican origin, identified two resistance loci associated with the molecular markers Pv-CTT001 and SU91, on chromosome 4 and 8, respectively. Resistance to CBB is assumed to be derived from an interspecific cross with Phaseolus acutifolius in the pedigree of OAC-Rex. Our current whole genome sequencing effort with OAC-Rex provided the opportunity to compare its genome in the regions associated with CBB resistance with the v1.0 release of the P. vulgaris line G19833, which is a large seeded bean of Andean origin, and (assumed to be) CBB susceptible. In addition, the genomic regions containing SAP6, a marker associated with P. vulgaris-derived CBB-resistance on chromosome 10, were compared. These analyses indicated that gene content was highly conserved between G19833 and OAC-Rex across the regions examined (>80%). However, fifty-nine genes unique to OAC Rex were identified, with resistance gene homologues making up the largest category (10 genes identified). Two unique genes in OAC-Rex located within the SU91 resistance QTL have homology to P. acutifolius ESTs and may be potential sources of CBB resistance. As the genomic sequence assembly of OAC-Rex is completed, we expect that further comparisons between it and the G19833 genome will lead to a greater understanding of CBB resistance in bean.

  5. Southern leaf blight disease severity is correlated with decreased maize leaf epiphytic bacterial species richness and the phyllosphere bacterial diversity decline is enhanced by nitrogen fertilization.

    PubMed

    Manching, Heather C; Balint-Kurti, Peter J; Stapleton, Ann E

    2014-01-01

    Plant leaves are inhabited by a diverse group of microorganisms that are important contributors to optimal growth. Biotic and abiotic effects on plant growth are usually studied in controlled settings examining response to variation in single factors and in field settings with large numbers of variables. Multi-factor experiments with combinations of stresses bridge this gap, increasing our understanding of the genotype-environment-phenotype functional map for the host plant and the affiliated epiphytic community. The maize inbred B73 was exposed to single and combination abiotic and the biotic stress treatments: low nitrogen fertilizer and high levels of infection with southern leaf blight (causal agent Cochliobolus heterostrophus). Microbial epiphyte samples were collected at the vegetative early-season phase and species composition was determined using 16S ribosomal intergenic spacer analysis. Plant traits and level of southern leaf blight disease were measured late-season. Bacterial diversity was different among stress treatment groups (P < 0.001). Lower species richness-alpha diversity-was correlated with increased severity of southern leaf blight disease when disease pressure was high. Nitrogen fertilization intensified the decline in bacterial alpha diversity. While no single bacterial ribotype was consistently associated with disease severity, small sets of ribotypes were good predictors of disease levels. Difference in leaf bacterial-epiphyte diversity early in the season were correlated with plant disease severity, supporting further tests of microbial epiphyte-disease correlations for use in predicting disease progression.

  6. Southern leaf blight disease severity is correlated with decreased maize leaf epiphytic bacterial species richness and the phyllosphere bacterial diversity decline is enhanced by nitrogen fertilization

    PubMed Central

    Manching, Heather C.; Balint-Kurti, Peter J.; Stapleton, Ann E.

    2014-01-01

    Plant leaves are inhabited by a diverse group of microorganisms that are important contributors to optimal growth. Biotic and abiotic effects on plant growth are usually studied in controlled settings examining response to variation in single factors and in field settings with large numbers of variables. Multi-factor experiments with combinations of stresses bridge this gap, increasing our understanding of the genotype-environment-phenotype functional map for the host plant and the affiliated epiphytic community. The maize inbred B73 was exposed to single and combination abiotic and the biotic stress treatments: low nitrogen fertilizer and high levels of infection with southern leaf blight (causal agent Cochliobolus heterostrophus). Microbial epiphyte samples were collected at the vegetative early-season phase and species composition was determined using 16S ribosomal intergenic spacer analysis. Plant traits and level of southern leaf blight disease were measured late-season. Bacterial diversity was different among stress treatment groups (P < 0.001). Lower species richness—alpha diversity—was correlated with increased severity of southern leaf blight disease when disease pressure was high. Nitrogen fertilization intensified the decline in bacterial alpha diversity. While no single bacterial ribotype was consistently associated with disease severity, small sets of ribotypes were good predictors of disease levels. Difference in leaf bacterial-epiphyte diversity early in the season were correlated with plant disease severity, supporting further tests of microbial epiphyte-disease correlations for use in predicting disease progression. PMID:25177328

  7. Quantitative trait Loci mapping for bacterial blight resistance in rice using bulked segregant analysis.

    PubMed

    Han, Xueying; Yang, Yong; Wang, Xuming; Zhou, Jie; Zhang, Wenhao; Yu, Chulang; Cheng, Chen; Cheng, Ye; Yan, Chengqi; Chen, Jianping

    2014-07-03

    Oryza meyeriana is highly resistant to rice bacterial blight (BB) and this resistance trait has been transferred to cultivated rice (O. sativa) using asymmetric somatic hybridization. However, no resistance genes have yet been cloned. In the present study, a progeny of the somatic hybridization with high BB resistance was crossed with a rice cultivar with high BB susceptibility to develop an F2 population. Using bulked segregant analysis (BSA), 17 polymorphic markers that were linked to rice BB resistance were obtained through scanning a total of 186 simple sequence repeats (SSR) and sequence-tagged site (STS) markers, evenly distributed on 12 chromosomes. A genetic linkage map was then constructed based on the 17 linkage markers and the F2 segregating population, which was followed by mapping for quantitative trait loci (QTLs) for BB resistance. Three QTLs were identified on chromosomes 1, 3 and 5, respectively, and the alleles of the resistant parent at any of the QTLs increased BB resistance. All of the three QTLs had a strong effect on resistance, explaining about 21.5%, 12.3% and 39.2% of the resistance variance, respectively. These QTLs were different from the loci of the BB resistance genes that have been identified in previous studies. The QTLs mapped in this work will facilitate the isolation of novel BB resistance genes and their utilization in rice resistance breeding.

  8. Nucleotide diversity analysis of three major bacterial blight resistance genes in rice.

    PubMed

    Bimolata, Waikhom; Kumar, Anirudh; M, Sai Kiran Reddy; Sundaram, Raman Meenakshi; Laha, Gouri Sankar; Qureshi, Insaf Ahmed; Ghazi, Irfan Ahmad

    2015-01-01

    Nucleotide sequence polymorphisms among R gene alleles influence the process of co-evolutionary interaction between host and pathogen by shaping the response of host plants towards invading pathogens. Here, we present the DNA sequence polymorphisms and diversities present among natural alleles of three rice bacterial blight resistance genes, Xa21, Xa26 and xa5. The diversity was examined across different wild relatives and cultivars of Oryza species. Functional significance of selected alleles was evaluated through semi-quantitative reverse transcription polymerase chain reaction and real time PCR. The greatest nucleotide diversity and singleton variable sites (SVS) were present in Xa26 (π = 0.01958; SVS = 182) followed by xa5 and Xa21 alleles. The highest frequency of single nucleotide polymorphisms were observed in Xa21 alleles and least in xa5. Transition bias was observed in all the genes and 'G' to 'A' transitions were more favored than other form of transitions. Neutrality tests failed to show the presence of selection at these loci, though negative Tajima's D values indicate the presence of a rare form of polymorphisms. At the interspecies level, O. nivara exhibited more diversity than O. sativa. We have also identified two nearly identical resistant alleles of xa5 and two sequentially identical alleles of Xa21. The alleles of xa5 showed basal levels of expression while Xa21 alleles were functionally not expressed.

  9. Finished Genome Sequences of Xanthomonas fragariae, the Cause of Bacterial Angular Leaf Spot of Strawberry

    PubMed Central

    Henry, Peter M.

    2016-01-01

    Xanthomonas fragariae is a foliar pathogen of strawberry that is of significant concern to nursery production of strawberry transplants and field production of strawberry fruit. Long-read sequencing was employed to generate finished genomes for two isolates (each with one chromosome and two plasmids) from symptomatic plants in northern California. PMID:27834715

  10. Draft Genome Sequence of Two Strains of Xanthomonas arboricola Isolated from Prunus persica Which Are Dissimilar to Strains That Cause Bacterial Spot Disease on Prunus spp.

    PubMed Central

    Garita-Cambronero, Jerson; Palacio-Bielsa, Ana; López, María M.

    2016-01-01

    The draft genome sequences of two strains of Xanthomonas arboricola, isolated from asymptomatic peach trees in Spain, are reported here. These strains are avirulent and do not belong to the same phylogroup as X. arboricola pv. pruni, a causal agent of bacterial spot disease of stone fruits and almonds. PMID:27609931

  11. The rice thylakoid membrane-bound ascorbate peroxidase OsAPX8 functions in tolerance to bacterial blight

    PubMed Central

    Jiang, Guanghuai; Yin, Dedong; Zhao, Jiying; Chen, Honglin; Guo, Lequn; Zhu, Lihuang; Zhai, Wenxue

    2016-01-01

    Thylakoid membrane-bound ascorbate peroxidase (tAPX) is a major H2O2-scavenging enzyme. To clarify its functions in tolerance to rice bacterial blight, we produced rice lines overexpressing and suppressing tAPX (OsAPX8). The overexpressing lines exhibited increased tolerance to bacterial pathogen. The RNA interference (RNAi) lines were considerably more sensitive than the control plant. Further analysis of the H2O2 content in these transgenic plants indicated that the H2O2 accumulation of OsAPX8-overexpressing plants was considerably less than that of wild-type and RNAi plants upon challenge with bacterial pathogen. Interestingly, H2O2 was the most important factor for the serious leaf dehydration and withering of rice without major resistance genes and was not the cause of hypersensitivity. It addition, wall tightening or loosening can occur according to the level of H2O2. In addition, OsAPX8 interacted with the susceptibility protein Os8N3/Xa13, and their binding repressed the reaction of OsAPX8 in tolerance to bacterial blight. PMID:27185545

  12. The rice thylakoid membrane-bound ascorbate peroxidase OsAPX8 functions in tolerance to bacterial blight.

    PubMed

    Jiang, Guanghuai; Yin, Dedong; Zhao, Jiying; Chen, Honglin; Guo, Lequn; Zhu, Lihuang; Zhai, Wenxue

    2016-05-17

    Thylakoid membrane-bound ascorbate peroxidase (tAPX) is a major H2O2-scavenging enzyme. To clarify its functions in tolerance to rice bacterial blight, we produced rice lines overexpressing and suppressing tAPX (OsAPX8). The overexpressing lines exhibited increased tolerance to bacterial pathogen. The RNA interference (RNAi) lines were considerably more sensitive than the control plant. Further analysis of the H2O2 content in these transgenic plants indicated that the H2O2 accumulation of OsAPX8-overexpressing plants was considerably less than that of wild-type and RNAi plants upon challenge with bacterial pathogen. Interestingly, H2O2 was the most important factor for the serious leaf dehydration and withering of rice without major resistance genes and was not the cause of hypersensitivity. It addition, wall tightening or loosening can occur according to the level of H2O2. In addition, OsAPX8 interacted with the susceptibility protein Os8N3/Xa13, and their binding repressed the reaction of OsAPX8 in tolerance to bacterial blight.

  13. Genome sequencing reveals a new lineage associated with lablab bean and genetic exchange between Xanthomonas axonopodis pv. phaseoli and Xanthomonas fuscans subsp. fuscans.

    PubMed

    Aritua, Valente; Harrison, James; Sapp, Melanie; Buruchara, Robin; Smith, Julian; Studholme, David J

    2015-01-01

    Common bacterial blight is a devastating seed-borne disease of common beans that also occurs on other legume species including lablab and Lima beans. We sequenced and analyzed the genomes of 26 strains of Xanthomonas axonopodis pv. phaseoli and X. fuscans subsp. fuscans, the causative agents of this disease, collected over four decades and six continents. This revealed considerable genetic variation within both taxa, encompassing both single-nucleotide variants and differences in gene content, that could be exploited for tracking pathogen spread. The bacterial strain from Lima bean fell within the previously described Genetic Lineage 1, along with the pathovar type strain (NCPPB 3035). The strains from lablab represent a new, previously unknown genetic lineage closely related to strains of X. axonopodis pv. glycines. Finally, we identified more than 100 genes that appear to have been recently acquired by Xanthomonas axonopodis pv. phaseoli from X. fuscans subsp. fuscans.

  14. Genome sequencing reveals a new lineage associated with lablab bean and genetic exchange between Xanthomonas axonopodis pv. phaseoli and Xanthomonas fuscans subsp. fuscans

    PubMed Central

    Aritua, Valente; Harrison, James; Sapp, Melanie; Buruchara, Robin; Smith, Julian; Studholme, David J.

    2015-01-01

    Common bacterial blight is a devastating seed-borne disease of common beans that also occurs on other legume species including lablab and Lima beans. We sequenced and analyzed the genomes of 26 strains of Xanthomonas axonopodis pv. phaseoli and X. fuscans subsp. fuscans, the causative agents of this disease, collected over four decades and six continents. This revealed considerable genetic variation within both taxa, encompassing both single-nucleotide variants and differences in gene content, that could be exploited for tracking pathogen spread. The bacterial strain from Lima bean fell within the previously described Genetic Lineage 1, along with the pathovar type strain (NCPPB 3035). The strains from lablab represent a new, previously unknown genetic lineage closely related to strains of X. axonopodis pv. glycines. Finally, we identified more than 100 genes that appear to have been recently acquired by Xanthomonas axonopodis pv. phaseoli from X. fuscans subsp. fuscans. PMID:26500625

  15. Genetic diversity and association mapping of bacterial blight and other horticulturally important traits with microsatellite markers in pomegranate from India.

    PubMed

    Singh, Nripendra Vikram; Abburi, Venkata Lakshmi; Ramajayam, D; Kumar, Ravinder; Chandra, Ram; Sharma, Kuldeep Kumar; Sharma, Jyotsana; Babu, K Dhinesh; Pal, Ram Krishna; Mundewadikar, Dhananjay M; Saminathan, Thangasamy; Cantrell, Robert; Nimmakayala, Padma; Reddy, Umesh K

    2015-08-01

    This genetic diversity study aimed to estimate the population structure and explore the use of association mapping strategies to identify linked markers for bacterial resistance, growth and fruit quality in pomegranate collections from India. In total, 88 accessions including 37 cultivated types were investigated. A total of 112 alleles were amplified by use of 44 publicly available microsatellites for estimating molecular genetic diversity and population structure. Neighbor-joining analysis, model-based population structure and principal component analysis corroborated the genetic relationships among wild-type and cultivated pomegranate collections from India. Our study placed all 88 germplasm into four clusters. We identified a cultivated clade of pomegranates in close proximity to Daru types of wild-type pomegranates that grow naturally near the foothills of the Himalayas. Admixture analysis sorted various lineages of cultivated pomegranates to their respective ancestral forms. We identified four linked markers for fruit weight, titratable acidity and bacterial blight severity. PGCT001 was found associated with both fruit weight and bacterial blight, and the association with fruit weight during both seasons analyzed was significant after Bonferroni correction. This research demonstrates effectiveness of microsatellites to resolve population structure among the wild and cultivar collection of pomegranates and future use for association mapping studies.

  16. The role of silicon in enhancing resistance to bacterial blight of hydroponic- and soil-cultured rice.

    PubMed

    Song, Alin; Xue, Gaofeng; Cui, Peiyuan; Fan, Fenliang; Liu, Hongfang; Yin, Chang; Sun, Wanchun; Liang, Yongchao

    2016-04-19

    Here we report for the first time that bacterial blight of rice can be alleviated by silicon (Si) added. In both inoculated and uninoculated plants, shoot dry weight was significantly higher in the +Si plants than in the -Si plants. A soil-cultured trial showed that disease severity was 24.3% lower in the Si-amended plants than in the non-Si-amended plants. Plants that were switched from -Si to +Si nutrient solution and simultaneously inoculated with Xoo also exhibited the same high resistance to bacterial blight as the plants that were treated continuously with Si, with control efficiencies of 52.8 and 62.9%, respectively. Moreover, total concentrations of soluble phenolics and lignin in rice leaves were significantly higher in the +Si plants than in the -Si plants. Polyphenoloxidase (PPO) and phenylalanine ammonia-lyase (PAL) activities in rice leaves were observed to be higher in the +Si plants than in the -Si plants. The expression levels of Os03g0109600, Prla, Rcht2 and Lox2osPil, were also higher in +Si plants than in -Si plants post-inoculation during the experimental time. Addition of Si resulted in increased Pal transcription, and inhibited CatA and Os03g0126000 expression in the earlier and later stages of bacterial inoculation, respectively.

  17. The role of silicon in enhancing resistance to bacterial blight of hydroponic- and soil-cultured rice

    PubMed Central

    Song, Alin; Xue, Gaofeng; Cui, Peiyuan; Fan, Fenliang; Liu, Hongfang; Yin, Chang; Sun, Wanchun; Liang, Yongchao

    2016-01-01

    Here we report for the first time that bacterial blight of rice can be alleviated by silicon (Si) added. In both inoculated and uninoculated plants, shoot dry weight was significantly higher in the +Si plants than in the −Si plants. A soil-cultured trial showed that disease severity was 24.3% lower in the Si-amended plants than in the non-Si-amended plants. Plants that were switched from −Si to +Si nutrient solution and simultaneously inoculated with Xoo also exhibited the same high resistance to bacterial blight as the plants that were treated continuously with Si, with control efficiencies of 52.8 and 62.9%, respectively. Moreover, total concentrations of soluble phenolics and lignin in rice leaves were significantly higher in the +Si plants than in the −Si plants. Polyphenoloxidase (PPO) and phenylalanine ammonia-lyase (PAL) activities in rice leaves were observed to be higher in the +Si plants than in the −Si plants. The expression levels of Os03g0109600, Prla, Rcht2 and Lox2osPil, were also higher in +Si plants than in −Si plants post-inoculation during the experimental time. Addition of Si resulted in increased Pal transcription, and inhibited CatA and Os03g0126000 expression in the earlier and later stages of bacterial inoculation, respectively. PMID:27091552

  18. Virulence deficiency caused by a transposon insertion in the purH gene of Xanthomonas oryzae pv. oryzae.

    PubMed

    Chatterjee, Subhadeep; Sonti, Ramesh V

    2005-07-01

    Xanthomonas oryzae pv. oryzae causes bacterial leaf blight, a serious disease of rice. We have identified a Tn5-induced virulence-deficient mutant (BXO1704) of X. oryzae pv. oryzae. The BXO1704 mutant exhibited growth deficiency in minimal medium but was proficient in inducing a hypersensitive response in a non-host tomato plant. Sequence analysis of the chromosomal DNA flanking the Tn5 insertion indicated that the Tn5 insertion is in the purH gene, which is highly homologous to purH genes of other closely related plant pathogenic bacteria Xanthomonas axonopodis pv. citri and Xanthomonas campestris pv. campestris. Purine supplementation reversed the growth deficiency of BXO1704 in minimal medium. These results suggest that the virulence deficiency of BXO1704 may be due to the inability to use sufficient purine in the host.

  19. Characterization of hypersensitive resistance to bacterial spot race T3 (Xanthomonas perforans) from tomato accession PI 128216.

    PubMed

    Robbins, Matthew D; Darrigues, Audrey; Sim, Sung-Chur; Masud, Mohammed Abu Taher; Francis, David M

    2009-09-01

    Bacterial spot of tomato is caused by four species of Xanthomonas. The accession PI 128216 (Solanum pimpinellifolium) displays a hypersensitive reaction (HR) to race T3 strains (predominantely Xanthomonas perforans). We developed an inbred backcross (IBC) population (BC(2)S(5), 178 families) derived from PI 128216 and OH88119 (S. lycopersicum) as the susceptible recurrent parent for simultaneous introgression and genetic analysis of the HR response. These IBC families were evaluated in the greenhouse for HR to race T3 strain Xcv761. The IBC population was genotyped with molecular markers distributed throughout the genome in order to identify candidate loci conferring resistance. We treated the IBC population as a hypothesis forming generation to guide validation in subsequent crosses. Nonparametric analysis identified an association between HR and markers clustered on chromosome 11 (P < 0.05 to 0.0001) and chromosome 6 (0.04 > P > 0.002). Further analysis of the IBC population suggested that markers on chromosome 6 and 11 failed to assort independently, a phenomenon known as gametic phase disequilibrium. Therefore, to validate marker-trait linkages, resistant IBC plants were crossed with OH88119 and BC(3)F(2) progeny were evaluated for HR in the greenhouse. In these subsequent populations, the HR response was associated with the chromosome 11 markers (P < 0.0002) but not with the markers on chromosome 6 (P > 0.25). Independent F(2) families were developed by crossing resistant IBC lines to OH8245, OH88119, and OH7530. These populations were genotyped, organized into classes based on chromosome 11 markers, and evaluated for resistance in the field. The PI 128216 locus on chromosome 11 provided resistance that was dependent on gene dosage and genetic background. These results define a single locus, Rx-4, from PI 128216, which provides resistance to bacterial spot race T3, has additive gene action, and is located on chromosome 11.

  20. First report of bacterial blight of crucifers caused by Pseudomonas cannabina pv. alisalensis in Minnesota on arugula (Eruca vesicaria subsp. sativa)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2011, bacterial blight of arugula (Eruca vesicaria subsp. sativa; cv. Roquette) was observed in organically grown plants under overhead irrigation near Delano, MN. Approximately 80 to 100% of each planting was affected. Blue-green fluorescent pseudomonads were isolated consistently on King’s Medi...

  1. First report of bacterial blight of Brussels sprouts (Brassica oleracea L. var. gemmifera) caused by Pseudomonas cannabina pv. alisalensis in California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A novel bacterial leaf blight was seen in commercial Brussels sprout (Brassica oleracea L. var. gemmifera) transplant production in 2006. Koch’s postulates were completed and etiology of the pathogen was determined. Physiological and molecular characterization showed that the pathogen was Pseudomona...

  2. Interactions Between QTL SAP6 and SU91 on Resistance to Common Bacterial Blight in Red Kidney Bean and Pinto Bean Populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Resistance to common bacterial blight in common bean is a complex trait that is quantitatively inherited. We examined the interaction between two independent QTL, SAP6 and SU91, which condition resistance to CBB.The QTL were studied in a pinto bean F2 population a cross between Othello (sap6 sap6 //...

  3. Development of a Model to Predict the Primary Infection Date of Bacterial Spot (Xanthomonas campestris pv. vesicatoria) on Hot Pepper

    PubMed Central

    Kim, Ji-Hoon; Kang, Wee-Soo; Yun, Sung-Chul

    2014-01-01

    A population model of bacterial spot caused by Xanthomonas campestris pv. vesicatoria on hot pepper was developed to predict the primary disease infection date. The model estimated the pathogen population on the surface and within the leaf of the host based on the wetness period and temperature. For successful infection, at least 5,000 cells/ml of the bacterial population were required. Also, wind and rain were necessary according to regression analyses of the monitored data. Bacterial spot on the model is initiated when the pathogen population exceeds 1015 cells/g within the leaf. The developed model was validated using 94 assessed samples from 2000 to 2007 obtained from monitored fields. Based on the validation study, the predicted initial infection dates varied based on the year rather than the location. Differences in initial infection dates between the model predictions and the monitored data in the field were minimal. For example, predicted infection dates for 7 locations were within the same month as the actual infection dates, 11 locations were within 1 month of the actual infection, and only 3 locations were more than 2 months apart from the actual infection. The predicted infection dates were mapped from 2009 to 2012; 2011 was the most severe year. Although the model was not sensitive enough to predict disease severity of less than 0.1% in the field, our model predicted bacterial spot severity of 1% or more. Therefore, this model can be applied in the field to determine when bacterial spot control is required. PMID:25288995

  4. Development of a Model to Predict the Primary Infection Date of Bacterial Spot (Xanthomonas campestris pv. vesicatoria) on Hot Pepper.

    PubMed

    Kim, Ji-Hoon; Kang, Wee-Soo; Yun, Sung-Chul

    2014-06-01

    A population model of bacterial spot caused by Xanthomonas campestris pv. vesicatoria on hot pepper was developed to predict the primary disease infection date. The model estimated the pathogen population on the surface and within the leaf of the host based on the wetness period and temperature. For successful infection, at least 5,000 cells/ml of the bacterial population were required. Also, wind and rain were necessary according to regression analyses of the monitored data. Bacterial spot on the model is initiated when the pathogen population exceeds 10(15) cells/g within the leaf. The developed model was validated using 94 assessed samples from 2000 to 2007 obtained from monitored fields. Based on the validation study, the predicted initial infection dates varied based on the year rather than the location. Differences in initial infection dates between the model predictions and the monitored data in the field were minimal. For example, predicted infection dates for 7 locations were within the same month as the actual infection dates, 11 locations were within 1 month of the actual infection, and only 3 locations were more than 2 months apart from the actual infection. The predicted infection dates were mapped from 2009 to 2012; 2011 was the most severe year. Although the model was not sensitive enough to predict disease severity of less than 0.1% in the field, our model predicted bacterial spot severity of 1% or more. Therefore, this model can be applied in the field to determine when bacterial spot control is required.

  5. Crystallization and preliminary crystallographic studies of CbsA, a secretory exoglucanase from Xanthomonas oryzae pv. oryzae.

    PubMed

    Kumar, Sushil; Haque, Asfarul S; Jha, Gopaljee; Sonti, Ramesh V; Sankaranarayanan, Rajan

    2012-10-01

    The bacterial pathogen Xanthomonas oryzae pv. oryzae causes bacterial leaf blight, a serious disease of rice. The secreted exoglucanase CbsA is an important virulence factor of this pathogen. It belongs to the glycosyl hydrolase 6 family of proteins based on the carbohydrate-active enzyme (CAZY) classification. In this study, CbsA has been overexpressed, purified and crystallized. The crystal diffracted to a resolution of 1.86 Å and belonged to space group P2(1)2(1)2(1). It contained one monomer per asymmetric unit, with a solvent content of 45.8%.

  6. Development of a variable number of tandem repeats typing scheme for the bacterial rice pathogen Xanthomonas oryzae pv. oryzicola.

    PubMed

    Zhao, Shuai; Poulin, Lucie; Rodriguez-R, Luis M; Serna, Natalia Forero; Liu, Shu-Yan; Wonni, Issa; Szurek, Boris; Verdier, Valérie; Leach, Jan E; He, Yong-Qiang; Feng, Jia-Xun; Koebnik, Ralf

    2012-10-01

    Xanthomonas oryzae pv. oryzicola is an important bacterial pathogen responsible for outbreaks of bacterial leaf streak (BLS) on rice, mostly occurring in Asia and parts of Africa. To better monitor epidemics and assess population structures, efficient tools that allow the precise identification and diagnosis of pathogenic populations are needed. In this study, we explored variable numbers of tandem repeats (VNTR) as a fast, reliable, and cost-effective molecular typing tool. Screening of three X. oryzae pv. oryzicola genome sequences (Philippine strain BLS256, Chinese strain GX01, and Malian strain MAI10) predicted 28 candidate VNTR loci. Primer pairs for polymerase chain reaction (PCR) amplification of all 28 loci were designed and applied to a panel of 20 X. oryzae pv. oryzicola strains originating from Asia and Africa. Sequencing of PCR amplicons revealed 25 robust and polymorphic VNTR loci that are shared among Asian and African X. oryzae pv. oryzicola strains. A dendrogram constructed from 25 VNTR loci indicated that most Asian strains are clearly discriminated from African strains. However, in agreement with previous reports, one strain from Mali is related to Asian strains, pointing to a possible introduction of Asian strains to the African continent. The new VNTR-based tool described here is useful for studies of population structures and epidemiological monitoring of X. oryzae pv. oryzicola.

  7. Structure and Origin of Xanthomonas arboricola pv. pruni Populations Causing Bacterial Spot of Stone Fruit Trees in Western Europe.

    PubMed

    Boudon, Sylvain; Manceau, Charles; Nottéghem, Jean-Loup

    2005-09-01

    ABSTRACT Xanthomonas arboricola pv. pruni, the causal agent of bacterial spot on stone fruit, was found in 1995 in several orchards in southeastern France. We studied population genetics of this emerging pathogen in comparison with populations from the United States, where the disease was first described, and from Italy, where the disease has occurred since 1920. Four housekeeping genes (atpD, dnaK, efp, and glnA) and the intergenic transcribed spacer region were sequenced from a total of 3.9 kb of sequences, and fluorescent amplified fragment length polymorphism (FAFLP) analysis was performed. A collection of 64 X. arboricola pv. pruni strains, including 23 strains from France, was analyzed. The X. arboricola pv. pruni population had a low diversity because no sequence polymorphisms were observed. Population diversity revealed by FAFLP was lower for the West European population than for the American population. The same bacterial genotype was detected from five countries on three continents, a geographic distribution that can be explained by human-aided migration of bacteria. Our data support the hypothesis that the pathogen originated in the United States and subsequently has been disseminated to other stone-fruit-growing regions of the world. In France, emergence of this disease was due to a recent introduction of the most prevalent genotype of the bacterium found worldwide.

  8. Characterization of Novel Bacteriophages for Biocontrol of Bacterial Blight in Leek Caused by Pseudomonas syringae pv. porri

    PubMed Central

    Rombouts, Sofie; Volckaert, Anneleen; Venneman, Sofie; Declercq, Bart; Vandenheuvel, Dieter; Allonsius, Camille N.; Van Malderghem, Cinzia; Jang, Ho B.; Briers, Yves; Noben, Jean P.; Klumpp, Jochen; Van Vaerenbergh, Johan; Maes, Martine; Lavigne, Rob

    2016-01-01

    Pseudomonas syringae pv. porri, the causative agent of bacterial blight in leek (Allium porrum), is increasingly frequent causing problems in leek cultivation. Because of the current lack of control measures, novel bacteriophages were isolated to control this pathogen using phage therapy. Five novel phages were isolated from infected fields in Flanders (vB_PsyM_KIL1, vB_PsyM_KIL2, vB_PsyM_KIL3, vB_PsyM_KIL4, and vB_PsyM_KIL5), and were complemented with one selected host range mutant phage (vB_PsyM_KIL3b). Genome analysis of the phages revealed genome sizes between 90 and 94 kb and an average GC-content of 44.8%. Phylogenomic networking classified them into a novel clade, named the “KIL-like viruses,” related to the Felixounalikevirus genus, together with phage phiPsa374 from P. syringae pv. actinidiae. In vitro characterization demonstrated the stability and lytic potential of these phages. Host range analysis confirmed heterogeneity within P. syringae pv. porri, leading to the development of a phage cocktail with a range that covers the entire set of 41 strains tested. Specific bio-assays demonstrated the in planta efficacy of phages vB_PsyM_KIL1, vB_PsyM_KIL2, vB_PsyM_KIL3, and vB_PsyM_KIL3b. In addition, two parallel field trial experiments on three locations using a phage cocktail of the six phages showed variable results. In one trial, symptom development was attenuated. These data suggest some potential for phage therapy in controlling bacterial blight of leek, pending optimization of formulation and application methods. PMID:27014204

  9. Characterization of Novel Bacteriophages for Biocontrol of Bacterial Blight in Leek Caused by Pseudomonas syringae pv. porri.

    PubMed

    Rombouts, Sofie; Volckaert, Anneleen; Venneman, Sofie; Declercq, Bart; Vandenheuvel, Dieter; Allonsius, Camille N; Van Malderghem, Cinzia; Jang, Ho B; Briers, Yves; Noben, Jean P; Klumpp, Jochen; Van Vaerenbergh, Johan; Maes, Martine; Lavigne, Rob

    2016-01-01

    Pseudomonas syringae pv. porri, the causative agent of bacterial blight in leek (Allium porrum), is increasingly frequent causing problems in leek cultivation. Because of the current lack of control measures, novel bacteriophages were isolated to control this pathogen using phage therapy. Five novel phages were isolated from infected fields in Flanders (vB_PsyM_KIL1, vB_PsyM_KIL2, vB_PsyM_KIL3, vB_PsyM_KIL4, and vB_PsyM_KIL5), and were complemented with one selected host range mutant phage (vB_PsyM_KIL3b). Genome analysis of the phages revealed genome sizes between 90 and 94 kb and an average GC-content of 44.8%. Phylogenomic networking classified them into a novel clade, named the "KIL-like viruses," related to the Felixounalikevirus genus, together with phage phiPsa374 from P. syringae pv. actinidiae. In vitro characterization demonstrated the stability and lytic potential of these phages. Host range analysis confirmed heterogeneity within P. syringae pv. porri, leading to the development of a phage cocktail with a range that covers the entire set of 41 strains tested. Specific bio-assays demonstrated the in planta efficacy of phages vB_PsyM_KIL1, vB_PsyM_KIL2, vB_PsyM_KIL3, and vB_PsyM_KIL3b. In addition, two parallel field trial experiments on three locations using a phage cocktail of the six phages showed variable results. In one trial, symptom development was attenuated. These data suggest some potential for phage therapy in controlling bacterial blight of leek, pending optimization of formulation and application methods.

  10. Mechanistically compatible mixtures of bacterial antagonists improve biological control of fire blight of pear.

    PubMed

    Stockwell, V O; Johnson, K B; Sugar, D; Loper, J E

    2011-01-01

    Mixtures of biological control agents can be superior to individual agents in suppressing plant disease, providing enhanced efficacy and reliability from field to field relative to single biocontrol strains. Nonetheless, the efficacy of combinations of Pseudomonas fluorescens A506, a commercial biological control agent for fire blight of pear, and Pantoea vagans strain C9-1 or Pantoea agglomerans strain Eh252 rarely exceeds that of individual strains. A506 suppresses growth of the pathogen on floral colonization and infection sites through preemptive exclusion. C9-1 and Eh252 produce peptide antibiotics that contribute to disease control. In culture, A506 produces an extracellular protease that degrades the peptide antibiotics of C9-1 and Eh252. We hypothesized that strain A506 diminishes the biological control activity of C9-1 and Eh252, thereby reducing the efficacy of biocontrol mixtures. This hypothesis was tested in five replicated field trials comparing biological control of fire blight using strain A506 and A506 aprX::Tn5, an extracellular protease-deficient mutant, as individuals and combined with C9-1 or Eh252. On average, mixtures containing A506 aprX::Tn5 were superior to those containing the wild-type strain, confirming that the extracellular protease of A506 diminished the biological control activity of C9-1 and Eh252 in situ. Mixtures of A506 aprX::Tn5 and C9-1 or Eh252 were superior to oxytetracycline or single biocontrol strains in suppressing fire blight of pear. These experiments demonstrate that certain biological control agents are mechanistically incompatible, in that one strain interferes with the mechanism by which a second strain suppresses plant disease. Mixtures composed of mechanistically compatible strains of biological control agents can suppress disease more effectively than individual biological control agents.

  11. Transgenic banana plants expressing Xanthomonas wilt resistance genes revealed a stable non-target bacterial colonization structure.

    PubMed

    Nimusiima, Jean; Köberl, Martina; Tumuhairwe, John Baptist; Kubiriba, Jerome; Staver, Charles; Berg, Gabriele

    2015-12-10

    Africa is among the continents where the battle over genetically modified crops is currently being played out. The impact of GM in Africa could potentially be very positive. In Uganda, researchers have developed transgenic banana lines resistant to banana Xanthomonas wilt. The transgenic lines expressing hrap and pflp can provide a timely solution to the pandemic. However, the impact of the transgenes expression on non-target microorganisms has not yet been investigated. To study this effect, transgenic and control lines were grown under field conditions and their associated microbiome was investigated by 16S rRNA gene profiling combining amplicon sequencing and molecular fingerprinting. Three years after sucker planting, no statistically significant differences between transgenic lines and their non-modified predecessors were detected for their associated bacterial communities. The overall gammaproteobacterial rhizosphere microbiome was highly dominated by Xanthomonadales, while Pseudomonadales and Enterobacteriales were accumulated in the pseudostem. Shannon indices revealed much higher diversity in the rhizosphere than in the pseudostem endosphere. However, the expression of the transgenes did not result in changes in the diversity of Gammaproteobacteria, the closest relatives of the target pathogen. In this field experiment, the expression of the resistance genes appears to have no consequences for non-target rhizobacteria and endophytes.

  12. Transgenic banana plants expressing Xanthomonas wilt resistance genes revealed a stable non-target bacterial colonization structure

    PubMed Central

    Nimusiima, Jean; Köberl, Martina; Tumuhairwe, John Baptist; Kubiriba, Jerome; Staver, Charles; Berg, Gabriele

    2015-01-01

    Africa is among the continents where the battle over genetically modified crops is currently being played out. The impact of GM in Africa could potentially be very positive. In Uganda, researchers have developed transgenic banana lines resistant to banana Xanthomonas wilt. The transgenic lines expressing hrap and pflp can provide a timely solution to the pandemic. However, the impact of the transgenes expression on non-target microorganisms has not yet been investigated. To study this effect, transgenic and control lines were grown under field conditions and their associated microbiome was investigated by 16S rRNA gene profiling combining amplicon sequencing and molecular fingerprinting. Three years after sucker planting, no statistically significant differences between transgenic lines and their non-modified predecessors were detected for their associated bacterial communities. The overall gammaproteobacterial rhizosphere microbiome was highly dominated by Xanthomonadales, while Pseudomonadales and Enterobacteriales were accumulated in the pseudostem. Shannon indices revealed much higher diversity in the rhizosphere than in the pseudostem endosphere. However, the expression of the transgenes did not result in changes in the diversity of Gammaproteobacteria, the closest relatives of the target pathogen. In this field experiment, the expression of the resistance genes appears to have no consequences for non-target rhizobacteria and endophytes. PMID:26657016

  13. The Xanthomonas Hrp type III system secretes proteins from plant and mammalian bacterial pathogens

    PubMed Central

    Rossier, Ombeline; Wengelnik, Kai; Hahn, Karoline; Bonas, Ulla

    1999-01-01

    Studies of essential pathogenicity determinants in Gram-negative bacteria have revealed the conservation of type III protein secretion systems that allow delivery of virulence factors into host cells from plant and animal pathogens. Ten of 21 Hrp proteins of the plant pathogen Xanthomonas campestris pv. vesicatoria have been suggested to be part of a type III machinery. Here, we report the hrp-dependent secretion of two avirulence proteins, AvrBs3 and AvrRxv, by X. campestris pv. vesicatoria strains that constitutively express hrp genes. Secretion occurred without leakage of a cytoplasmic marker in minimal medium containing BSA, at pH 5.4. Secretion was strictly hrp-dependent because a mutant carrying a deletion in hrcV, a conserved hrp gene, did not secrete AvrBs3 and AvrRxv. Moreover, the Hrp system of X. campestris pv. vesicatoria was able to secrete proteins from two other plant pathogens: PopA, a protein secreted via the Hrp system in Ralstonia solanacearum, and AvrB, an avirulence protein from Pseudomonas syringae pv. glycinea. Interestingly, X. campestris pv. vesicatoria also secreted YopE, a type III-secreted cytotoxin of the mammalian pathogen Yersinia pseudotuberculosis in a hrp-dependent manner. YerA, a YopE-specific chaperone, was required for YopE stability but not for secretion in X. campestris pv. vesicatoria. Our results demonstrate the functional conservation of the type III system of X. campestris for secretion of proteins from both plant and mammalian pathogens and imply recognition of their respective secretion signals. PMID:10430949

  14. ON THE RELATION BETWEEN THE KINDS OF WINTER CROPS AND THE OCCURRENCE OF THE BACTERIAL LEAF BLIGHT OF RICE PLANT

    DTIC Science & Technology

    The present report, as a part of the research on the ecology of rice leaf blight , is the result of an investigation to determine whether there was a...difference in the occurrence of rice leaf blight on the post-winter crop-fields according to the variety of winter crops. In order to make comparisons...outbreak of rice leaf blight , cultivation procedures, flooding, wind and drainage systems, the winter crops were different from each other, two adjoining

  15. Genetic enhancement of host plant-resistance of the Lalat cultivar of rice against bacterial blight employing marker-assisted selection.

    PubMed

    Dokku, Prasad; Das, K M; Rao, G J N

    2013-08-01

    To incorporate durable resistance against bacterial blight, a major disease rice, three resistance genes, xa 5, xa13 and Xa21, from IRBB 60 were transferred through marker-assisted backcrossing using RG 556, RG 136 and pTA248 markers linked to the three genes to supplement the Xa4 gene present in Lalat, a popular rice cultivar. Effective selection enabled the transfer in three back-crosses and a generation of selfing and background selection employing morphological and grain quality traits and molecular markers, led to >90 % recovery of the recurrent parental genome. The gene pyramids exhibited high levels of resistance against the pathogen in multi-location evaluation trials conducted over several locations of bacterial blight in India. IL-2 (CRMAS2621-7-1), a gene pyramid, was identified as being promising for several endemic regions of bacterial blight and was released as Improved Lalat in one of the identified regions. The success of the study demonstrates the vast potential of marker-assisted selection for gene stacking and recovery of the parental genome with high precision.

  16. First report of bacterial leaf blight on mustard greens (Brassica juncea) caused by pseudomonas cannabina pv. alisalensis in Mississippi

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2010, a brassica leafy greens grower in Sunflower County, Mississippi, observed scattered outbreaks of a leaf blight disease on mustard greens (Brassica juncea) in a 180-hectare field. A severe outbreak of leaf blight occurred on mustard greens and turnip greens (Brassica rapa) in the same field...

  17. Mutants of Xanthomonas oryzae pv. oryzae deficient in general secretory pathway are virulence deficient and unable to secrete xylanase.

    PubMed

    Ray, S K; Rajeshwari, R; Sonti, R V

    2000-04-01

    Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight, a serious disease of rice. A virulence- and xylanase-deficient mutant of Xoo was isolated following ethyl methane sulfonate (EMS) mutagenesis. A cosmid clone that restored virulence and xylanase secretion was obtained from a genomic library by functional complementation. Transposon mutagenesis and marker exchange studies revealed genes on the cloned DNA that were required for xylanase production and virulence. Sequence analysis with transposon-specific primers revealed that these genes were homologues of xps F and xps D, which encode components of a protein secretion system in Xanthomonas campestris pv. campestris. Enzyme assays showed xylanase accumulation in the periplasmic space and cytoplasm of the xps F mutant and the complementing clone restored transport to the extracellular space.

  18. Recessive resistance genes and the Oryza sativa-Xanthomonas oryzae pv. oryzae pathosystem.

    PubMed

    Iyer-Pascuzzi, Anjali S; McCouch, Susan R

    2007-07-01

    Though recessive resistance is well-studied in viral systems, little is understood regarding the phenomenon in plant-bacterial interactions. The Oryza sativa-Xanthomonas oryzae pv. orzyae pathosystem provides an excellent opportunity to examine recessive resistance in plant-bacterial interactions, in which nine of 30 documented resistance (R) genes are recessively inherited. Infestations of X. oryzae pv. oryzae, the causal agent of bacterial blight, result in significant crop loss and damage throughout South and Southeast Asia. Two recently cloned novel recessive R genes, xa5 and xa13, have yielded insights to this system. Like their viral counterparts, these bacterial recessive R gene products do not conform to the five commonly described classes of R proteins. New findings suggest that such genes may more aptly be viewed as mutations in dominant susceptibility alleles and may also function in a gene-for-gene manner. In this review, we discuss recent accomplishments in the understanding of recessively inherited R genes in the rice-bacterial blight pathosystem and suggest a new model for the function of recessive resistance in plant-bacterial interactions.

  19. Management of Bacterial Blight of Lilac Caused by Pseudomonas syringae by Growing Plants under Plastic Shelters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas syringae pv. syringae causes some of the most economically-important bacterial diseases affecting woody perennials grown by the nursery industry in the Pacific Northwest of the United States. In this study, we evaluated a cultural control practice, placement of plants in plastic shelter...

  20. Small scale production and characterization of xanthan gum synthesized by local isolates of Xanthomonas campestris.

    PubMed

    Barua, Rajesh; Alam, Md Jahangir; Salim, Mohammad; Ashrafee, Tamzida Shamim

    2016-02-01

    Xanthan gum is a commercially important microbial exopolysaccharide (EPS) produced by Xanthomonas campestris. X. campestris is a plant pathogen causing various plant diseases such as black rot of crucifers, bacterial leaf blight and citrus canker disease resulting in crop damage. In this study, we isolated efficient local bacterial isolates which are capable to produce xanthan gum utilizing different sources of carbon (maltose, sucrose and glucose). Bacterial isolates from different plant leaves and fruits were identified as Xanthomonas campestris based on their morphological and biochemical characteristics. Among the 23 isolates, 70% were capable of producing gum. Taro plant, considered as new bacterial host, also have the capability to produce xanthan gum. Production conditions of xanthan gum and their relative viscosity by these bacterial isolates were optimized using basal medium containing commercial carbon and nitrogen sources and various temperature and rotation. Highest level of xanthan gum (18.286 g/l) with relative viscosity (7.2) was produced (Host, Citrus macroptera) at 28 degrees C, pH 7.0, 150 rpm using sucrose as a carbon source at orbital shaker. Whereas, in lab fermenter, same conditions gave best result (19.587 g/l gum) with 7.8 relative viscosity. Chilled alcohol (96%) was used to recover the xanthan gum. FTIR studies also carried out for further confirmation of compatibility by detecting the chemical groups.

  1. [Pyramiding of senescence-inhibition IPT gene and Xa23 for resistance to bacterial blight in rice (Oryza sativa L.)].

    PubMed

    He, Guang-Ming; Sun, Chuan-Qing; Fu, Yong-Cai; Fu, Qiang; Zhao, Kai-Jun; Wang, Chun-Lian; Zhang, Qi; Ling, Zhong-Zhuan; Wang, Xiang-Kun

    2004-08-01

    Transgenic lines (GC-1) carrying a senescence-inhibition cheimeric gene, IPT (isopentenyl transferase) gene, CBB23, a isogenic lines carrying Xa23 gene for resistance to bacterial blight, and Hexi15, a commercial cultivar showing high resistance to blast disease, were used as donors to pyramid IPT gene and Xa23 by marker-assisted selection (MAS). Seventeen BC1F1 plants pyramiding Xa23 gene and IPT genes were obtained from three multi-cross combinations. Then, the plants carrying Xa23 and IPT genes were crossed with parental lines of two-line hybrid rice, such as 9311, E32, Pei' ai 64S and W9834S. The progenies were backcrossed the acceptor parents. A total of 17 plants carrying Xa23 and IPT genes were detected by PCR, disease resistance identification and analysis of CTK contents of in the four combinations of "(9311///Hexi15/CBB23// GC-1) x 9311", "(E32///Hexi15/CBB23//GC-1) x E32", "(Pei'ai 64S///Hexi15/CBB23//GC-1) x Pei' ai 64S" and "(GC-1/CBB23//W9834S/Hexi15) x W9834S". These plants showed resistance to blast disease by inoculating test using 21 the lines of Pyricularia grisea from Northern China. Six plants of BC2F1 pyramiding Xa23 and IPT genes were further obtained in the combinations of "[(9311///Hexi15/CBB23//GC-1) x 9311] x 9311", "[(E32///Hexi15/CBB23//GC-1) x E32] x E32". After backcrossed and self-crossed 1 approximately 2nd, the plants pyramiding Xa23 and IPT genes can be used in the program of hybrid rice breeding.

  2. Comparative genomic analysis of Xanthomonas axonopodis pv. citrumelo F1, which causes citrus bacterial spot disease, and related strains provides insights into virulence and host specificity.

    PubMed

    Jalan, Neha; Aritua, Valente; Kumar, Dibyendu; Yu, Fahong; Jones, Jeffrey B; Graham, James H; Setubal, João C; Wang, Nian

    2011-11-01

    Xanthomonas axonopodis pv. citrumelo is a citrus pathogen causing citrus bacterial spot disease that is geographically restricted within the state of Florida. Illumina, 454 sequencing, and optical mapping were used to obtain a complete genome sequence of X. axonopodis pv. citrumelo strain F1, 4.9 Mb in size. The strain lacks plasmids, in contrast to other citrus Xanthomonas pathogens. Phylogenetic analysis revealed that this pathogen is very close to the tomato bacterial spot pathogen X. campestris pv. vesicatoria 85-10, with a completely different host range. We also compared X. axonopodis pv. citrumelo to the genome of citrus canker pathogen X. axonopodis pv. citri 306. Comparative genomic analysis showed differences in several gene clusters, like those for type III effectors, the type IV secretion system, lipopolysaccharide synthesis, and others. In addition to pthA, effectors such as xopE3, xopAI, and hrpW were absent from X. axonopodis pv. citrumelo while present in X. axonopodis pv. citri. These effectors might be responsible for survival and the low virulence of this pathogen on citrus compared to that of X. axonopodis pv. citri. We also identified unique effectors in X. axonopodis pv. citrumelo that may be related to the different host range as compared to that of X. axonopodis pv. citri. X. axonopodis pv. citrumelo also lacks various genes, such as syrE1, syrE2, and RTX toxin family genes, which were present in X. axonopodis pv. citri. These may be associated with the distinct virulences of X. axonopodis pv. citrumelo and X. axonopodis pv. citri. Comparison of the complete genome sequence of X. axonopodis pv. citrumelo to those of X. axonopodis pv. citri and X. campestris pv. vesicatoria provides valuable insights into the mechanism of bacterial virulence and host specificity.

  3. Comparative Genomic and Phenotypic Characterization of Pathogenic and Non-Pathogenic Strains of Xanthomonas arboricola Reveals Insights into the Infection Process of Bacterial Spot Disease of Stone Fruits

    PubMed Central

    Garita-Cambronero, Jerson; Palacio-Bielsa, Ana; López, María M.

    2016-01-01

    Xanthomonas arboricola pv. pruni is the causal agent of bacterial spot disease of stone fruits, a quarantinable pathogen in several areas worldwide, including the European Union. In order to develop efficient control methods for this disease, it is necessary to improve the understanding of the key determinants associated with host restriction, colonization and the development of pathogenesis. After an initial characterization, by multilocus sequence analysis, of 15 strains of X. arboricola isolated from Prunus, one strain did not group into the pathovar pruni or into other pathovars of this species and therefore it was identified and defined as a X. arboricola pv. pruni look-a-like. This non-pathogenic strain and two typical strains of X. arboricola pv. pruni were selected for a whole genome and phenotype comparative analysis in features associated with the pathogenesis process in Xanthomonas. Comparative analysis among these bacterial strains isolated from Prunus spp. and the inclusion of 15 publicly available genome sequences from other pathogenic and non-pathogenic strains of X. arboricola revealed variations in the phenotype associated with variations in the profiles of TonB-dependent transporters, sensors of the two-component regulatory system, methyl accepting chemotaxis proteins, components of the flagella and the type IV pilus, as well as in the repertoire of cell-wall degrading enzymes and the components of the type III secretion system and related effectors. These variations provide a global overview of those mechanisms that could be associated with the development of bacterial spot disease. Additionally, it pointed out some features that might influence the host specificity and the variable virulence observed in X. arboricola. PMID:27571391

  4. Genetic engineering of the Xa10 promoter for broad-spectrum and durable resistance to Xanthomonas oryzae pv. oryzae.

    PubMed

    Zeng, Xuan; Tian, Dongsheng; Gu, Keyu; Zhou, Zhiyun; Yang, Xiaobei; Luo, Yanchang; White, Frank F; Yin, Zhongchao

    2015-09-01

    Many pathovars of plant pathogenic bacteria Xanthomonas species inject transcription activator-like (TAL) effectors into plant host cells to promote disease susceptibility or trigger disease resistance. The rice TAL effector-dependent disease resistance gene Xa10 confers narrow-spectrum race-specific resistance to Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial blight disease in rice. To generate broad-spectrum and durable resistance to Xoo, we developed a modified Xa10 gene, designated as Xa10(E5) . Xa10(E5) has an EBE-amended promoter containing 5 tandemly arranged EBEs each responding specifically to a corresponding virulent or avirulent TAL effector and a stable transgenic rice line containing Xa10(E5) was generated in the cultivar Nipponbare. The Xa10(E5) gene was specifically induced by Xoo strains that harbour the corresponding TAL effectors and conferred TAL effector-dependent resistance to the pathogens at all developmental stages of rice. Further disease evaluation demonstrated that the Xa10(E5) gene in either Nipponbare or 9311 genetic backgrounds provided broad-spectrum disease resistance to 27 of the 28 Xoo strains collected from 11 countries. The development of Xa10(E5) and transgenic rice lines provides new genetic materials for molecular breeding of rice for broad-spectrum and durable disease resistance to bacterial blight.

  5. Close linkage of a blast resistance gene, Pias(t), with a bacterial leaf blight resistance gene, Xa1-as(t), in a rice cultivar 'Asominori'.

    PubMed

    Endo, Takashi; Yamaguchi, Masayuki; Kaji, Ryota; Nakagomi, Koji; Kataoka, Tomomori; Yokogami, Narifumi; Nakamura, Toshiki; Ishikawa, Goro; Yonemaru, Jun-Ichi; Nishio, Takeshi

    2012-12-01

    It has long been known that a bacterial leaf blight-resistant line in rice obtained from a crossing using 'Asominori' as a resistant parent also has resistance to blast, but a blast resistance gene in 'Asominori' has not been investigated in detail. In the present study, a blast resistance gene in 'Asominori', tentatively named Pias(t), was revealed to be located within 162-kb region between DNA markers YX4-3 and NX4-1 on chromosome 4 and to be linked with an 'Asominori' allele of the bacterial leaf blight resistance gene Xa1, tentatively named Xa1-as(t). An 'Asominori' allele of Pias(t) was found to be dominant and difference of disease severity between lines having the 'Asominori' allele of Pias(t) and those without it was 1.2 in disease index from 0 to 10. Pias(t) was also closely linked with the Ph gene controlling phenol reaction, suggesting the possibility of successful selection of blast resistance using the phenol reaction. Since blast-resistant commercial cultivars have been developed using 'Asominori' as a parent, Pias(t) is considered to be a useful gene in rice breeding for blast resistance.

  6. Development of Gene-Pyramid Lines of the Elite Restorer Line, RPHR-1005 Possessing Durable Bacterial Blight and Blast Resistance.

    PubMed

    Abhilash Kumar, V; Balachiranjeevi, C H; Bhaskar Naik, S; Rambabu, R; Rekha, G; Harika, G; Hajira, S K; Pranathi, K; Anila, M; Kousik, M; Vijay Kumar, S; Yugander, A; Aruna, J; Dilip Kumar, T; Vijaya Sudhakara Rao, K; Hari Prasad, A S; Madhav, M S; Laha, G S; Balachandran, S M; Prasad, M S; Viraktamath, B C; Ravindra Babu, V; Sundaram, R M

    2016-01-01

    RPHR-1005, the stable restorer line of the popular medium slender (MS) grain type rice hybrid, DRRH-3 was improved in this study for resistance against bacterial blight (BB) and blast diseases through marker-assisted backcross breeding (MABB). In this study, four major resistance genes (i.e., Xa21 and Xa33 for BB resistance and Pi2 and Pi54 for blast resistance) have been transferred to RPHR-1005 using RPBio Patho-1 (possessing Xa21 + Pi2), RPBio Patho-2 (possessing Xa21 + Pi54) and FBR1-15EM (possessing Xa33) as the donors. Foreground selection was carried out using PCR-based molecular markers specific for the target resistance genes and the major fertility restorer genes, Rf3 and Rf4, while background selection was carried out using a set of parental polymorphic rice SSR markers and backcrossing was continued uptoBC2 generation. At BC2F2, plants possessing the gene combination- Xa21 + Pi2, Xa21 + Pi54 and Xa33 in homozygous condition and with >92% recovery of the recurrent parent genome (RPG) were identified and intercrossed to combine all the four resistance genes. Twenty-two homozygous, pyramid lines of RPHR-1005 comprising of three single-gene containing lines, six 2-gene containing lines, eight 3-gene containing lines, and five 4-gene containing lines were identified among the double intercross lines at F3 generation (DICF3). They were then evaluated for their resistance against BB and blast, fertility restoration ability and for key agro-morphological traits. While single gene containing lines were resistant to either BB or blast, the 2-gene, 3-gene, and 4-gene pyramid lines showed good level of resistance against both and/or either of the two diseases. Most of the 2-gene, 3-gene, and 4-gene containing pyramid lines showed yield levels and other key agro-morphological and grain quality traits comparable to the original recurrent parent and showed complete fertility restoration ability, with a few showing higher yield as compared to RPHR-1005. Further, the

  7. Development of Gene-Pyramid Lines of the Elite Restorer Line, RPHR-1005 Possessing Durable Bacterial Blight and Blast Resistance

    PubMed Central

    Abhilash Kumar, V.; Balachiranjeevi, C. H.; Bhaskar Naik, S.; Rambabu, R.; Rekha, G.; Harika, G.; Hajira, S. K.; Pranathi, K.; Anila, M.; Kousik, M.; Vijay Kumar, S.; Yugander, A.; Aruna, J.; Dilip Kumar, T.; Vijaya Sudhakara Rao, K.; Hari Prasad, A. S.; Madhav, M. S.; Laha, G. S.; Balachandran, S. M.; Prasad, M. S.; Viraktamath, B. C.; Ravindra Babu, V.; Sundaram, R. M.

    2016-01-01

    RPHR-1005, the stable restorer line of the popular medium slender (MS) grain type rice hybrid, DRRH-3 was improved in this study for resistance against bacterial blight (BB) and blast diseases through marker-assisted backcross breeding (MABB). In this study, four major resistance genes (i.e., Xa21 and Xa33 for BB resistance and Pi2 and Pi54 for blast resistance) have been transferred to RPHR-1005 using RPBio Patho-1 (possessing Xa21 + Pi2), RPBio Patho-2 (possessing Xa21 + Pi54) and FBR1-15EM (possessing Xa33) as the donors. Foreground selection was carried out using PCR-based molecular markers specific for the target resistance genes and the major fertility restorer genes, Rf3 and Rf4, while background selection was carried out using a set of parental polymorphic rice SSR markers and backcrossing was continued uptoBC2 generation. At BC2F2, plants possessing the gene combination- Xa21 + Pi2, Xa21 + Pi54 and Xa33 in homozygous condition and with >92% recovery of the recurrent parent genome (RPG) were identified and intercrossed to combine all the four resistance genes. Twenty-two homozygous, pyramid lines of RPHR-1005 comprising of three single-gene containing lines, six 2-gene containing lines, eight 3-gene containing lines, and five 4-gene containing lines were identified among the double intercross lines at F3 generation (DICF3). They were then evaluated for their resistance against BB and blast, fertility restoration ability and for key agro-morphological traits. While single gene containing lines were resistant to either BB or blast, the 2-gene, 3-gene, and 4-gene pyramid lines showed good level of resistance against both and/or either of the two diseases. Most of the 2-gene, 3-gene, and 4-gene containing pyramid lines showed yield levels and other key agro-morphological and grain quality traits comparable to the original recurrent parent and showed complete fertility restoration ability, with a few showing higher yield as compared to RPHR-1005. Further, the

  8. The role of type III effectors from Xanthomonas axonopodis pv. manihotis in virulence and suppression of plant immunity.

    PubMed

    Medina, Cesar Augusto; Reyes, Paola Andrea; Trujillo, Cesar Augusto; Gonzalez, Juan Luis; Bejarano, David Alejandro; Montenegro, Nathaly Andrea; Jacobs, Jonathan M; Joe, Anna; Restrepo, Silvia; Alfano, James R; Bernal, Adriana

    2017-02-20

    Xanthomonas axonopodis pv. manihotis (Xam) causes cassava bacterial blight, the most important bacterial disease of cassava. Xam, like other Xanthomonas species, requires type III effectors (T3Es) for maximal virulence. Xam strain CIO151 possesses 17 predicted T3Es belonging to the Xanthomonas outer protein (Xop) class. This work aimed to characterize nine Xop effectors present in Xam CIO151 for their role in virulence and modulation of plant immunity. Our findings demonstrate the importance of XopZ, XopX, XopAO1 and AvrBs2 for full virulence, as well as a redundant function in virulence between XopN and XopQ in susceptible cassava plants. We tested their role in pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity (ETI) using heterologous systems. AvrBs2, XopR and XopAO1 are capable of suppressing PTI. ETI suppression activity was only detected for XopE4 and XopAO1. These results demonstrate the overall importance and diversity in functions of major virulence effectors AvrBs2 and XopAO1 in Xam during cassava infection.

  9. Genome Sequence of Burkholderia plantarii ZJ171, a Tropolone-Producing Bacterial Pathogen Responsible for Rice Seedling Blight.

    PubMed

    Qian, Yuan; Matsumoto, Haruna; Li, Wenzhuo; Zhu, Guonian; Hashidoko, Yasuyuki; Hu, Yang; Wang, Mengcen

    2016-12-08

    Burkholderia plantarii is the causal agent of rice seedling blight. Here, we report the draft genome sequence of B. plantarii, which contains 8,020,831 bp, with a G+C content of 68.66% and a predicted 7,688 coding sequences. The annotated genome sequence will provide further insight into its pathogenicity.

  10. First Report of Bacterial Leaf Blight on Broccoli and Cabbage Caused by Pseudomonas syringae pv. alisalensis in South Carolina

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In May 2009, leaf spot and leaf blight symptoms were observed on broccoli (B. oleracea var. italica) and cabbage (Brassica oleracea var. capitata) on several farms in Lexington County, the major brassica-growing region of South Carolina. Affected areas ranged from scattered disease foci within fiel...

  11. Complete nucleotide sequence of a new filamentous phage, Xf109, which integrates its genome into the chromosomal DNA of Xanthomonas oryzae.

    PubMed

    Yeh, Ting Y

    2017-02-01

    Unlike Ff-like coliphages, certain filamentous Inoviridae phages integrate their genomes into the host chromosome and enter a prophage state in their infectious cycle. This lysogenic life cycle was first reported for Xanthomonas citri Cf phage. However, except for the X. citri phages Cf and XacF1, complete genome sequence information about lysogenic Xanthomonas phages is not available to date. A proviral sequence of Xf109 phage was identified in the genome of Xanthomonas oryzae, the rice bacterial blight pathogen, and revived as infectious virions to lysogenize its host de novo. The genome of Xf109 phage is 7190 nucleotides in size and contains 12 predicted open reading frames in an organization similar to that of the Cf phage genome. Seven of the Xf109 proteins show significant sequence similarity to Cf and XacF1 phage proteins, while its ORF4 shares 92 % identity with the major coat protein of X. phage oryzae Xf. Integration of Xf109 phage DNA into the host genome is site-specific, and the attP/attB sequence contains the dif core sequence 5'-TATACATTATGCGAA-3', which is identical to that of Cf, XacF1, and Xanthomonas campestris phage ϕLf. To my knowledge, this is the first complete genome sequence of a filamentous bacteriophage that infects X. oryzae.

  12. Deletion of pilA, a Minor Pilin-Like Gene, from Xanthomonas citri subsp. citri Influences Bacterial Physiology and Pathogenesis.

    PubMed

    Petrocelli, Silvana; Arana, Maite R; Cabrini, Marcela N; Casabuono, Adriana C; Moyano, Laura; Beltramino, Matías; Moreira, Leandro M; Couto, Alicia S; Orellano, Elena G

    2016-12-01

    Type IV pili (Tfp) are widely distributed adhesins of bacterial surfaces. In plant pathogenic bacteria, Tfp are involved in host colonization and pathogenesis. Xanthomonas citri subsp. citri (Xcc) is the phytopathogen responsible for citrus canker disease. In this work, three Tfp structural genes, fimA, fimA1, and pilA from Xcc were studied. A pilA mutant strain from Xcc (XccΔpilA) was constructed and differences in physiological features, such as motilities, adhesion, and biofilm formation, were observed. A structural study of the purified Tfp fractions from Xcc wild-type and Xcc∆pilA showed that pilins are glycosylated in both strains and that FimA and FimA1 are the main structural components of the pili. Furthermore, smaller lesion symptoms and reduced bacterial growth were produced by Xcc∆pilA in orange plants compared to the wild-type strain. These results indicate that the minor pilin-like gene, pilA, is involved in Tfp performance during the infection process.

  13. An operon for production of bioactive gibberellin A4 phytohormone with wide distribution in the bacterial rice leaf streak pathogen Xanthomonas oryzae pv. oryzicola.

    PubMed

    Nagel, Raimund; Turrini, Paula C G; Nett, Ryan S; Leach, Jan E; Verdier, Valérie; Van Sluys, Marie-Anne; Peters, Reuben J

    2017-01-30

    Phytopathogens have developed elaborate mechanisms to attenuate the defense response of their host plants, including convergent evolution of complex pathways for production of the GA phytohormones, which were actually first isolated from the rice fungal pathogen Gibberella fujikuroi. The rice bacterial pathogen Xanthomonas oryzae pv. oryzicola (Xoc) has been demonstrated to contain a biosynthetic operon with cyclases capable of producing the universal GA precursor ent-kaurene. Genetic (knock-out) studies indicate that the derived diterpenoid serves as a virulence factor for this rice leaf streak pathogen, serving to reduce the jasmonic acid-mediated defense response. Here the functions of the remaining genes in the Xoc operon are elucidated and the distribution of the operon in X. oryzae is investigated in over 100 isolates. The Xoc operon leads to production of the bioactive GA4 , an additional step beyond production of the penultimate precursor GA9 mediated by the homologous operons recently characterized from rhizobia. Moreover, this GA biosynthetic operon was found to be widespread in Xoc (> 90%), but absent in the other major X. oryzae pathovar. These results indicate selective pressure for production of GA4 in the distinct lifestyle of Xoc, and the importance of GA to both fungal and bacterial pathogens of rice.

  14. Crystal structure of XoLAP, a leucine aminopeptidase, from Xanthomonas oryzae pv. oryzae.

    PubMed

    Kim, Jin-Kwang; Natarajan, Sampath; Park, Hanseul; Huynh, Kim-Hung; Lee, Sang Hee; Kim, Jeong-Gu; Ahn, Yeh-Jin; Kang, Lin-Woo

    2013-10-01

    Aminopeptidases are metalloproteinases that degrade N-terminal residues from protein and play important roles in cell growth and development by controlling cell homeostasis and protein maturation. We determined the crystal structure of XoLAP, a leucyl aminopeptidase, at 2.6 Å resolution from Xanthomonas oryzae pv. oryzae, causing the destructive rice disease of bacterial blight. It is the first crystal structure of aminopeptidase from phytopathogens as a drug target. XoLAP existed as a hexamer and the monomer structure consisted of an N-terminal cap domain and a C-terminal peptidase domain with two divalent zinc ions. XoLAP structure was compared with BlLAP and EcLAP (EcPepA) structures. Based on the structural comparison, the molecular model of XoLAP in complex with the natural aminopeptidase inhibitor of microginin FR1 was proposed. The model structure will be useful to develop a novel antibacterial drug against Xoo.

  15. Comparative proteomics reveals differential induction of both biotic and abiotic stress response associated proteins in rice during Xanthomonas oryzae pv. oryzae infection.

    PubMed

    Kumar, Anirudh; Bimolata, Waikhom; Kannan, Monica; Kirti, P B; Qureshi, Insaf Ahmed; Ghazi, Irfan Ahmad

    2015-07-01

    Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight disease in rice and brutally affects the yield up to 50 % of total production. Here, we report a comparative proteomics analysis of total foliar protein isolated from infected rice leaves of susceptible Pusa Basmati 1 (PB1) and resistant Oryza longistaminata genotypes. Two-dimensional gel electrophoresis (2-DE) coupled with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) approaches identified 29 protein spots encoding unique proteins from both the genotypes. Identified proteins belonged to a large number of biological and molecular functions related to biotic and abiotic stress proteins which are potentially involved during Xoo infection. Biotic and abiotic stress-related proteins were induced during Xoo infection, indicating the activation of common stress pathway during bacterial blight infection. Candidate genes conferring tolerance against bacterial blight, which include germin-like protein, putative r40c1, cyclin-dependent kinase C, Ent-isokaur-15-ene synthase and glutathione-dependent dehydroascorbate reductase 1 (GSH-DHAR1), were also induced, with germin-like proteins induced only in the resistant rice genotype O. longistaminata. Energy, metabolism and hypothetical proteins were common among both the genotypes. Further, host defence/stress-related proteins were mostly expressed in resistant genotype O. longistaminata, indicating possible co-evolution of the pathogen and the wild rice, O. longistaminata.

  16. The Hemileia vastatrix effector HvEC-016 suppresses bacterial blight symptoms in coffee genotypes with the SH 1 rust resistance gene.

    PubMed

    Maia, Thiago; Badel, Jorge L; Marin-Ramirez, Gustavo; Rocha, Cynthia de M; Fernandes, Michelle B; da Silva, José C F; de Azevedo-Junior, Gilson M; Brommonschenkel, Sérgio H

    2017-02-01

    A number of genes that confer resistance to coffee leaf rust (SH 1-SH 9) have been identified within the genus Coffea, but despite many years of research on this pathosystem, the complementary avirulence genes of Hemileia vastatrix have not been reported. After identification of H. vastatrix effector candidate genes (HvECs) expressed at different stages of its lifecycle, we established an assay to characterize HvEC proteins by delivering them into coffee cells via the type-three secretion system (T3SS) of Pseudomonas syringae pv. garcae (Psgc). Employing a calmodulin-dependent adenylate cyclase assay, we demonstrate that Psgc recognizes a heterologous P. syringae T3SS secretion signal which enables us to translocate HvECs into the cytoplasm of coffee cells. Using this Psgc-adapted effector detector vector (EDV) system, we found that HvEC-016 suppresses the growth of Psgc on coffee genotypes with the SH 1 resistance gene. Suppression of bacterial blight symptoms in SH 1 plants was associated with reduced bacterial multiplication. By contrast, HvEC-016 enhanced bacterial multiplication in SH 1-lacking plants. Our findings suggest that HvEC-016 may be recognized by the plant immune system in a SH 1-dependent manner. Thus, our experimental approach is an effective tool for the characterization of effector/avirulence proteins of this important pathogen.

  17. Quantitative disease resistance to the bacterial pathogen Xanthomonas campestris involves an Arabidopsis immune receptor pair and a gene of unknown function.

    PubMed

    Debieu, Marilyne; Huard-Chauveau, Carine; Genissel, Anne; Roux, Fabrice; Roby, Dominique

    2016-05-01

    Although quantitative disease resistance (QDR) is a durable and broad-spectrum form of resistance in plants, the identification of the genes underlying QDR is still in its infancy. RKS1 (Resistance related KinaSe1) has been reported recently to confer QDR in Arabidopsis thaliana to most but not all races of the bacterial pathogen Xanthomonas campestris pv. campestris (Xcc). We therefore explored the genetic bases of QDR in A. thaliana to diverse races of X. campestris (Xc). A nested genome-wide association mapping approach was used to finely map the genomic regions associated with QDR to Xcc12824 (race 2) and XccCFBP6943 (race 6). To identify the gene(s) implicated in QDR, insertional mutants (T-DNA) were selected for the candidate genes and phenotyped in response to Xc. We identified two major QTLs that confer resistance specifically to Xcc12824 and XccCFBP6943. Although QDR to Xcc12824 is conferred by At5g22540 encoding for a protein of unknown function, QDR to XccCFBP6943 involves the well-known immune receptor pair RRS1/RPS4. In addition to RKS1, this study reveals that three genes are involved in resistance to Xc with strikingly different ranges of specificity, suggesting that QDR to Xc involves a complex network integrating multiple response pathways triggered by distinct pathogen molecular determinants.

  18. The galU gene of Xanthomonas campestris pv. campestris is involved in bacterial attachment, cell motility, polysaccharide synthesis, virulence, and tolerance to various stresses.

    PubMed

    Liao, Chao-Tsai; Du, Shin-Chiao; Lo, Hsueh-Hsia; Hsiao, Yi-Min

    2014-10-01

    Uridine triphosphate (UTP)-glucose-1-phosphate uridylyltransferase (GalU; EC 2.7.7.9) is an enzyme that catalyzes the formation of uridine diphosphate (UDP)-glucose from UTP and glucose-1-phosphate. GalU is involved in virulence in a number of animal-pathogenic bacteria since its product, UDP-glucose, is indispensable for the biosynthesis of virulence factors such as lipopolysaccharide and exopolysaccharide. However, its function in Xanthomonas campestris pv. campestris, the phytopathogen that causes black rot in cruciferous plants, is unclear. Here, we characterized a galU mutant of X. campestris pv. campestris and showed that the X. campestris pv. campestris galU mutant resulted in a reduction in virulence on the host cabbage. We also demonstrated that galU is involved in bacterial attachment, cell motility, and polysaccharide synthesis. Furthermore, the galU mutant showed increased sensitivity to various stress conditions including copper sulfate, hydrogen peroxide, and sodium dodecyl sulfate. In addition, mutation of galU impairs the expression of the flagellin gene fliC as well as the attachment-related genes xadA, fhaC, and yapH. In conclusion, our results indicate involvement of galU in the virulence factor production and pathogenicity in X. campestris pv. campestris, and a role for galU in stress tolerance of this crucifer pathogen.

  19. Resistance in Lycopersicon esculentum Intraspecific Crosses to Race T1 Strains of Xanthomonas campestris pv. vesicatoria Causing Bacterial Spot of Tomato.

    PubMed

    Yang, Wencai; Sacks, Erik J; Lewis Ivey, Melanie L; Miller, Sally A; Francis, David M

    2005-05-01

    ABSTRACT We used molecular markers to identify quantitative trait loci (QTL) that confer resistance in the field to Xanthomonas campestris pv. vesicatoria race T1, a causal agent of bacterial spot of tomato. An F(2) population derived from a cross between Hawaii 7998 (H 7998) and an elite breeding line, Ohio 88119, was used for the initial identification of an association between molecular markers and resistance as measured by bacterial populations in individual plants in the greenhouse. Polymorphism in this cross between a Lycopersicon esculentum donor of resistance and an elite L. esculentum parent was limited. The targeted use of a core set of 148 polymerase chain reaction-based markers that were identified as polymorphic in L. esculentum x L. esculentum crosses resulted in the identification of 37 markers that were polymorphic for the cross of interest. Previous studies using an H 7998 x L. pennellii wide cross implicated three loci, Rx1, Rx2, and Rx3, in the hypersensitive response to T1 strains. Markers that we identified were linked to the Rx1 and Rx3 loci, but no markers were identified in the region of chromosome 1 where Rx2 is located. Single marker-trait analysis suggested that chromosome 5, near the Rx3 locus, contributed to reduced bacterial populations in lines carrying the locus from H 7998. The locus on chromosome 5 explained 25% of the phenotypic variation in bacterial populations developing in infected plants. An advanced backcross population and subsequent inbred backcross lines developed using Ohio 88119 as a recurrent parent were used to confirm QTL associations detected in the F(2) population. Markers on chromosome 5 explained 41% of the phenotypic variation for resistance in replicated field trials. In contrast, the Rx1 locus on chromosome 1 did not play a role in resistance to X. campestris pv. vesicatoria race T1 strains as measured by bacterial populations in the greenhouse or symptoms in the field. A locus from H 7998 on chromosome 4 was

  20. Genome sequence of Xanthomonas fuscans subsp. fuscans strain 4834-R reveals that flagellar motility is not a general feature of xanthomonads

    PubMed Central

    2013-01-01

    Background Xanthomonads are plant-associated bacteria responsible for diseases on economically important crops. Xanthomonas fuscans subsp. fuscans (Xff) is one of the causal agents of common bacterial blight of bean. In this study, the complete genome sequence of strain Xff 4834-R was determined and compared to other Xanthomonas genome sequences. Results Comparative genomics analyses revealed core characteristics shared between Xff 4834-R and other xanthomonads including chemotaxis elements, two-component systems, TonB-dependent transporters, secretion systems (from T1SS to T6SS) and multiple effectors. For instance a repertoire of 29 Type 3 Effectors (T3Es) with two Transcription Activator-Like Effectors was predicted. Mobile elements were associated with major modifications in the genome structure and gene content in comparison to other Xanthomonas genomes. Notably, a deletion of 33 kbp affects flagellum biosynthesis in Xff 4834-R. The presence of a complete flagellar cluster was assessed in a collection of more than 300 strains representing different species and pathovars of Xanthomonas. Five percent of the tested strains presented a deletion in the flagellar cluster and were non-motile. Moreover, half of the Xff strains isolated from the same epidemic than 4834-R was non-motile and this ratio was conserved in the strains colonizing the next bean seed generations. Conclusions This work describes the first genome of a Xanthomonas strain pathogenic on bean and reports the existence of non-motile xanthomonads belonging to different species and pathovars. Isolation of such Xff variants from a natural epidemic may suggest that flagellar motility is not a key function for in planta fitness. PMID:24195767

  1. Comparative Genomics of Pathogenic and Nonpathogenic Strains of Xanthomonas arboricola Unveil Molecular and Evolutionary Events Linked to Pathoadaptation.

    PubMed

    Cesbron, Sophie; Briand, Martial; Essakhi, Salwa; Gironde, Sophie; Boureau, Tristan; Manceau, Charles; Fischer-Le Saux, Marion; Jacques, Marie-Agnès

    2015-01-01

    The bacterial species Xanthomonas arboricola contains plant pathogenic and nonpathogenic strains. It includes the pathogen X. arboricola pv. juglandis, causing the bacterial blight of Juglans regia. The emergence of a new bacterial disease of J. regia in France called vertical oozing canker (VOC) was previously described and the causal agent was identified as a distinct genetic lineage within the pathovar juglandis. Symptoms on walnut leaves and fruits are similar to those of a bacterial blight but VOC includes also cankers on trunk and branches. In this work, we used comparative genomics and physiological tests to detect differences between four X. arboricola strains isolated from walnut tree: strain CFBP 2528 causing walnut blight (WB), strain CFBP 7179 causing VOC and two nonpathogenic strains, CFBP 7634 and CFBP 7651, isolated from healthy walnut buds. Whole genome sequence comparisons revealed that pathogenic strains possess a larger and wider range of mobile genetic elements than nonpathogenic strains. One pathogenic strain, CFBP 7179, possessed a specific integrative and conjugative element (ICE) of 95 kb encoding genes involved in copper resistance, transport and regulation. The type three effector repertoire was larger in pathogenic strains than in nonpathogenic strains. Moreover, CFBP 7634 strain lacked the type three secretion system encoding genes. The flagellar system appeared incomplete and nonfunctional in the pathogenic strain CFBP 2528. Differential sets of chemoreceptor and different repertoires of genes coding adhesins were identified between pathogenic and nonpathogenic strains. Besides these differences, some strain-specific differences were also observed. Altogether, this study provides valuable insights to highlight the mechanisms involved in ecology, environment perception, plant adhesion and interaction, leading to the emergence of new strains in a dynamic environment.

  2. Comparative Genomics of Pathogenic and Nonpathogenic Strains of Xanthomonas arboricola Unveil Molecular and Evolutionary Events Linked to Pathoadaptation

    PubMed Central

    Cesbron, Sophie; Briand, Martial; Essakhi, Salwa; Gironde, Sophie; Boureau, Tristan; Manceau, Charles; Fischer-Le Saux, Marion; Jacques, Marie-Agnès

    2015-01-01

    The bacterial species Xanthomonas arboricola contains plant pathogenic and nonpathogenic strains. It includes the pathogen X. arboricola pv. juglandis, causing the bacterial blight of Juglans regia. The emergence of a new bacterial disease of J. regia in France called vertical oozing canker (VOC) was previously described and the causal agent was identified as a distinct genetic lineage within the pathovar juglandis. Symptoms on walnut leaves and fruits are similar to those of a bacterial blight but VOC includes also cankers on trunk and branches. In this work, we used comparative genomics and physiological tests to detect differences between four X. arboricola strains isolated from walnut tree: strain CFBP 2528 causing walnut blight (WB), strain CFBP 7179 causing VOC and two nonpathogenic strains, CFBP 7634 and CFBP 7651, isolated from healthy walnut buds. Whole genome sequence comparisons revealed that pathogenic strains possess a larger and wider range of mobile genetic elements than nonpathogenic strains. One pathogenic strain, CFBP 7179, possessed a specific integrative and conjugative element (ICE) of 95 kb encoding genes involved in copper resistance, transport and regulation. The type three effector repertoire was larger in pathogenic strains than in nonpathogenic strains. Moreover, CFBP 7634 strain lacked the type three secretion system encoding genes. The flagellar system appeared incomplete and nonfunctional in the pathogenic strain CFBP 2528. Differential sets of chemoreceptor and different repertoires of genes coding adhesins were identified between pathogenic and nonpathogenic strains. Besides these differences, some strain-specific differences were also observed. Altogether, this study provides valuable insights to highlight the mechanisms involved in ecology, environment perception, plant adhesion and interaction, leading to the emergence of new strains in a dynamic environment. PMID:26734033

  3. Genome sequence and rapid evolution of the rice pathogen Xanthomonas oryzae pv. oryzae PXO99A

    PubMed Central

    Salzberg, Steven L; Sommer, Daniel D; Schatz, Michael C; Phillippy, Adam M; Rabinowicz, Pablo D; Tsuge, Seiji; Furutani, Ayako; Ochiai, Hirokazu; Delcher, Arthur L; Kelley, David; Madupu, Ramana; Puiu, Daniela; Radune, Diana; Shumway, Martin; Trapnell, Cole; Aparna, Gudlur; Jha, Gopaljee; Pandey, Alok; Patil, Prabhu B; Ishihara, Hiromichi; Meyer, Damien F; Szurek, Boris; Verdier, Valerie; Koebnik, Ralf; Dow, J Maxwell; Ryan, Robert P; Hirata, Hisae; Tsuyumu, Shinji; Won Lee, Sang; Ronald, Pamela C; Sonti, Ramesh V; Van Sluys, Marie-Anne; Leach, Jan E; White, Frank F; Bogdanove, Adam J

    2008-01-01

    Background Xanthomonas oryzae pv. oryzae causes bacterial blight of rice (Oryza sativa L.), a major disease that constrains production of this staple crop in many parts of the world. We report here on the complete genome sequence of strain PXO99A and its comparison to two previously sequenced strains, KACC10331 and MAFF311018, which are highly similar to one another. Results The PXO99A genome is a single circular chromosome of 5,240,075 bp, considerably longer than the genomes of the other strains (4,941,439 bp and 4,940,217 bp, respectively), and it contains 5083 protein-coding genes, including 87 not found in KACC10331 or MAFF311018. PXO99A contains a greater number of virulence-associated transcription activator-like effector genes and has at least ten major chromosomal rearrangements relative to KACC10331 and MAFF311018. PXO99A contains numerous copies of diverse insertion sequence elements, members of which are associated with 7 out of 10 of the major rearrangements. A rapidly-evolving CRISPR (clustered regularly interspersed short palindromic repeats) region contains evidence of dozens of phage infections unique to the PXO99A lineage. PXO99A also contains a unique, near-perfect tandem repeat of 212 kilobases close to the replication terminus. Conclusion Our results provide striking evidence of genome plasticity and rapid evolution within Xanthomonas oryzae pv. oryzae. The comparisons point to sources of genomic variation and candidates for strain-specific adaptations of this pathogen that help to explain the extraordinary diversity of Xanthomonas oryzae pv. oryzae genotypes and races that have been isolated from around the world. PMID:18452608

  4. Genomic comparison between Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola, using suppression-subtractive hybridization.

    PubMed

    Soto-Suárez, Mauricio; González, Carolina; Piégu, Benoît; Tohme, Joe; Verdier, Valérie

    2010-07-01

    Xanthomonas oryzae pathovar oryzae (Xoo) and X. oryzae pv. oryzicola (Xoc) cause bacterial diseases in rice: leaf blight and leaf streak, respectively. Although both the Asian and the African strains of Xoo induce similar symptoms, they are genetically different, with the African Xoo strains being more closely related to the Asian Xoc. To identify the sequences responsible for differences between African and Asian Xoo strains and their relatedness to Xoc strains, a suppression-subtractive hybridization (SSH) procedure was performed, using the African Xoo MAI1 strain as a tester and the Philippine Xoo PXO86 strain and Xoc BLS256 strain as drivers. A nonredundant set of 134 sequences from MAI1 was generated. Several DNA fragments isolated by SSH were similar to genes of unknown function, hypothetical proteins, genes related to the type III secretion system, and other pathogenicity-related genes. The specificity of various fragments was validated by Southern blot analysis. SSH sequences were compared with several xanthomonad genomes. In silico analysis revealed SSH sequences as specific to strain MAI1, revealing their potential as specific markers for further epidemiological and diagnostic studies. SSH proved to be a useful method for rapidly identifying specific genes among closely related X. oryzae strains.

  5. Crystal Structures of Peptide Deformylase from Rice Pathogen Xanthomonas oryzae pv. oryzae in Complex with Substrate Peptides, Actinonin, and Fragment Chemical Compounds.

    PubMed

    Ngo, Ho-Phuong-Thuy; Ho, Thien-Hoang; Lee, Inho; Tran, Huyen-Thi; Sur, Bookyo; Kim, Seunghwan; Kim, Jeong-Gu; Ahn, Yeh-Jin; Cha, Sun-Shin; Kang, Lin-Woo

    2016-10-05

    Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight on rice; this species is one of the most destructive pathogenic bacteria in rice cultivation worldwide. Peptide deformylase (PDF) catalyzes the removal of the N-formyl group from the N-terminus of newly synthesized polypeptides in bacterial cells and is an important target to develop antibacterial agents. We determined crystal structures of Xoo PDF (XoPDF) at up to 1.9 Å resolution, which include apo, two substrate-bound (methionine-alanine or methionine-alanine-serine), an inhibitor-bound (actinonin), and six fragment chemical-bound structures. Six fragment chemical compounds were bound in the substrate-binding pocket. The fragment chemical-bound structures were compared to the natural PDF inhibitor actinonin-bound structure. The fragment chemical molecules will be useful to design an inhibitor specific to XoPDF and a potential pesticide against Xoo.

  6. Marker-assisted improvement of the elite restorer line of rice, RPHR-1005 for resistance against bacterial blight and blast diseases.

    PubMed

    Kumar, V Abhilash; Balachiranjeevi, C H; Naik, S Bhaskar; Rambabu, R; Rekha, G; Harika, G; Hajira, S K; Pranathi, K; Vijay, S; Anila, M; Mahadevaswamy, H K; Kousik, M; Yugander, A; Aruna, J; Hari Prasad, A S; Madhav, M S; Laha, G S; Balachandran, S M; Prasad, M S; Babu, V Ravindra; Sundaram, R M

    2016-12-01

    This study was carried out to improve the RPHR-1005, a stable restorer line of the popular medium slender grain type rice hybrid, DRRH-3 for bacterial blight (BB) and blast resistance through marker-assisted backcross breeding (MABB). Two major BB resistance genes, Xa21 and Xa33 and a major blast resistance gene, Pi2 were transferred to RPHR-1005 as two individual crosses. Foreground selection for Xa21, Xa33, Pi2, Rf3 and Rf4 was done by using gene-specific functional markers, while 59 simple sequence repeat (SSR) markers polymorphic between the donors and recipient parents were used to select the best plant possessing target resistance genes at each backcross generation. Backcrossing was continued till BC2F2 and a promising homozygous backcross derived line possessing Xa21+ Pi2 and another possessing Xa33 were intercrossed to stack the target resistance genes into the genetic background of RPHR-1005. At ICF4, 10 promising lines possessing three resistance genes in homozygous condition along with fine-grain type, complete fertility restoration, better panicle exertion and taller plant type (compared to RPHR-1005) were identified.

  7. Xanthan production by Xanthomonas albilineans infecting sugarcane stalks.

    PubMed

    Blanch, María; Legaz, María-Estrella; Vicente, Carlos

    2008-03-13

    Xanthomonas albilineans is the causal organism of leaf scald, a bacterial vascular disease of sugarcane. Xanthomonas may invade the parenchyma between the bundles and cause reddened pockets of gum, identified as a xanthan-like polysaccharide. Since xanthan contains glucuronic acid, the ability of Xanthomonas to produce an active UDP glucose dehydrogenase is often seen as a virulence factor. X. albilineans axenically cultured did not secrete xanthans to Willbrink liquid media, but the use of inoculated sugarcane tissues for producing and characterizing xanthans has been required. A hypothesis about the role of sugarcane polysaccharides to assure the production of bacterial xanthan is discussed.

  8. Measurement of haplotypic variation in Xanthomonas oryzae pv. oryzae within a single field by rep-PCR and RFLP analyses

    SciTech Connect

    Vera Cruz, C.M.; Leach, J.E.; Ardales, E.Y.; Talag, J.

    1996-12-01

    The haplotypic variation of Xanthomonas oryzae pv. oryzae in a farmer;s field that had endemic bacterial blight in the Philippines was evaluated at a single time. The genomic structure of the field population was analyzed by repetitive sequence-based polymerase chain reaction with oligonucleotide primers corresponding to interspersed repeated sequences in prokaryotic genomes and restriction fragment length polymorphism (RFLP) with the insertion sequence IS1113. The techniques and specific probes and primers were selected because they grouped consistently into the same lineages a set of 30 selected X. oryzae pv. oryzae strains that represented the four distinct RFLP lineages found in the Philippines did. Strains (155) were systematically collected from a field planted to rice cv. Sinandomeng, which is susceptible to the indigenous pathogen population. Two of the four Philippine lineages, B and C, which included race 2 and races 3 and 9, respectively, were detected in the field. Lineage C was the predominant population (74.8%). The haplotypic diversities of 10 of the 25 blocks were significantly greater than the total haplotypic diversity of the collection in the entire field; however, between individual blocks the haplotypic diversities were not significantly different. Haplo-types from both lineages were distributed randomly across the field. Analysis of genetic diversity at the microgeographic scale provided insights into the finer scale of variation of X. oryzae pv. oryzae, which are useful in designing experiments to study effects of host resistance on the population structure of the bacterial blight pathogen. 46 refs., 4 figs., 2 tabs.

  9. The thiG Gene Is Required for Full Virulence of Xanthomonas oryzae pv. oryzae by Preventing Cell Aggregation

    PubMed Central

    Yu, Xiaoyue; Liang, Xiaoyu; Liu, Kexue; Dong, Wenxia; Wang, Jianxin; Zhou, Ming-guo

    2015-01-01

    Bacterial blight of rice is an important serious bacterial diseases of rice in many rice-growing regions, caused by Xanthomonas oryzae pv. oryzae (Xoo). The thiG gene from Xoo strain ZJ173, which is involved with thiazole moiety production in the thiamine biosynthesis pathway, is highly conserved among the members of Xanthomonas. The thiG deletion mutant displayed impaired virulence and growth in thiamine-free medium but maintained its normal growth rate in the rice tissues, indicating that the thiG gene is involved in Xoo virulence. Compared to the wild type strain, the formation of cell-cell aggregates was affected in thiG deletion mutants. Although biofilm formation was promoted, motility and migration in rice leaves were repressed in the thiG mutants, and therefore limited the expansion of pathogen infection in rice. Quorum sensing and extracellular substance are two key factors that contribute to the formation of cell-cell aggregates. Our study found that in the thiG mutant the expression of two genes, rpfC and rpfG, which form a two-component regulatory signal system involved in the regulation of biofilm formation by a second messenger cyclic di-GMP is down-regulated. In addition, our study showed that xanthan production was not affected but the expression of some genes associated with xanthan biosynthesis, like gumD, gumE, gumH and gumM, were up-regulated in thiG mutants. Taken together, these findings are the first to demonstrate the role of the thiazole biosynthsis gene, thiG, in virulence and the formation of aggregates in Xanthomonas oryzae pv. oryzae. PMID:26222282

  10. First report of bacterial blight of sugar beet caused by Pseudomonas syringae pv. aptata in Georgia, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sugarbeet [Beta vulgaris L.] is not currently a commercial crop in Georgia, but experimental plantings as a winter rotational crop are promising in terms of yield and industrial sugar production. A disease outbreak of suspected bacterial origin occurred in some plots of sugarbeet [experimental lin...

  11. First Report of Bacterial Blight on Conventionally and Organically Grown Arugula in Nevada Caused by Pseudomonas syringae pv. alisalensis.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A novel bacterial leaf spot was detected in commercial organic and conventional plantings of the arugula (Eruca vesicaria spp. sativa) cv. My Way in 2007. Koch’s postulates were completed and etiology of the pathogen was determined. Physiological and molecular characterization showed that the pathog...

  12. Comparative genomic and transcriptome analyses of pathotypes of Xanthomonas citri subsp. citri provide insights into mechanisms of bacterial virulence and host range

    PubMed Central

    2013-01-01

    Background Citrus bacterial canker is a disease that has severe economic impact on citrus industries worldwide and is caused by a few species and pathotypes of Xanthomonas. X. citri subsp. citri strain 306 (XccA306) is a type A (Asiatic) strain with a wide host range, whereas its variant X. citri subsp. citri strain Aw12879 (Xcaw12879, Wellington strain) is restricted to Mexican lime. Results To characterize the mechanism for the differences in host range of XccA and Xcaw, the genome of Xcaw12879 that was completed recently was compared with XccA306 genome. Effectors xopAF and avrGf1 are present in Xcaw12879, but were absent in XccA306. AvrGf1 was shown previously for Xcaw to cause hypersensitive response in Duncan grapefruit. Mutation analysis of xopAF indicates that the gene contributes to Xcaw growth in Mexican lime but does not contribute to the limited host range of Xcaw. RNA-Seq analysis was conducted to compare the expression profiles of Xcaw12879 and XccA306 in Nutrient Broth (NB) medium and XVM2 medium, which induces hrp gene expression. Two hundred ninety two and 281 genes showed differential expression in XVM2 compared to in NB for XccA306 and Xcaw12879, respectively. Twenty-five type 3 secretion system genes were up-regulated in XVM2 for both XccA and Xcaw. Among the 4,370 common genes of Xcaw12879 compared to XccA306, 603 genes in NB and 450 genes in XVM2 conditions were differentially regulated. Xcaw12879 showed higher protease activity than XccA306 whereas Xcaw12879 showed lower pectate lyase activity in comparison to XccA306. Conclusions Comparative genomic analysis of XccA306 and Xcaw12879 identified strain specific genes. Our study indicated that AvrGf1 contributes to the host range limitation of Xcaw12879 whereas XopAF contributes to virulence. Transcriptome analyses of XccA306 and Xcaw12879 presented insights into the expression of the two closely related strains of X. citri subsp. citri. Virulence genes including genes encoding T3SS components

  13. Sensitive Detection of Xanthomonas oryzae Pathovars oryzae and oryzicola by Loop-Mediated Isothermal Amplification

    PubMed Central

    Lang, Jillian M.; Langlois, Paul; Nguyen, Marian Hanna R.; Triplett, Lindsay R.; Purdie, Laura; Holton, Timothy A.; Djikeng, Appolinaire; Vera Cruz, Casiana M.; Verdier, Valérie

    2014-01-01

    Molecular diagnostics for crop diseases can enhance food security by enabling the rapid identification of threatening pathogens and providing critical information for the deployment of disease management strategies. Loop-mediated isothermal amplification (LAMP) is a PCR-based tool that allows the rapid, highly specific amplification of target DNA sequences at a single temperature and is thus ideal for field-level diagnosis of plant diseases. We developed primers highly specific for two globally important rice pathogens, Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight (BB) disease, and X. oryzae pv. oryzicola, the causal agent of bacterial leaf streak disease (BLS), for use in reliable, sensitive LAMP assays. In addition to pathovar distinction, two assays that differentiate X. oryzae pv. oryzae by African or Asian lineage were developed. Using these LAMP primer sets, the presence of each pathogen was detected from DNA and bacterial cells, as well as leaf and seed samples. Thresholds of detection for all assays were consistently 104 to 105 CFU ml−1, while genomic DNA thresholds were between 1 pg and 10 fg. Use of the unique sequences combined with the LAMP assay provides a sensitive, accurate, rapid, simple, and inexpensive protocol to detect both BB and BLS pathogens. PMID:24837384

  14. The oxalyl-CoA synthetase-regulated oxalate and its distinct effects on resistance to bacterial blight and aluminium toxicity in rice.

    PubMed

    Peng, C; Liang, X; Liu, E-E; Zhang, J-J; Peng, X-X

    2016-12-31

    Oxalic acid is widely distributed in biological systems and known to play functional roles in plants. The gene AAE3 was recently identified to encode an oxalyl-CoA synthetase (OCS) in Arabidopsis that catalyses the conversion of oxalate and CoA into oxalyl-CoA. It will be particularly important to characterise the homologous gene in rice since rice is not only a monocotyledonous model plant, but also a staple food crop. Various enzymatic and biological methods have been used to characterise the homologous gene. We first defined that AAE3 in the rice genome (OsAAE3) also encodes an OCS enzyme. Its Km for oxalate is 1.73 ± 0.12 mm, and Vm is 6824.9 ± 410.29 U·min(-1) ·mg protein(-1) . Chemical modification and site-directed mutagenesis analyses identified thiols as the active site residues for rice OCS catalysis, suggesting that the enzyme might be regulated by redox state. Subcellular localisation assay showed that the enzyme is located in the cytosol and predominantly distributed in leaf epidermal cells. As expected, oxalate levels increased when OCS was suppressed in RNAi transgenic plants. More interestingly, OCS-suppressed plants were more susceptible to bacterial blight but more resistant to Al toxicity. The results demonstrate that the OsAAE3-encoded protein also acts as an OCS in rice, and may play different roles in coping with stresses. These molecular, enzymatic and functional data provide first-hand information to further clarify the function and mechanism of OCS in rice plants.

  15. Corn blight watch experiment

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The corn blight problem is briefly described how the experiment was organized and conducted, the effect of the blight on the 1971 crop, and some conclusions that may be drawn as a result of the experiment. The information is based on preliminary reports of the Corn Blight Watch Steering Committee and incorporates much illustrative material conceived at Purdue University.

  16. Effects of phenazine-1-carboxylic acid on the biology of the plant-pathogenic bacterium Xanthomonas oryzae pv. oryzae.

    PubMed

    Xu, Shu; Pan, Xiayan; Luo, Jianying; Wu, Jian; Zhou, Zehua; Liang, Xiaoyu; He, Yawen; Zhou, Mingguo

    2015-01-01

    Xanthomonas oryzae pv. oryzae (Xoo) is the casual agent of bacterial blight, which is one of the most serious diseases of rice. The antibiotic phenazine-1-carboxylic acid (PCA), which is primarily produced by Pseudomonas spp., was found and previously reported very effective against Xoo. However, the biological effects of PCA on Xoo remain unclear. In this study, we found that PCA increased the accumulation of reactive oxygen species (ROS) and reduced the activities of catalase (CAT) and superoxide dismutase (SOD) in Xoo. Xoo was more sensitive to H2O2 than Xanthomonas oryzae pv. oryzicola (Xoc), and had a much lower expression of CAT genes. In addition, proteomic analysis indicated that PCA inhibited carbohydrate metabolism and nutrient uptake in Xoo, and analysis of carbon source utilization further confirmed that carbohydrate metabolism in Xoo was repressed by PCA. In conclusion, PCA acted as a redox-cycling agent that disturbed the redox balance in Xoo and reduced CAT and SOD activities, resulting in higher accumulation of ROS, altered carbohydrate metabolism, and lower energy production and nutrient uptake. Moreover, a deficient antioxidant system in Xoo made it very sensitive to PCA.

  17. Type II Toxin-Antitoxin Distribution and Adaptive Aspects on Xanthomonas Genomes: Focus on Xanthomonas citri

    PubMed Central

    Martins, Paula M. M.; Machado, Marcos A.; Silva, Nicholas V.; Takita, Marco A.; de Souza, Alessandra A.

    2016-01-01

    Prokaryotic toxin-antitoxin (TA) systems were first described as being designed to prevent plasmid loss in bacteria. However, with the increase in prokaryotic genome sequencing, recently many TAs have been found in bacterial chromosomes, having other biological functions, such as environmental stress response. To date, only few studies have focused on TA systems in phytopathogens, and their possible impact on the bacterial fitness. This may be especially important for pathogens like Xanthomonas spp., which live epiphytically before entering the host. In this study, we looked for TA systems in the genomes of 10 Xanthomonas strains. We verified that citrus-infecting pathovars have, on average, 50% more TAs than other Xanthomonas spp. and no genome harbors classical toxins such as MqsR, RelB, and HicA. Only one TA system (PIN_VapC-FitB-like/SpoVT_AbrB) was conserved among the Xanthomonas genomes, suggesting adaptive aspects concerning its broad occurrence. We also detected a trend of toxin gene loss in this genus, while the antitoxin gene was preferably maintained. This study discovers the quantitative and qualitative differences among the type II TA systems present in Xanthomonas spp., especially concerning the citrus-infecting strains. In addition, the antitoxin retention in the genomes is possibly related with the resistance mechanism of further TA infections as an anti-addiction system or might also be involved in regulation of certain specific genes. PMID:27242687

  18. Cloning, expression, crystallization and preliminary X-ray crystallographic analysis of leucine aminopeptidase (LAP) from the pepA gene of Xanthomonas oryzae pv. oryzae.

    PubMed

    Huynh, Kim-Hung; Natarajan, Sampath; Choi, Jeongyoon; Song, Na-Hyun; Kim, Jeong-Gu; Lee, Byoung-Moo; Ahn, Yeh-Jin; Kang, Lin-Woo

    2009-09-01

    Xanthomonas oryzae pv. oryzae (Xoo) causes the serious disease bacterial blight in rice. The pepA (Xoo0834) gene from Xoo is one of around 100 genes that have been selected for the design of antibacterial drugs. The pepA gene encodes leucine aminopeptidase (LAP), an exopeptidase that catalyzes the hydrolysis of leucine residues from the N-terminus of a protein or peptide. This enzyme was expressed in Escherichia coli, purified and crystallized, and preliminary X-ray structural studies have been carried out. The LAP crystal diffracted to 2.6 A resolution and belonged to the cubic space group P2(1)3. The unit-cell volume of the crystal was compatible with the presence of two monomers in the asymmetric unit.

  19. TALE1 from Xanthomonas axonopodis pv. manihotis acts as a transcriptional activator in plant cells and is important for pathogenicity in cassava plants.

    PubMed

    Castiblanco, Luisa F; Gil, Juliana; Rojas, Alejandro; Osorio, Daniela; Gutiérrez, Sonia; Muñoz-Bodnar, Alejandra; Perez-Quintero, Alvaro L; Koebnik, Ralf; Szurek, Boris; López, Camilo; Restrepo, Silvia; Verdier, Valérie; Bernal, Adriana J

    2013-01-01

    Many plant-pathogenic bacteria suppress pathogen-associated molecular pattern (PAMP)-triggered immunity by injecting effector proteins into the host cytoplasm during infection through the type III secretion system (TTSS). This type III secretome plays an important role in bacterial pathogenicity in susceptible hosts. Xanthomonas axonopodis pv. manihotis (Xam), the causal agent of cassava bacterial blight, injects several effector proteins into the host cell, including TALE1(Xam) . This protein is a member of the Transcriptional Activator-Like effector (TALE) protein family, formerly known as the AvrBs3/PthA family. TALE1(Xam) has 13.5 tandem repeats of 34 amino acids each, as well as two nuclear localization signals and an acidic activation domain at the C-terminus. In this work, we demonstrate the importance of TALE1(Xam) in the pathogenicity of Xam. We use versions of the gene that lack different domains in the protein in structure-function studies to show that the eukaryotic domains at the 3' end are critical for pathogenicity. In addition, we demonstrate that, similar to the characterized TALE proteins from other Xanthomonas species, TALE1(Xam) acts as a transcriptional activator in plant cells. This is the first report of the identification of a TALE in Xam, and contributes to our understanding of the pathogenicity mechanisms employed by this bacterium to colonize and cause disease in cassava.

  20. Novel roles of SoxR, a transcriptional regulator from Xanthomonas campestris, in sensing redox-cycling drugs and regulating a protective gene that have overall implications for bacterial stress physiology and virulence on a host plant.

    PubMed

    Mahavihakanont, Aekkapol; Charoenlap, Nisanart; Namchaiw, Poommaree; Eiamphungporn, Warawan; Chattrakarn, Sorayut; Vattanaviboon, Paiboon; Mongkolsuk, Skorn

    2012-01-01

    In Xanthomonas campestris pv. campestris, SoxR likely functions as a sensor of redox-cycling drugs and as a transcriptional regulator. Oxidized SoxR binds directly to its target site and activates the expression of xcc0300, a gene that has protective roles against the toxicity of redox-cycling compounds. In addition, SoxR acts as a noninducible repressor of its own expression. X. campestris pv. campestris requires SoxR both for protection against redox-cycling drugs and for full virulence on a host plant. The X. campestris model of the gene regulation and physiological roles of SoxR represents a novel variant of existing bacterial SoxR models.

  1. Adhesion and fitness in the bean phyllosphere and transmission to seed of Xanthomonas fuscans subsp. fuscans.

    PubMed

    Darsonval, A; Darrasse, A; Durand, K; Bureau, C; Cesbron, S; Jacques, M-A

    2009-06-01

    Deciphering the mechanisms enabling plant-pathogenic bacteria to disperse, colonize, and survive on their hosts provides the necessary basis to set up new control methods. We evaluated the role of bacterial attachment and biofilm formation in host colonization processes for Xanthomonas fuscans subsp. fuscans on its host. This bacterium is responsible for the common bacterial blight of bean (Phaseolus vulgaris), a seedborne disease. The five adhesin genes (pilA, fhab, xadA1, xadA2, and yapH) identified in X. fuscans subsp. fuscans CFBP4834-R strain were mutated. All mutants were altered in their abilities to adhere to polypropylene or seed. PilA was involved in adhesion and transmission to seed, and mutation of pilA led to lower pathogenicity on bean. YapH was required for adhesion to seed, leaves, and abiotic surfaces but not for in planta transmission to seed or aggressiveness on leaves. Transmission to seed through floral structures did not require any of the known adhesins. Conversely, all mutants tested, except in yapH, were altered in their vascular transmission to seed. In conclusion, we showed that adhesins are implicated in the various processes leading to host phyllosphere colonization and transmission to seed by plant-pathogenic bacteria.

  2. Deciphering the Role of Tyrosine Sulfation in Xanthomonas oryzae pv. oryzae Using Shotgun Proteomic Analysis

    PubMed Central

    Park, Hye-Jee; Park, Chang-Jin; Bae, Nahee; Han, Sang-Wook

    2016-01-01

    A bacterial tyrosine sulfotransferase, RaxST, is required for activation of rice XA21-mediated immunity, and it catalyzes sulfation of tyrosine residues of Omp1X and RaxX in Xanthomonas oryzae pv. oryzae, a causal agent of bacterial blight in rice. Although RaxST is biochemically well-characterized, biological functions of tyrosine sulfation have not been fully elucidated. We compared protein expression patterns between the wildtype and a raxST knockout mutant using shotgun proteomic analysis. Forty nine proteins displayed a more than 1.5-fold difference in their expression between the wildtype and the mutant strains. Clusters of orthologous groups analysis revealed that proteins involved in cell motility were most abundant, and phenotypic observation also showed that the twitching motility of the mutant was dramatically changed. These results indicate that tyrosine sulfation by RaxST is essential for Xoo movement, and they provide new insights into the biological roles of RaxST in cellular processes. PMID:27298602

  3. Genetic Structure and Population Dynamics of Xanthomonas axonopodis pv. manihotis in Colombia from 1995 to 1999

    PubMed Central

    Restrepo, Silvia; Velez, Claudia M.; Duque, Myriam C.; Verdier, Valérie

    2004-01-01

    Restriction fragment length polymorphisms (RFLPs) were used to study the population genetics and temporal dynamics of the cassava bacterial pathogen Xanthomonas axonopodis pv. manihotis. The population dynamics were addressed by comparing samples collected from 1995 to 1999 from six locations, spanning four different edaphoclimatic zones (ECZs). Forty-five different X. axonopodis pv. manihotis RFLP types or haplotypes were identified between 1995 and 1999. High genetic diversity of the X. axonopodis pv. manihotis strains was evident within most of the fields sampled. In all but one site, diversity decreased over time within fields. Haplotype frequencies significantly differed over the years in all but one location. Studies of the rate of change of X. axonopodis pv. manihotis populations during the cropping cycle in two sites showed significant changes in the haplotype frequencies but not composition. However, variations in pathotype composition were observed from one year to the next at a single site in ECZs 1 and 2 and new pathotypes were described after 1997 in these ECZs, thus revealing the dramatic change in the pathogen population structure of X. axonopodis pv. manihotis. Disease incidence was used to show the progress of cassava bacterial blight in Colombia during the 5-year period in different ecosystems. Low disease incidence values were correlated with low rainfall in 1997 in ECZ 1. PMID:14711649

  4. Small, stable shuttle vectors for use in Xanthomonas.

    PubMed

    DeFeyter, R; Kado, C I; Gabriel, D W

    1990-03-30

    Plasmids from three broad-host-range (bhr) incompatibility groups (Inc) were evaluated for use as cloning vectors in Xanthomonas campestris pv. malvacearum (Xcm), the causal agent of bacterial blight of cotton. The IncP vectors pLAFR3 and pVK102 could not be introduced into Xcm at a significant frequency (less than 1 x 10(-10] and IncQ vectors such as pKT210 were unstable in their maintenance and tended to delete cloned inserts. IncW vectors such as pSa747 also were lost readily from Xcm in the absence of selection pressure. We constructed two plasmids, pUFR027 and a cosmid derivative, pUFR034, which have proven useful as cloning vectors in Xcm and other xanthomonads. They contain the pSa origin of DNA replication, the partition locus parA from the Agrobacterium plasmid pTAR, a neomycin-resistance selection marker, and alacZ alpha cassette with cloning sites. pUFR027 is 9.3 kb, and pUFR034 is 8.7 kb in size. They can be mobilized by conjugation into Xcm at a frequency of approx. 1 x 10(-6) per recipient and are maintained stably (greater than 95% retention over 36 generations without selection pressure) in both broth culture and in planta. The plasmids were introduced and maintained stably in X. citri, and in X. campestris pathovars campestris, citrumelo, vesicatoria and translucens, and were moderately stable in X. phaseoli. No effects of the plasmids on pathogenicity have been observed.

  5. Regulation and secretion of Xanthomonas virulence factors.

    PubMed

    Büttner, Daniela; Bonas, Ulla

    2010-03-01

    Plant pathogenic bacteria of the genus Xanthomonas cause a variety of diseases in economically important monocotyledonous and dicotyledonous crop plants worldwide. Successful infection and bacterial multiplication in the host tissue often depend on the virulence factors secreted including adhesins, polysaccharides, LPS and degradative enzymes. One of the key pathogenicity factors is the type III secretion system, which injects effector proteins into the host cell cytosol to manipulate plant cellular processes such as basal defense to the benefit of the pathogen. The coordinated expression of bacterial virulence factors is orchestrated by quorum-sensing pathways, multiple two-component systems and transcriptional regulators such as Clp, Zur, FhrR, HrpX and HpaR. Furthermore, virulence gene expression is post-transcriptionally controlled by the RNA-binding protein RsmA. In this review, we summarize the current knowledge on the infection strategies and regulatory networks controlling secreted virulence factors from Xanthomonas species.

  6. Unconventional membrane lipid biosynthesis in Xanthomonas campestris.

    PubMed

    Aktas, Meriyem; Narberhaus, Franz

    2015-09-01

    All bacteria are surrounded by at least one bilayer membrane mainly composed of phospholipids (PLs). Biosynthesis of the most abundant PLs phosphatidylethanolamine (PE), phosphatidylglycerol (PG) and cardiolipin (CL) is well understood in model bacteria such as Escherichia coli. It recently emerged, however, that the diversity of bacterial membrane lipids is huge and that not yet explored biosynthesis pathways exist, even for the common PLs. A good example is the plant pathogen Xanthomonas campestris pv. campestris. It contains PE, PG and CL as major lipids and small amounts of the N-methylated PE derivatives monomethyl PE and phosphatidylcholine (PC = trimethylated PE). Xanthomonas campestris uses a repertoire of canonical and non-canonical enzymes for the synthesis of its membrane lipids. In this minireview, we briefly recapitulate standard pathways and integrate three recently discovered pathways into the overall picture of bacterial membrane biosynthesis.

  7. High-Quality Draft Genome Sequences of Two Xanthomonas Pathotype Strains Infecting Aroid Plants

    PubMed Central

    Bolot, S.; Pruvost, O.; Arlat, M.; Noël, L. D.; Carrère, S.; Jacques, M.-A.

    2016-01-01

    We present here the draft genome sequences of bacterial pathogens of the Araceae family, Xanthomonas axonopodis pv. dieffenbachiae LMG 695 and Xanthomonas campestris pv. syngonii LMG 9055, differing in host range. A comparison between genome sequences will help understand the mechanisms involved in tissue specificity and adaptation to host plants. PMID:27587819

  8. Simultaneous Detection of Three Bacterial Seed-Borne Diseases in Rice Using Multiplex Polymerase Chain Reaction

    PubMed Central

    Kang, In Jeong; Kang, Mi-Hyung; Noh, Tae-Hwan; Shim, Hyeong Kwon; Shin, Dong Bum; Heu, Suggi

    2016-01-01

    Burkholderia glumae (bacterial grain rot), Xanthomonas oryzae pv. oryzae (bacterial leaf blight), and Acidovorax avenae subsp. avenae (bacterial brown stripe) are major seedborne pathogens of rice. Based on the 16S and 23S rDNA sequences for A. avenae subsp. avenae and B. glumae, and transposase A gene sequence for X. oryzae pv. oryzae, three sets of primers had been designed to produce 402 bp for B. glumae, 490 bp for X. oryzae, and 290 bp for A. avenae subsp. avenae with the 63°C as an optimum annealing temperature. Samples collected from naturally infected fields were detected with two bacteria, B. glumae and A. avenae subsp. avenae but X. oryzae pv. oryzae was not detected. This assay can be used to identify pathogens directly from infected seeds, and will be an effective tool for the identification of the three pathogens in rice plants. PMID:27904465

  9. XadM, a novel adhesin of Xanthomonas oryzae pv. oryzae, exhibits similarity to Rhs family proteins and is required for optimum attachment, biofilm formation, and virulence.

    PubMed

    Pradhan, Binod B; Ranjan, Manish; Chatterjee, Subhadeep

    2012-09-01

    By screening a transposon-induced mutant library of Xanthomonas oryzae pv. oryzae, the bacterial blight pathogen of rice, we have identified a novel 5.241-kb open reading frame (ORF) named xadM that is required for optimum virulence and colonization. This ORF encodes a protein, XadM, of 1,746 amino acids that exhibits significant similarity to Rhs family proteins. The XadM protein contains several repeat domains similar to a wall-associated surface protein of Bacillus subtilis, which has been proposed to be involved in carbohydrate binding. The role of XadM in X. oryzae pv. oryzae adhesion was demonstrated by the impaired ability of an xadM mutant strain to attach and form biofilms. Furthermore, we show that XadM is exposed on the cell surface and its expression is regulated by growth conditions and plays an important role in the early attachment and entry inside rice leaves. Interestingly, XadM homologs are present in several diverse bacteria, including many Xanthomonas spp. and animal-pathogenic bacteria belonging to Burkholderia spp. This is the first report of a role for XadM, an Rhs family protein, in adhesion and virulence of any pathogenic bacteria.

  10. Rhizoctonia web blight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rhizoctonia web blight, caused by several Rhizoctonia spp., is an important disease of evergreen azaleas and other ornamental plants in nurseries. The primary pathogens causing web blight are binucleate Rhizoctonia anastomosis groups (AG) (= Ceratobasidium D.P. Rogers, teleomorph). In southern AL an...

  11. Citrus blight research

    Technology Transfer Automated Retrieval System (TEKTRAN)

    With HLB now occurring throughout Florida citrus groves, citrus blight has been getting less attention even though the problem still exists. In fact, the combination of HLB and citrus blight has compounded the problem that the citrus industry is facing with decreased yields, small fruit size and tre...

  12. MultiLocus Sequence Analysis- and Amplified Fragment Length Polymorphism-based characterization of xanthomonads associated with bacterial spot of tomato and pepper and their relatedness to Xanthomonas species.

    PubMed

    Hamza, A A; Robene-Soustrade, I; Jouen, E; Lefeuvre, P; Chiroleu, F; Fisher-Le Saux, M; Gagnevin, L; Pruvost, O

    2012-05-01

    MultiLocus Sequence Analysis (MLSA) and Amplified Fragment Length Polymorphism (AFLP) were used to measure the genetic relatedness of a comprehensive collection of xanthomonads pathogenic to solaneous hosts to Xanthomonas species. The MLSA scheme was based on partial sequences of four housekeeping genes (atpD, dnaK, efp and gyrB). Globally, MLSA data unambiguously identified strains causing bacterial spot of tomato and pepper at the species level and was consistent with AFLP data. Genetic distances derived from both techniques showed a close relatedness of (i) X. euvesicatoria, X. perforans and X. alfalfae and (ii) X. gardneri and X. cynarae. Maximum likelihood tree topologies derived from each gene portion and the concatenated data set for species in the X. campestris 16S rRNA core (i.e. the species cluster comprising all strains causing bacterial spot of tomato and pepper) were not congruent, consistent with the detection of several putative recombination events in our data sets by several recombination search algorithms. One recombinant region in atpD was identified in most strains of X. euvesicatoria including the type strain.

  13. A filamentous hemagglutinin-like protein of Xanthomonas axonopodis pv. citri, the phytopathogen responsible for citrus canker, is involved in bacterial virulence.

    PubMed

    Gottig, Natalia; Garavaglia, Betiana S; Garofalo, Cecilia G; Orellano, Elena G; Ottado, Jorgelina

    2009-01-01

    Xanthomonas axonopodis pv. citri, the phytopathogen responsible for citrus canker has a number of protein secretion systems and among them, at least one type V protein secretion system belonging to the two-partner secretion pathway. This system is mainly associated to the translocation of large proteins such as adhesins to the outer membrane of several pathogens. Xanthomonas axonopodis pv. citri possess a filamentous hemagglutinin-like protein in close vicinity to its putative transporter protein, XacFhaB and XacFhaC, respectively. Expression analysis indicated that XacFhaB was induced in planta during plant-pathogen interaction. By mutation analysis of XacFhaB and XacFhaC genes we determined that XacFhaB is involved in virulence both in epiphytic and wound inoculations, displaying more dispersed and fewer canker lesions. Unexpectedly, the XacFhaC mutant in the transporter protein produced an intermediate virulence phenotype resembling wild type infection, suggesting that XacFhaB could be secreted by another partner different from XacFhaC. Moreover, XacFhaB mutants showed a general lack of adhesion and were affected in leaf surface attachment and biofilm formation. In agreement with the in planta phenotype, adhesin lacking cells moved faster in swarming plates. Since no hyperflagellation phenotype was observed in this bacteria, the faster movement may be attributed to the lack of cell-to-cell aggregation. Moreover, XacFhaB mutants secreted more exopolysaccharide that in turn may facilitate its motility. Our results suggest that this hemagglutinin-like protein is required for tissue colonization being mainly involved in surface attachment and biofilm formation, and that plant tissue attachment and cell-to-cell aggregation are dependent on the coordinated action of adhesin molecules and exopolysaccharides.

  14. Proteome analysis of the plant-pathogenic bacterium Xanthomonas oryzae pv. oryzae.

    PubMed

    Xu, Shu; Luo, Jianying; Pan, Xiayan; Liang, Xiaoyu; Wu, Jian; Zheng, Wenjun; Chen, Changjun; Hou, Yiping; Ma, Hongyu; Zhou, Mingguo

    2013-08-01

    The plant-pathogenic bacterium Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of bacterial blight, which is one of the most serious diseases of rice. Xoo has been studied for over one century, and much has been learned about it, but proteomic investigation has been neglected. In this study, proteome reference maps of Xoo were constructed by two-dimensional gel electrophoresis, and 628 spots in the gels representing 469 different protein species were identified with MALDI-TOF/TOF MS. The identified spots were assigned to 15 functional categories according to the Kyoto Encyclopedia of Genes and Genomes (KEGG) database and the annotations from the National Center for Biotechnology Information (NCBI) database. The data set has been deposited in the World-2DPAGE database (Database ID: 0044). In addition, comparative proteomic analysis revealed that proteins related to the TonB-dependent transportation system and energy metabolism are involved in the phenazine-1-carboxylic acid resistance in Xoo. In conclusion, we have established a proteome database for Xoo and have used this database in a comparative proteomic analysis that identified proteins potentially contributing to phenazine-1-carboxylic acid resistance in Xoo.

  15. Molecular analysis of the hrp gene cluster in Xanthomonas oryzae pathovar oryzae KACC10859.

    PubMed

    Cho, Hee-Jung; Park, Young-Jin; Noh, Tae-Hwan; Kim, Yeong-Tae; Kim, Jeong-Gu; Song, Eun-Sung; Lee, Dong-Hee; Lee, Byoung-Moo

    2008-06-01

    Xanthomonas oryzae pathovar oryzae is the causal agent of rice bacterial blight. The plant pathogenic bacterium X. oryzae pv. oryzae expresses a type III secretion system that is necessary for both the pathogenicity in susceptible hosts and the induction of the hypersensitive response in resistant plants. This specialized protein transport system is encoded by a 32.18kb hrp (hypersensitive response and pathogenicity) gene cluster. The hrp gene cluster is composed of nine hrp, nine hrc (hrp conserved) and eight hpa (hrp-associated) genes and is controlled by HrpG and HrpX, which are known as regulators of the hrp gene cluster. Before mutational analysis of these hrp genes, the transcriptional linkages of the core region of the hrp gene cluster from hpaB to hrcC of the X. oryzae pv. oryzae KACC10859 was determined and the non-polarity of EZTn5 insertional mutagenesis was demonstrated by reverse transcription polymerase chain reaction. Pathogenicity assays of these non-polar hrp mutants were carried out on the susceptible rice cultivar, Milyang-23. According to the results of these assays, all hrp-hrc, except hrpF, and hpaB mutants lost their pathogenicity, which indicates that most hrp-hrc genes encode essential pathogenicity factors. On the other hand, most hpa mutants showed decreased virulence in a different pattern, i.e., hpa genes are not essential but are important for pathogenicity.

  16. Population genomic insights into variation and evolution of Xanthomonas oryzae pv. oryzae

    PubMed Central

    Midha, Samriti; Bansal, Kanika; Kumar, Sanjeet; Girija, Anil Madhusoodana; Mishra, Deo; Brahma, Kranthi; Laha, Gouri Sankar; Sundaram, Raman Meenakshi; Sonti, Ramesh V.; Patil, Prabhu B.

    2017-01-01

    Xanthomonas oryzae pv. oryzae ( Xoo) is a serious pathogen of rice causing bacterial leaf blight disease. Resistant varieties and breeding programs are being hampered by the emergence of highly virulent strains. Herein we report population based whole genome sequencing and analysis of 100 Xoo strains from India. Phylogenomic analysis revealed the clustering of Xoo strains from India along with other Asian strains, distinct from African and US Xo strains. The Indian Xoo population consists of a major clonal lineage and four minor but highly diverse lineages. Interestingly, the variant alleles, gene clusters and highly pathogenic strains are primarily restricted to minor lineages L-II to L-V and in particularly to lineage L-III. We could also find the association of an expanded CRISPR cassette and a highly variant LPS gene cluster with the dominant lineage. Molecular dating revealed that the major lineage, L-I is youngest and of recent origin compared to remaining minor lineages that seems to have originated much earlier in the past. Further, we were also able to identify core effector genes that may be helpful in efforts towards building durable resistance against this pathogen. PMID:28084432

  17. Small non-coding RNAs in plant-pathogenic Xanthomonas spp.

    PubMed

    Abendroth, Ulrike; Schmidtke, Cornelius; Bonas, Ulla

    2014-01-01

    The genus Xanthomonas comprises a large group of plant-pathogenic bacteria. The infection and bacterial multiplication in the plant tissue depends on the type III secretion system and other virulence determinants. Recent studies revealed that bacterial virulence is also controlled at the post-transcriptional level by small non-coding RNAs (sRNAs). In this review, we highlight our current knowledge about sRNAs and RNA-binding proteins in Xanthomonas species.

  18. Crystallization and preliminary crystallographic studies of LipA, a secretory lipase/esterase from Xanthomonas oryzae pv. oryzae

    SciTech Connect

    Aparna, Gudlur; Chatterjee, Avradip; Jha, Gopaljee; Sonti, Ramesh V.; Sankaranarayanan, Rajan

    2007-08-01

    The crystallization and preliminary crystallographic studies of LipA, a lipase/esterase secreted by X. oryzae pv. oryzae during its infection of rice plants, are reported. Xanthomonas oryzae pv. oryzae is the causal agent of bacterial leaf blight, a serious disease of rice. Several enzymes that are secreted through the type II secretion system of this bacterium play an important role in the plant–microbe interaction, being important for virulence and also being able to induce potent host defence responses. One of these enzymes is a secretory lipase/esterase, LipA, which shows a very weak homology to other bacterial lipases and gives a positive tributyrin plate assay. In this study, LipA was purified from the culture supernatant of an overexpressing clone of X. oryzae pv. oryzae and two types of crystals belonging to space group C2 but with two different unit-cell parameters were obtained using the hanging-drop vapour-diffusion method. Type I crystals diffract to a maximum resolution of 1.89 Å and have unit-cell parameters a = 93.1, b = 62.3, c = 66.1 Å, β = 90.8°. Type II crystals have unit-cell parameters a = 103.6, b = 54.6, c = 66.3 Å, β = 92.6° and diffract to 1.86 Å. Solvent-content analysis shows one monomer in the asymmetric unit in both the crystal forms.

  19. The Fd-GOGAT1 mutant gene lc7 confers resistance to Xanthomonas oryzae pv. Oryzae in rice

    PubMed Central

    Chen, Honglin; Li, Chunrong; Liu, Liping; Zhao, Jiying; Cheng, Xuzhen; Jiang, Guanghuai; Zhai, Wenxue

    2016-01-01

    Disease resistance is an important goal of crop improvement. The molecular mechanism of resistance requires further study. Here, we report the identification of a rice leaf color mutant, lc7, which is defective in chlorophyll synthesis and photosynthesis but confers resistance to Xanthomonas oryzae pv. Oryzae (Xoo). Map-based cloning revealed that lc7 encodes a mutant ferredoxin-dependent glutamate synthase1 (Fd-GOGAT1). Fd-GOGAT1 has been proposed to have great potential for improving nitrogen-use efficiency, but its function in bacterial resistance has not been reported. The lc7 mutant accumulates excessive levels of ROS (reactive oxygen species) in the leaves, causing the leaf color to become yellow after the four-leaf stage. Compared to the wild type, lc7 mutants have a broad-spectrum high resistance to seven Xoo strains. Differentially expressed genes (DEGs) and qRT-PCR analysis indicate that many defense pathways that are involved in this broad-spectrum resistance are activated in the lc7 mutant. These results suggest that Fd-GOGAT1 plays an important role in broad-spectrum bacterial blight resistance, in addition to modulating nitrogen assimilation and chloroplast development. PMID:27211925

  20. Crystallization and preliminary crystallographic studies of LipA, a secretory lipase/esterase from Xanthomonas oryzae pv. oryzae.

    PubMed

    Aparna, Gudlur; Chatterjee, Avradip; Jha, Gopaljee; Sonti, Ramesh V; Sankaranarayanan, Rajan

    2007-08-01

    Xanthomonas oryzae pv. oryzae is the causal agent of bacterial leaf blight, a serious disease of rice. Several enzymes that are secreted through the type II secretion system of this bacterium play an important role in the plant-microbe interaction, being important for virulence and also being able to induce potent host defence responses. One of these enzymes is a secretory lipase/esterase, LipA, which shows a very weak homology to other bacterial lipases and gives a positive tributyrin plate assay. In this study, LipA was purified from the culture supernatant of an overexpressing clone of X. oryzae pv. oryzae and two types of crystals belonging to space group C2 but with two different unit-cell parameters were obtained using the hanging-drop vapour-diffusion method. Type I crystals diffract to a maximum resolution of 1.89 A and have unit-cell parameters a = 93.1, b = 62.3, c = 66.1 A, beta = 90.8 degrees . Type II crystals have unit-cell parameters a = 103.6, b = 54.6, c = 66.3 A, beta = 92.6 degrees and diffract to 1.86 A. Solvent-content analysis shows one monomer in the asymmetric unit in both the crystal forms.

  1. Ascochyta blight of peas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Identification, taxonomy & nomenclature, epidemiology, symptoms, host ranges, and management are described for three fungal pathogens which collectively and individually cause Ascochyta blight of field pea (Pisum sativum): Ascochyta pisi, Ascochyta pinodes, and Ascochyta pinodella. The first two are...

  2. The Arabidopsis Elongator complex is required for nonhost resistance against the bacterial pathogens Xanthomonas citri subsp. citri and Pseudomonas syringae pv. phaseolicola NPS3121.

    PubMed

    An, Chuanfu; Wang, Chenggang; Mou, Zhonglin

    2017-01-30

    Although in recent years nonhost resistance has attracted considerable attention for its broad spectrum and durability, the genetic and mechanistic components of nonhost resistance have not been fully understood. We used molecular and histochemical approaches including quantitative PCR, chromatin immunoprecipitation, and 3,3'-diaminobenzidine and aniline blue staining. The evolutionarily conserved histone acetyltransferase complex Elongator was identified as a major component of nonhost resistance against Xanthomonas citri subsp. citri (Xcc) and Pseudomonas syringae pv. phaseolicola (Psp) NPS3121. Mutations in Elongator genes inhibit Xcc-, Psp NPS3121- and/or flg22-induced defense responses including defense gene expression, callose deposition, and reactive oxygen species (ROS) and salicylic acid (SA) accumulation. Mutations in Elongator also attenuate the ROS-SA amplification loop. We show that suppressed ROS and SA accumulation in Elongator mutants is correlated with reduced expression of the Arabidopsis respiratory burst oxidase homologue AtrbohD and the SA biosynthesis gene ISOCHORISMATE SYNTHASE1 (ICS1). Furthermore, we found that the Elongator subunit ELP2 is associated with the chromatin of AtrbohD and ICS1 and is required for maintaining basal histone H3 acetylation levels in these key defense genes. As both AtrbohD and ICS1 contribute to nonhost resistance against Xcc, our results reveal an epigenetic mechanism by which Elongator regulates nonhost resistance in Arabidopsis.

  3. Multilocus Variable Number of Tandem Repeat Analysis Reveals Multiple Introductions in Spain of Xanthomonas arboricola pv. pruni, the Causal Agent of Bacterial Spot Disease of Stone Fruits and Almond.

    PubMed

    López-Soriano, Pablo; Boyer, Karine; Cesbron, Sophie; Morente, María Clara; Peñalver, Javier; Palacio-Bielsa, Ana; Vernière, Christian; López, María M; Pruvost, Olivier

    Xanthomonas arboricola pv. pruni is the causal agent of the bacterial spot disease of stone fruits, almond and some ornamental Prunus species. In Spain it was first detected in 2002 and since then, several outbreaks have occurred in different regions affecting mainly Japanese plum, peach and almond, both in commercial orchards and nurseries. As the origin of the introduction(s) was unknown, we have assessed the genetic diversity of 239 X. arboricola pv. pruni strains collected from 11 Spanish provinces from 2002 to 2013 and 25 reference strains from international collections. We have developed an optimized multilocus variable number of tandem repeat analysis (MLVA) scheme targeting 18 microsatellites and five minisatellites. A high discriminatory power was achieved since almost 50% of the Spanish strains were distinguishable, confirming the usefulness of this genotyping technique at small spatio-temporal scales. Spanish strains grouped in 18 genetic clusters (conservatively delineated so that each cluster contained haplotype networks linked by up to quadruple-locus variations). Furthermore, pairwise comparisons among populations from different provinces showed a strong genetic differentiation. Our results suggest multiple introductions of this pathogen in Spain and redistribution through contaminated nursery propagative plant material.

  4. Multilocus Variable Number of Tandem Repeat Analysis Reveals Multiple Introductions in Spain of Xanthomonas arboricola pv. pruni, the Causal Agent of Bacterial Spot Disease of Stone Fruits and Almond

    PubMed Central

    López-Soriano, Pablo; Boyer, Karine; Cesbron, Sophie; Morente, María Clara; Peñalver, Javier; Palacio-Bielsa, Ana; Vernière, Christian; López, María M.; Pruvost, Olivier

    2016-01-01

    Xanthomonas arboricola pv. pruni is the causal agent of the bacterial spot disease of stone fruits, almond and some ornamental Prunus species. In Spain it was first detected in 2002 and since then, several outbreaks have occurred in different regions affecting mainly Japanese plum, peach and almond, both in commercial orchards and nurseries. As the origin of the introduction(s) was unknown, we have assessed the genetic diversity of 239 X. arboricola pv. pruni strains collected from 11 Spanish provinces from 2002 to 2013 and 25 reference strains from international collections. We have developed an optimized multilocus variable number of tandem repeat analysis (MLVA) scheme targeting 18 microsatellites and five minisatellites. A high discriminatory power was achieved since almost 50% of the Spanish strains were distinguishable, confirming the usefulness of this genotyping technique at small spatio-temporal scales. Spanish strains grouped in 18 genetic clusters (conservatively delineated so that each cluster contained haplotype networks linked by up to quadruple-locus variations). Furthermore, pairwise comparisons among populations from different provinces showed a strong genetic differentiation. Our results suggest multiple introductions of this pathogen in Spain and redistribution through contaminated nursery propagative plant material. PMID:27669415

  5. The Type III secretion system of Xanthomonas fuscans subsp. fuscans is involved in the phyllosphere colonization process and in transmission to seeds of susceptible beans.

    PubMed

    Darsonval, A; Darrasse, A; Meyer, D; Demarty, M; Durand, K; Bureau, C; Manceau, C; Jacques, M-A

    2008-05-01

    Understanding the survival, multiplication, and transmission to seeds of plant pathogenic bacteria is central to study their pathogenesis. We hypothesized that the type III secretion system (T3SS), encoded by hrp genes, could have a role in host colonization by plant pathogenic bacteria. The seed-borne pathogen Xanthomonas fuscans subsp. fuscans causes common bacterial blight of bean (Phaseolus vulgaris). Directed mutagenesis in strain CFBP4834-R of X. fuscans subsp. fuscans and bacterial population density monitoring on bean leaves showed that strains with mutations in the hrp regulatory genes, hrpG and hrpX, were impaired in their phyllospheric growth, as in the null interaction with Escherichia coli C600 and bean. In the compatible interaction, CFBP4834-R reached high phyllospheric population densities and was transmitted to seeds at high frequencies with high densities. Strains with mutations in structural hrp genes maintained the same constant epiphytic population densities (1 x 10(5) CFU g(-1) of fresh weight) as in the incompatible interaction with Xanthomonas campestris pv. campestris ATCC 33913 and the bean. Low frequencies of transmission to seeds and low bacterial concentrations were recorded for CFBP4834-R hrp mutants and for ATCC 33913, whereas E. coli C600 was not transmitted. Moreover, unlike the wild-type strain, strains with mutations in hrp genes were not transmitted to seeds by vascular pathway. Transmission to seeds by floral structures remained possible for both. This study revealed the involvement of the X. fuscans subsp. fuscans T3SS in phyllospheric multiplication and systemic colonization of bean, leading to transmission to seeds. Our findings suggest a major contribution of hrp regulatory genes in host colonization processes.

  6. Lettuce cultivar influences Xanthomonas campestris pv. vitians population levels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial Leaf Spot, caused by Xanthomonas campestris pv. vitians (Xcv), is a widespread and economically important disease of lettuce. Cultivars with resistance to Xcv have been identified, but mechanisms for resistance in this pathosystem have not been investigated. We hypothesized that susceptibl...

  7. Involvement of bacterial TonB-dependent signaling in the generation of an oligogalacturonide damage-associated molecular pattern from plant cell walls exposed to Xanthomonas campestris pv. campestris pectate lyases

    PubMed Central

    2012-01-01

    Background Efficient perception of attacking pathogens is essential for plants. Plant defense is evoked by molecules termed elicitors. Endogenous elicitors or damage-associated molecular patterns (DAMPs) originate from plant materials upon injury or pathogen activity. While there are comparably well-characterized examples for DAMPs, often oligogalacturonides (OGAs), generated by the activity of fungal pathogens, endogenous elicitors evoked by bacterial pathogens have been rarely described. In particular, the signal perception and transduction processes involved in DAMP generation are poorly characterized. Results A mutant strain of the phytopathogenic bacterium Xanthomonas campestris pv. campestris deficient in exbD2, which encodes a component of its unusual elaborate TonB system, had impaired pectate lyase activity and caused no visible symptoms for defense on the non-host plant pepper (Capsicum annuum). A co-incubation of X. campestris pv. campestris with isolated cell wall material from C. annuum led to the release of compounds which induced an oxidative burst in cell suspension cultures of the non-host plant. Lipopolysaccharides and proteins were ruled out as elicitors by polymyxin B and heat treatment, respectively. After hydrolysis with trifluoroacetic acid and subsequent HPAE chromatography, the elicitor preparation contained galacturonic acid, the monosaccharide constituent of pectate. OGAs were isolated from this crude elicitor preparation by HPAEC and tested for their biological activity. While small OGAs were unable to induce an oxidative burst, the elicitor activity in cell suspension cultures of the non-host plants tobacco and pepper increased with the degree of polymerization (DP). Maximal elicitor activity was observed for DPs exceeding 8. In contrast to the X. campestris pv. campestris wild type B100, the exbD2 mutant was unable to generate elicitor activity from plant cell wall material or from pectin. Conclusions To our knowledge, this is the

  8. Transcriptome analysis confers a complex disease resistance network in wild rice Oryza meyeriana against Xanthomonas oryzae pv. oryzae

    PubMed Central

    Cheng, Xiao-Jie; He, Bin; Chen, Lin; Xiao, Su-qin; Fu, Jian; Chen, Yue; Yu, Teng-qiong; Cheng, Zai-Quan; Feng, Hong

    2016-01-01

    Rice bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the devastating diseases of rice. It is well established that the wild rice Oryza meyeriana is immune to BB. In this study, the transcriptomic analysis was carried out by RNA sequencing of O. meyeriana leaves, inoculated with Xoo to understand the transcriptional responses and interaction between the host and pathogen. Totally, 57,313 unitranscripts were de novo assembled from 58.7 Gb clean reads and 14,143 unitranscripts were identified after Xoo inoculation. The significant metabolic pathways related to the disease resistance enriched by KEGG, were revealed to plant-pathogen interaction, phytohormone signaling, ubiquitin mediated proteolysis, and phenylpropanoid biosynthesis. Further, many disease resistance genes were also identified to be differentially expressed in response to Xoo infection. Conclusively, the present study indicated that the induced innate immunity comprise the basal defence frontier of O. meyeriana against Xoo infection. And then, the resistance genes are activated. Simultaneously, the other signaling transduction pathways like phytohormones and ubiquitin mediated proteolysis may contribute to the disease defence through modulation of the disease-related genes or pathways. This could be an useful information for further investigating the molecular mechanism associated with disease resistance in O. meyeriana. PMID:27905546

  9. Transcriptome-Based Identification of Differently Expressed Genes from Xanthomonas oryzae pv. oryzae Strains Exhibiting Different Virulence in Rice Varieties

    PubMed Central

    Noh, Tae-Hwan; Song, Eun-Sung; Kim, Hong-Il; Kang, Mi-Hyung; Park, Young-Jin

    2016-01-01

    Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight (BB) in rice (Oryza sativa L.). In this study, we investigated the genome-wide transcription patterns of two Xoo strains (KACC10331 and HB1009), which showed different virulence patterns against eight rice cultivars, including IRBB21 (carrying Xa21). In total, 743 genes showed a significant change (p-value < 0.001 in t-tests) in their mRNA expression levels in the HB1009 (K3a race) strain compared with the Xoo KACC10331 strain (K1 race). Among them, four remarkably enriched GO terms, DNA binding, transposition, cellular nitrogen compound metabolic process, and cellular macromolecule metabolic process, were identified in the upregulated genes. In addition, the expression of 44 genes was considerably higher (log2 fold changes > 2) in the HB1009 (K3a race) strain than in the Xoo KACC10331 (K1 race) strain. Furthermore, 13 and 12 genes involved in hypersensitive response and pathogenicity (hrp) and two-component regulatory systems (TCSs), respectively, were upregulated in the HB1009 (K3a race) strain compared with the Xoo KACC10331 (K1 race) strain, which we determined using either quantitative real-time PCR analysis or next-generation RNA sequencing. These results will be helpful to improve our understanding of Xoo and to gain a better insight into the Xoo–rice interactions. PMID:26907259

  10. Development and validation of a real-time quantitative PCR assay to detect Xanthomonas axonopodis pv. allii from onion seed.

    PubMed

    Robène, Isabelle; Perret, Marion; Jouen, Emmanuel; Escalon, Aline; Maillot, Marie-Véronique; Chabirand, Aude; Moreau, Aurélie; Laurent, Annie; Chiroleu, Frédéric; Pruvost, Olivier

    2015-07-01

    Bacterial blight of onion is an emerging disease threatening world onion production. The causal agent Xanthomonas axonopodis pv. allii is seed transmitted and a reliable and sensitive tool is needed to monitor seed exchanges. A triplex quantitative real-time PCR assay was developed targeting two X. axonopodis pv. allii-specific markers and an internal control chosen in 5.8S rRNA gene from Alliaceae. Amplification of at least one marker indicates the presence of the bacterium in seed extracts. This real-time PCR assay detected all the 79 X. axonopodis pv. allii strains tested and excluded 85.2% of the 135 non-target strains and particularly all 39 saprophytic and pathogenic bacteria associated with onion. Cross-reactions were mainly obtained for strains assigned to nine phylogenetically related X. axonopodis pathovars. The cycle cut-off was estimated statistically at 36.3 considering a risk of false positive of 1%. The limit of detection obtained in at least 95% of the time (LOD 95%) was 5×10(3) CFU/g (colony forming unit/g). The sensitivity threshold was found to be 1 infected seed in 32,790 seeds. This real-time PCR assay should be useful for preventing the long-distance spread of X. axonopodis pv. allii via contaminated seed lots and determining the epidemiology of the bacterium.

  11. Transcriptome analysis confers a complex disease resistance network in wild rice Oryza meyeriana against Xanthomonas oryzae pv. oryzae.

    PubMed

    Cheng, Xiao-Jie; He, Bin; Chen, Lin; Xiao, Su-Qin; Fu, Jian; Chen, Yue; Yu, Teng-Qiong; Cheng, Zai-Quan; Feng, Hong

    2016-12-01

    Rice bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the devastating diseases of rice. It is well established that the wild rice Oryza meyeriana is immune to BB. In this study, the transcriptomic analysis was carried out by RNA sequencing of O. meyeriana leaves, inoculated with Xoo to understand the transcriptional responses and interaction between the host and pathogen. Totally, 57,313 unitranscripts were de novo assembled from 58.7 Gb clean reads and 14,143 unitranscripts were identified after Xoo inoculation. The significant metabolic pathways related to the disease resistance enriched by KEGG, were revealed to plant-pathogen interaction, phytohormone signaling, ubiquitin mediated proteolysis, and phenylpropanoid biosynthesis. Further, many disease resistance genes were also identified to be differentially expressed in response to Xoo infection. Conclusively, the present study indicated that the induced innate immunity comprise the basal defence frontier of O. meyeriana against Xoo infection. And then, the resistance genes are activated. Simultaneously, the other signaling transduction pathways like phytohormones and ubiquitin mediated proteolysis may contribute to the disease defence through modulation of the disease-related genes or pathways. This could be an useful information for further investigating the molecular mechanism associated with disease resistance in O. meyeriana.

  12. Molecular and pathogenic characterization of new Xanthomonas oryzae pv. oryzae strains from the coastline region of Fangchenggang city in China.

    PubMed

    Yang, Shu-Qing; Liu, Shu-Yan; Zhao, Shuai; Yu, Yan-Hua; Li, Rong-Bai; Duan, Cheng-Jie; Tang, Ji-Liang; Feng, Jia-Xun

    2013-04-01

    Virulence assays and DNA polymorphism analyses were used to characterize 33 Xanthomonas oryzae pv. oryzae (Xoo) strains collected from the coastline region of Fangchenggang city in China. Two new pathogenic races (FXP1 and FXP2), were determined by leaf-clipping inoculation of 12 near-isogenic International Rice-Bacterial Blight (IRBB) rice lines, each containing a single resistance gene. Race FXP1 consisted of twenty-eight strains that were incompatible on IRBB5 and IRBB7, while race FXP2 included five strains that were incompatible on IRBB5 and IRBB7 and moderately virulent on IRBB8 containing the xa8 gene. Restriction fragment length polymorphism (RFLP) analysis revealed that each probe of avrXa10 and IS1112 resolved two haplotypes. In a dendrogram generated from the combined RFLP data, the 33 Xoo strains were resolved into two clusters. There was a weak correlation (r = 0.53) between race and haplotype. All of the rice cultivars planted in the coastline region of Fangchenggang city were susceptible to the representative Xoo strains tested above. However, we found that four rice cultivars used as breeding materials in the laboratory could fully resist infection by the Xoo strains, suggesting that the isolated Xoo strains could be used to detect resistant rice cultivars suitable for planting in the local rice field.

  13. Analysis of the Proteins Secreted from the Oryza meyeriana Suspension-Cultured Cells Induced by Xanthomonas oryzae pv. oryzae

    PubMed Central

    Chen, Xian; Dong, Yan; Yu, Chulang; Fang, XianPing; Deng, Zhiping; Yan, Chengqi; Chen, Jianping

    2016-01-01

    Oryza meyeriana, a wild species of rice from China, shows high resistance to Xanthomonas oryzae pv. oryzae (Xoo), the cause of rice bacterial blight, one of the most serious rice pathogens. To better understand the resistance mechanism, a proteomic study was conducted to identify changes in the proteins secreted in embryo cell suspension cultures in response to Xoo. After two-dimensional difference gel electrophoresis (2D-DIGE), 72 differentially expressed protein spots corresponding to 34 proteins were identified by Matrix-Assisted Laser Desorption/ Ionization Time of Flight Mass Spectrometry. Of the 34 proteins, 10 were up regulated and 24 down regulated. The secreted proteins identified were predicted to be involved in various biological processes, including signal transduction, defense, ROS and cell wall modification. 77% of the 34 proteins were predicted to have a signal peptide by Signal P. Quantitative Real-Time PCR showed that transcript levels of 14 secreted proteins were not well correlated with secreted protein levels. Peroxidase activity was up regulated in both O. meyriana and susceptible rice but was about three times higher in O. meyeriana. This suggests that peroxidases may play an important role in the early response to Xoo in O. meyeriana. These results not only provide a better understanding of the resistance mechanism of O. meyeriana, but have implications for studies of the interactions between other plants and their pathogens. PMID:27196123

  14. Crystal structures of d-alanine-d-alanine ligase from Xanthomonas oryzae pv. oryzae alone and in complex with nucleotides.

    PubMed

    Doan, Thanh Thi Ngoc; Kim, Jin-Kwang; Ngo, Ho-Phuong-Thuy; Tran, Huyen-Thi; Cha, Sun-Shin; Min Chung, Kyung; Huynh, Kim-Hung; Ahn, Yeh-Jin; Kang, Lin-Woo

    2014-03-01

    D-Alanine-D-alanine ligase (DDL) catalyzes the biosynthesis of d-alanyl-d-alanine, an essential bacterial peptidoglycan precursor, and is an important drug target for the development of antibacterials. We determined four different crystal structures of DDL from Xanthomonas oryzae pv. oryzae (Xoo) causing Bacteria Blight (BB), which include apo, ADP-bound, ATP-bound, and AMPPNP-bound structures at the resolution between 2.3 and 2.0 Å. Similarly with other DDLs, the active site of XoDDL is formed by three loops from three domains at the center of enzyme. Compared with d-alanyl-d-alanine and ATP-bound TtDDL structure, the γ-phosphate of ATP in XoDDL structure was shifted outside toward solution. We swapped the ω-loop (loop3) of XoDDL with those of Escherichia coli and Helicobacter pylori DDLs, and measured the enzymatic kinetics of wild-type XoDDL and two mutant XoDDLs with the swapped ω-loops. Results showed that the direct interactions between ω-loop and other two loops are essential for the active ATP conformation for D-ala-phosphate formation.

  15. A multilocus sequence analysis of Xanthomonas campestris reveals a complex structure within crucifer-attacking pathovars of this species.

    PubMed

    Fargier, E; Fischer-Le Saux, M; Manceau, C

    2011-04-01

    Previous classification of Xanthomonas campestris has defined six pathovars (aberrans, armoraciae, barbareae, campestris, incanae, and raphani) that cause diseases on cruciferous plants. However, pathogenicity assays with a range of strains and different hosts identifies only three types of symptom: black rot, leaf spot and bacterial blight. These findings raise the question of the genetic relatedness between strains assigned to different pathovars or symptom phenotypes. Here we have addressed this issue by multilocus sequence analysis of 42 strains. The X. campestris species was polymorphic at the 8 loci analysed and had a high genetic diversity; 23 sequence types were identified of which 16 were unique. All strains that induce black rot (pathovars aberrans and campestris) were genetically close but split in two groups. Only three clonal complexes were found, all within pathovar campestris. The assignment of the genome-sequenced strain 756C to pathovar raphani suggested from disease symptoms was confirmed, although this group of strains was particularly polymorphic. Strains belonging to pathovars barbareae and incanae were closely related, but distinct from pathovar campestris. There is evidence of genetic exchanges of housekeeping genes within this species as deduced from a clear incongruence between individual gene phylogenies and from network structures from SplitsTree analysis. Overall this study showed that the high genetic diversity derived equally from recombination and point mutation accumulation. However, X. campestris remains a species with a clonal evolution driven by a differential adaptation to cruciferous hosts.

  16. Identification of ta-siRNAs and Cis-nat-siRNAs in Cassava and Their Roles in Response to Cassava Bacterial Blight

    PubMed Central

    Quintero, Andrés; Pérez-Quintero, Alvaro L.; López, Camilo

    2013-01-01

    Trans-acting small interfering RNAs (ta-siRNAs) and natural cis-antisense siRNAs (cis-nat-siRNAs) are recently discovered small RNAs (sRNAs) involved in post-transcriptional gene silencing. ta-siRNAs are transcribed from genomic loci and require processing by microRNAs (miRNAs). cis-nat-siRNAs are derived from antisense RNAs produced by the simultaneous transcription of overlapping antisense genes. Their roles in many plant processes, including pathogen response, are mostly unknown. In this work, we employed a bioinformatic approach to identify ta-siRNAs and cis-nat-siRNAs in cassava from two sRNA libraries, one constructed from healthy cassava plants and one from plants inoculated with the bacterium Xanthomonas axonopodis pv. manihotis (Xam). A total of 54 possible ta-siRNA loci were identified in cassava, including a homolog of TAS3, the best studied plant ta-siRNA. Fifteen of these loci were induced, while 39 were repressed in response to Xam infection. In addition, 15 possible cis-natural antisense transcript (cis-NAT) loci producing siRNAs were identified from overlapping antisense regions in the genome, and were found to be differentially expressed upon Xam infection. Roles of sRNAs were predicted by sequence complementarity and our results showed that many sRNAs identified in this work might be directed against various transcription factors. This work represents a significant step toward understanding the roles of sRNAs in the immune response of cassava. PMID:23665476

  17. Marker-aided Incorporation of Xa38, a Novel Bacterial Blight Resistance Gene, in PB1121 and Comparison of its Resistance Spectrum with xa13 + Xa21.

    PubMed

    Ellur, Ranjith K; Khanna, Apurva; S, Gopala Krishnan; Bhowmick, Prolay K; Vinod, K K; Nagarajan, M; Mondal, Kalyan K; Singh, Nagendra K; Singh, Kuldeep; Prabhu, Kumble Vinod; Singh, Ashok K

    2016-07-11

    Basmati rice is preferred internationally because of its appealing taste, mouth feel and aroma. Pusa Basmati 1121 (PB1121) is a widely grown variety known for its excellent grain and cooking quality in the international and domestic market. It contributes approximately USD 3 billion to India's forex earning annually by being the most traded variety. However, PB1121 is highly susceptible to bacterial blight (BB) disease. A novel BB resistance gene Xa38 was incorporated in PB1121 from donor parent PR114-Xa38 using a modified marker-assisted backcross breeding (MABB) scheme. Phenotypic selection prior to background selection was instrumental in identifying the novel recombinants with maximum recovery of recurrent parent phenome. The strategy was effective in delimiting the linkage drag to <0.5 mb upstream and <1.9 mb downstream of Xa38 with recurrent parent genome recovery upto 96.9% in the developed NILs. The NILs of PB1121 carrying Xa38 were compared with PB1121 NILs carrying xa13 + Xa21 (developed earlier in our lab) for their resistance to BB. Both NILs showed resistance against the Xoo races 1, 2, 3 and 6. Additionally, Xa38 also resisted Xoo race 5 to which xa13 + Xa21 was susceptible. The PB1121 NILs carrying Xa38 gene will provide effective control of BB in the Basmati growing region.

  18. Marker-aided Incorporation of Xa38, a Novel Bacterial Blight Resistance Gene, in PB1121 and Comparison of its Resistance Spectrum with xa13 + Xa21

    PubMed Central

    Ellur, Ranjith K.; Khanna, Apurva; S, Gopala Krishnan.; Bhowmick, Prolay K.; Vinod, K. K.; Nagarajan, M.; Mondal, Kalyan K.; Singh, Nagendra K.; Singh, Kuldeep; Prabhu, Kumble Vinod; Singh, Ashok K.

    2016-01-01

    Basmati rice is preferred internationally because of its appealing taste, mouth feel and aroma. Pusa Basmati 1121 (PB1121) is a widely grown variety known for its excellent grain and cooking quality in the international and domestic market. It contributes approximately USD 3 billion to India’s forex earning annually by being the most traded variety. However, PB1121 is highly susceptible to bacterial blight (BB) disease. A novel BB resistance gene Xa38 was incorporated in PB1121 from donor parent PR114-Xa38 using a modified marker-assisted backcross breeding (MABB) scheme. Phenotypic selection prior to background selection was instrumental in identifying the novel recombinants with maximum recovery of recurrent parent phenome. The strategy was effective in delimiting the linkage drag to <0.5 mb upstream and <1.9 mb downstream of Xa38 with recurrent parent genome recovery upto 96.9% in the developed NILs. The NILs of PB1121 carrying Xa38 were compared with PB1121 NILs carrying xa13 + Xa21 (developed earlier in our lab) for their resistance to BB. Both NILs showed resistance against the Xoo races 1, 2, 3 and 6. Additionally, Xa38 also resisted Xoo race 5 to which xa13 + Xa21 was susceptible. The PB1121 NILs carrying Xa38 gene will provide effective control of BB in the Basmati growing region. PMID:27403778

  19. Expression, crystallization and preliminary X-ray crystallographic analysis of XometC, a cystathionine γ-lyase-like protein from Xanthomonas oryzae pv. oryzae

    SciTech Connect

    Ngo, Phuong-Thuy Ho; Kim, Jin-Kwang; Kim, Hyesoon; Jung, Junho; Ahn, Yeh-Jin; Kim, Jeong-Gu; Lee, Byoung-Moo; Kang, Hee-Wan; Kang, Lin-Woo

    2008-08-01

    XometC, a cystathionine γ-lyase-like protein from X. oryzae pv. oryzae and an antibacterial drug-target protein against bacterial blight, was cloned, purified and crystallized. Preliminary X-ray crystallographic analysis of XometC crystals was carried out. Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight of rice (Oryza sativa L.), one of the most devastating diseases of rice in most rice-growing countries. XometC, a cystathionine γ-lyase (CGL) like protein that is an antibacterial drug-target protein against Xoo, was cloned, expressed, purified and crystallized. CGL catalyzes the second step in the reverse-transsulfuration pathway, which is essential for the metabolic interconversion of the sulfur-containing amino acids cysteine and methionine. Crystals of two different shapes, plate-shaped and pyramid-shaped, diffracted to 2.9 and 3.2 Å resolution and belonged to the primitive orthogonal space group P2{sub 1}2{sub 1}2{sub 1} and the tetragonal space group P4{sub 1} (or P4{sub 3}), with unit-cell parameters a = 73.0, b = 144.9, c = 152.3 Å and a = b = 78.2, c = 300.7 Å, respectively. For the P2{sub 1}2{sub 1}2{sub 1} crystals, three or four monomers exist in the asymmetric unit with a corresponding V{sub M} of 3.02 or 2.26 Å{sup 3} Da{sup −1} and a solvent content of 59.3 or 45.7%. For the P4{sub 1} (or P4{sub 3}) crystals, four or five monomers exist in the asymmetric unit with a corresponding V{sub M} of 2.59 or 2.09 Å{sup 3} Da{sup −1} and a solvent content of 52.5 or 40.6%.

  20. Ascochyta blight of chickpeas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chickpea is becoming increasingly important as a rotational crop in cereal production systems. Ascochyta blight is the most devastating disease of chickpea and must be appropriately managed to minimize its damage to crops and increase chickpea yield. The disease is caused by the fungus Ascochyta r...

  1. Disease Alert: Stemphylium Blight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lentil leaves showing symptoms of Stemphylium blight were collected from a lentil field northeast of Garfield (near Idaho border) on July 8, 2013, and incubation of the diseased leaves showed typical spores of the pathogen Stemphylium botryosum or other Stemphylium sp. The field was planted with ‘Mo...

  2. Rootstock-regulated gene expression patterns associated with fire blight resistance in apple

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Desirable apple varieties are clonally propagated by grafting vegetative scions onto rootstocks. Rootstocks influence many phenotypic traits of the scion, including resistance to pathogens such as Erwinia amylovora, which causes fire blight, the most serious bacterial disease of apple....

  3. Expression, crystallization and preliminary X-ray crystallographic analysis of Xoo0352, D-alanine-D-alanine ligase A, from Xanthomonas oryzae pv. oryzae.

    PubMed

    Doan, Thanh Thi Ngoc; Kim, Jin-Kwang; Kim, Hyesoon; Ahn, Yeh-Jin; Kim, Jeong-Gu; Lee, Byoung-Moo; Kang, Lin-Woo

    2008-12-01

    Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight (BB), which is one of the most devastating diseases of rice in most rice-growing countries. D-Alanine-D-alanine ligase A (DdlA), coded by the Xoo0352 gene, was expressed, purified and crystallized. DdlA is an enzyme that is involved in D-alanine metabolism and the biosynthesis of an essential bacterial peptidoglycan precursor, in which it catalyzes the formation of D-alanyl-D-alanine from two D-alanines, and is thus an attractive antibacterial drug target against Xoo. The DdlA crystals diffracted to 2.3 A resolution and belonged to the primitive tetragonal space group P4(3)2(1)2, with unit-cell parameters a = b = 83.0, c = 97.6 A. There is one molecule in the asymmetric unit, with a corresponding V(M) of 1.88 A(3) Da(-1) and a solvent content of 34.6%. The initial structure was determined by molecular replacement using D-alanine-D-alanine ligase from Staphylococcus aureus (PDB code 2i87) as a template model.

  4. Cloning, expression, crystallization and preliminary X-ray crystallographic analysis of beta-ketoacyl-ACP synthase III (FabH) from Xanthomonas oryzae pv. oryzae.

    PubMed

    Huynh, Kim Hung; Natarajan, Sampath; Song, Na Hyun; Ngo, Phuong Thuy Ho; Ahn, Yeh Jin; Kim, Jeong Gu; Lee, Byoung Moo; Eo, Yang Dam; Kang, Lin Woo

    2009-05-01

    The bacterial beta-ketoacyl-ACP synthase III (KASIII) encoded by the gene fabH (Xoo4209) from Xanthomonas oryzae pv. oryzae, a plant pathogen, is an important enzyme in the elongation steps of fatty-acid biosynthesis. It is expected to be one of the enzymes responsible for bacterial blight (BB), a serious disease that results in huge production losses of rice. As it represents an important target for the development of new antibacterial drugs against BB, determination of the crystal structure of the KAS III enzyme is essential in order to understand its reaction mechanism. In order to analyze the structure and function of KAS III, the fabH (Xoo4209) gene was cloned and the enzyme was expressed and purified. The KASIII crystal diffracted to 2.05 A resolution and belonged to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 69.8, b = 79.5, c = 62.3 A. The unit-cell volume of the crystal is compatible with the presence of a single monomer in the asymmetric unit, with a corresponding Matthews coefficient V(M) of 2.27 A(3) Da(-1) and a solvent content of 45.8%.

  5. CatB is Critical for Total Catalase Activity and Reduces Bactericidal Effects of Phenazine-1-Carboxylic Acid on Xanthomonas oryzae pv. oryzae and X. oryzae pv. oryzicola.

    PubMed

    Pan, Xiayan; Wu, Jian; Xu, Shu; Duan, Yabing; Zhou, Mingguo

    2017-02-01

    Rice bacterial leaf blight, caused by Xanthomonas oryzae pv. oryzae, and rice bacterial leaf streak, caused by X. oryzae pv. oryzicola, are major diseases of rice. Phenazine-1-carboxylic acid (PCA) is a natural product that is isolated from Pseudomonas spp. and is used to control many important rice diseases in China. We previously reported that PCA disturbs the redox balance, which results in the accumulation of reactive oxygen species in X. oryzae pv. oryzae. In this study, we found that PCA significantly upregulated the transcript levels of catB and katE, which encode catalases, and that PCA sensitivity was reduced when X. oryzae pvs. oryzae and oryzicola were cultured with exogenous catalase. Furthermore, catB deletion mutants of X. oryzae pvs. oryzae and oryzicola showed dramatically decreased total catalase activity, increased sensitivity to PCA, and reduced virulence in rice. In contrast, deletion mutants of srpA and katG, which also encode catalases, exhibited little change in PCA sensitivity. The results indicate that catB in both X. oryzae pvs. oryzae and oryzicola encodes a catalase that helps protect the bacteria against PCA-induced stress.

  6. Pathotype and Genetic Diversity amongst Indian Isolates of Xanthomonas oryzae pv. oryzae

    PubMed Central

    Mishra, Deo; Vishnupriya, Manne Ramachander; Anil, Madhusoodana Girija; Konda, Kotilingam; Raj, Yog; Sonti, Ramesh V.

    2013-01-01

    A number of rice resistance genes, called Xa genes, have been identified that confer resistance against various strains of Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial blight. An understanding of pathotype diversity within the target pathogen population is required for identifying the Xa genes that are to be deployed for development of resistant rice cultivars. Among 1024 isolates of Xoo collected from 20 different states of India, 11 major pathotypes were distinguished based on their reaction towards ten Xa genes (Xa1, Xa3, Xa4, xa5, Xa7, xa8, Xa10, Xa11, xa13, Xa21). Isolates belonging to pathotype III showing incompatible interaction towards xa8, xa13 and Xa21 and compatible interaction towards the rest of Xa genes formed the most frequent (41%) and widely distributed pathotype. The vast majority of the assayed Xoo isolates were incompatible with one or more Xa genes. Exceptionally, the isolates of pathotype XI were virulent on all Xa genes, but have restricted distribution. Considering the individual R-genes, Xa21 appeared as the most broadly effective, conferring resistance against 88 % of the isolates, followed in decreasing order by xa13 (84 %), xa8 (64 %), xa5 (30 %), Xa7 (17 %) and Xa4 (14 %). Fifty isolates representing all the eleven pathotypes were analyzed by southern hybridization to determine their genetic relatedness using the IS1112 repeat element of Xoo. Isolates belonging to pathotype XI were the most divergent. The results suggest that one RFLP haplotype that is widely distributed all over India and is represented in strains from five different pathotypes might be an ancestral haplotype. A rice line with xa5, xa13 and Xa21 resistance genes is resistant to all strains, including those belonging to pathotype XI. This three gene combination appears to be the most suitable Xa gene combination to be deployed in Indian rice cultivars. PMID:24312391

  7. Pathotype and genetic diversity amongst Indian isolates of Xanthomonas oryzae pv. oryzae.

    PubMed

    Mishra, Deo; Vishnupriya, Manne Ramachander; Anil, Madhusoodana Girija; Konda, Kotilingam; Raj, Yog; Sonti, Ramesh V

    2013-01-01

    A number of rice resistance genes, called Xa genes, have been identified that confer resistance against various strains of Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial blight. An understanding of pathotype diversity within the target pathogen population is required for identifying the Xa genes that are to be deployed for development of resistant rice cultivars. Among 1024 isolates of Xoo collected from 20 different states of India, 11 major pathotypes were distinguished based on their reaction towards ten Xa genes (Xa1, Xa3, Xa4, xa5, Xa7, xa8, Xa10, Xa11, xa13, Xa21). Isolates belonging to pathotype III showing incompatible interaction towards xa8, xa13 and Xa21 and compatible interaction towards the rest of Xa genes formed the most frequent (41%) and widely distributed pathotype. The vast majority of the assayed Xoo isolates were incompatible with one or more Xa genes. Exceptionally, the isolates of pathotype XI were virulent on all Xa genes, but have restricted distribution. Considering the individual R-genes, Xa21 appeared as the most broadly effective, conferring resistance against 88 % of the isolates, followed in decreasing order by xa13 (84 %), xa8 (64 %), xa5 (30 %), Xa7 (17 %) and Xa4 (14 %). Fifty isolates representing all the eleven pathotypes were analyzed by southern hybridization to determine their genetic relatedness using the IS1112 repeat element of Xoo. Isolates belonging to pathotype XI were the most divergent. The results suggest that one RFLP haplotype that is widely distributed all over India and is represented in strains from five different pathotypes might be an ancestral haplotype. A rice line with xa5, xa13 and Xa21 resistance genes is resistant to all strains, including those belonging to pathotype XI. This three gene combination appears to be the most suitable Xa gene combination to be deployed in Indian rice cultivars.

  8. [SERS spectra of Xanthomonas oryzae pv. Oryzae (Xoo) on nano silver film prepared by electrolysis method].

    PubMed

    Kang, Yi-Pu; Si, Min-Zhen; Li, Qing-Yu; Huang, Qiong; Liu, Ren-Ming

    2010-02-01

    The nano silver film was prepared by electrolysis method using silver nitrate and polyvinyl alcohol (PVA) in deionized water as the electrolyte, with four glass slides put in the electrolyte and two silver rods dipped into the electrolyte as the anode and cathode. A direct current was applied to the rods, then the four glass slides stayed in the silver colloids. Thus the authors got the nano silver film. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to detect the silver particles in the silver colloids and on the nano silver film. From the SEM we can see that the silver particles on the film formed different layers. In one layer, the distance between two particles was about 100 nm. The samples of Xanthomonas oryzae pv. Oryzae (Xoo) were 7 different kinds of bacterial blight, namely 1-YN1, 2-YN7, 3-YN11, 4-GD414, 5-SCYC6, 6-HEN11 and 7-FWJ. Because the silver particles in the colloids were aggregated on the film, there was large electromagnetic potentiation. So the SERS spectra of Xoo were perfect. The authors used the area analytical method to distinguish the different kinds of Xoo. The silver film prepared by electrolysis was cheap and active, the preparation time of the samples was short, and any normal chemistry lab can make it, which can find excellent application to detecting the Xoo in agriculture. On the other hand, this film is active on biomolecules and bioorganism, which may be a new kind of SERS fundus to explain the creation of the SERS. Further study was under way.

  9. Dispersal of Xanthomonas citri subsp. citri bacteria downwind from harvested, infected fruit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus canker (Xanthomonas axonopodis pv. citri , Xac) is a bacterial disease that severely damages citrus crops. Its recent introduction to Florida has created difficulties with international and domestic trade and movement of citrus material. This study examined the potential dispersal of bacteri...

  10. OryR is a LuxR-family protein involved in interkingdom signaling between pathogenic Xanthomonas oryzae pv. oryzae and rice.

    PubMed

    Ferluga, Sara; Venturi, Vittorio

    2009-02-01

    Xanthomonas oryzae pv. oryzae, the causal agent of bacterial leaf blight in rice, contains a regulator that is encoded in the genome, designated OryR, which belongs to the N-acyl homoserine lactone (AHL)-dependent quorum-sensing LuxR subfamily of proteins. However, we previously reported that X. oryzae pv. oryzae does not make AHLs and does not possess a LuxI-family AHL synthase and that the OryR protein is solubilized by a compound present in rice. In this study we obtained further evidence that OryR interacts with a rice signal molecule (RSM) and that the OryR concentration increases when rice is infected with X. oryzae pv. oryzae. We also describe three OryR target promoters which are regulated differently: (i) the neighboring proline iminopeptidase (pip) virulence gene, which is positively regulated by OryR in the presence of the RSM; (ii) the oryR promoter, which is negatively autoregulated independent of the RSM; and (iii) the 1,4-beta-cellobiosidase cbsA gene, which is positively regulated by OryR independent of the RSM. We also found that the RSM for OryR is small, is not related to AHLs, and is not able to activate the broad-range AHL biosensor Agrobacterium tumefaciens NT1(pZLQR). Furthermore, OryR does not regulate production of the quorum-sensing diffusible signal factor present in the genus Xanthomonas. Therefore, OryR has unique features and is an important regulator involved in interkingdom communication between the host and the pathogen.

  11. AnnoTALE: bioinformatics tools for identification, annotation, and nomenclature of TALEs from Xanthomonas genomic sequences

    PubMed Central

    Grau, Jan; Reschke, Maik; Erkes, Annett; Streubel, Jana; Morgan, Richard D.; Wilson, Geoffrey G.; Koebnik, Ralf; Boch, Jens

    2016-01-01

    Transcription activator-like effectors (TALEs) are virulence factors, produced by the bacterial plant-pathogen Xanthomonas, that function as gene activators inside plant cells. Although the contribution of individual TALEs to infectivity has been shown, the specific roles of most TALEs, and the overall TALE diversity in Xanthomonas spp. is not known. TALEs possess a highly repetitive DNA-binding domain, which is notoriously difficult to sequence. Here, we describe an improved method for characterizing TALE genes by the use of PacBio sequencing. We present ‘AnnoTALE’, a suite of applications for the analysis and annotation of TALE genes from Xanthomonas genomes, and for grouping similar TALEs into classes. Based on these classes, we propose a unified nomenclature for Xanthomonas TALEs that reveals similarities pointing to related functionalities. This new classification enables us to compare related TALEs and to identify base substitutions responsible for the evolution of TALE specificities. PMID:26876161

  12. Putative resistance gene markers associated with quantitative trait loci for fire blight resistance in Malus 'Robusta 5' accessions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Breeding of fire blight resistant scions and rootstocks is a goal of several international apple breeding programs, as options are limited for management of this destructive disease caused by the bacterial pathogen Erwinia amylovora. A broad, large effect QTL for fire blight resistance has been pre...

  13. The degenerate EAL-GGDEF domain protein Filp functions as a cyclic di-GMP receptor and specifically interacts with the PilZ-domain protein PXO_02715 to regulate virulence in Xanthomonas oryzae pv. oryzae.

    PubMed

    Yang, Fenghuan; Tian, Fang; Li, Xiaotong; Fan, Susu; Chen, Huamin; Wu, Maosen; Yang, Ching-Hong; He, Chenyang

    2014-06-01

    Degenerate GGDEF and EAL domain proteins represent major types of cyclic diguanylic acid (c-di-GMP) receptors in pathogenic bacteria. Here, we characterized a FimX-like protein (Filp) which possesses both GGDEF and EAL domains in Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight of rice. Both in silico analysis and enzyme assays indicated that the GGDEF and EAL domains of Filp were degenerate and enzymatically inactive. However, Filp bound to c-di-GMP efficiently within the EAL domain, where Q(477), E(653), and F(654) residues were crucial for the binding. Deletion of the filp gene in X. oryzae pv. oryzae resulted in attenuated virulence in rice and reduced type III secretion system (T3SS) gene expression. Complementation analysis with different truncated proteins indicated that REC, PAS, and EAL domains but not the GGDEF domain were required for the full activity of Filp in vivo. In addition, a PilZ-domain protein (PXO_02715) was identified as a Filp interactor by yeast two-hybrid and glutathione-S-transferase pull-down assays. Deletion of the PXO_02715 gene demonstrated changes in bacterial virulence and T3SS gene expression similar to Δfilp. Moreover, both mutants were impaired in their ability to induce hypersensitive response in nonhost plants. Thus, we concluded that Filp was a novel c-di-GMP receptor of X. oryzae pv. oryzae, and its function to regulate bacterial virulence expression might be via the interaction with PXO_02715.

  14. The bacterial effector DspA/E is toxic in Arabidopsis thaliana and is required for multiplication and survival of fire blight pathogen.

    PubMed

    Degrave, Alexandre; Moreau, Manon; Launay, Alban; Barny, Marie-Anne; Brisset, Marie-Noëlle; Patrit, Oriane; Taconnat, Ludivine; Vedel, Regine; Fagard, Mathilde

    2013-06-01

    The type III effector DspA/E is an essential pathogenicity factor of the phytopathogenic bacterium Erwinia amylovora. We showed that DspA/E was required for transient bacterial growth in nonhost Arabidopsis thaliana leaves, as an E. amylovora dspA/E mutant was unable to grow. We expressed DspA/E in A. thaliana transgenic plants under the control of an oestradiol-inducible promoter, and found that DspA/E expressed in planta restored the growth of a dspA/E mutant. DspA/E expression in these transgenic plants led to the modulation by at least two-fold of the expression of 384 genes, mostly induced (324 genes). Both induced and repressed genes contained high proportions of defence genes. DspA/E expression ultimately resulted in plant cell death without requiring a functional salicylic acid signalling pathway. Analysis of A. thaliana transgenic seedlings expressing a green fluorescent protein (GFP):DspA/E fusion indicated that the fusion protein could only be detected in a few cells per seedling, suggesting the degradation or absence of accumulation of DspA/E in plant cells. Consistently, we found that DspA/E repressed plant protein synthesis when injected by E. amylovora or when expressed in transgenic plants. Thus, we conclude that DspA/E is toxic to A. thaliana: it promotes modifications, among which the repression of protein synthesis could be determinant in the facilitation of necrosis and bacterial growth.

  15. Polyphasic characterization of xanthomonads pathogenic to members of the Anacardiaceae and their relatedness to species of Xanthomonas.

    PubMed

    Ah-You, N; Gagnevin, L; Grimont, P A D; Brisse, S; Nesme, X; Chiroleu, F; Bui Thi Ngoc, L; Jouen, E; Lefeuvre, P; Vernière, C; Pruvost, O

    2009-02-01

    We have used amplified fragment length polymorphism (AFLP), multilocus sequence analysis (MLSA) and DNA-DNA hybridization for genotypic classification of Xanthomonas pathovars associated with the plant family Anacardiaceae. AFLP and MLSA results showed congruent phylogenetic relationships of the pathovar mangiferaeindicae (responsible for mango bacterial canker) with strains of Xanthomonas axonopodis subgroup 9.5. This subgroup includes X. axonopodis pv. citri (synonym Xanthomonas citri). Similarly, the pathovar anacardii, which causes cashew bacterial spot in Brazil, was included in X. axonopodis subgroup 9.6 (synonym Xanthomonas fuscans). Based on the thermal stability of DNA reassociation, consistent with the AFLP and MLSA data, the two pathovars share a level of similarity consistent with their being members of the same species. The recent proposal to elevate X. axonopodis pv. citri to species level as X. citri is supported by our data. Therefore, the causal agents of mango bacterial canker and cashew bacterial spot should be classified as pathovars of X. citri, namely X. citri pv. mangiferaeindicae (pathotype strain CFBP 1716) and X. citri pv. anacardii (pathotype strain CFBP 2913), respectively. Xanthomonas fuscans should be considered to be a later heterotypic synonym of Xanthomonas citri.

  16. The quantitative regulation of the hrp regulator HrpX is involved in sugar-source-dependent hrp gene expression in Xanthomonas oryzae pv. oryzae.

    PubMed

    Ikawa, Yumi; Tsuge, Seiji

    2016-05-01

    In Xanthomonas oryzae pv. oryzae, the pathogen of bacterial leaf blight of rice, hrp gene expression is regulated by the key hrp regulators HrpG and HrpX. HrpG regulates hrpX and hrpA, and HrpX regulates the other hrp genes on hrpB-hrpF operons. We previously examined the expression of the HrpX-regulated hrp gene hrcU and demonstrated that hrp gene expression is highly induced in a certain nutrient-poor medium containing xylose. In the present study, we found that the induction level of HrpX-regulated hrp genes was higher in medium with xylose than in media with any other sugar sources (glucose, sucrose and fructose), but that expression of hrpG, hrpX and hrpA was independent of the sugar sources. In western blot analysis, the accumulation of HrpX was reduced in media with a sugar other than xylose, probably as a result of proteolysis, but the addition of xylose canceled this reduced accumulation of the protein. The results suggest that proteolysis of HrpX is an important hrp regulatory mechanism and that xylose specifically suppresses this proteolysis, resulting in active hrp gene expression in X. oryzae pv. oryzae.

  17. Expression, crystallization and preliminary X-ray crystallographic analysis of Xoo2316, a predicted 6-phosphogluconolactonase, from Xanthomonas oryzae pv. oryzae.

    PubMed

    Hong, Myoung-Ki; Kim, Jin-Kwang; Kim, Hyesoon; Jung, Junho; Ahn, Yeh-Jin; Kim, Jeong-Gu; Lee, Byoung-Moo; Kang, Lin-Woo

    2008-11-01

    Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight, which is one of the most devastating diseases of rice (Oryza sativa L.) in many rice-growing countries. The coding sequence of Xoo2316 (a predicted 6-phosphogluconolactonase; 6PGL) from Xoo was cloned and expressed in Escherichia coli. 6PGL is an enzyme that is involved in the second step of the pentose phosphate pathway, which is essential for the synthesis of nucleotide sugars and NADPH, the main source of reducing power. The protein was purified and crystallized in order to elucidate the molecular basis for its enzymatic reaction. Native crystals diffracted to 2.4 A resolution and belonged to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 40.0, b = 65.1, c = 78.8 A. A monomer exists in the asymmetric unit with a corresponding V(M) of 1.93 A(3) Da(-1) and a solvent content of 36.5%.

  18. Cloning, expression, crystallization and preliminary X-ray crystallographic analysis of 3-dehydroquinate synthase, Xoo1243, from Xanthomonas oryzae pv. oryzae.

    PubMed

    Ngo, Phuong-Thuy Ho; Natarajan, Sampath; Kim, Hyesoon; Hung, Huynh Kim; Kim, Jeong-Gu; Lee, Byoung-Moo; Ahn, Yeh-Jin; Kang, Lin-Woo

    2008-12-01

    The disease bacterial blight results in serious production losses of rice in Asian countries. The aroB gene encoding dehydroquinate synthase (DHQS), which is a potential antibiotic target, was identified from the plant-pathogenic bacterium Xanthomonas oryzae pv. oryzae (Xoo). DHQS plays an essential role in the synthesis of aromatic compounds in the shikimate pathway. The aroB gene (Xoo1243) was cloned from Xoo and the corresponding DHQS protein was subsequently overexpressed in Escherichia coli. The purified protein was crystallized using the hanging-drop vapour-diffusion method and yielded crystals that diffracted to 2.5 A resolution. The crystals belonged to the tetragonal space group P4(3)2(1)2, with unit-cell parameters a = b = 118.2, c = 98.2 A. According to a Matthews coefficient calculation, the crystal contained two molecules in the asymmetric unit, with a corresponding V(M) of 2.06 A(3) Da(-1) and a solvent content of 40.4%.

  19. Cloning, expression, crystallization and preliminary X-ray crystallographic analysis of glutamyl-tRNA synthetase (Xoo1504) from Xanthomonas oryzae pv. oryzae.

    PubMed

    Doan, Thanh Thi Ngoc; Natarajan, Sampath; Kim, Hyesoon; Ahn, Yeh-Jin; Kim, Jeong-Gu; Lee, Byoung-Moo; Kang, Lin-Woo

    2009-01-01

    The gltX gene from Xanthomonas oryzae pv. oryzae (Xoo1504) encodes glutamyl-tRNA synthetase (GluRS), one of the most important enzymes involved in bacterial blight (BB), which causes huge production losses of rice worldwide. GluRS is a class I-type aminoacyl-tRNA synthetase (aaRS) that is primarily responsible for the glutamylation of tRNA(Glu). It plays an essential role in protein synthesis, as well as the regulation of cells, in all organisms. As it represents an important target for the development of new antibacterial drugs against BB, determination of the three-dimensional structure of GluRS is essential in order to understand its catalytic mechanism. In order to analyze its structure and function, the gltX gene was cloned and the GluRS enzyme was expressed, purified and then crystallized. A GluRS crystal belonging to the monoclinic space group C2 diffracted to 2.8 A resolution and had unit-cell parameters a = 186.8, b = 108.4, c = 166.1 A, beta = 96.3 degrees . The unit-cell volume of the crystal allowed the presence of six to eight monomers in the asymmetric unit, with a corresponding Matthews coefficient (V(M)) range of 2.70-2.02 A(3) Da(-1) and a solvent-content range of 54.5-39.3%.

  20. Crystallization and preliminary X-ray crystallographic analysis of β-ketoacyl-ACP synthase I (XoFabB) from Xanthomonas oryzae pv. oryzae.

    PubMed

    Doan, Thanh Thi Ngoc; Kim, Jin Kwang; Mac, Qui Khanh; Chung, Cheolwon; Sampath, Natarajan; Kim, Jeong Gu; Ahn, Yeh Jin; Kang, Lin Woo

    2011-12-01

    The proteins in the fatty-acid synthesis pathway in bacteria have significant potential as targets for the development of antibacterial agents. An essential elongation step in fatty-acid synthesis is performed by β-ketoacyl-acyl carrier protein synthase I (FabB). The organism Xanthomonas oryzae pv. oryzae (Xoo) causes a destructive bacterial blight disease of rice. The XoFabB protein from Xoo was expressed, purified and crystallized for the three-dimensional structure determination that is essential for the development of specific inhibitors of the enzyme. An XoFabB crystal diffracted to 3.0 Å resolution and belonged to the tetragonal space group P4(1), with unit-cell parameters a = b = 82.2, c = 233.2 Å. Assuming that the crystallographic structure contains four molecules in the asymmetric unit, the corresponding V(M) would be 2.18 Å(3) Da(-1) and the solvent content would be 43.5%. The initial structure was determined by the MOLREP program with an R factor of 44.0% and does contain four monomers in the asymmetric unit.

  1. Cloning, expression, crystallization and preliminary X-ray crystallographic analysis of malonyl-CoA-acyl carrier protein transacylase (FabD) from Xanthomonas oryzae pv. oryzae.

    PubMed

    Jung, Jae-Wook; Natarajan, Sampath; Kim, Hyesoon; Ahn, Yeh-Jin; Kim, Seunghwan; Kim, Jeong-Gu; Lee, Byoung-Moo; Kang, Lin-Woo

    2008-12-01

    Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight in rice, which is one of the most devastating diseases in rice-cultivating countries. The Xoo0880 (fabD) gene coding for a malonyl-CoA-acyl carrier protein transacylase (MCAT) from Xoo was cloned and expressed in Escherichia coli. MCAT is an essential enzyme that catalyzes a key reaction of fatty-acid synthesis in bacteria and plants: the conversion of malonyl-CoA to malonyl-acyl carrier protein. The FabD enzyme was purified and crystallized in order to elucidate its three-dimensional structure and to determine its enzymatic reaction mechanism and biological importance. The crystal obtained diffracted to 1.9 A resolution and belonged to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 41.4, b = 74.6, c = 98.5 A. According to Matthews coefficient calculations, the crystallographic structure contains only one monomeric unit in the asymmetric unit with a V(M) of 2.21 A(3) Da(-1) and a solvent content of 44.3%.

  2. Cloning, expression, crystallization and preliminary X-ray crystallographic analysis of the co-chaperonin XoGroES from Xanthomonas oryzae pv. oryzae.

    PubMed

    Doan, Thanh Thi Ngoc; Natarajan, Sampath; Song, Na-Hyun; Kim, Jisun; Kim, Jin-Kwang; Kim, Seung-hwan; Viet, Pham Tan; Kim, Jeong-Gu; Lee, Byoung-Moo; Ahn, Yeh-Jin; Kang, Lin-Woo

    2011-01-01

    Bacterial blight (BB), a devastating disease caused by Xanthomonas oryzae pv. oryzae (Xoo), causes serious production losses of rice in Asian countries. Protein misfolding may interfere with the function of proteins in all living cells and must be prevented to avoid cellular disaster. All cells naturally contain molecular chaperones that assist the unfolded proteins in folding into the native structure. One of the well characterized chaperone complexes is GroEL-GroES. GroEL, which consists of two chambers, captures misfolded proteins and refolds them. GroES is a co-chaperonin protein that assists the GroEL protein as a lid that temporarily closes the chamber during the folding process. Xoo4289, the GroES gene from Xoo, was cloned and expressed for X-ray crystallographic study. The purified protein (XoGroES) was crystallized using the hanging-drop vapour-diffusion method and a crystal diffracted to 2.0 Å resolution. The crystal belonged to the hexagonal space group P6(1), with unit-cell parameters a=64.4, c=36.5 Å. The crystal contains a single molecule in the asymmetric unit, with a corresponding VM of 2.05 Å3 Da(-1) and a solvent content of 39.9%.

  3. Induction of antimicrobial 3-deoxyflavonoids in pome fruit trees controls fire blight.

    PubMed

    Halbwirth, Heidrun; Fischer, Thilo C; Roemmelt, Susanne; Spinelli, Francesco; Schlangen, Karin; Peterek, Silke; Sabatini, Emidio; Messina, Christian; Speakman, John-Bryan; Andreotti, Carlo; Rademacher, Wilhelm; Bazzi, Carlo; Costa, Guglielmo; Treutter, Dieter; Forkmann, Gert; Stich, Karl

    2003-01-01

    Fire blight, a devastating bacterial disease in pome fruits, causes severe economic losses worldwide. Hitherto, an effective control could only be achieved by using antibiotics, but this implies potential risks for human health, livestock and environment. A new approach allows transient inhibition of a step in the flavonoid pathway, thereby inducing the formation of a novel antimicrobial 3-deoxyflavonoid controlling fire blight in apple and pear leaves. This compound is closely related to natural phytoalexins in sorghum. The approach does not only provide a safe method to control fire blight: Resistance against different pathogens is also induced in other crop plants.

  4. Identification of New Sources of Resistance to Xanthomonas translucens pv. undulosa in Winter Wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    : Bacterial leaf streak (BLS) caused by Xanthomonas translucens pv. undulosa, has emerged as an important disease of wheat in the United States. Planting resistant varieties offers the best strategy to manage BLS in the absence of effective bactericides. However, most of the wheat varieties current...

  5. Pathogenic and genetic diversity of Xanthomonas translucens pv. undulosa populations in North Dakota

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Xanthomonas translucens pv. undulosa causes bacterial leaf streak (BLS) disease in wheat (Triticum aestivum L.). In recent years, severe BLS outbreaks have been reported in the Upper Midwest of the United States, particularly in North Dakota and adjacent wheat growing states. To assess pathogenic an...

  6. Draft genome of the xanthan producer Xanthomonas campestris NRRL B-1459 (ATCC 13951).

    PubMed

    Wibberg, Daniel; Alkhateeb, Rabeaa S; Winkler, Anika; Albersmeier, Andreas; Schatschneider, Sarah; Albaum, Stefan; Niehaus, Karsten; Hublik, Gerd; Pühler, Alfred; Vorhölter, Frank-Jörg

    2015-06-20

    Xanthomonas campestris NRRL B-1459 was used in pioneering studies related to the biotechnological production of xanthan, the commercially most important polysaccharide of bacterial origin. The analysis of its genome revealed a 5.1Mb chromosome plus the first complete plasmid of an X. campestris strain applied in biotechnology.

  7. Identification of Pectin Degrading Enzymes Secreted by Xanthomonas oryzae pv. oryzae and Determination of Their Role in Virulence on Rice

    PubMed Central

    Tayi, Lavanya; Maku, Roshan V.; Patel, Hitendra Kumar; Sonti, Ramesh V.

    2016-01-01

    Xanthomonas oryzae pv.oryzae (Xoo) causes the serious bacterial blight disease of rice. Xoo secretes a repertoire of plant cell wall degrading enzymes (CWDEs) like cellulases, xylanases, esterases etc., which act on various components of the rice cell wall. The major cellulases and xylanases secreted by Xoo have been identified and their role in virulence has been determined. In this study, we have identified some of the pectin degrading enzymes of Xoo and assessed their role in virulence. Bioinformatics analysis indicated the presence of four pectin homogalacturonan (HG) degrading genes in the genome of Xoo. The four HG degrading genes include one polygalacturonase (pglA), one pectin methyl esterase (pmt) and two pectate lyases (pel and pelL). There was no difference in the expression of pglA, pmt and pel genes by laboratory wild type Xoo strain (BXO43) grown in either nutrient rich PS medium or in plant mimic XOM2 medium whereas the expression of pelL gene was induced in XOM2 medium as indicated by qRT-PCR experiments. Gene disruption mutations were generated in each of these four genes. The polygalacturonase mutant pglA- was completely deficient in degrading the substrate Na-polygalacturonicacid (PGA). Strains carrying mutations in the pmt, pel and pelL genes were as efficient as wild type Xoo (BXO43) in cleaving PGA. These observations clearly indicate that PglA is the major pectin degrading enzyme produced by Xoo. The pectin methyl esterase, Pmt, is the pectin de-esterifying enzyme secreted by Xoo as evident from the enzymatic activity assay performed using pectin as the substrate. Mutations in the pglA, pmt, pel and pelL genes have minimal effects on virulence. This suggests that, as compared to cellulases and xylanases, the HG degrading enzymes may not have a major role in the pathogenicity of Xoo. PMID:27907079

  8. Development of late blight resistant potatoes by cisgene stacking

    PubMed Central

    2014-01-01

    Background Phytophthora infestans, causing late blight in potato, remains one of the most devastating pathogens in potato production and late blight resistance is a top priority in potato breeding. The introduction of multiple resistance (R) genes with different spectra from crossable species into potato varieties is required. Cisgenesis is a promising approach that introduces native genes from the crops own gene pool using GM technology, thereby retaining favourable characteristics of established varieties. Results We pursued a cisgenesis approach to introduce two broad spectrum potato late blight R genes, Rpi-sto1 and Rpi-vnt1.1 from the crossable species Solanum stoloniferum and Solanum venturii, respectively, into three different potato varieties. First, single R gene-containing transgenic plants were produced for all varieties to be used as references for the resistance levels and spectra to be expected in the respective genetic backgrounds. Next, a construct containing both cisgenic late blight R genes (Rpi-vnt1.1 and Rpi-sto1), but lacking the bacterial kanamycin resistance selection marker (NPTII) was transformed to the three selected potato varieties using Agrobacterium-mediated transformation. Gene transfer events were selected by PCR among regenerated shoots. Through further analyses involving morphological evaluations in the greenhouse, responsiveness to Avr genes and late blight resistance in detached leaf assays, the selection was narrowed down to eight independent events. These cisgenic events were selected because they showed broad spectrum late blight resistance due to the activity of both introduced R genes. The marker-free transformation was compared to kanamycin resistance assisted transformation in terms of T-DNA and vector backbone integration frequency. Also, differences in regeneration time and genotype dependency were evaluated. Conclusions We developed a marker-free transformation pipeline to select potato plants functionally expressing a

  9. Chemical products induce resistance to Xanthomonas perforans in tomato

    PubMed Central

    Itako, Adriana Terumi; Tolentino, João Batista; da Silva, Tadeu Antônio Fernandes; Soman, José Marcelo; Maringoni, Antonio Carlos

    2015-01-01

    The bacterial spot of tomato, caused by Xanthomonas spp., is a very important disease, especially in the hot and humid periods of the year. The chemical control of the disease has not been very effective for a number of reasons. This study aimed to evaluate, under greenhouse conditions, the efficacy of leaf-spraying chemicals (acibenzolar-S-methyl (ASM) (0.025 g.L−1), fluazinam (0.25 g.L−1), pyraclostrobin (0.08 g.L−1), pyraclostrobin + methiran (0.02 g.L−1 + 2.2 g.L−1), copper oxychloride (1.50 g.L−1), mancozeb + copper oxychloride (0.88 g.L−1 + 0.60 g.L−1), and oxytetracycline (0.40 g.L−1)) on control of bacterial spot. Tomatoes Santa Clara and Gisele cultivars were pulverized 3 days before inoculation with Xanthomonas perforans. The production of enzymes associated with resistance induction (peroxidase, polyphenol oxidase, phenylalanine ammonia-lyase, β-1,3-glucanase, and protease) was quantified from leaf samples collected 24 hours before and 24 hours after chemical spraying and at 1, 2, 4, 6, and 8 days after bacterial inoculation. All products tested controlled bacterial spot, but only ASM, pyraclostrobin, and pyraclostrobin + metiram increased the production of peroxidase in the leaves of the two tomato cultivars, and increased the production of polyphenol oxidase and β-1,3-glucanase in the Santa Clara cultivar. PMID:26413050

  10. Overexpression of BSR1 confers broad-spectrum resistance against two bacterial diseases and two major fungal diseases in rice

    PubMed Central

    Maeda, Satoru; Hayashi, Nagao; Sasaya, Takahide; Mori, Masaki

    2016-01-01

    Broad-spectrum disease resistance against two or more types of pathogen species is desirable for crop improvement. In rice, Xanthomonas oryzae pv. oryzae (Xoo), the causal bacteria of rice leaf blight, and Magnaporthe oryzae, the fungal pathogen causing rice blast, are two of the most devastating pathogens. We identified the rice BROAD-SPECTRUM RESISTANCE 1 (BSR1) gene for a BIK1-like receptor-like cytoplasmic kinase using the FOX hunting system, and demonstrated that BSR1-overexpressing (OX) rice showed strong resistance to the bacterial pathogen, Xoo and the fungal pathogen, M. oryzae. Here, we report that BSR1-OX rice showed extended resistance against two other different races of Xoo, and to at least one other race of M. oryzae. In addition, the rice showed resistance to another bacterial species, Burkholderia glumae, which causes bacterial seedling rot and bacterial grain rot, and to Cochliobolus miyabeanus, another fungal species causing brown spot. Furthermore, BSR1-OX rice showed slight resistance to rice stripe disease, a major viral disease caused by rice stripe virus. Thus, we demonstrated that BSR1-OX rice shows remarkable broad-spectrum resistance to at least two major bacterial species and two major fungal species, and slight resistance to one viral pathogen. PMID:27436950

  11. Overexpression of BSR1 confers broad-spectrum resistance against two bacterial diseases and two major fungal diseases in rice.

    PubMed

    Maeda, Satoru; Hayashi, Nagao; Sasaya, Takahide; Mori, Masaki

    2016-06-01

    Broad-spectrum disease resistance against two or more types of pathogen species is desirable for crop improvement. In rice, Xanthomonas oryzae pv. oryzae (Xoo), the causal bacteria of rice leaf blight, and Magnaporthe oryzae, the fungal pathogen causing rice blast, are two of the most devastating pathogens. We identified the rice BROAD-SPECTRUM RESISTANCE 1 (BSR1) gene for a BIK1-like receptor-like cytoplasmic kinase using the FOX hunting system, and demonstrated that BSR1-overexpressing (OX) rice showed strong resistance to the bacterial pathogen, Xoo and the fungal pathogen, M. oryzae. Here, we report that BSR1-OX rice showed extended resistance against two other different races of Xoo, and to at least one other race of M. oryzae. In addition, the rice showed resistance to another bacterial species, Burkholderia glumae, which causes bacterial seedling rot and bacterial grain rot, and to Cochliobolus miyabeanus, another fungal species causing brown spot. Furthermore, BSR1-OX rice showed slight resistance to rice stripe disease, a major viral disease caused by rice stripe virus. Thus, we demonstrated that BSR1-OX rice shows remarkable broad-spectrum resistance to at least two major bacterial species and two major fungal species, and slight resistance to one viral pathogen.

  12. Characterization of a new pathovar of Agrobacterium vitis causing banana leaf blight in China.

    PubMed

    Huang, Siliang; Long, Mengling; Fu, Gang; Lin, Shanhai; Qin, Liping; Hu, Chunjin; Cen, Zhenlu; Lu, Jie; Li, Qiqin

    2015-01-01

    A new banana leaf blight was found in Nanning city, China, during a 7-year survey (2003-2009) of the bacterial diseases on banana plants. Eight bacterial strains were isolated from affected banana leaves, and identified as an intraspecific taxon of Agrobacterium vitis based on their 16S rDNA sequence similarities with those of 37 randomly selected bacterial strains registered in GenBank database. The representative strain Ag-1 was virulent on banana leaves and shared similar growth and biochemical reactions with the reference strain IAM14140 of A. vitis. The strains causing banana leaf blight were denominated as A. vitis pv. musae. The traditional A. vitis strains virulent to grapevines were proposed to be revised as A. vitis pv. vitis. This is the first record of a new type of A. vitis causing banana leaf blight in China.

  13. Late blight – Is resistance futile?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This article will provide an overview of late blight resistance research that has been done within the USDA/ARS and the University of Wisconsin-Madison. The article is meant to be an informative look at the history of late blight resistance and the ability of the late blight pathogen to overcome res...

  14. Suppression of Xo1-Mediated Disease Resistance in Rice by a Truncated, Non-DNA-Binding TAL Effector of Xanthomonas oryzae

    PubMed Central

    Read, Andrew C.; Rinaldi, Fabio C.; Hutin, Mathilde; He, Yong-Qiang; Triplett, Lindsay R.; Bogdanove, Adam J.

    2016-01-01

    Delivered into plant cells by type III secretion from pathogenic Xanthomonas species, TAL (transcription activator-like) effectors are nuclear-localized, DNA-binding proteins that directly activate specific host genes. Targets include genes important for disease, genes that confer resistance, and genes inconsequential to the host-pathogen interaction. TAL effector specificity is encoded by polymorphic repeats of 33–35 amino acids that interact one-to-one with nucleotides in the recognition site. Activity depends also on N-terminal sequences important for DNA binding and C-terminal nuclear localization signals (NLS) and an acidic activation domain (AD). Coding sequences missing much of the N- and C-terminal regions due to conserved, in-frame deletions are present and annotated as pseudogenes in sequenced strains of Xanthomonas oryzae pv. oryzicola (Xoc) and pv. oryzae (Xoo), which cause bacterial leaf streak and bacterial blight of rice, respectively. Here we provide evidence that these sequences encode proteins we call “truncTALEs,” for “truncated TAL effectors.” We show that truncTALE Tal2h of Xoc strain BLS256, and by correlation truncTALEs in other strains, specifically suppress resistance mediated by the Xo1 locus recently described in the heirloom rice variety Carolina Gold. Xo1-mediated resistance is triggered by different TAL effectors from diverse X. oryzae strains, irrespective of their DNA binding specificity, and does not require the AD. This implies a direct protein-protein rather than protein-DNA interaction. Similarly, truncTALEs exhibit diverse predicted DNA recognition specificities. And, in vitro, Tal2h did not bind any of several potential recognition sites. Further, a single candidate NLS sequence in Tal2h was dispensable for resistance suppression. Many truncTALEs have one 28 aa repeat, a length not observed previously. Tested in an engineered TAL effector, this repeat required a single base pair deletion in the DNA, suggesting that it

  15. Genome mining reveals the genus Xanthomonas to be a promising reservoir for new bioactive non-ribosomally synthesized peptides

    PubMed Central

    2013-01-01

    Background Various bacteria can use non-ribosomal peptide synthesis (NRPS) to produce peptides or other small molecules. Conserved features within the NRPS machinery allow the type, and sometimes even the structure, of the synthesized polypeptide to be predicted. Thus, bacterial genome mining via in silico analyses of NRPS genes offers an attractive opportunity to uncover new bioactive non-ribosomally synthesized peptides. Xanthomonas is a large genus of Gram-negative bacteria that cause disease in hundreds of plant species. To date, the only known small molecule synthesized by NRPS in this genus is albicidin produced by Xanthomonas albilineans. This study aims to estimate the biosynthetic potential of Xanthomonas spp. by in silico analyses of NRPS genes with unknown function recently identified in the sequenced genomes of X. albilineans and related species of Xanthomonas. Results We performed in silico analyses of NRPS genes present in all published genome sequences of Xanthomonas spp., as well as in unpublished draft genome sequences of Xanthomonas oryzae pv. oryzae strain BAI3 and Xanthomonas spp. strain XaS3. These two latter strains, together with X. albilineans strain GPE PC73 and X. oryzae pv. oryzae strains X8-1A and X11-5A, possess novel NRPS gene clusters and share related NRPS-associated genes such as those required for the biosynthesis of non-proteinogenic amino acids or the secretion of peptides. In silico prediction of peptide structures according to NRPS architecture suggests eight different peptides, each specific to its producing strain. Interestingly, these eight peptides cannot be assigned to any known gene cluster or related to known compounds from natural product databases. PCR screening of a collection of 94 plant pathogenic bacteria indicates that these novel NRPS gene clusters are specific to the genus Xanthomonas and are also present in Xanthomonas translucens and X. oryzae pv. oryzicola. Further genome mining revealed other novel NRPS

  16. Restoration of pathogenicity of avirulent Xanthomonas oryzae pv. oryzae and X. campestris pathovars by reciprocal complementation with the hrpXo and hrpXc genes and identification of HrpX function by sequence analyses.

    PubMed Central

    Kamdar, H V; Kamoun, S; Kado, C I

    1993-01-01

    The molecular basis of pathogenesis by Xanthomonas oryzae pv. oryzae has been partly elucidated by the identification of a gene, hrpXo, required for bacterial blight on rice. A mutation in hrpXo results in the loss of pathogenicity on rice and the loss of hypersensitivity on nonhosts such as Datura stramonium and radishes. Pathogenicity and its ability to cause the hypersensitive reaction is restored by complementing the mutant with the heterologous hrpXc gene derived from X. campestris pv. campestris. Conversely, hrpXo complements nonpathogenic mutants of X. campestris pv. campestris and X. campetstris pv, armoraciae. Mutants bearing the heterologous hrpX gene are restored in their abilities to cause diseases typical of their chromosomal background and not the hypersensitive reaction on their respective hosts. The hrpXo and hrpXc genes are therefore functionally equivalent, and this functional equivalence extends into X. campestris pv. armoraciae and possibly into other X. campestris pathovars, since this gene is highly conserved among eight other pathovars tested. Sequence analyses of hrpXo revealed an open reading frame of 1,452 bp with a coding capacity for a protein of 52.3 kDa. The protein contains a consensus domain for possible protein myristoylation whose consequence may result in a loss of recognition by host defense and surveillance systems. Images PMID:8458844

  17. Overexpression of MoSM1, encoding for an immunity-inducing protein from Magnaporthe oryzae, in rice confers broad-spectrum resistance against fungal and bacterial diseases

    PubMed Central

    Hong, Yongbo; Yang, Yayun; Zhang, Huijuan; Huang, Lei; Li, Dayong; Song, Fengming

    2017-01-01

    Potential of MoSM1, encoding for a cerato-platanin protein from Magnaporthe oryzae, in improvement of rice disease resistance was examined. Transient expression of MoSM1 in rice leaves initiated hypersensitive response and upregulated expression of defense genes. When transiently expressed in tobacco leaves, MoSM1 targeted to plasma membrane. The MoSM1-overexpressing (MoSM1-OE) transgenic rice lines showed an improved resistance, as revealed by the reduced disease severity and decreased in planta pathogen growth, against 2 strains belonging to two different races of M. oryzae, causing blast disease, and against 2 strains of Xanthomonas oryzae pv. oryzae, causing bacterial leaf blight disease. However, no alteration in resistance to sheath blight disease was observed in MoSM1-OE lines. The MoSM1-OE plants contained elevated levels of salicylic acid (SA) and jasmonic acid (JA) and constitutively activated the expression of SA and JA signaling-related regulatory and defense genes. Furthermore, the MoSM1-OE plants had no effect on drought and salt stress tolerance and on grain yield. We conclude that MoSM1 confers a broad-spectrum resistance against different pathogens through modulating SA- and JA-mediated signaling pathways without any penalty on abiotic stress tolerance and grain yield, providing a promising potential for application of MoSM1 in improvement of disease resistance in crops. PMID:28106116

  18. Overexpression of MoSM1, encoding for an immunity-inducing protein from Magnaporthe oryzae, in rice confers broad-spectrum resistance against fungal and bacterial diseases.

    PubMed

    Hong, Yongbo; Yang, Yayun; Zhang, Huijuan; Huang, Lei; Li, Dayong; Song, Fengming

    2017-01-20

    Potential of MoSM1, encoding for a cerato-platanin protein from Magnaporthe oryzae, in improvement of rice disease resistance was examined. Transient expression of MoSM1 in rice leaves initiated hypersensitive response and upregulated expression of defense genes. When transiently expressed in tobacco leaves, MoSM1 targeted to plasma membrane. The MoSM1-overexpressing (MoSM1-OE) transgenic rice lines showed an improved resistance, as revealed by the reduced disease severity and decreased in planta pathogen growth, against 2 strains belonging to two different races of M. oryzae, causing blast disease, and against 2 strains of Xanthomonas oryzae pv. oryzae, causing bacterial leaf blight disease. However, no alteration in resistance to sheath blight disease was observed in MoSM1-OE lines. The MoSM1-OE plants contained elevated levels of salicylic acid (SA) and jasmonic acid (JA) and constitutively activated the expression of SA and JA signaling-related regulatory and defense genes. Furthermore, the MoSM1-OE plants had no effect on drought and salt stress tolerance and on grain yield. We conclude that MoSM1 confers a broad-spectrum resistance against different pathogens through modulating SA- and JA-mediated signaling pathways without any penalty on abiotic stress tolerance and grain yield, providing a promising potential for application of MoSM1 in improvement of disease resistance in crops.

  19. Erwinia amylovora pyrC mutant causes fire blight despite pyrimidine auxotrophy.

    PubMed

    Ramos, L S; Sinn, J P; Lehman, B L; Pfeufer, E E; Peter, K A; McNellis, T W

    2015-06-01

    Erwinia amylovora bacteria cause fire blight disease, which affects apple and pear production worldwide. The Erw. amylovora pyrC gene encodes a predicted dihydroorotase enzyme involved in pyrimidine biosynthesis. Here, we discovered that the Erw. amylovora pyrC244::Tn5 mutant was a uracil auxotroph. Unexpectedly, the Erw. amylovora pyrC244::Tn5 mutant grew as well as the wild-type in detached immature apple and pear fruits. Fire blight symptoms caused by the pyrC244::Tn5 mutant in immature apple and pear fruits were attenuated compared to those caused by the wild-type. The pyrC244::Tn5 mutant also caused severe fire blight symptoms in apple tree shoots. A plasmid-borne copy of the wild-type pyrC gene restored prototrophy and symptom induction in apple and pear fruit to the pyrC244::Tn5 mutant. These results suggest that Erw. amylovora can obtain sufficient pyrimidine from the host to support bacterial growth and fire blight disease development, although de novo pyrimidine synthesis by Erw. amylovora is required for full symptom development in fruits. Significance and impact of the study: This study provides information about the fire blight host-pathogen interaction. Although the Erwinia amylovora pyrC mutant was strictly auxotrophic for pyrimidine, it grew as well as the wild-type in immature pear and apple fruits and caused severe fire blight disease in apple trees. This suggests that Erw. amylovora can obtain sufficient pyrimidines from host tissue to support growth and fire blight disease development. This situation contrasts with findings in some human bacterial pathogens, which require de novo pyrimidine synthesis for growth in host blood, for example.

  20. Late blight and early blight resistance from Solanum hougasii introgressed into Solanum tuberosum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Late blight, caused by Phytophthora infestans, and early blight, incited by Alternaria solani,are the two most widely occurring foliar diseases of potato in the U.S. Resistance to both diseases is necessary if growers are to reduce fungicide applications. Field resistance to late blight has previous...

  1. Progress in breeding Andean common bean for resistance to common bacerial blight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Common bacterial blight is a severe disease of common bean worldwide. Use of resistant cultivars is crucial for its control. The objectives were: 1. assess the progress made in breeding large-seeded Andean bean developed between 1974 and 2010, and 2. determine their resistance-linked SCAR marker com...

  2. Controlled release of Pantoea agglomerans E325 for biocontrol of fire blight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microencapsulation and controlled release of Pantoea agglomerans strain E325 (E325), which is an antagonist to bacterial pathogen (Erwinia amylovora) of fire blight, a devastating disease of apple and pear, have been investigated. Uniform core-shell alginate microcapsules (AMCs), 60-300 µm in diamet...

  3. The 1971 corn blight watch experiment

    NASA Technical Reports Server (NTRS)

    Clifton, J. W.

    1972-01-01

    The successful fulfillment of the objectives for the 1971 corn blight watch experiment is reported. The objectives were: (1) detect the development and spread of corn blight during the growing season across the Corn Belt; (2) assess different levels of infection in the Corn Belt; (3) amplify data acquired by ground observations to better appraise current blight status and the probable impact on crop production; and (4) estimate through extrapolation the applicability of these techniques to similar situations occurring in the future.

  4. Genetic diversity of transcriptional activator-like effector genes in Chinese isolates of Xanthomonas oryzae pv. oryzicola.

    PubMed

    Ji, Zhi-Yuan; Zakria, Muhammad; Zou, Li-Fang; Xiong, Li; Li, Zheng; Ji, Guang-Hai; Chen, Gong-You

    2014-07-01

    Xanthomonas oryzae pv. oryzicola causes bacterial leaf streak (BLS), a devastating disease of rice in Asia countries. X. oryzae pv. oryzicola utilizes repertoires of transcriptional activator-like effectors (TALEs) to manipulate host resistance or susceptibility; thus, TALEs can determine the outcome of BLS. In this report, we studied genetic diversity in putative tale genes of 65 X. oryzae pv. oryzicola strains that originated from nine provinces of southern China. Genomic DNAs from the 65 strains were digested with BamHI and hybridized with an internal fragment of avrXa3, a tale gene originating from the related pathogen, X. oryzae pv. oryzae, which causes bacterial leaf blight (BLB). Southern blot analysis indicated that the strains contained a variable number (9 to 22) of avrXa3-hybridizing fragments (e.g., putative tale genes). Based on the number and size of hybridizing bands, strains were classified into 14 genotypes (designated 1 to 14), and genotypes 3 and 10 represented 29.23 and 24.64% of the total, respectively. A high molecular weight BamHI fragment (HMWB; ≈6.0 kb) was present in 12 of the 14 genotypes, and sequence analysis of the HMWB revealed the presence of a C-terminally truncated tale, an insertion element related to IS1403, and genes encoding phosphoglycerate mutase and endonuclease V. Primers were developed from the 6.0-kb HMWB fragment and showed potential in genotyping X. oryzae pv. oryzicola strains by polymerase chain reaction. Virulence of X. oryzae pv. oryzicola strains was assessed on 23 rice cultivars containing different resistance genes for BLB. The X. oryzae pv. oryzicola strains could be grouped into 14 pathotypes (I to XIV), and the grouping of strains was almost identical to the categories determined by genotypic analysis. In general, strains containing higher numbers of putative tale genes were more virulent on rice than strains containing fewer tales. The results also indicate that there are no gene-for-gene relationships

  5. A transcription activator-like effector from Xanthomonas oryzae pv. oryzicola elicits dose-dependent resistance in rice.

    PubMed

    Hummel, Aaron W; Wilkins, Katherine E; Wang, Li; Cernadas, R Andres; Bogdanove, Adam J

    2017-01-01

    Xanthomonas spp. reduce crop yields and quality worldwide. During infection of their plant hosts, many strains secrete transcription activator-like (TAL) effectors, which enter the host cell nucleus and activate specific corresponding host genes at effector binding elements (EBEs) in the promoter. TAL effectors may contribute to disease by activating the expression of susceptibility genes or trigger resistance associated with the hypersensitive reaction (HR) by activating an executor resistance (R) gene. The rice bacterial leaf streak pathogen X. oryzae pv. oryzicola (Xoc) is known to suppress host resistance, and no host R gene has been identified against it, despite considerable effort. To further investigate Xoc suppression of host resistance, we conducted a screen of effectors from BLS256 and identified Tal2a as an HR elicitor in rice when delivered heterologously by a strain of the closely related rice bacterial blight pathogen X. oryzae pv. oryzae (Xoo) or by the soybean pathogen X. axonopodis pv. glycines. The HR required the Tal2a activation domain, suggesting an executor R gene. Tal2a activity was differentially distributed among geographically diverse Xoc isolates, being largely conserved among Asian isolates. We identified four genes induced by Tal2a in next-generation RNA sequencing experiments and confirmed them using quantitative real-time reverse transcription-polymerase chain reaction (qPCR). However, neither individual nor collective activation of these genes by designer TAL effectors resulted in HR. A tal2a knockout mutant of BLS256 showed virulence comparable with the wild-type, but plasmid-based overexpression of tal2a at different levels in the wild-type reduced virulence in a directly corresponding way. Overall, the results reveal that host resistance suppression by Xoc plays a critical role in pathogenesis. Further, the dose-dependent avirulence activity of Tal2a and the apparent lack of a single canonical target that accounts for HR point to

  6. Complete Genome Sequence of the Barley Pathogen Xanthomonas translucens pv. translucens DSM 18974T (ATCC 19319T)

    PubMed Central

    Jaenicke, Sebastian; Bunk, Boyke; Wibberg, Daniel; Spröer, Cathrin; Hersemann, Lena; Blom, Jochen; Winkler, Anika; Schatschneider, Sarah; Albaum, Stefan P.; Goesmann, Alexander; Pühler, Alfred; Overmann, Jörg

    2016-01-01

    We report here the complete 4.7-Mb genome sequence of Xanthomonas translucens pv. translucens DSM 18974T, which causes black chaff disease on barley (Hordeum vulgare). Genome data of this X. translucens type strain will improve our understanding of this bacterial species. PMID:27908994

  7. FaRXf1: a locus conferring resistance to angular leaf spot caused by Xanthomonas fragariae in octoploid strawberry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Angular leaf spot caused by Xanthomonas fragariae is the only major bacterial disease of cultivated strawberry (Fragaria ×ananassa). While this disease may cause reductions of up to 8 % of marketable yield in Florida winter annual production, no resistant cultivars have been commercialized. Wild acc...

  8. Influence of epidemiological factors on the bioherbicidal efficacy of a Xanthomonas capestris isolate on common cocklebur (Xanthium strumarium)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Greenhouse and controlled-environment studies were conducted to determine the effects of incubation temperature, dew period temperature and duration, plant growth stage, and cell concentration on the bioherbicidal efficacy of a highly virulent isolate (LVA987) of the bacterial pathogen, Xanthomonas ...

  9. A loop-mediated isothermal amplification assay and sample preparation procedure for sensitive detection of Xanthomonas fragariae in strawberry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Xanthomonas fragariae is a bacterium that causes angular leaf spot of strawberry. Asymptomatic infections are common and contribute to the difficulties in disease management. The aim of this study was to develop a loop-mediated isothermal amplification (LAMP) assay with a bacterial enrichment proced...

  10. The Xanthomonas oryzae pv. oryzae PilZ Domain Proteins Function Differentially in Cyclic di-GMP Binding and Regulation of Virulence and Motility.

    PubMed

    Yang, Fenghuan; Tian, Fang; Chen, Huamin; Hutchins, William; Yang, Ching-Hong; He, Chenyang

    2015-07-01

    The PilZ domain proteins have been demonstrated to be one of the major types of receptors mediating cyclic di-GMP (c-di-GMP) signaling pathways in several pathogenic bacteria. However, little is known about the function of PilZ domain proteins in c-di-GMP regulation of virulence in the bacterial blight pathogen of rice Xanthomonas oryzae pv. oryzae. Here, the roles of PilZ domain proteins PXO_00049 and PXO_02374 in c-di-GMP binding, regulation of virulence and motility, and subcellular localization were characterized in comparison with PXO_02715, identified previously as an interactor with the c-di-GMP receptor Filp to regulate virulence. The c-di-GMP binding motifs in the PilZ domains were conserved in PXO_00049 and PXO_02374 but were less well conserved in PXO_02715. PXO_00049 and PXO_02374 but not PXO_02715 proteins bound to c-di-GMP with high affinity in vitro, and the R(141) and R(10) residues in the PilZ domains of PXO_00049 and PXO_02374, respectively, were crucial for c-di-GMP binding. Gene deletion of PXO_00049 and PXO_02374 resulted in significant increases in virulence and hrp gene transcription, indicating their negative regulation of virulence via type III secretion system expression. All mutants showed significant changes in sliding motility but not exopolysaccharide production and biofilm formation. In trans expression of the full-length open reading frame (ORF) of each gene in the relevant mutants led to restoration of the phenotype to wild-type levels. Moreover, PXO_00049 and PXO_02374 displayed mainly multisite subcellular localizations, whereas PXO_02715 showed nonpolar distributions in the X. oryzae pv. oryzae cells. Therefore, this study demonstrated the different functions of the PilZ domain proteins in mediation of c-di-GMP regulation of virulence and motility in X. oryzae pv. oryzae.

  11. The ColRS system of Xanthomonas oryzae pv. oryzae is required for virulence and growth in iron-limiting conditions.

    PubMed

    Subramoni, Sujatha; Pandey, Alok; Vishnu Priya, M R; Patel, Hitendra Kumar; Sonti, Ramesh V

    2012-09-01

    Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight of rice, produces siderophores only under iron-limiting conditions. We screened 15 400 mTn5-induced mutants of X. oryzae pv. oryzae and isolated 27 mutants that produced siderophores even under iron-replete conditions. We found that the mTn5 insertions in 25 of these mutants were in or close to six genes. Mutants with insertions in five of these genes [colS, XOO1806 (a conserved hypothetical protein), acnB, prpR and prpB] exhibited a deficiency for growth on iron-limiting medium and a decrease in virulence. Insertions in a sixth gene, XOO0007 (a conserved hypothetical protein), were found to affect the ability to grow on iron-limiting medium, but did not affect the virulence. Targeted gene disruptants for colR (encoding the predicted cognate regulatory protein for ColS) also exhibited a deficiency for growth on iron-limiting medium and a decrease in virulence. colR and colS mutants were defective in the elicitation of hypersensitive response symptoms on the nonhost tomato. In addition, colR and colS mutants induced a rice basal defence response, suggesting that they are compromised in the suppression of host innate immunity. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis demonstrated that a functional ColRS system is required for the optimal expression of several genes encoding components of the type 3 secretion system (T3SS) of X. oryzae pv. oryzae. Our results demonstrate the role of several novel genes, including colR/colS, in the promotion of growth on iron-limiting medium and the virulence of X. oryzae pv. oryzae.

  12. Expression, crystallization and preliminary X-ray crystallographic analysis of XometC, a cystathionine gamma-lyase-like protein from Xanthomonas oryzae pv. oryzae.

    PubMed

    Ngo, Phuong Thuy Ho; Kim, Jin Kwang; Kim, Hyesoon; Jung, Junho; Ahn, Yeh Jin; Kim, Jeong Gu; Lee, Byoung Moo; Kang, Hee Wan; Kang, Lin Woo

    2008-08-01

    Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight of rice (Oryza sativa L.), one of the most devastating diseases of rice in most rice-growing countries. XometC, a cystathionine gamma-lyase (CGL) like protein that is an antibacterial drug-target protein against Xoo, was cloned, expressed, purified and crystallized. CGL catalyzes the second step in the reverse-transsulfuration pathway, which is essential for the metabolic interconversion of the sulfur-containing amino acids cysteine and methionine. Crystals of two different shapes, plate-shaped and pyramid-shaped, diffracted to 2.9 and 3.2 A resolution and belonged to the primitive orthogonal space group P2(1)2(1)2(1) and the tetragonal space group P4(1) (or P4(3)), with unit-cell parameters a = 73.0, b = 144.9, c = 152.3 A and a = b = 78.2, c = 300.7 A, respectively. For the P2(1)2(1)2(1) crystals, three or four monomers exist in the asymmetric unit with a corresponding V(M) of 3.02 or 2.26 A(3) Da(-1) and a solvent content of 59.3 or 45.7%. For the P4(1) (or P4(3)) crystals, four or five monomers exist in the asymmetric unit with a corresponding V(M) of 2.59 or 2.09 A(3) Da(-1) and a solvent content of 52.5 or 40.6%.

  13. Construction of a genetic linkage map for identification of molecular markers associated with resistance to Xanthomonas arboriciola pv. pruni in peach [Prunus persica (L.) Batsch

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial spot, caused by Xanthomonas campestris pv. pruni, is a serious disease that can affect peach fruit quality and production. The molecular basis of its tolerance and susceptibility is yet to be understood. To study the genetics of the peach in response to bacterial spot, an F2 population of ...

  14. The corn blight problem: 1970 and 1971

    NASA Technical Reports Server (NTRS)

    Bauer, M. E.

    1972-01-01

    Southern corn leaf blight is caused by the fungus, Helminthosporium maydis. Race T of H maydis adapted itself to the Texas male sterile cytoplasm corn. The problems caused by this variety of the blight in 1970 and 1971 are discussed, as well as the symptoms and development of the disease.

  15. Iron homeostasis and fire blight susceptibility in transgenic pear plants overexpressing a pea ferritin gene.

    PubMed

    Djennane, Samia; Cesbron, Colette; Sourice, Sophie; Cournol, Raphael; Dupuis, Fabrice; Eychenne, Magali; Loridon, Karine; Chevreau, Elisabeth

    2011-05-01

    The bacterial pathogen Erwinia amylovora causes the devastating disease known as fire blight in some rosaceous plants including apple and pear. One of the pathogenicity factors affecting fire blight development is the production of a siderophore, desferrioxamine, which overcomes the limiting conditions in plant tissues and also protects bacteria against active oxygen species. In this paper we examine the effect of an iron chelator protein encoded by the pea ferritin gene on the fire blight susceptibility of pear (Pyrus communis). Transgenic pear clones expressing this gene controlled either by the constitutive promoter CaMV 35S or by the inducible promoter sgd24 promoter were produced. The transgenic clones produced were analysed by Q-RT-PCR to determine the level of expression of the pea transgene. A pathogen-inducible pattern of expression of the pea transgene was observed in sgd24-promoter transformants. Adaptation to iron deficiency in vitro was tested in some transgenic clones and different iron metabolism parameters were measured. No strong effect on iron and chlorophyll content, root reductase activity and fire blight susceptibility was detected in the transgenic lines tested. No transformants showed a significant reduction in susceptibility to fire blight in greenhouse conditions when inoculated with E. amylovora.

  16. Minimal phenotypic test for simple differentiation of Xanthomonas campestris from other yellow-pigmented bacteria isolated from soil

    PubMed Central

    Soudi, MR; Alimadadi, N; Ghadam, P

    2011-01-01

    Background and Objectives Isolation of Xanthomonas campestris from soil has a wide range of applications from monitoring of phytopathogenic populations in soil to screening of improved xanthan-producing strains. Identification of Xanthomonas campestris and its pathovars requires pathogenicity tests in addition to phenotypic and molecular characterization. Materials and Methods Thirty phenotypic tests were carried out on 57 yellow-pigmented bacterial isolates obtained from soil of cabbage farms after screening on Selective Xanthomonas (SX) agar and transferring on Yeast Malt agar. Absorption spectra of pigments and capability of biopolymer production were determined for the isolates. Some characteristics of the biopolymer produced and presence of a X. campestris-specific gene marker were investigated for nine putative X. campestris isolates. Results The present study introduces a set of simple phenotypic tests including urease, acid production from sucrose, mucoid growth on 5% sucrose, starch hydrolysis, growth in 4% NaCl, motility and utilization of asparagine as sole carbon and nitrogen source for quick and inexpensive tentative identification of Xanthomonas campestris. Validation of these tests was confirmed in 100% of the cases by characterization of bacterial exopolysaccharide as xanthan and production of genus-specific xanthomonadin pigment. Moreover, tracking of hrc gene among putative X. campestris isolates gave positive results in 80% of cases. Conclusion The Minimal simple phenotypic tests facilitate the screening and differentiation of putative X. campestris isolates from other false bacterial strains isolated from soil on semiselective SX agar. PMID:22347588

  17. Ectopic expression of Hrf1 enhances bacterial resistance via regulation of diterpene phytoalexins, silicon and reactive oxygen species burst in rice.

    PubMed

    Li, Wenqi; Shao, Min; Zhong, Weigong; Yang, Jie; Okada, Kazunori; Yamane, Hisakazu; Zhang, Lei; Wang, Guang; Wang, Dong; Xiao, Shanshan; Chang, Shanshan; Qian, Guoliang; Liu, Fengquan

    2012-01-01

    Harpin proteins as elicitor derived from plant gram negative bacteria such as Xanthomonas oryzae pv. oryzae (Xoo), Erwinia amylovora induce disease resistance in plants by activating multiple defense responses. However, it is unclear whether phytoalexin production and ROS burst are involved in the disease resistance conferred by the expression of the harpin(Xoo) protein in rice. In this article, ectopic expression of hrf1 in rice enhanced resistance to bacterial blight. Accompanying with the activation of genes related to the phytoalexin biosynthesis pathway in hrf1-transformed rice, phytoalexins quickly and consistently accumulated concurrent with the limitation of bacterial growth rate. Moreover, the hrf1-transformed rice showed an increased ability for ROS scavenging and decreased hydrogen peroxide (H(2)O(2)) concentration. Furthermore, the localization and relative quantification of silicon deposition in rice leaves was detected by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometer (EDS). Finally, the transcript levels of defense response genes increased in transformed rice. These results show a correlation between Xoo resistance and phytoalexin production, H(2)O(2), silicon deposition and defense gene expression in hrf1-transformed rice. These data are significant because they provide evidence for a better understanding the role of defense responses in the incompatible interaction between bacterial disease and hrf1-transformed plants. These data also supply an opportunity for generating nonspecific resistance to pathogens.

  18. “Genetic Species” Concept in Xanthomonas

    PubMed Central

    Friedman, S.; De Ley, J.

    1965-01-01

    Friedman, S. (State University, Ghent, Belgium), and J. De Ley. “Genetic species” concept in Xanthomonas. J. Bacteriol. 89:95–100. 1965.—Deuterated, N15-labeled deoxyribonucleic acid (DNA) from Xanthomonas pelargonii forms distinct hybrids with ordinary DNA from X. hederae, X. juglandis, and X. carotae. Hybridization is less pronounced with X. phaseoli and X. begoniae. There is evidence that some hybridization occurs with X. vesicatoria, X. campestris, and X. tamarindi. These results favor the concept of a “genetic species,” rather than a division of the genus into many separate species based almost entirely on phytopathogenic host specificity. PMID:14255686

  19. Gluconacetobacter diazotrophicus, a sugar cane endosymbiont, produces a bacteriocin against Xanthomonas albilineans, a sugar cane pathogen.

    PubMed

    Piñón, Dolores; Casas, Mario; Blanch, María; Fontaniella, Blanca; Blanco, Yolanda; Vicente, Carlos; Solas, María-Teresa; Legaz, María-Estrella

    2002-01-01

    Gluconacetobacter diazotrophicus in liquid culture secretes proteins into the medium. Both medium containing Gluconacetobacter protein and a solution of this protein after acetone precipitation appeared to inhibit the growth of Xanthomonas albilineans in solid culture. This apparent inhibition of bacterial growth has, in fact, been revealed to be lysis of bacterial cells, as demonstrated by transmission electron microscopy. Fractionation of the Gluconacetobacter protein mixture in size-exclusion chromatography reveals a main fraction with lysozyme-like activity which produces lysis of both living bacteria and isolated cell walls.

  20. Xanthan Pyruvilation Is Essential for the Virulence of Xanthomonas campestris pv. campestris.

    PubMed

    Bianco, María Isabel; Toum, Laila; Yaryura, Pablo Marcelo; Mielnichuk, Natalia; Gudesblat, Gustavo Eduardo; Roeschlin, Roxana; Marano, María Rosa; Ielpi, Luis; Vojnov, Adrián A

    2016-09-01

    Xanthan, the main exopolysaccharide (EPS) synthesized by Xanthomonas spp., contributes to bacterial stress tolerance and enhances attachment to plant surfaces by helping in biofilm formation. Therefore, xanthan is essential for successful colonization and growth in planta and has also been proposed to be involved in the promotion of pathogenesis by calcium ion chelation and, hence, in the suppression of the plant defense responses in which this cation acts as a signal. The aim of this work was to study the relationship between xanthan structure and its role as a virulence factor. We analyzed four Xanthomonas campestris pv. campestris mutants that synthesize structural variants of xanthan. We found that the lack of acetyl groups that decorate the internal mannose residues, ketal-pyruvate groups, and external mannose residues affects bacterial adhesion and biofilm architecture. In addition, the mutants that synthesized EPS without pyruvilation or without the external mannose residues did not develop disease symptoms in Arabidopsis thaliana. We also observed that the presence of the external mannose residues and, hence, pyruvilation is required for xanthan to suppress callose deposition as well as to interfere with stomatal defense. In conclusion, pyruvilation of xanthan seems to be essential for Xanthomonas campestris pv. campestris virulence.

  1. Presence of Extracellular DNA during Biofilm Formation by Xanthomonas citri subsp. citri Strains with Different Host Range

    PubMed Central

    Sena-Vélez, Marta; Redondo, Cristina; Graham, James H.; Cubero, Jaime

    2016-01-01

    Xanthomonas citri subsp. citri (Xcc) A strain causes citrus bacterial canker, a serious leaf, fruit and stem spotting disease of several Citrus species. X. alfalfae subsp. citrumelonis (Xac) is the cause of citrus bacterial spot, a minor disease of citrus nursery plants and X. campestris pv. campestris (Xc) is a systemic pathogen that causes black rot of cabbage. Xanthomonas spp. form biofilms in planta that facilitate the host infection process. Herein, the role of extracellular DNA (eDNA) was evaluated in the formation and stabilization of the biofilm matrix at different stages of biofilm development. Fluorescence and light microscopy, as well as DNAse treatments, were used to determine the presence of eDNA in biofilms and bacterial cultures. DNAse treatments of Xcc strains and Xac reduced biofilm formation at the initial stage of development, as well as disrupted preformed biofilm. By comparison, no significant effect of the DNAse was detected for biofilm formation by Xc. DNAse effects on biofilm formation or disruption varied among Xcc strains and Xanthomonas species which suggest different roles for eDNA. Variation in the structure of fibers containing eDNA in biofilms, bacterial cultures, and in twitching motility was also visualized by microscopy. The proposed roles for eDNA are as an adhesin in the early stages of biofilm formation, as an structural component of mature bacterial aggregates, and twitching motility structures. PMID:27248687

  2. Glutamate transport and xanthan gum production in the plant pathogen Xanthomonas axonopodis pv. citri.

    PubMed

    Rojas, Robert; Nishidomi, Sabrina; Nepomuceno, Roberto; Oshiro, Elisa; de Cassia Café Ferreira, Rita

    2013-11-01

    L-glutamate plays a central role in nitrogen metabolism in all living organisms. In the genus Xanthomonas, the nitrogen nutrition is an important factor involved in the xanthan gum production, an important exopolysaccharide with various industrial and biotechnological applications. In this report, we demonstrate that the use of L-glutamate by the phytopathogen Xanthomonas axonopodis pv. citri as a nitrogen source in defined medium significantly increases the production of xanthan gum. This increase is dependent on the L-glutamate concentration. In addition, we have also characterized a glutamate transport system that is dependent on a proton gradient and on ATP and is modulated by amino acids that are structurally related to glutamate. This is the first biochemical characterization of an energy substrate transport system observed in a bacterial phytopathogen with a broad economic and industrial impact due to xanthan gum production.

  3. Interfering TAL effectors of Xanthomonas oryzae neutralize R-gene-mediated plant disease resistance

    PubMed Central

    Ji, Zhiyuan; Ji, Chonghui; Liu, Bo; Zou, Lifang; Chen, Gongyou; Yang, Bing

    2016-01-01

    Plant pathogenic bacteria of the genus Xanthomonas possess transcription activator-like effectors (TALEs) that activate transcription of disease susceptibility genes in the host, inducing a state of disease. Here we report that some isolates of the rice pathogen Xanthomonas oryzae use truncated versions of TALEs (which we term interfering TALEs, or iTALEs) to overcome disease resistance. In comparison with typical TALEs, iTALEs lack a transcription activation domain but retain nuclear localization motifs and are expressed from genes that were previously considered pseudogenes. We show that the rice gene Xa1, encoding a nucleotide-binding leucine-rich repeat protein, confers resistance against X. oryzae isolates by recognizing multiple TALEs. However, the iTALEs present in many isolates interfere with the otherwise broad-spectrum resistance conferred by Xa1. Our findings illustrate how bacterial effectors that trigger disease resistance in the host can evolve to interfere with the resistance process and, thus, promote disease. PMID:27811915

  4. Genomes-based phylogeny of the genus Xanthomonas

    PubMed Central

    2012-01-01

    Background The genus Xanthomonas comprises several plant pathogenic bacteria affecting a wide range of hosts. Despite the economic, industrial and biological importance of Xanthomonas, the classification and phylogenetic relationships within the genus are still under active debate. Some of the relationships between pathovars and species have not been thoroughly clarified, with old pathovars becoming new species. A change in the genus name has been recently suggested for Xanthomonas albilineans, an early branching species currently located in this genus, but a thorough phylogenomic reconstruction would aid in solving these and other discrepancies in this genus. Results Here we report the results of the genome-wide analysis of DNA sequences from 989 orthologous groups from 17 Xanthomonas spp. genomes available to date, representing all major lineages within the genus. The phylogenetic and computational analyses used in this study have been automated in a Perl package designated Unus, which provides a framework for phylogenomic analyses which can be applied to other datasets at the genomic level. Unus can also be easily incorporated into other phylogenomic pipelines. Conclusions Our phylogeny agrees with previous phylogenetic topologies on the genus, but revealed that the genomes of Xanthomonas citri and Xanthomonas fuscans belong to the same species, and that of Xanthomonas albilineans is basal to the joint clade of Xanthomonas and Xylella fastidiosa. Genome reduction was identified in the species Xanthomonas vasicola in addition to the previously identified reduction in Xanthomonas albilineans. Lateral gene transfer was also observed in two gene clusters. PMID:22443110

  5. Xanthomonas axonopodis pv. citri uses a plant natriuretic peptide-like protein to modify host homeostasis.

    PubMed

    Gottig, Natalia; Garavaglia, Betiana S; Daurelio, Lucas D; Valentine, Alex; Gehring, Chris; Orellano, Elena G; Ottado, Jorgelina

    2008-11-25

    Plant natriuretic peptides (PNPs) are a class of extracellular, systemically mobile molecules that elicit a number of plant responses important in homeostasis and growth. The bacterial citrus pathogen, Xanthomonas axonopodis pv. citri, also contains a gene encoding a PNP-like protein, XacPNP, that shares significant sequence similarity and identical domain organization with plant PNPs but has no homologues in other bacteria. We have expressed and purified XacPNP and demonstrated that the bacterial protein alters physiological responses including stomatal opening in plants. Although XacPNP is not expressed under standard nutrient rich culture conditions, it is strongly induced under conditions that mimic the nutrient poor intercellular apoplastic environment of leaves, as well as in infected tissue, suggesting that XacPNP transcription can respond to the host environment. To characterize the role of XacPNP during bacterial infection, we constructed a XacPNP deletion mutant. The lesions caused by this mutant were more necrotic than those observed with the wild-type, and bacterial cell death occurred earlier in the mutant. Moreover, when we expressed XacPNP in Xanthomonas axonopodis pv. vesicatoria, the transgenic bacteria caused less necrotic lesions in the host than the wild-type. In conclusion, we present evidence that a plant-like bacterial PNP can enable a plant pathogen to modify host responses to create conditions favorable to its own survival.

  6. Genomic analysis of Bacillus subtilis OH 131.1 and coculturing with Cryptococcus flavescens for control of fusarium head blight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacillus subtilis OH131.1 is a bacterial antagonist of Fusarium graminearum, a plant pathogen which causes Fusarium head blight in wheat. The genome of B. subtilis OH131.1 was sequenced, annotated and analyzed to understand its potential to produce bioactive metabolites. The analysis identified 6 sy...

  7. TRANSGENIC EXPRESSION OF THE ERWINIA AMYLOVORA (FIRE BLIGHT) EFFECTOR PROTEIN EOP1 SUPRESSES HOST BASAL DEFENSE MECHANISMS IN MALUS (APPLE)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Erwinia amylovora (Ea) is the causative agent of fire blight, a devastating disease of apple and pear. Like many other plant and animal bacterial pathogens Ea utilizes a type three secretion system (TTSS) to deliver effector proteins into plant host cells. Once inside the host cell, effector protei...

  8. Tagging and mapping Pse-1 gene for resistance to halo blight in common bean differential cultivar UI-3

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Halo blight [caused by Pseudomonas syringae pv. phaseolicola (Psp)] is a serious seed-borne bacterial disease of common bean (Phaseolus vulgaris L.). A few R genes and QTL provide control to one or more races of the pathogen. To better understand monogenic resistance and improve breeding efficienc...

  9. Draft Genome Sequences of Xanthomonas sacchari and Two Banana-Associated Xanthomonads Reveal Insights into the Xanthomonas Group 1 Clade

    PubMed Central

    Studholme, David J.; Wasukira, Arthur; Paszkiewicz, Konrad; Aritua, Valente; Thwaites, Richard; Smith, Julian; Grant, Murray

    2011-01-01

    We present draft genome sequences for three strains of Xanthomonas species, each of which was associated with banana plants (Musa species) but is not closely related to the previously sequenced banana-pathogen Xanthomonas campestris pathovar musacearum. Strain NCPPB4393 had been deposited as Xanthomonas campestris pathovar musacearum but in fact falls within the species Xanthomonas sacchari. Strain NCPPB1132 is more distantly related to Xanthomonas sacchari whilst strain NCPPB 1131 grouped in a distinct species-level clade related to X. sacchari, along with strains from ginger, rice, cotton and sugarcane. These three newly sequenced strains share many genomic features with the previously sequenced Xanthomonas albilineans, for example possessing an unsual metE allele and lacking the Hrp type III secretion system. However, they are distinct from Xanthomonas albilineans in many respects, for example showing little evidence of genome reduction. They also lack the SPI-1 type III secretion system found in Xanthomonas albilineans. Unlike X. albilineans, all three strains possess a gum gene cluster. The data reported here provide the first genome-wide survey of non-Hrp Xanthomonas species other than Xanthomonas albilineans, which is an atypical member of this group. We hope that the availability of complete sequence data for this group of organisms is the first step towards understanding their interactions with plants and identifying potential virulence factors. PMID:24710305

  10. Draft Genome Sequences of Xanthomonas sacchari and Two Banana-Associated Xanthomonads Reveal Insights into the Xanthomonas Group 1 Clade.

    PubMed

    Studholme, David J; Wasukira, Arthur; Paszkiewicz, Konrad; Aritua, Valente; Thwaites, Richard; Smith, Julian; Grant, Murray

    2011-12-02

    We present draft genome sequences for three strains of Xanthomonas species, each of which was associated with banana plants (Musa species) but is not closely related to the previously sequenced banana-pathogen Xanthomonas campestris pathovar musacearum. Strain NCPPB4393 had been deposited as Xanthomonas campestris pathovar musacearum but in fact falls within the species Xanthomonas sacchari. Strain NCPPB1132 is more distantly related to Xanthomonas sacchari whilst strain NCPPB 1131 grouped in a distinct species-level clade related to X. sacchari, along with strains from ginger, rice, cotton and sugarcane. These three newly sequenced strains share many genomic features with the previously sequenced Xanthomonas albilineans, for example possessing an unsual metE allele and lacking the Hrp type III secretion system. However, they are distinct from Xanthomonas albilineans in many respects, for example showing little evidence of genome reduction. They also lack the SPI-1 type III secretion system found in Xanthomonas albilineans. Unlike X. albilineans, all three strains possess a gum gene cluster. The data reported here provide the first genome-wide survey of non-Hrp Xanthomonas species other than Xanthomonas albilineans, which is an atypical member of this group. We hope that the availability of complete sequence data for this group of organisms is the first step towards understanding their interactions with plants and identifying potential virulence factors.

  11. Rootstock-regulated gene expression patterns associated with fire blight resistance in apple

    PubMed Central

    2012-01-01

    Background Desirable apple varieties are clonally propagated by grafting vegetative scions onto rootstocks. Rootstocks influence many phenotypic traits of the scion, including resistance to pathogens such as Erwinia amylovora, which causes fire blight, the most serious bacterial disease of apple. The purpose of the present study was to quantify rootstock-mediated differences in scion fire blight susceptibility and to identify transcripts in the scion whose expression levels correlated with this response. Results Rootstock influence on scion fire blight resistance was quantified by inoculating three-year old, orchard-grown apple trees, consisting of 'Gala' scions grafted to a range of rootstocks, with E. amylovora. Disease severity was measured by the extent of shoot necrosis over time. 'Gala' scions grafted to G.30 or MM.111 rootstocks showed the lowest rates of necrosis, while 'Gala' on M.27 and B.9 showed the highest rates of necrosis. 'Gala' scions on M.7, S.4 or M.9F56 had intermediate necrosis rates. Using an apple DNA microarray representing 55,230 unique transcripts, gene expression patterns were compared in healthy, un-inoculated, greenhouse-grown 'Gala' scions on the same series of rootstocks. We identified 690 transcripts whose steady-state expression levels correlated with the degree of fire blight susceptibility of the scion/rootstock combinations. Transcripts known to be differentially expressed during E. amylovora infection were disproportionately represented among these transcripts. A second-generation apple microarray representing 26,000 transcripts was developed and was used to test these correlations in an orchard-grown population of trees segregating for fire blight resistance. Of the 690 transcripts originally identified using the first-generation array, 39 had expression levels that correlated with fire blight resistance in the breeding population. Conclusions Rootstocks had significant effects on the fire blight susceptibility of 'Gala' scions

  12. Positive selection is the main driving force for evolution of citrus canker-causing Xanthomonas.

    PubMed

    Zhang, Yunzeng; Jalan, Neha; Zhou, Xiaofeng; Goss, Erica; Jones, Jeffrey B; Setubal, João C; Deng, Xiaoling; Wang, Nian

    2015-10-01

    Understanding the evolutionary history and potential of bacterial pathogens is critical to prevent the emergence of new infectious bacterial diseases. Xanthomonas axonopodis subsp. citri (Xac) (synonym X. citri subsp. citri), which causes citrus canker, is one of the hardest-fought plant bacterial pathogens in US history. Here, we sequenced 21 Xac strains (14 XacA, 3 XacA* and 4 XacA(w)) with different host ranges from North America and Asia and conducted comparative genomic and evolutionary analyses. Our analyses suggest that acquisition of beneficial genes and loss of detrimental genes most likely allowed XacA to infect a broader range of hosts as compared with XacA(w) and XacA*. Recombination was found to have occurred frequently on the relative ancient branches, but rarely on the young branches of the clonal genealogy. The ratio of recombination/mutation ρ/θ was 0.0790±0.0005, implying that the Xac population was clonal in structure. Positive selection has affected 14% (395 out of 2822) of core genes of the citrus canker-causing Xanthomonas. The genes affected are enriched in 'carbohydrate transport and metabolism' and 'DNA replication, recombination and repair' genes (P<0.05). Many genes related to virulence, especially genes involved in the type III secretion system and effectors, are affected by positive selection, further highlighting the contribution of positive selection to the evolution of citrus canker-causing Xanthomonas. Our results suggest that both metabolism and virulence genes provide advantages to endow XacA with higher virulence and a wider host range. Our analysis advances our understanding of the genomic basis of specialization by positive selection in bacterial evolution.

  13. OsWRKY62 is a negative regulator of basal and Xa21-mediated defense against Xanthomonas oryzae pv. oryzae in rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rice Xa21 gene, which confers resistance to the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo), encodes a receptor-like kinase. Few components involved in transducing the Xa21-mediated defense response have yet been identified. It is reported that XA21 binds to a WRKY transcription fac...

  14. Light filtering by epidermal flavonoids during the resistant response of cotton to Xanthomonas protects leaf tissue from light-dependent phytoalexin toxicity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    2,7-Dihydroxycadalene and lacinilene C, sesquiterpenoid phytoalexins that accumulate at infection sites during the hypersensitive resistant response of cotton foliage to Xanthomonas campestris pv. malvacearum, have light-dependent toxicity toward host cells, as well as toward the bacterial pathogen....

  15. Disease Alert: Chickpea Ascochyta blight has shown up early

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The manuscript describes the early appearance of Ascochyta blight in north Idaho, provides pictorial guide for identification of the disease, discusses the disease cycle, and advises chickpea growers options in managing Ascochyta blight....

  16. Results of the 1971 Corn Blight Watch experiment

    NASA Technical Reports Server (NTRS)

    Macdonald, R. B.; Allen, R. D.; Bauer, M. E.; Clifton, J. W.; Frickson, J. D.; Landgrebe, D. A.

    1972-01-01

    Advanced remote sensing techniques are used to: (1)Detect development and spread of corn leaf blight during the growing season; (2) assess the extent and severity of blight infection; (3) assess the impact of blight on corn production; and (4) estimate the applicability of these techniques to similar situations occurring in the future.

  17. Validation of a tuber blight (Phytophthora infestans) prediction model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Potato tuber blight caused by Phytophthora infestans accounts for significant losses in storage. There is limited published quantitative data on predicting tuber blight. We validated a tuber blight prediction model developed in New York with cultivars Allegany, NY 101, and Katahdin using independent...

  18. Visual Blight in America, Resource Paper No. 23.

    ERIC Educational Resources Information Center

    Lewis, Peirce F.; And Others

    Five articles comprise this resource paper that considers "visual blight" in the United States and the role that geographers can play in preserving the physical environment. The first article contends that visual blight is a proper subject for debate for geographers. The second article interprets causes and effects of visual blight and suggests…

  19. Sensitive and specific detection of Xanthomonas axonopodis pv. citri by PCR using pathovar specific primers based on hrpW gene sequences.

    PubMed

    Park, Dong Suk; Hyun, Jae Wook; Park, Young Jin; Kim, Jung Sun; Kang, Hee Wan; Hahn, Jang Ho; Go, Seung Joo

    2006-01-01

    A sensitive and specific assay was developed to detect citrus bacterial canker caused by Xanthomonas axonopodis pv. citri, in leaves and fruits of citrus. Primers XACF and XACR from hrpW homologous to pectate lyase, modifying the structure of pectin in plants, were used to amplify a 561 bp DNA fragment. PCR technique was applied to detect the pathogen in naturally or artificially infected leaves of citrus. The PCR product was only produced from X. axonopodis pv. citri among 26 isolates of Xanthomonas strains, Escherichia coli (O157:H7), Pectobacterium carotovorum subsp. carotovorum, and other reference microbes.

  20. Phylogenomics of Xanthomonas field strains infecting pepper and tomato reveals diversity in effector repertoires and identifies determinants of host specificity

    PubMed Central

    Schwartz, Allison R.; Potnis, Neha; Timilsina, Sujan; Wilson, Mark; Patané, José; Martins, Joaquim; Minsavage, Gerald V.; Dahlbeck, Douglas; Akhunova, Alina; Almeida, Nalvo; Vallad, Gary E.; Barak, Jeri D.; White, Frank F.; Miller, Sally A.; Ritchie, David; Goss, Erica; Bart, Rebecca S.; Setubal, João C.; Jones, Jeffrey B.; Staskawicz, Brian J.

    2015-01-01

    Bacterial spot disease of pepper and tomato is caused by four distinct Xanthomonas species and is a severely limiting factor on fruit yield in these crops. The genetic diversity and the type III effector repertoires of a large sampling of field strains for this disease have yet to be explored on a genomic scale, limiting our understanding of pathogen evolution in an agricultural setting. Genomes of 67 Xanthomonas euvesicatoria (Xe), Xanthomonas perforans (Xp), and Xanthomonas gardneri (Xg) strains isolated from diseased pepper and tomato fields in the southeastern and midwestern United States were sequenced in order to determine the genetic diversity in field strains. Type III effector repertoires were computationally predicted for each strain, and multiple methods of constructing phylogenies were employed to understand better the genetic relationship of strains in the collection. A division in the Xp population was detected based on core genome phylogeny, supporting a model whereby the host-range expansion of Xp field strains on pepper is due, in part, to a loss of the effector AvrBsT. Xp-host compatibility was further studied with the observation that a double deletion of AvrBsT and XopQ allows a host range expansion for Nicotiana benthamiana. Extensive sampling of field strains and an improved understanding of effector content will aid in efforts to design disease resistance strategies targeted against highly conserved core effectors. PMID:26089818

  1. Identification of a novel type III secretion-associated outer membrane-bound protein from Xanthomonas campestris pv. campestris

    PubMed Central

    Li, Lei; Li, Rui-Fang; Ming, Zhen-Hua; Lu, Guang-Tao; Tang, Ji-Liang

    2017-01-01

    Many bacterial pathogens employ the type III secretion system (T3SS) to translocate effector proteins into eukaryotic cells to overcome host defenses. To date, most of our knowledge about the T3SS molecular architecture comes from the studies on animal pathogens. In plant pathogens, nine Hrc proteins are believed to be structural components of the T3SS, of which HrcC and HrcJ form the outer and inner rings of the T3SS, respectively. Here, we demonstrated that a novel outer membrane-bound protein (HpaM) of Xanthomonas campestris pv. campestris is critical for the type III secretion and is structurally and functionally conserved in phytopathogenic Xanthomonas spp. We showed that the C-terminus of HpaM extends into the periplasm to interact physically with HrcJ and the middle part of HpaM interacts physically with HrcC. It is clear that the outer and inner rings compose the main basal body of the T3SS apparatus in animal pathogens. Therefore, we presume that HpaM may act as a T3SS structural component, or play a role in assisting assembling or affecting the stability of the T3SS apparatus. HpaM is a highly prevalent and specific protein in Xanthomonas spp., suggesting that the T3SS of Xanthomonas is distinctive in some aspects from other pathogens. PMID:28198457

  2. Specific genomic fingerprints of phytopathogenic Xanthomonas and Pseudomonas pathovars and strains generated with repetitive sequences and PCR

    SciTech Connect

    Louws, F.J.; Stephens, C.T.; Fulbright, D.W.

    1994-07-01

    DNA primers corresponding to conserved motifs in bacterial repetitive (REP, ERIC, and BOX) elements and PCR were used to show that REP-, ERIC-, and BOX-like DNA sequences are widely distributed in phytopathogenic Xanthomonas and Pseudomonas strains. REP-, ERIC-, and BOX-PCR (collectively known as rep-PCR) were used to generate genomic fingerprints of a variety of Xanthomonas and Pseudomonas isolates and to to identify pathovars and strains that were previously not distinguishable by other classification methods. Analogous rep-PCR-derived genomic fingerprints were generated from purified genomic DNA, colonies on agar plates, liquid cultures, and directly from lesions on infected plants. REP-, ERIC-, and BOX-PCR-generated fingerprints of specific Xanthomonas and Pseudomonas strains were found to yield similar conclusions with regard to the identity of and relationship between these strains. This suggests that the distribution of REP-, ERIC-, and BOX-like sequences in these strains is a reflection of their genomic structure. Thus, the rep-PCR technique appears to be a rapid, simple, and reproducible method to identify and classify Xanthomonas and Pseudomonas strains, and it may be a useful diagnostic tool for these important plant pathogens. 70 refs., 5 figs., 1 tab.

  3. Identification of a novel type III secretion-associated outer membrane-bound protein from Xanthomonas campestris pv. campestris.

    PubMed

    Li, Lei; Li, Rui-Fang; Ming, Zhen-Hua; Lu, Guang-Tao; Tang, Ji-Liang

    2017-02-15

    Many bacterial pathogens employ the type III secretion system (T3SS) to translocate effector proteins into eukaryotic cells to overcome host defenses. To date, most of our knowledge about the T3SS molecular architecture comes from the studies on animal pathogens. In plant pathogens, nine Hrc proteins are believed to be structural components of the T3SS, of which HrcC and HrcJ form the outer and inner rings of the T3SS, respectively. Here, we demonstrated that a novel outer membrane-bound protein (HpaM) of Xanthomonas campestris pv. campestris is critical for the type III secretion and is structurally and functionally conserved in phytopathogenic Xanthomonas spp. We showed that the C-terminus of HpaM extends into the periplasm to interact physically with HrcJ and the middle part of HpaM interacts physically with HrcC. It is clear that the outer and inner rings compose the main basal body of the T3SS apparatus in animal pathogens. Therefore, we presume that HpaM may act as a T3SS structural component, or play a role in assisting assembling or affecting the stability of the T3SS apparatus. HpaM is a highly prevalent and specific protein in Xanthomonas spp., suggesting that the T3SS of Xanthomonas is distinctive in some aspects from other pathogens.

  4. Upregulation of jasmonate biosynthesis and jasmonate-responsive genes in rice leaves in response to a bacterial pathogen mimic.

    PubMed

    Ranjan, Ashish; Vadassery, Jyothilakshmi; Patel, Hitendra Kumar; Pandey, Alok; Palaparthi, Ramesh; Mithöfer, Axel; Sonti, Ramesh V

    2015-05-01

    Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight of rice, secretes several cell wall degrading enzymes including cellulase (ClsA) and lipase/esterase (LipA). Prior treatment of rice leaves with purified cell wall degrading enzymes such as LipA can confer enhanced resistance against subsequent X. oryzae pv. oryzae infection. To understand LipA-induced rice defense responses, microarray analysis was performed 12 h after enzyme treatment of rice leaves. This reveals that 867 (720 upregulated and 147 downregulated) genes are differentially regulated (≥2-fold). A number of genes involved in defense, stress, signal transduction, and catabolic processes were upregulated while a number of genes involved in photosynthesis and anabolic processes were downregulated. The microarray data also suggested upregulation of jasmonic acid (JA) biosynthetic and JA-responsive genes. Estimation of various phytohormones in LipA-treated rice leaves demonstrated a significant increase in the level of JA-Ile (a known active form of JA) while the levels of other phytohormones were not changed significantly with respect to buffer-treated control. This suggests a role for JA-Ile in cell wall damage induced innate immunity. Furthermore, a comparative analysis of ClsA- and LipA-induced rice genes has identified key rice functions that might be involved in elaboration of damage-associated molecular pattern (DAMP)-induced innate immunity.

  5. The type III effectors of Xanthomonas.

    PubMed

    White, Frank F; Potnis, Neha; Jones, Jeffrey B; Koebnik, Ralf

    2009-11-01

    A review of type III effectors (T3 effectors) from strains of Xanthomonas reveals a growing list of candidate and known effectors based on functional assays and sequence and structural similarity searches of genomic data. We propose that the effectors and suspected effectors should be distributed into 39 so-called Xop groups reflecting sequence similarity. Some groups have structural motifs for putative enzymatic functions, and recent studies have provided considerable insight into the interaction with host factors in their function as mediators of virulence and elicitors of resistance for a few specific T3 effectors. Many groups are related to T3 effectors of plant and animal pathogenic bacteria, and several groups appear to have been exploited primarily by Xanthomonas species based on available data. At the same time, a relatively large number of candidate effectors remain to be examined in more detail with regard to their function within host cells.

  6. Method for improving Xanthan yield. [Xanthomonas sp

    SciTech Connect

    Weisrock, W.P.

    1981-11-17

    A process is provided for producing heteropolysaccharides by culturing a microorganism of genus Xanthomonas in a nutrient medium and recovering the heteropolysaccharide containing product. The method covers culturing the microorganism in the presence of a sufficient amount of an additive compound selected from a group consisting of deoxycholic acid, cholic acid, salts thereof, and mixtures thereof, whereby the yield of the heteropolysaccharide produced is increased. 11 claims.

  7. Method for improving xanthan yield. [Xanthomonas sp

    SciTech Connect

    Weisrock, W.P.

    1981-11-17

    A process is provided for producing heteropolysaccharides by culturing a microorganism of genus Xanthomonas in a nutrient medium and recovering the heteropolysaccharide containing product. The method covers culturing the microorganism in the presence of a sufficient amount of an additive compound selected from a group consisting of deoxycholic acid, cholic acid, salts thereof, and mixtures thereof, whereby the yield of the heteropolysaccharide produced is increased. 11 claims.

  8. What makes Xanthomonas albilineans unique amongst xanthomonads?

    PubMed Central

    Pieretti, Isabelle; Pesic, Alexander; Petras, Daniel; Royer, Monique; Süssmuth, Roderich D.; Cociancich, Stéphane

    2015-01-01

    Xanthomonas albilineans causes leaf scald, a lethal disease of sugarcane. Compared to other species of Xanthomonas, X. albilineans exhibits distinctive pathogenic mechanisms, ecology and taxonomy. Its genome, which has experienced significant erosion, has unique genomic features. It lacks two loci required for pathogenicity in other plant pathogenic species of Xanthomonas: the xanthan gum biosynthesis and the Hrp-T3SS (hypersensitive response and pathogenicity-type three secretion system) gene clusters. Instead, X. albilineans harbors in its genome an SPI-1 (Salmonella pathogenicity island-1) T3SS gene cluster usually found in animal pathogens. X. albilineans produces a potent DNA gyrase inhibitor called albicidin, which blocks chloroplast differentiation, resulting in the characteristic white foliar stripe symptoms. The antibacterial activity of albicidin also confers on X. albilineans a competitive advantage against rival bacteria during sugarcane colonization. Recent chemical studies have uncovered the unique structure of albicidin and allowed us to partially elucidate its fascinating biosynthesis apparatus, which involves an enigmatic hybrid PKS/NRPS (polyketide synthase/non-ribosomal peptide synthetase) machinery. PMID:25964795

  9. Specific detection of Xanthomonas oryzae pv. oryzicola in infected rice plant by use of PCR assay targeting a membrane fusion protein gene.

    PubMed

    Kang, Man Jung; Shim, Jae Kyung; Cho, Min Seok; Seol, Young Joo; Hahn, Jang Ho; Hwang, Duk Ju; Park, Dong Suk

    2008-09-01

    Successful control of Xanthomonas oryzae pv. oryzicola, the causal agent of bacterial leaf streak, requires a specific and reliable diagnostic tool. A pathovar-specific PCR assay was developed for the rapid and accurate detection of the plant pathogenic bacterium Xanthomonas oryzae pv. oryzicola in diseased plant. Based on differences in a membrane fusion protein gene of Xanthomonas oryzae pv. oryzicola and other microorganisms, which was generated from NCBI (http://www.ncbi.nlm.nih.gov/) and CMR (http://cmr.tigr.org/) BLAST searches, one pair of pathovar-specific primers, XOCMF/XOCMR, was synthesized. Primers XOCMF and XOCMR from a membrane fusion protein gene were used to amplify a 488-bp DNA fragment. The PCR product was only produced from 4 isolates of Xanthomonas oryzae pv. oryzicola among 37 isolates of other pathovars and species of Xanthomonas, Pectobacterium, Pseudomonas, Burkholderia, Escherichia coli, and Fusarium oxysporum f.sp. dianthi. The results suggested that the assay detected the pathogen more rapidly and accurately than standard isolation methods.

  10. Race nonspecific resistance for potato late blight.

    PubMed

    Staples, Richard C

    2004-01-01

    The late blight fungus (Phytophthora infestans) rots susceptible species of potato plants. None of the major varieties of potato (Solanum tuberosum) grown in the USA is resistant to US-8, the most prevalent genotype of the fungus. Now, Junqi Song, James Bradeen and colleagues have cloned the RB gene from the wild diploid potato species, Solanum bulbocastanum, using a map-based approach in combination with long-range PCR. Transgenic plants containing the gene, normally fully susceptible, displayed broad-spectrum late blight resistance.

  11. Pseudomonas blight discovered on raspberry in Watsonville

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the winter (February) of 2013, a field of raspberries in Watsonville was discovered to be infected with Pseudomonas syringae, the causal agent of Pseudomonas blight disease. This was the first documentation of this disease on raspberry in our region. The infection of raspberry plants is manifeste...

  12. Infection and immune response in the nematode Caenorhabditis elegans elicited by the phytopathogen Xanthomonas.

    PubMed

    Bai, Yanli; Zhi, Dejuan; Li, Chanhe; Liu, Dongling; Zhang, Juan; Tian, Jing; Wang, Xin; Ren, Hui; Li, Hongyu

    2014-09-01

    Xanthomonas oryzae pv. oryzae (Xoo) strains are plant pathogenic bacteria that can cause serious blight of rice, and their virulence towards plant host is complex, making it difficult to be elucidated. Caenorhabditis elegans has been used as a powerful model organism to simplify the host and pathogen system. However, whether the C. elegans is feasible for studying plant pathogens such as Xoo has not been explored. In the present work, we report that Xoo strains PXO99 and JXOIII reduce the lifespan of worms not through acute toxicity, but in an infectious manner; pathogens proliferate and persist in the intestinal lumen to cause marked anterior intestine distension. In addition, Xoo triggers (i) the p38 MAPK signal pathway to upregulate its downstream C17H12.8 expression, and (ii) the DAF-2/DAF-16 pathway to upregulate its downstream gene expressions of mtl-1 and sod-3 under the condition of daf-2 mutation. Our findings suggest that C. elegans can be used as a model to evaluate the virulence of Xoo phytopathogens to host.

  13. Colonization of Dormant Walnut Buds by Xanthomonas arboricola pv. juglandis Is Predictive of Subsequent Disease.

    PubMed

    Lindow, Steven; Olson, William; Buchner, Richard

    2014-11-01

    The potential role of walnut buds as a driver of walnut blight disease, caused by Xanthomonas arboricola pv. juglandis, was addressed by quantifying its temporal dynamics in a large number of orchards in California. The abundance of X. arboricola pv. juglandis on individual dormant and developing buds and shoots of walnut trees varied by >10(6)-fold at any sample time and within a given tree. X. arboricola pv. juglandis population size in shoots was often no larger than that in the buds from which the shoots were derived but was strongly correlated with prior pathogen population sizes in buds. X. arboricola pv. juglandis populations on developing nuts were strongly related to that on the shoots on which they were borne. The incidence of disease of nuts in June was strongly correlated with the logarithm of the population size of X. arboricola pv. juglandis in dormant buds in March. Inoculum efficiency, the slope of this linear relationship, varied between years but was strongly related to the number of rain events following bud break in each year. Thus, inoculum of X. arboricola pv. juglandis present on dormant buds is the primary determinant of nut infections and the risk of disease can be predicted from both the numbers of X. arboricola pv. juglandis in buds and the incidence of early spring rain.

  14. In silico analysis of nonribosomal peptide synthetases of Xanthomonas axonopodis pv. citri: identification of putative siderophore and lipopeptide biosynthetic genes.

    PubMed

    Etchegaray, Augusto; Silva-Stenico, Maria E; Moon, David H; Tsai, Siu M

    2004-01-01

    The genomes of the plant pathogens Xanthomonas axonopodis (Xac) and Xanthomonas campestris (Xcc) were analysed with the aim of deducing their ability to produce nonribosomal peptides. Nonribosomal peptide synthetase (NRPS) genes were identified in two separate loci of Xac. While the genes of locus 1 are common to both strains, locus 2 was only found in Xac. Dissection and phylogenetic analysis of the condensation and thioesterase domains of the NRPSs of loci 1 and 2 of Xac revealed homology, respectively, with siderophore and lipopeptide synthetases. Further analysis of locus 1 revealed genes related to polyketide and polyamine biosynthesis that could be involved in the assembly of substrates for siderophore biosynthesis in both strains. In vitro production of siderophores by both Xac and Xcc was confirmed. Since bacterial siderophores and lipopeptides can be pathogenic and are typically produced nonribosomally, these results suggest that the identified genes could be involved in phytotoxin production.

  15. Pathogenic and genetic diversity of Xanthomonas translucens pv. undulosa in North Dakota.

    PubMed

    Adhikari, Tika B; Gurung, Suraj; Hansen, Jana M; Bonman, J Michael

    2012-04-01

    Bacterial leaf streak (BLS), caused by Xanthomonas translucens pv. undulosa, has become more prevalent recently in North Dakota and neighboring states. From five locations in North Dakota, 226 strains of X. translucens pv. undulosa were collected and evaluated for pathogenicity and then selected strains were inoculated on a set of 12 wheat cultivars and other cereal hosts. The genetic diversity of all strains was determined using repetitive sequence-based polymerase chain reaction (rep-PCR) and insertion sequence-based (IS)-PCR. Bacterial strains were pathogenic on wheat and barley but symptom severity was greatest on wheat. Strains varied greatly in aggressiveness, and wheat cultivars also showed differential responses to several strains. The 16S ribosomal DNA sequences of the strains were identical, and distinct from those of the other Xanthomonas pathovars. Combined rep-PCR and IS-PCR data produced 213 haplotypes. Similar haplotypes were detected in more than one location. Although diversity was greatest (≈92%) among individuals within a location, statistically significant (P ≤ 0.001 or 0.05) genetic differentiation among locations was estimated, indicating geographic differentiation between pathogen populations. The results of this study provide information on the pathogen diversity in North Dakota, which will be useful to better identify and characterize resistant germplasm.

  16. Rapid and accurate identification of Xanthomonas citri subspecies citri by fluorescence in situ hybridization.

    PubMed

    Waite, D W; Griffin, R; Taylor, R; George, S

    2016-11-01

    Citrus canker is an economically important disease caused by the bacterial pathogen Xanthomonas citri subsp. citri (Xcc). This organism targets a wide range of citrus plants, including sweet orange, grapefruit, lemon and lime. As Xcc is spread by environmental factors such as wind and rain, it is difficult to control its movement once the disease has established. In order to facilitate monitoring of citrus canker we sought to design a novel diagnostic protocol based on fluorescence in situ hybridization (FISH) for identification of bacterial cells directly from canker pustules without cultivation or DNA extraction. This method was validated for specificity against a range of Xanthomonas species and strains. We show that our assay is extremely rapid (typically requiring between 2 and 3 h), and possesses a similar specificity to existing PCR diagnostic tools. The sensitivity of the assay is comparable to that of an existing PCR-based technique and sufficient for identifying Xcc in symptomatic plant material. The method is easily transferable to diagnosticians without prior experience using FISH.

  17. Cloning and Characterization of a Late Blight Resistance Gene (Rpi-bt1) and other Resistance Gene Analogs from Solanum bulbocastanum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phytophthora infestans, the causal agent of late blight is the most devastating pathogen of potatoes. Utilizing map based chromosome walking a genomic region containing a cluster of six nucleotide binding site-leucine-rich repeat resistance gene analogs was isolated from a bacterial artificial chro...

  18. Xanthomonas perforans Colonization Influences Salmonella enterica in the Tomato Phyllosphere

    PubMed Central

    Potnis, Neha; Soto-Arias, José Pablo; Cowles, Kimberly N.; van Bruggen, Ariena H. C.; Jones, Jeffrey B.

    2014-01-01

    Salmonella enterica rarely grows on healthy, undamaged plants, but its persistence is influenced by bacterial plant pathogens. The interactions between S. enterica, Xanthomonas perforans (a tomato bacterial spot pathogen), and tomato were characterized. We observed that virulent X. perforans, which establishes disease by suppressing pathogen-associated molecular pattern (PAMP)-triggered immunity that leads to effector-triggered susceptibility, created a conducive environment for persistence of S. enterica in the tomato phyllosphere, while activation of effector-triggered immunity by avirulent X. perforans resulted in a dramatic reduction in S. enterica populations. S. enterica populations persisted at ∼10 times higher levels in leaves coinoculated with virulent X. perforans than in those where S. enterica was applied alone. In contrast, S. enterica populations were ∼5 times smaller in leaves coinoculated with avirulent X. perforans than in leaves inoculated with S. enterica alone. Coinoculation with virulent X. perforans increased S. enterica aggregate formation; however, S. enterica was not found in mixed aggregates with X. perforans. Increased aggregate formation by S. enterica may serve as the mechanism of persistence on leaves cocolonized by virulent X. perforans. S. enterica association with stomata was altered by X. perforans; however, it did not result in appreciable populations of S. enterica in the apoplast even in the presence of large virulent X. perforans populations. Gene-for-gene resistance against X. perforans successively restricted S. enterica populations. Given the effect of this interaction, breeding for disease-resistant cultivars may be an effective strategy to limit both plant disease and S. enterica populations and, consequently, human illness. PMID:24632252

  19. XA21-specific induction of stress-related genes following Xanthomonas infection of detached rice leaves

    PubMed Central

    Liu, Furong; Chen, Huamin; Wei, Tong; Nguyen, Yen P.; Shaker, Isaac W.F.

    2016-01-01

    The rice XA21 receptor kinase confers robust resistance to the bacterial pathogen Xanthomonas oryzaepv. oryzae (Xoo). We developed a detached leaf infection assay to quickly and reliably measure activation of the XA21-mediated immune response using genetic markers. We used RNA sequencing of elf18 treated EFR:XA21:GFP plants to identify candidate genes that could serve as markers for XA21 activation. From this analysis, we identified eight genes that are up-regulated in both in elf18 treated EFR:XA21:GFP rice leaves and Xoo infected XA21 rice leaves. These results provide a rapid and reliable method to assess bacterial-rice interactions. PMID:27703843

  20. Medfly Ceratitis capitata as Potential Vector for Fire Blight Pathogen Erwinia amylovora: Survival and Transmission.

    PubMed

    Ordax, Mónica; Piquer-Salcedo, Jaime E; Santander, Ricardo D; Sabater-Muñoz, Beatriz; Biosca, Elena G; López, María M; Marco-Noales, Ester

    2015-01-01

    Monitoring the ability of bacterial plant pathogens to survive in insects is required for elucidating unknown aspects of their epidemiology and for designing appropriate control strategies. Erwinia amylovora is a plant pathogenic bacterium that causes fire blight, a devastating disease in apple and pear commercial orchards. Studies on fire blight spread by insects have mainly focused on pollinating agents, such as honeybees. However, the Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera: Tephritidae), one of the most damaging fruit pests worldwide, is also common in pome fruit orchards. The main objective of the study was to investigate whether E. amylovora can survive and be transmitted by the medfly. Our experimental results show: i) E. amylovora can survive for at least 8 days inside the digestive tract of the medfly and until 28 days on its external surface, and ii) medflies are able to transmit the bacteria from inoculated apples to both detached shoots and pear plants, being the pathogen recovered from lesions in both cases. This is the first report on E. amylovora internalization and survival in/on C. capitata, as well as the experimental transmission of the fire blight pathogen by this insect. Our results suggest that medfly can act as a potential vector for E. amylovora, and expand our knowledge on the possible role of these and other insects in its life cycle.

  1. Method for improving specific xanthan productivity during continuous fermentation. [Xanthomonas sp. , Xanthomonas campestris

    SciTech Connect

    Weisrock, W.P.

    1982-01-19

    The heteropolysaccharides produced by the action of Xanthomonas bacteria on carbohydrate media have a potential application as film forming agents and as thickeners for oil field drilling fluids, fracturing liquids, and emulsifying, stabilizing, and sizing agents. Heteropolysaccharides, particularly xanthan gum, have significant potential as mobility control agents in micellar polymer flooding. Xanthan gum has excellent viscosifying properties at low concentration; it is resistant to shear degradation and exhibits only minimal losses in viscosity as a function of temperature, pH, and ionic strength. During continuous culture, the concentration of biomass is set by the concentration of the limiting nutrient being fed with the medium and biomass concentration is varied by raising or lowering the limiting nutrient concentration. By growing a species of the genus Xanthomonas such as Xanthomonas campestris, in continuous culture in a medium containing glucose, mineral salts, and NH/sub 4/Cl and either glutamate or glutamate plus yeast extract, the specific productivity is improved by first operating and then raising the cell concentration. 16 claims.

  2. Method for improving specific Xanthan productivity during continuous fermentation. [Xanthomonas sp. , Xanthomonas campestris

    SciTech Connect

    Weisrock, W.P.

    1982-01-19

    The heteropolysaccharides produced by the action of Xanthomonas bacteria on carbohydrate media have a potential application as film forming agents and as thickeners for oil field drilling fluids, fracturing liquids, and emulsifying, stabilizing, and sizing agents. Heteropolysaccharides, particularly xanthan gum, have significant potential as mobility control agents in micellar polymer flooding. Xanthan gum has excellent viscosifying properties at low concentration; it is resistant to shear degradation and exhibits only minimal losses in viscosity as a function of temperature, pH, and ionic strength. During continuous culture, the concentration of biomass is set by the concentration of the limiting nutrient being fed with the medium and biomass concentration is varied by raising or lowering the limiting nutrient concentration. By growing a species of the genus Xanthomonas such as Xanthomonas campestris, in continuous culture in a medium containing glucose, mineral salts, and NH/sub 4/Cl and either glutamate or glutamate plus yeast extract, the specific productivity is improved by first operating and then raising the cell concentration. 16 claims.

  3. A genetic screen to isolate type III effectors translocated into pepper cells during Xanthomonas infection

    SciTech Connect

    Julie Anne Roden, Branids Belt, Jason Barzel Ross, Thomas Tachibana, Joe Vargas, Mary Beth Mudgett

    2004-11-23

    The bacterial pathogen Xanthomonas campestris pv. vesicatoria (Xcv) uses a type III secretion system (TTSS) to translocate effector proteins into host plant cells. The TTSS is required for Xcv colonization, yet the identity of many proteins translocated through this apparatus is not known. We used a genetic screen to functionally identify Xcv TTSS effectors. A transposon 5 (Tn5)-based transposon construct including the coding sequence for the Xcv AvrBs2 effector devoid of its TTSS signal was randomly inserted into the Xcv genome. Insertion of the avrBs2 reporter gene into Xcv genes coding for proteins containing a functional TTSS signal peptide resulted in the creation of chimeric TTSS effector::AvrBs2 fusion proteins. Xcv strains containing these fusions translocated the AvrBs2 reporter in a TTSS-dependent manner into resistant BS2 pepper cells during infection, activating the avrBs2-dependent hypersensitive response (HR). We isolated seven chimeric fusion proteins and designated the identified TTSS effectors as Xanthomonas outer proteins (Xops). Translocation of each Xop was confirmed by using the calmodulin-dependent adenylate cydase reporter assay. Three xop genes are Xanthomonas spp.-specific, whereas homologs for the rest are found in other phytopathogenic bacteria. XopF1 and XopF2 define an effector gene family in Xcv. XopN contains a eukaryotic protein fold repeat and is required for full Xcv pathogenicity in pepper and tomato. The translocated effectors identified in this work expand our knowledge of the diversity of proteins that Xcv uses to manipulate its hosts.

  4. GamR, the LysR-Type Galactose Metabolism Regulator, Regulates hrp Gene Expression via Transcriptional Activation of Two Key hrp Regulators, HrpG and HrpX, in Xanthomonas oryzae pv. oryzae

    PubMed Central

    Rashid, M. Mamunur; Ikawa, Yumi

    2016-01-01

    ABSTRACT Xanthomonas oryzae pv. oryzae is the causal agent of bacterial leaf blight of rice. For the virulence of the bacterium, the hrp genes, encoding components of the type III secretion system, are indispensable. The expression of hrp genes is regulated by two key hrp regulators, HrpG and HrpX: HrpG regulates hrpX, and HrpX regulates other hrp genes. Several other regulators have been shown to be involved in the regulation of hrp genes. Here, we found that a LysR-type transcriptional regulator that we named GamR, encoded by XOO_2767 of X. oryzae pv. oryzae strain MAFF311018, positively regulated the transcription of both hrpG and hrpX, which are adjacent to each other but have opposite orientations, with an intergenic upstream region in common. In a gel electrophoresis mobility shift assay, GamR bound directly to the middle of the upstream region common to hrpG and hrpX. The loss of either GamR or its binding sites decreased hrpG and hrpX expression. Also, GamR bound to the upstream region of either a galactose metabolism-related gene (XOO_2768) or a galactose metabolism-related operon (XOO_2768 to XOO_2771) located next to gamR itself and positively regulated the genes. The deletion of the regulator gene resulted in less bacterial growth in a synthetic medium with galactose as a sole sugar source. Interestingly, induction of the galactose metabolism-related gene was dependent on galactose, while that of the hrp regulator genes was galactose independent. Our results indicate that the LysR-type transcriptional regulator that regulates the galactose metabolism-related gene(s) also acts in positive regulation of two key hrp regulators and the following hrp genes in X. oryzae pv. oryzae. IMPORTANCE The expression of hrp genes encoding components of the type III secretion system is essential for the virulence of many plant-pathogenic bacteria, including Xanthomonas oryzae pv. oryzae. It is specifically induced during infection. Research has revealed that in this

  5. The 2009 late blight pandemic in eastern USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The tomato late blight pandemic of 2009 made late blight into a household term in much of the eastern United States. Many home gardeners and organic producers lost most, if not all, of their tomato crop, and their experiences were reported in the mainstream press. This article, which is written for ...

  6. Characterization of AvrHah1, a novel AvrBs3-like effector from Xanthomonas gardneri with virulence and avirulence activity.

    PubMed

    Schornack, Sebastian; Minsavage, Gerald V; Stall, Robert E; Jones, Jeffrey B; Lahaye, Thomas

    2008-07-01

    Many phytopathogenic bacteria inject virulence effector proteins into plant cells. To identify novel virulence effectors of the bacterial plant pathogen Xanthomonas, a worldwide collection of pepper (Capsicum annuum) pathogenic Xanthomonas strains was studied. Xanthomonas gardneri strains produced in pepper enhanced watersoaking, a phenotype that is typical of a compatible interaction. Transfer of X. gardneri library clones into a Xanthomonas euvesicatoria recipient strain revealed that enhanced watersoaking was attributable to avrHah1 (avirulence (avr) gene homologous to avrBs3 and hax2, No. 1), a novel avrBs3-like gene. avrHah1 is a novel member of the avrBs3 family that encodes tandemly arranged repeat units of both 34 and 35 amino acid lengths. Although AvrHah1 is only distantly related to AvrBs3, it was shown to trigger a Bs3-dependent hypersensitive response (HR). When fused to a nuclear export signal, AvrHah1 is no longer capable of triggering a Bs3 HR, indicating that nuclear targeting of AvrHah1 is crucial to its recognition. Phylogenetic analysis revealed that, although AvrBs3 and AvrHah1 are only distantly related, they share blocks of high homology within potentially solvent-exposed repeat units. Thus, these data suggest that the recognition specificity of AvrBs3-like proteins is predominantly determined by solvent-exposed residues, rather than by overall homology or repeat unit length.

  7. Genome Sequencing of Xanthomonas vasicola Pathovar vasculorum Reveals Variation in Plasmids and Genes Encoding Lipopolysaccharide Synthesis, Type-IV Pilus and Type-III Secretion Effectors.

    PubMed

    Wasukira, Arthur; Coulter, Max; Al-Sowayeh, Noorah; Thwaites, Richard; Paszkiewicz, Konrad; Kubiriba, Jerome; Smith, Julian; Grant, Murray; Studholme, David J

    2014-03-18

    Xanthomonas vasicola pathovar vasculorum (Xvv) is the bacterial agent causing gumming disease in sugarcane. Here, we compare complete genome sequences for five isolates of Xvv originating from sugarcane and one from maize. This identified two distinct types of lipopolysaccharide synthesis gene clusters among Xvv isolates: one is similar to that of Xanthomonas axonopodis pathovar citri (Xac) and is probably the ancestral type, while the other is similar to those of the sugarcane-inhabiting species, Xanthomonas sacchari. Four of six Xvv isolates harboured sequences similar to the Xac plasmid, pXAC47, and showed a distinct Type-IV pilus (T4P) sequence type, whereas the T4P locus of the other two isolates resembled that of the closely related banana pathogen, Xanthomonas campestris pathovar musacearum (Xcm). The Xvv isolate from maize has lost a gene encoding a homologue of the virulence effector, xopAF, which was present in all five of the sugarcane isolates, while xopL contained a premature stop codon in four out of six isolates. These findings shed new light on evolutionary events since the divergence of Xvv and Xcm, as well as further elucidating the relationships between the two closely related pathogens.

  8. Genome Sequencing of Xanthomonas vasicola Pathovar vasculorum Reveals Variation in Plasmids and Genes Encoding Lipopolysaccharide Synthesis, Type-IV Pilus and Type-III Secretion Effectors

    PubMed Central

    Wasukira, Arthur; Coulter, Max; Al-Sowayeh, Noorah; Thwaites, Richard; Paszkiewicz, Konrad; Kubiriba, Jerome; Smith, Julian; Grant, Murray; Studholme, David J.

    2014-01-01

    Xanthomonas vasicola pathovar vasculorum (Xvv) is the bacterial agent causing gumming disease in sugarcane. Here, we compare complete genome sequences for five isolates of Xvv originating from sugarcane and one from maize. This identified two distinct types of lipopolysaccharide synthesis gene clusters among Xvv isolates: one is similar to that of Xanthomonas axonopodis pathovar citri (Xac) and is probably the ancestral type, while the other is similar to those of the sugarcane-inhabiting species, Xanthomonas sacchari. Four of six Xvv isolates harboured sequences similar to the Xac plasmid, pXAC47, and showed a distinct Type-IV pilus (T4P) sequence type, whereas the T4P locus of the other two isolates resembled that of the closely related banana pathogen, Xanthomonas campestris pathovar musacearum (Xcm). The Xvv isolate from maize has lost a gene encoding a homologue of the virulence effector, xopAF, which was present in all five of the sugarcane isolates, while xopL contained a premature stop codon in four out of six isolates. These findings shed new light on evolutionary events since the divergence of Xvv and Xcm, as well as further elucidating the relationships between the two closely related pathogens. PMID:25437615

  9. Detection of early blight and late blight diseases on tomato leaves using hyperspectral imaging

    PubMed Central

    Xie, Chuanqi; Shao, Yongni; Li, Xiaoli; He, Yong

    2015-01-01

    This study investigated the potential of using hyperspectral imaging for detecting different diseases on tomato leaves. One hundred and twenty healthy, one hundred and twenty early blight and seventy late blight diseased leaves were selected to obtain hyperspectral images covering spectral wavelengths from 380 to 1023 nm. An extreme learning machine (ELM) classifier model was established based on full wavelengths. Successive projections algorithm (SPA) was used to identify the most important wavelengths. Based on the five selected wavelengths (442, 508, 573, 696 and 715 nm), an ELM model was re-established. Then, eight texture features (mean, variance, homogeneity, contrast, dissimilarity, entropy, second moment and correlation) based on gray level co-occurrence matrix (GLCM) at the five effective wavelengths were extracted to establish detection models. Among the models which were established based on spectral information, all performed excellently with the overall classification accuracy ranging from 97.1% to 100% in testing sets. Among the eight texture features, dissimilarity, second moment and entropy carried most of the effective information with the classification accuracy of 71.8%, 70.9% and 69.9% in the ELM models. The results demonstrated that hyperspectral imaging has the potential as a non-invasive method to identify early blight and late blight diseases on tomato leaves. PMID:26572857

  10. Detection of early blight and late blight diseases on tomato leaves using hyperspectral imaging.

    PubMed

    Xie, Chuanqi; Shao, Yongni; Li, Xiaoli; He, Yong

    2015-11-17

    This study investigated the potential of using hyperspectral imaging for detecting different diseases on tomato leaves. One hundred and twenty healthy, one hundred and twenty early blight and seventy late blight diseased leaves were selected to obtain hyperspectral images covering spectral wavelengths from 380 to 1023 nm. An extreme learning machine (ELM) classifier model was established based on full wavelengths. Successive projections algorithm (SPA) was used to identify the most important wavelengths. Based on the five selected wavelengths (442, 508, 573, 696 and 715 nm), an ELM model was re-established. Then, eight texture features (mean, variance, homogeneity, contrast, dissimilarity, entropy, second moment and correlation) based on gray level co-occurrence matrix (GLCM) at the five effective wavelengths were extracted to establish detection models. Among the models which were established based on spectral information, all performed excellently with the overall classification accuracy ranging from 97.1% to 100% in testing sets. Among the eight texture features, dissimilarity, second moment and entropy carried most of the effective information with the classification accuracy of 71.8%, 70.9% and 69.9% in the ELM models. The results demonstrated that hyperspectral imaging has the potential as a non-invasive method to identify early blight and late blight diseases on tomato leaves.

  11. Genomic insights into the evolutionary origin of Xanthomonas axonopodis pv. citri and its ecological relatives.

    PubMed

    Midha, Samriti; Patil, Prabhu B

    2014-10-01

    Xanthomonas axonopodis pv. citri (Xac) is the causal agent of citrus bacterial canker (CBC) and is a serious problem worldwide. Like CBC, several important diseases in other fruits, such as mango, pomegranate, and grape, are also caused by Xanthomonas pathovars that display remarkable specificity toward their hosts. While citrus and mango diseases were documented more than 100 years ago, the pomegranate and grape diseases have been known only since the 1950s and 1970s, respectively. Interestingly, diseases caused by all these pathovars were noted first in India. Our genome-based phylogenetic studies suggest that these diverse pathogens belong to a single species and these pathovars may be just a group of rapidly evolving strains. Furthermore, the recently reported pathovars, such as those infecting grape and pomegranate, form independent clonal lineages, while the citrus and mango pathovars that have been known for a long time form one clonal lineage. Such an understanding of their phylogenomic relationship has further allowed us to understand major and unique variations in the lineages that give rise to these pathovars. Whole-genome sequencing studies including ecological relatives from their putative country of origin has allowed us to understand the evolutionary history of Xac and other pathovars that infect fruits.

  12. Establishment of an inducing medium for type III effector secretion in Xanthomonas campestris pv. campestris.

    PubMed

    Jiang, Guo-Feng; Jiang, Bo-Le; Yang, Mei; Liu, San; Liu, Jiao; Liang, Xiao-Xia; Bai, Xian-Fang; Tang, Dong-Jie; Lu, Guang-Tao; He, Yong-Qiang; Yu, Di-Qiu; Tang, Ji-Liang

    2013-01-01

    It is well known that the type III secretion system (T3SS) and type III (T3) effectors are essential for the pathogenicity of most bacterial phytopathogens and that the expression of T3SS and T3 effectors is suppressed in rich media but induced in minimal media and plants. To facilitate in-depth studies on T3SS and T3 effectors, it is crucial to establish a medium for T3 effector expression and secretion. Xanthomonas campestris pv. campestris (Xcc) is a model bacterium for studying plant-pathogen interactions. To date no medium for Xcc T3 effector secretion has been defined. Here, we compared four minimal media (MME, MMX, XVM2, and XOM2) which are reported for T3 expression induction in Xanthomonas spp. and found that MME is most efficient for expression and secretion of Xcc T3 effectors. By optimization of carbon and nitrogen sources and pH value based on MME, we established XCM1 medium, which is about 3 times stronger than MME for Xcc T3 effectors secretion. We further optimized the concentration of phosphate, calcium, and magnesium in XCM1 and found that XCM1 with a lower concentration of magnesium (renamed as XCM2) is about 10 times as efficient as XCM1 (meanwhile, about 30 times stronger than MME). Thus, we established an inducing medium XCM2 which is preferred for T3 effector secretion in Xcc.

  13. Evolutionary and Experimental Assessment of Novel Markers for Detection of Xanthomonas euvesicatoria in Plant Samples

    PubMed Central

    Albuquerque, Pedro; Caridade, Cristina M. R.; Rodrigues, Arlete S.; Marcal, Andre R. S.; Cruz, Joana; Cruz, Leonor; Santos, Catarina L.; Mendes, Marta V.; Tavares, Fernando

    2012-01-01

    Background Bacterial spot-causing xanthomonads (BSX) are quarantine phytopathogenic bacteria responsible for heavy losses in tomato and pepper production. Despite the research on improved plant spraying methods and resistant cultivars, the use of healthy plant material is still considered as the most effective bacterial spot control measure. Therefore, rapid and efficient detection methods are crucial for an early detection of these phytopathogens. Methodology In this work, we selected and validated novel DNA markers for reliable detection of the BSX Xanthomonas euvesicatoria (Xeu). Xeu-specific DNA regions were selected using two online applications, CUPID and Insignia. Furthermore, to facilitate the selection of putative DNA markers, a customized C program was designed to retrieve the regions outputted by both databases. The in silico validation was further extended in order to provide an insight on the origin of these Xeu-specific regions by assessing chromosomal location, GC content, codon usage and synteny analyses. Primer-pairs were designed for amplification of those regions and the PCR validation assays showed that most primers allowed for positive amplification with different Xeu strains. The obtained amplicons were labeled and used as probes in dot blot assays, which allowed testing the probes against a collection of 12 non-BSX Xanthomonas and 23 other phytopathogenic bacteria. These assays confirmed the specificity of the selected DNA markers. Finally, we designed and tested a duplex PCR assay and an inverted dot blot platform for culture-independent detection of Xeu in infected plants. Significance This study details a selection strategy able to provide a large number of Xeu-specific DNA markers. As demonstrated, the selected markers can detect Xeu in infected plants both by PCR and by hybridization-based assays coupled with automatic data analysis. Furthermore, this work is a contribution to implement more efficient DNA-based methods of bacterial

  14. The type III protein secretion system contributes to Xanthomonas citri subsp. citri biofilm formation

    PubMed Central

    2014-01-01

    Background Several bacterial plant pathogens colonize their hosts through the secretion of effector proteins by a Type III protein secretion system (T3SS). The role of T3SS in bacterial pathogenesis is well established but whether this system is involved in multicellular processes, such as bacterial biofilm formation has not been elucidated. Here, the phytopathogen Xanthomonas citri subsp. citri (X. citri) was used as a model to gain further insights about the role of the T3SS in biofilm formation. Results The capacity of biofilm formation of different X. citri T3SS mutants was compared to the wild type strain and it was observed that this secretion system was necessary for this process. Moreover, the T3SS mutants adhered proficiently to leaf surfaces but were impaired in leaf-associated growth. A proteomic study of biofilm cells showed that the lack of the T3SS causes changes in the expression of proteins involved in metabolic processes, energy generation, exopolysaccharide (EPS) production and bacterial motility as well as outer membrane proteins. Furthermore, EPS production and bacterial motility were also altered in the T3SS mutants. Conclusions Our results indicate a novel role for T3SS in X. citri in the modulation of biofilm formation. Since this process increases X. citri virulence, this study reveals new functions of T3SS in pathogenesis. PMID:24742141

  15. Effects of Mulch and Potato Hilling on Development of Foliar Blight (Phytophthora infestans) and Control of Tuber Blight Infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Foliar and tuber blight caused by Phytophthora infestans accounts for significant losses in potatoes in field and storage, however; limited research has documented the effect of cultural practices on late blight control. Field experiments were conducted for two years on Howard gravely loam soil in N...

  16. Evolutionary history of the plant pathogenic bacterium Xanthomonas axonopodis.

    PubMed

    Mhedbi-Hajri, Nadia; Hajri, Ahmed; Boureau, Tristan; Darrasse, Armelle; Durand, Karine; Brin, Chrystelle; Fischer-Le Saux, Marion; Manceau, Charles; Poussier, Stéphane; Pruvost, Olivier; Lemaire, Christophe; Jacques, Marie-Agnès

    2013-01-01

    Deciphering mechanisms shaping bacterial diversity should help to build tools to predict the emergence of infectious diseases. Xanthomonads are plant pathogenic bacteria found worldwide. Xanthomonas axonopodis is a genetically heterogeneous species clustering, into six groups, strains that are collectively pathogenic on a large number of plants. However, each strain displays a narrow host range. We address the question of the nature of the evolutionary processes--geographical and ecological speciation--that shaped this diversity. We assembled a large collection of X. axonopodis strains that were isolated over a long period, over continents, and from various hosts. Based on the sequence analysis of seven housekeeping genes, we found that recombination occurred as frequently as point mutation in the evolutionary history of X. axonopodis. However, the impact of recombination was about three times greater than the impact of mutation on the diversity observed in the whole dataset. We then reconstructed the clonal genealogy of the strains using coalescent and genealogy approaches and we studied the diversification of the pathogen using a model of divergence with migration. The suggested scenario involves a first step of generalist diversification that spanned over the last 25,000 years. A second step of ecology-driven specialization occurred during the past two centuries. Eventually, secondary contacts between host-specialized strains probably occurred as a result of agricultural development and intensification, allowing genetic exchanges of virulence-associated genes. These transfers may have favored the emergence of novel pathotypes. Finally, we argue that the largest ecological entity within X. axonopodis is the pathovar.

  17. Evolutionary History of the Plant Pathogenic Bacterium Xanthomonas axonopodis

    PubMed Central

    Mhedbi-Hajri, Nadia; Hajri, Ahmed; Boureau, Tristan; Darrasse, Armelle; Durand, Karine; Brin, Chrystelle; Saux, Marion Fischer-Le; Manceau, Charles; Poussier, Stéphane; Pruvost, Olivier

    2013-01-01

    Deciphering mechanisms shaping bacterial diversity should help to build tools to predict the emergence of infectious diseases. Xanthomonads are plant pathogenic bacteria found worldwide. Xanthomonas axonopodis is a genetically heterogeneous species clustering, into six groups, strains that are collectively pathogenic on a large number of plants. However, each strain displays a narrow host range. We address the question of the nature of the evolutionary processes – geographical and ecological speciation – that shaped this diversity. We assembled a large collection of X. axonopodis strains that were isolated over a long period, over continents, and from various hosts. Based on the sequence analysis of seven housekeeping genes, we found that recombination occurred as frequently as point mutation in the evolutionary history of X. axonopodis. However, the impact of recombination was about three times greater than the impact of mutation on the diversity observed in the whole dataset. We then reconstructed the clonal genealogy of the strains using coalescent and genealogy approaches and we studied the diversification of the pathogen using a model of divergence with migration. The suggested scenario involves a first step of generalist diversification that spanned over the last 25 000 years. A second step of ecology-driven specialization occurred during the past two centuries. Eventually, secondary contacts between host-specialized strains probably occurred as a result of agricultural development and intensification, allowing genetic exchanges of virulence-associated genes. These transfers may have favored the emergence of novel pathotypes. Finally, we argue that the largest ecological entity within X. axonopodis is the pathovar. PMID:23505513

  18. Genetics and breeding of bacterial leaf spot resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial leaf spot (BLS) caused by the pathogen Xanthomonas campestris pv. vitians (Xcv) is a globally important disease of whole head and baby leaf lettuce that reduces crop yield and quality. Host resistance is the most feasible method to reduce disease losses. Screening Lactuca accessions has id...

  19. Bacterial Leaf Spot of Lettuce: Request for Samples

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial leaf spot of lettuce caused by by Xanthomonas campestris pv. vitians has been affecting coastal California crops for many years and has become a chronic problem. Differences in pathogen genotypes have been demonstrated and correlated to disease responses on resistant and susceptible cultiv...

  20. Draft genome sequence of Xanthomonas axonopodis pv. glycines 8ra possessing transcription activator-like effectors used for genetic engineering.

    PubMed

    Lee, Ju-Hoon; Shin, Hakdong; Park, Hye-Jee; Ryu, Sangryeol; Han, Sang-Wook

    2014-06-10

    Xanthomonas axonopodis pv. glycines 8ra is a causal agent of bacterial pustule disease in soybean. This bacterium possesses transcription activator-like (TAL) effectors which are useful for genetic/protein engineering applications in higher organisms including plants and humans. Here, we report that the draft genome sequence consists of 5,337,885-bp double-stranded DNA encoding 4674 open reading frames (ORFs) in 13 different contigs. This genome sequence would be useful in applications of TAL effectors in genetic engineering and in elucidating virulence factors against plants.

  1. Significant alterations in anisotropic ice growth rate induced by the ice nucleation-active bacteria Xanthomonas campestris

    NASA Astrophysics Data System (ADS)

    Nada, Hiroki; Zepeda, Salvador; Miura, Hitoshi; Furukawa, Yoshinori

    2010-09-01

    In the present study, we found that the ice nucleation-active bacteria Xanthomonas campestris significantly altered anisotropic ice growth rate. Results of ice growth experiments in the presence of X. campestris showed that this bacterium decreased the ice crystal growth rate in the c-axis, whereas it increased growth rates in directions normal to the c-axis. These results indicate that these alterations in anisotropic growth rate are the result of selective binding of bacterial ice-nucleating proteins along the {0 0 0 1} basal plane.

  2. Real time live imaging of phytopathogenic bacteria Xanthomonas campestris pv. campestris MAFF106712 in 'plant sweet home'.

    PubMed

    Akimoto-Tomiyama, Chiharu; Furutani, Ayako; Ochiai, Hirokazu

    2014-01-01

    Xanthomonas is one of the most widespread phytobacteria, causing diseases on a variety of agricultural plants. To develop novel control techniques, knowledge of bacterial behavior inside plant cells is essential. Xanthomonas campestris pv. campestris, a vascular pathogen, is the causal agent of black rot on leaves of Brassicaceae, including Arabidopsis thaliana. Among the X. campestris pv. campestris stocks in the MAFF collection, we selected XccMAFF106712 as a model compatible pathogen for the A. thaliana reference ecotype Columbia (Col-0). Using modified green fluorescent protein (AcGFP) as a reporter, we observed real time XccMAFF106712 colonization in planta with confocal microscopy. AcGFP-expressing bacteria colonized the inside of epidermal cells and the apoplast, as well as the xylem vessels of the vasculature. In the case of the type III mutant, bacteria colonization was never detected in the xylem vessel or apoplast, though they freely enter the xylem vessel through the wound. After 9 days post inoculation with XccMAFF106712, the xylem vessel became filled with bacterial aggregates. This suggests that Xcc colonization can be divided into main four steps, (1) movement in the xylem vessel, (2) movement to the next cell, (3) adhesion to the host plant cells, and (4) formation of bacterial aggregates. The type III mutant abolished at least steps (1) and (2). Better understanding of Xcc colonization is essential for development of novel control techniques for black rot.

  3. The Xanthomonas campestris effector protein XopDXcc8004 triggers plant disease tolerance by targeting DELLA proteins.

    PubMed

    Tan, Leitao; Rong, Wei; Luo, Hongli; Chen, Yinhua; He, Chaozu

    2014-11-01

    Plants protect themselves from the harmful effects of pathogens by resistance and tolerance. Disease resistance, which eliminates pathogens, can be modulated by bacterial type III effectors. Little is known about whether disease tolerance, which sustains host fitness with a given pathogen burden, is regulated by effectors. Here, we examined the effects of the Xanthomonas effector protein XopDXcc8004 on plant disease defenses by constructing knockout and complemented Xanthomonas strains, and performing inoculation studies in radish (Raphanus sativus L. var. radiculus XiaoJinZhong) and Arabidopsis plants. XopDXcc8004 suppresses disease symptoms without changing bacterial titers in infected leaves. In Arabidopsis, XopDXcc8004 delays the hormone gibberellin (GA)-mediated degradation of RGA (repressor of ga1-3), one of five DELLA proteins that repress GA signaling and promote plant tolerance under biotic and abiotic stresses. The ERF-associated amphiphilic repression (EAR) motif-containing region of XopDXcc8004 interacts with the DELLA domain of RGA and might interfere with the GA-induced binding of GID1, a GA receptor, to RGA. The EAR motif was found to be present in a number of plant transcriptional regulators. Thus, our data suggest that bacterial pathogens might have evolved effectors, which probably mimic host components, to initiate disease tolerance and enhance their survival.

  4. Enhanced Biological Control of Phytophthora Blight of Pepper by Biosurfactant-Producing Pseudomonas

    PubMed Central

    Özyilmaz, Ümit; Benlioglu, Kemal

    2013-01-01

    Pseudomonas isolates from different crop plants were screened for in vitro growth inhibition of Phytophthora capsici and production of biosurfactant. Two in vivo experiments were performed to determine the efficacy of selected Pseudomonas strains against Phytophthora blight of pepper by comparing two fungicide treatments [acibenzolar-S-methyl (ASM) and ASM + mefenoxam]. Bacterial isolates were applied by soil drenching (1 × 109 cells/ml), ASM (0.1 μg a.i./ml) and ASM + mefenoxam (0.2 mg product/ml) were applied by foliar spraying, and P. capsici inoculum was incorporated into the pot soil three days after treatments. In the first experiment, four Pseudomonas strains resulted in significant reduction from 48.4 to 61.3% in Phytophthora blight severity. In the second experiment, bacterial treatments combining with olive oil (5 mL per plant) significantly enhanced biological control activity, resulting in a reduction of disease level ranging from 56.8 to 81.1%. ASM + mefenoxam was the most effective treatment while ASM alone was less effective in both bioassays. These results indicate that our Pseudomonas fluorescens strains (6L10, 6ba6 and 3ss9) that have biosurfactant-producing abilities are effective against P. capsici on pepper, and enhanced disease suppression could be achieved when they were used in combination with olive oil. PMID:25288970

  5. Structural insights on two hypothetical secretion chaperones from Xanthomonas axonopodis pv. citri.

    PubMed

    Fattori, Juliana; Prando, Alessandra; Assis, Leandro H P; Aparicio, Ricardo; Tasic, Ljubica

    2011-06-01

    Several Gram-negative bacterial pathogens have developed type III secretion systems (T3SSs) to deliver virulence proteins directly into eukaryotic cells in a process essential for many diseases. The type III secretion processes require customized chaperones with high specificity for binding partners, thus providing the secretion to occur. Due to the very low sequence similarities among secretion chaperones, annotation and discrimination of a great majority of them is extremely difficult and a task with low scores even if genes are encountered that codify for small (<20 kDa) proteins with low pI and a tendency to dimerise. Concerning about this, herein, we present structural features on two hypothetical T3SSs chaperones belonging to plant pathogen Xanthomonas axonopodis pv. citri and suggest how low resolution models based on Small Angle X-ray Scattering patterns can provide new structural insights that could be very helpful in their analysis and posterior classification.

  6. Structural model and ligand interactions of the Xanthomonas axonopodis pv. citri oligopeptide-binding protein.

    PubMed

    Moutran, A; Balan, A; Ferreira, L C S; Giorgetti, A; Tramontano, A; Ferreira, R C C

    2007-12-11

    The oligopeptide-binding protein, OppA, ushers oligopeptide substrates to the membrane-associated oligopeptide permease (Opp), a multi-component ABC-type transporter involved in the uptake of oligopeptides by several bacterial species. In the present study, we report a structural model and an oligopeptide docking analysis of the OppA protein expressed by Xanthomonas axonopodis pv. citri (X. citri), the etiological agent of citrus canker. The X. citri OppA structural model showed a conserved three-dimensional structure, irrespective of the low amino acid identities with previously defined structures of Bacillus subtilis and Salmonella typhimurium orthologs. Oligopeptide docking analysis carried out with the proposed model indicated that the X. citri OppA preferentially binds tri- and tetrapeptides. The present study represents the first structural analysis of an OppA ortholog expressed by a phytopathogen and contributes to the understanding of the physiology and nutritional strategies of X. citri.

  7. A simple method for in vivo expression studies of Xanthomonas axonopodis pv. citri.

    PubMed

    Mehta, Angela; Rosato, Yoko B

    2003-11-01

    A major problem in studying bacterial plant pathogens is obtaining the microorganism directly from the plant tissue to perform in vivo expression (protein or mRNA) analyses. Here we report an easy and fast protocol to isolate Xanthomonas axonopodis pv. citri directly from the host plant, in sufficient amounts to perform protein fingerprinting by 2-D gel electrophoresis as well as RNA expression assays. The protein profile obtained was very similar to that of X. axonopodis pv. citri grown in the presence of a leaf extract of Citrus sinensis; however, some differential proteins expressed in vivo were observed. Total RNA extraction revealed typical 16S and 23S bands in the agarose gel, and RT-PCR reactions using primers specific for genes of the bacterium confirmed the quality of the RNA preparation. Also, RT-PCR reactions using plant ribosomal primers were employed, and no amplification product was obtained, indicating that plant RNA is not present in the bacterium RNA sample.

  8. Registration of PR0401-259 and PR0650-31 Dry Bean Germplasm Lines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Web blight, caused by Thanatephorus cucumeris (Frank) Donk (anamorph: Rhizoctonia solani Kühn), is a serious disease in the humid tropics that reduces both yield and seed quality. Common bacterial blight (CBB), caused by Xanthomonas axonopodis pv. phaseoli (Smith) Vauterin et al., and Bean common m...

  9. Production of xanthan gum by free and immobilized cells of Xanthomonas campestris and Xanthomonas pelargonii.

    PubMed

    Niknezhad, Seyyed Vahid; Asadollahi, Mohammad Ali; Zamani, Akram; Biria, Davoud

    2016-01-01

    Production of xanthan gum using immobilized cells of Xanthomonas campestris and Xanthomonas pelargonii grown on glucose or hydrolyzed starch as carbon sources was investigated. Calcium alginate (CA) and calcium alginate-polyvinyl alcohol-boric acid (CA-PVA) beads were used for the immobilization of cells. Xanthan titers of 8.2 and 9.2g/L were obtained for X. campestris cells immobilized in CA-PVA beads using glucose and hydrolyzed starch, respectively, whereas those for X. pelargonii were 8 and 7.9 g/L, respectively. Immobilized cells in CA-PVA beads were successfully employed in three consecutive cycles for xanthan production without any noticeable degradation of the beads whereas the CA beads were broken after the first cycle. The results of this study suggested that immobilized cells are advantageous over the free cells for xanthan production. Also it was shown that the cells immobilized in CA-PVA beads are more efficient than cells immobilized in CA beads for xanthan production.

  10. Methylome Analysis of Two Xanthomonas spp. Using Single-Molecule Real-Time Sequencing

    PubMed Central

    Seong, Hoon Je; Park, Hye-Jee; Hong, Eunji; Lee, Sung Chul; Sul, Woo Jun; Han, Sang-Wook

    2016-01-01

    Single-molecule real-time (SMRT) sequencing allows identification of methylated DNA bases and methylation patterns/motifs at the genome level. Using SMRT sequencing, diverse bacterial methylomes including those of Helicobacter pylori, Lactobacillus spp., and Escherichia coli have been determined, and previously unreported DNA methylation motifs have been identified. However, the methylomes of Xanthomonas species, which belong to the most important plant pathogenic bacterial genus, have not been documented. Here, we report the methylomes of Xanthomonas axonopodis pv. glycines (Xag) strain 8ra and X. campestris pv. vesicatoria (Xcv) strain 85-10. We identified N6-methyladenine (6mA) and N4-methylcytosine (4mC) modification in both genomes. In addition, we assigned putative DNA methylation motifs including previously unreported methylation motifs via REBASE and MotifMaker, and compared methylation patterns in both species. Although Xag and Xcv belong to the same genus, their methylation patterns were dramatically different. The number of 4mC DNA bases in Xag (66,682) was significantly higher (29 fold) than in Xcv (2,321). In contrast, the number of 6mA DNA bases (4,147) in Xag was comparable to the number in Xcv (5,491). Strikingly, there were no common or shared motifs in the 10 most frequently methylated motifs of both strains, indicating they possess unique species- or strain-specific methylation motifs. Among the 20 most frequent motifs from both strains, for 9 motifs at least 1% of the methylated bases were located in putative promoter regions. Methylome analysis by SMRT sequencing technology is the first step toward understanding the biology and functions of DNA methylation in this genus. PMID:27904456

  11. Three potato clones incorporating combined resistances to early blight from S. palustre and late blight from S. bulbocastanum into a S. tuberosum background

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three individuals from a segregating population derived from a cross between +297 and K41 are being released as germplasm with resistance to both early blight, caused by Alternaria solani, and late blight, caused by Phytophthora infestans. The source of resistance to early blight from +297 is the wi...

  12. Xanthan Gum Removal for 1H-NMR Analysis of the Intracellular Metabolome of the Bacteria Xanthomonas axonopodis pv. citri 306.

    PubMed

    Pegos, Vanessa R; Canevarolo, Rafael R; Sampaio, Aline P; Balan, Andrea; Zeri, Ana C M

    2014-04-22

    Xanthomonas is a genus of phytopathogenic bacteria, which produces a slimy, polysaccharide matrix known as xanthan gum, which involves, protects and helps the bacteria during host colonization. Although broadly used as a stabilizer and thickener in the cosmetic and food industries, xanthan gum can be a troubling artifact in molecular investigations due to its rheological properties. In particular, a cross-reaction between reference compounds and the xanthan gum could compromise metabolic quantification by NMR spectroscopy. Aiming at an efficient gum extraction protocol, for a 1H-NMR-based metabolic profiling study of Xanthomonas, we tested four different interventions on the broadly used methanol-chloroform extraction protocol for the intracellular metabolic contents observation. Lower limits for bacterial pellet volumes for extraction were also probed, and a strategy is illustrated with an initial analysis of X. citri's metabolism by 1H-NMR spectroscopy.

  13. Draft genome sequences of three Xanthomonas translucens pathovar reference strains (pv. arrhenatheri, pv. poae and pv. phlei) with different specificities for forage grasses.

    PubMed

    Hersemann, Lena; Wibberg, Daniel; Widmer, Franco; Vorhölter, Frank-Jörg; Kölliker, Roland

    2016-01-01

    As causal agents of bacterial wilt in pastures and meadows, bacteria of the species Xanthomonas translucens are a serious issue in forage grass production. So far, only little is known about host-pathogen interactions at the molecular level and the lack of comprehensive genome data impeded targeted breeding strategies towards resistant forage grass cultivars. Here we announce the draft genome sequences of three grass-pathogenic Xanthomonas translucens pathotype strains, i.e. pv. arrhenatheri LMG 727, pv. poae LMG 728 and pv. phlei LMG 730 isolated from Arrhenatherum elatius (L.) P. Beauv. ex J. Presl & C. Presl (Switzerland), Poa trivialis L. (Switzerland) and Phleum pratense L. (Norway), respectively. The genomes of all three strains revealed a non-canonical type III secretion system and a set of 22 type III effectors as common virulence-related traits. Distinct inter-pathovar differences were observed for the lipopolysaccharide biosynthesis gene cluster and the presence of nonribosomal peptide synthetases.

  14. Five phylogenetically close rice SWEET genes confer TAL effector-mediated susceptibility to Xanthomonas oryzae pv. oryzae.

    PubMed

    Streubel, Jana; Pesce, Céline; Hutin, Mathilde; Koebnik, Ralf; Boch, Jens; Szurek, Boris

    2013-11-01

    Bacterial plant-pathogenic Xanthomonas strains translocate transcription activator-like (TAL) effectors into plant cells to function as specific transcription factors. Only a few plant target genes of TAL effectors have been identified, so far. Three plant SWEET genes encoding putative sugar transporters are known to be induced by TAL effectors from rice-pathogenic Xanthomonas oryzae pv. oryzae (Xoo). We predict and validate that expression of OsSWEET14 is induced by a novel TAL effector, Tal5, from an African Xoo strain. Artificial TAL effectors (ArtTALs) were constructed to individually target 20 SWEET orthologs in rice. They were used as designer virulence factors to study which rice SWEET genes can support Xoo virulence. The Tal5 target box differs from those of the already known TAL effectors TalC, AvrXa7 and PthXo3, which also induce expression of OsSWEET14, suggesting evolutionary convergence on key targets. ArtTALs efficiently complemented an Xoo talC mutant, demonstrating that specific induction of OsSWEET14 is the key target of TalC. ArtTALs that specifically target individual members of the rice SWEET family revealed three known and two novel SWEET genes to support bacterial virulence. Our results demonstrate that five phylogenetically close SWEET proteins, which presumably act as sucrose transporters, can support Xoo virulence.

  15. Detection of Xanthomonas arboricola pv. pruni by PCR using primers based on DNA sequences related to the hrp genes.

    PubMed

    Park, So Yeon; Lee, Young Sun; Koh, Young Jin; Hur, Jae-Sun; Jung, Jae Sung

    2010-10-01

    Efficient control of Xanthomonas arboricola pv. pruni, the causal agent of bacterial spot on stone fruit, requires a sensitive and reliable diagnostic tool. A PCR detection method that utilizes primers to target the hrp gene cluster region was developed in this study. The nucleotide sequence of the PCR product amplified with primers specific for the hrp region of the xanthomonads and genomic DNA of X. arboricola pv. pruni was determined, and the sequence was aligned with that of X. campestris pv. campestris, which was obtained from the GenBank database. On the basis of the sequence of the amplified hrp region, a PCR primer set of XapF/R specific to X. arboricola pv. pruni was designed. This primer set yielded a 243-bp product from the genomic DNA of X. aboricola pv. pruni strains, but no products from other 21 strains of Xanthomonas or from two epiphytic bacterial species. Southern blot hybridization with the probe derived from the PCR product with the primer set and X. aboricola pv. pruni DNA confirmed the PCR results. The Xap primer system was successfully applied to detect the pathogen from infected peach fruits. When it was applied in field samples, the primer set was proved as a reliable diagnostic tool for specific detection of X. aboricola pv. pruni from peach orchards.

  16. Draft genome sequence for virulent and avirulent strains of Xanthomonas arboricola isolated from Prunus spp. in Spain.

    PubMed

    Garita-Cambronero, Jerson; Palacio-Bielsa, Ana; López, María M; Cubero, Jaime

    2016-01-01

    Xanthomonas arboricola is a species in genus Xanthomonas which is mainly comprised of plant pathogens. Among the members of this taxon, X. arboricola pv. pruni, the causal agent of bacterial spot disease of stone fruits and almond, is distributed worldwide although it is considered a quarantine pathogen in the European Union. Herein, we report the draft genome sequence, the classification, the annotation and the sequence analyses of a virulent strain, IVIA 2626.1, and an avirulent strain, CITA 44, of X. arboricola associated with Prunus spp. The draft genome sequence of IVIA 2626.1 consists of 5,027,671 bp, 4,720 protein coding genes and 50 RNA encoding genes. The draft genome sequence of strain CITA 44 consists of 4,760,482 bp, 4,250 protein coding genes and 56 RNA coding genes. Initial comparative analyses reveals differences in the presence of structural and regulatory components of the type IV pilus, the type III secretion system, the type III effectors as well as variations in the number of the type IV secretion systems. The genome sequence data for these strains will facilitate the development of molecular diagnostics protocols that differentiate virulent and avirulent strains. In addition, comparative genome analysis will provide insights into the plant-pathogen interaction during the bacterial spot disease process.

  17. Xanthomonas campestris attenuates virulence by sensing light through a bacteriophytochrome photoreceptor.

    PubMed

    Bonomi, Hernán R; Toum, Laila; Sycz, Gabriela; Sieira, Rodrigo; Toscani, Andrés M; Gudesblat, Gustavo E; Leskow, Federico C; Goldbaum, Fernando A; Vojnov, Adrián A; Malamud, Florencia

    2016-11-01

    Phytochromes constitute a major photoreceptor family found in plants, algae, fungi, and prokaryotes, including pathogens. Here, we report that Xanthomonas campestris pv. campestris (Xcc), the causal agent of black rot disease which affects cruciferous crops worldwide, codes for a functional bacteriophytochrome (XccBphP). XccBphP possesses an N-terminal PAS2-GAF-PHY photosensory domain triad and a C-terminal PAS9 domain as its output module. Our results show that illumination of Xcc, prior to plant infection, attenuates its virulence in an XccBphP-dependent manner. Moreover, in response to light, XccBphP downregulates xanthan exopolysaccharide production and biofilm formation, two known Xcc virulence factors. Furthermore, the XccbphP null mutant shows enhanced virulence, similar to that of dark-adapted Xcc cultures. Stomatal aperture regulation and callose deposition, both well-established plant defense mechanisms against bacterial pathogens, are overridden by the XccbphP strain. Additionally, an RNA-Seq analysis reveals that far-red light or XccBphP overexpression produces genomewide transcriptional changes, including the inhibition of several Xcc virulence systems. Our findings indicate that Xcc senses light through XccBphP, eliciting bacterial virulence attenuation via downregulation of bacterial virulence factors. The capacity of XccBphP to respond to light both in vitro and in vivo was abolished by a mutation on the conserved Cys13 residue. These results provide evidence for a novel bacteriophytochrome function affecting an infectious process.

  18. Hypersensitive response and acyl‐homoserine lactone production of the fire blight antagonists Erwinia tasmaniensis and Erwinia billingiae

    PubMed Central

    Jakovljevic, Vladimir; Jock, Susanne; Du, Zhiqiang; Geider, Klaus

    2008-01-01

    Summary Fire blight caused by the Gram‐negative bacterium Erwinia amylovora can be controlled by antagonistic microorganisms. We characterized epiphytic bacteria isolated from healthy apple and pear trees in Australia, named Erwinia tasmaniensis, and the epiphytic bacterium Erwinia billingiae from England for physiological properties, interaction with plants and interference with growth of E. amylovora. They reduced symptom formation by the fire blight pathogen on immature pears and the colonization of apple flowers. In contrast to E. billingiae, E. tasmaniensis strains induced a hypersensitive response in tobacco leaves and synthesized levan in the presence of sucrose. With consensus primers deduced from lsc as well as hrpL, hrcC and hrcR of the hrp region of E. amylovora and of related bacteria, these genes were successfully amplified from E. tasmaniensis DNA and alignment of the encoded proteins to other Erwinia species supported a role for environmental fitness of the epiphytic bacterium. Unlike E. tasmaniensis, the epiphytic bacterium E. billingiae produced an acyl‐homoserine lactone for bacterial cell‐to‐cell communication. Their competition with the growth of E. amylovora may be involved in controlling fire blight. PMID:21261861

  19. Breeding lines and host QTL interaction with bacterial strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Resistance to common bacterial blight (CBB) is controlled by more than 20 QTL (Miklas and Singh, 2007). A QTL on Pv10 linked to SAP6 SCAR markers is derived from common bean. Higher levels of resistance associated with BC420 QTL on Pv06 (Yu et al., 2000) and SU91-CG11 QTL on Pv08 (Pedraza et al., 20...

  20. Production of the refolded oligopeptide-binding protein (OppA) encoded by the citrus pathogen Xanthomonas axonopodis pv. Citri.

    PubMed

    Balan, A; Ferreira, R C C; Ferreira, L C S

    2008-02-01

    The oligopeptide-binding protein, OppA, binds and ushers oligopeptide substrates to the membrane-associated oligopeptide permease (Opp), a multi-component ABC-type transporter involved in the uptake of oligopeptides expressed by several bacterial species. In the present study, we report the cloning, purification, refolding and conformational analysis of a recombinant OppA protein derived from Xanthomonas axonopodis pv. citri (X. citri), the etiological agent of citrus canker. The oppA gene was expressed in Escherichia coli BL21 (DE3) strain under optimized inducing conditions and the recombinant protein remained largely insoluble. Solubilization was achieved following refolding of the denatured protein. Circular dichroism analysis indicated that the recombinant OppA protein preserved conformational features of orthologs expressed by other bacterial species. The refolded recombinant OppA represents a useful tool for structural and functional analyses of the X. citri protein.

  1. Nanotechnology in plant disease management: DNA-directed silver nanoparticles on graphene oxide as an antibacterial against Xanthomonas perforans.

    PubMed

    Ocsoy, Ismail; Paret, Mathews L; Ocsoy, Muserref Arslan; Kunwar, Sanju; Chen, Tao; You, Mingxu; Tan, Weihong

    2013-10-22

    Bacterial spot caused by Xanthomonas perforans is a major disease of tomatoes, leading to reduction in production by 10-50%. While copper (Cu)-based bactericides have been used for disease management, most of the X. perforans strains isolated from tomatoes in Florida and other locations worldwide are Cu-resistant. We have developed DNA-directed silver (Ag) nanoparticles (NPs) grown on graphene oxide (GO). These Ag@dsDNA@GO composites effectively decrease X. perforans cell viability in culture and on plants. At the very low concentration of 16 ppm of Ag@dsDNA@GO, composites show excellent antibacterial capability in culture with significant advantages in improved stability, enhanced antibacterial activity, and stronger adsorption properties. Application of Ag@dsDNA@GO at 100 ppm on tomato transplants in a greenhouse experiment significantly reduced the severity of bacterial spot disease compared to untreated plants, giving results similar to those of the current grower standard treatment, with no phytotoxicity.

  2. Molecular detection of Xanthomonas oryzae pv. oryzae, Xanthomonas oryzae pv. oryzicola, and Burkholderia glumae in infected rice seeds and leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polymerase chain reaction (PCR) is particularly useful for plant pathogen detection. In the present study, multiplex PCR and SYBR green real-time PCR were developed to facilitate simultaneous detection of three important rice pathogens, Xanthomonas oryzae pv. oryzae, X. oryzae pv. oryzicola, and Bur...

  3. Full Genome Sequence Analysis of Two Isolates Reveals a Novel Xanthomonas Species Close to the Sugarcane Pathogen Xanthomonas albilineans

    PubMed Central

    Pieretti, Isabelle; Cociancich, Stéphane; Bolot, Stéphanie; Carrère, Sébastien; Morisset, Alexandre; Rott, Philippe; Royer, Monique

    2015-01-01

    Xanthomonas albilineans is the bacterium responsible for leaf scald, a lethal disease of sugarcane. Within the Xanthomonas genus, X. albilineans exhibits distinctive genomic characteristics including the presence of significant genome erosion, a non-ribosomal peptide synthesis (NRPS) locus involved in albicidin biosynthesis, and a type 3 secretion system (T3SS) of the Salmonella pathogenicity island-1 (SPI-1) family. We sequenced two X. albilineans-like strains isolated from unusual environments, i.e., from dew droplets on sugarcane leaves and from the wild grass Paspalum dilatatum, and compared these genomes sequences with those of two strains of X. albilineans and three of Xanthomonas sacchari. Average nucleotide identity (ANI) and multi-locus sequence analysis (MLSA) showed that both X. albilineans-like strains belong to a new species close to X. albilineans that we have named “Xanthomonas pseudalbilineans”. X. albilineans and “X. pseudalbilineans” share many genomic features including (i) the lack of genes encoding a hypersensitive response and pathogenicity type 3 secretion system (Hrp-T3SS), and (ii) genome erosion that probably occurred in a common progenitor of both species. Our comparative analyses also revealed specific genomic features that may help X. albilineans interact with sugarcane, e.g., a PglA endoglucanase, three TonB-dependent transporters and a glycogen metabolism gene cluster. Other specific genomic features found in the “X. pseudalbilineans” genome may contribute to its fitness and specific ecological niche. PMID:26213974

  4. Preparation and evaluation of Bacillus megaterium-alginate microcapsules for control of rice sheath blight disease.

    PubMed

    Wiwattanapatapee, R; Chumthong, A; Pengnoo, A; Kanjanamaneesathian, M

    2013-08-01

    Bacillus megaterium encapsulated in calcium alginate microcapsules was prepared and tested for its efficacy against sheath blight disease of rice. In laboratory conditions, the aqueous suspension (1:100, v/v in potato dextrose agar) of the bacterial microcapsules (10(10) spores/ml) inhibited mycelial growth of Rhizoctonia solani (>99 %) after the microcapsules were produced and stored for 12 months at room temperature (28 ± 2 °C). The survival of the bacterium in the microcapsules in response to ultraviolet (u.v.) irradiation and high temperature was investigated. The survivability of the bacterium in the encapsulated form was greater than that of the fresh cells when it was subjected to u.v. (20-W General electric u.v. lamp from a 25 cm distance for 48 h) and a high temperature treatment (80 °C for 48 h). Cells of the bacterium were detected by scanning electron microscope on both the leaf sheath and the leaf blade (in pot tests in a greenhouse) after spraying encapsulated product. The number of bacteria on the surface of both rice tissues (5 Log. number/g of plant) after spraying with encapsulated product was not significantly different from that after spraying with fresh cells onto the rice seedlings. Spraying the encapsulated B. megaterium on rice plants in the greenhouse was as effective as spraying a chemical fungicide for suppressing rice sheath blight disease.

  5. Preliminary results on the ability of pentatomidae to transfer fire blight Erwinia amylovora under controlled conditions.

    PubMed

    Peusens, G; Schoofs, H; Deckers, T; Belien, T

    2013-01-01

    With their piercing-sucking mouthparts stink bugs (Heteroptera: Pentatomidae), a major pest in especially organic orchards, create wounds in fruit of pear trees. As Erwinia amylovora (Burrill, Winslow et al.), a wide spread bacterial disease affecting many rosaceous plants including pome fruit trees and hawthorn, enters through openings in flowers, leaves, shoots and fruit, feeding punctures caused by these bugs might be inoculated with Erwinia bacteria. In order to investigate the ability of the bugs Pentotoma rufipes L. and Polomena prasina L. to transmit fire blight, insects were caught in an organically managed orchard without fire blight, brought into contact with artificially inoculated immature pear fruit/slices and transferred to healthy, mechanically wounded pear fruit/slices. After an incubation period potential transmission of bacteria was examined by evaluation of symptom expression (necrosis, ooze production). To assess the presence of bacteria on the exoskeleton of the tested bugs, all bugs were forced to walk on a semiselective nutrient agar medium. In another experiment the viability of Ea on the exoskeleton was tested -after previous contact with ooze- through washing and plating of the wash water. All experiments were conducted under optimal climatological conditions and according to quarantine standards. Results demonstrated the ability of stink bugs to transfer E. amylovora to fruit and the viability of bacteria on stink bugs externally - both under lab conditions.

  6. Designer TAL effectors induce disease susceptibility and resistance to Xanthomonas oryzae pv. oryzae in rice.

    PubMed

    Li, Ting; Huang, Sheng; Zhou, Junhui; Yang, Bing

    2013-05-01

    TAL (transcription activator-like) effectors from Xanthomonas bacteria activate the cognate host genes, leading to disease susceptibility or resistance dependent on the genetic context of host target genes. The modular nature and DNA recognition code of TAL effectors enable custom-engineering of designer TAL effectors (dTALE) for gene activation. However, the feasibility of dTALEs as transcription activators for gene functional analysis has not been demonstrated. Here, we report the use of dTALEs, as expressed and delivered by the pathogenic Xanthomonas oryzae pv. oryzae (Xoo), in revealing the new function of two previously identified disease-related genes and the potential of one developmental gene for disease susceptibility in rice/Xoo interactions. The dTALE gene dTALE-xa27, designed to target the susceptible allele of the resistance gene Xa27, elicited a resistant reaction in the otherwise susceptible rice cultivar IR24. Four dTALE genes were made to induce the four annotated Xa27 homologous genes in rice cultivar Nipponbare, but none of the four induced Xa27-like genes conferred resistance to the dTALE-containing Xoo strains. A dTALE gene was also generated to activate the recessive resistance gene xa13, an allele of the disease-susceptibility gene Os8N3 (also named Xa13 or OsSWEET11, a member of sucrose efflux transporter SWEET gene family). The induction of xa13 by the dTALE rendered the resistant rice IRBB13 (xa13/xa13) susceptible to Xoo. Finally, OsSWEET12, an as-yet uncharacterized SWEET gene with no corresponding naturally occurring TAL effector identified, conferred susceptibility to the Xoo strains expressing the corresponding dTALE genes. Our results demonstrate that dTALEs can be delivered through the bacterial secretion system to activate genes of interest for functional analysis in plants.

  7. The causal agent of halo blight in bean, Pseudomonas syringae pv. phaseolicola, attaches to stomata via its pili.

    PubMed

    Romantschuk, M; Bamford, D H

    1986-04-01

    The phytopathogenic pseudomonad Pseudomonas syringae pv. phaseolicola causes halo blight of bean (Phaseolus vulgaris L.). Initiation of infection depends on the ability of the cells to adhere to the target cell surface. P. syringae pv. phaseolicola expresses pili, which are the receptors of the lipid-containing dsRNA bacteriophage phi 6. phi 6-resistant bacterial strains can be divided into different piliation types. It was possible to show that the adhesion of the bacteria onto plant cell surface was dependent on the pili. Non-piliated bacterial stains showed a much lower adherence to the leaf surface than strains expressing phi 6 specific pili. Scanning electron microscopy showed that the piliated bacteria attached to the leaf surface at the site of stomata. Non-piliated bacteria were evenly distributed on the leaf surface. All bacterial strains used in this study were capable of causing halo blight if injected into the plant. If the bacteria were sprayed on the plants, followed by spraying of sterile buffer, only piliated bacteria caused symptoms.

  8. The American Chestnut Blight: An Agent of Biological and Cultural Catastrophe.

    ERIC Educational Resources Information Center

    Lunsford, Eddie

    1999-01-01

    Reviews the history and habits of the fungus commonly referred to as the "chestnut blight." Considers the impact of the blight and efforts to control it, offers personal and cultural reflections on the blight, and gives tips for incorporating the information into cross-disciplinary lessons. Contains 17 references. (WRM)

  9. Identification of Xanthomonas fragariae, Xanthomonas axonopodis pv. phaseoli, and Xanthomonas fuscans subsp. fuscans with Novel Markers and Using a Dot Blot Platform Coupled with Automatic Data Analysis ▿ †

    PubMed Central

    Albuquerque, Pedro; Caridade, Cristina M. R.; Marcal, Andre R. S.; Cruz, Joana; Cruz, Leonor; Santos, Catarina L.; Mendes, Marta V.; Tavares, Fernando

    2011-01-01

    Phytosanitary regulations and the provision of plant health certificates still rely mainly on long and laborious culture-based methods of diagnosis, which are frequently inconclusive. DNA-based methods of detection can circumvent many of the limitations of currently used screening methods, allowing a fast and accurate monitoring of samples. The genus Xanthomonas includes 13 phytopathogenic quarantine organisms for which improved methods of diagnosis are needed. In this work, we propose 21 new Xanthomonas-specific molecular markers, within loci coding for Xanthomonas-specific protein domains, useful for DNA-based methods of identification of xanthomonads. The specificity of these markers was assessed by a dot blot hybridization array using 23 non-Xanthomonas species, mostly soil dwelling and/or phytopathogens for the same host plants. In addition, the validation of these markers on 15 Xanthomonas spp. suggested species-specific hybridization patterns, which allowed discrimination among the different Xanthomonas species. Having in mind that DNA-based methods of diagnosis are particularly hampered for unsequenced species, namely, Xanthomonas fragariae, Xanthomonas axonopodis pv. phaseoli, and Xanthomonas fuscans subsp. fuscans, for which comparative genomics tools to search for DNA signatures are not yet applicable, emphasis was given to the selection of informative markers able to identify X. fragariae, X. axonopodis pv. phaseoli, and X. fuscans subsp. fuscans strains. In order to avoid inconsistencies due to operator-dependent interpretation of dot blot data, an image-processing algorithm was developed to analyze automatically the dot blot patterns. Ultimately, the proposed markers and the dot blot platform, coupled with automatic data analyses, have the potential to foster a thorough monitoring of phytopathogenic xanthomonads. PMID:21705524

  10. New protein-protein interactions identified for the regulatory and structural components and substrates of the type III Secretion system of the phytopathogen Xanthomonas axonopodis Pathovar citri.

    PubMed

    Alegria, Marcos C; Docena, Cassia; Khater, Leticia; Ramos, Carlos H I; da Silva, Ana C R; Farah, Chuck S

    2004-09-01

    We have initiated a project to identify protein-protein interactions involved in the pathogenicity of the bacterial plant pathogen Xanthomonas axonopodis pv. citri. Using a yeast two-hybrid system based on Gal4 DNA-binding and activation domains, we have focused on identifying interactions involving subunits, regulators, and substrates of the type III secretion system coded by the hrp (for hypersensitive response and pathogenicity), hrc (for hrp conserved), and hpa (for hrp associated) genes. We have identified several previously uncharacterized interactions involving (i) HrpG, a two-component system response regulator responsible for the expression of X. axonopodis pv. citri hrp operons, and XAC0095, a previously uncharacterized protein encountered only in Xanthomonas spp.; (ii) HpaA, a protein secreted by the type III secretion system, HpaB, and the C-terminal domain of HrcV; (iii) HrpB1, HrpD6, and HrpW; and (iv) HrpB2 and HrcU. Homotropic interactions were also identified for the ATPase HrcN. These newly identified protein-protein interactions increase our understanding of the functional integration of phytopathogen-specific type III secretion system components and suggest new hypotheses regarding the molecular mechanisms underlying Xanthomonas pathogenicity.

  11. Identification of new protein-protein interactions involving the products of the chromosome- and plasmid-encoded type IV secretion loci of the phytopathogen Xanthomonas axonopodis pv. citri.

    PubMed

    Alegria, Marcos C; Souza, Diorge P; Andrade, Maxuel O; Docena, Cassia; Khater, Leticia; Ramos, Carlos H I; da Silva, Ana C R; Farah, Chuck S

    2005-04-01

    The recently sequenced genome of the bacterial plant pathogen Xanthomonas axonopodis pv. citri contains two virB gene clusters, one on the chromosome and one on a 64-kb plasmid, each of which codes for a previously uncharacterized type IV secretion system (T4SS). Here we used a yeast two-hybrid assay to identify protein-protein interactions in these two systems. Our results revealed interactions between known T4SS components as well as previously uncharacterized interactions involving hypothetical proteins coded by open reading frames in the two X. axonopodis pv. citri virB loci. Our results indicate that both loci may code for previously unidentified VirB7 proteins, which we show interact with either VirB6 or VirB9 or with a hypothetical protein coded by the same locus. Furthermore, a set of previously uncharacterized Xanthomonas proteins have been found to interact with VirD4, whose gene is adjacent to the chromosomal virB locus. The gene for one member of this family is found within the chromosomal virB locus. All these uncharacterized proteins possess a conserved 120-amino-acid domain in their C termini and may represent a family of cofactors or substrates of the Xanthomonas T4SS.

  12. Molecular identification of the turf grass rapid blight pathogen.

    PubMed

    Craven, K D; Peterson, P D; Windham, D E; Mitchell, T K; Martin, S B

    2005-01-01

    Rapid blight is a newly described disease on turf grasses, primarily found on golf courses using suboptimal water for irrigation purposes. On the basis of shared morphological characteristics, it has been proposed that the rapid blight pathogen belongs to a genus of stramenopiles, Labyrinthula, which had been known to cause disease of marine plants only. We have collected 10 isolates from four species of turf grass in five states and sequenced portions of the SSU (18S) rDNA gene from each to provide a definitive taxonomic placement for rapid blight pathogens. We also included sequences from Labyrinthuloides yorkensis, Schizochytrium aggregatum, Aplanochytrium sp., Thraustochytrium striatum, Achlya bisexualis and several nonturf-grass isolates of Labyrinthula. We found that rapid blight isolates indeed are placed firmly within the genus Labyrinthula and that they lack detectable genetic diversity in the 18S rDNA region. We propose that the rapid blight pathogens share a recent common ancestor and might have originated from a single, infected population.

  13. Ascochyta blight of chickpea: production of phytotoxins and disease management.

    PubMed

    Shahid, Ahmad Ali; Husnain, Tayyab; Riazuddin, Sheikh

    2008-01-01

    Ascochyta blight caused by Ascochyta rabiei (Pass.) Lab., is the most devastating disease of chickpea and can occur anywhere the crop is grown. Several epidemics of blight causing complete yield losses have been reported. Despite extensive pathological and molecular studies, the nature and extent of pathogenic variability in A. rabiei have not been clearly established. Several isolates of A. rabiei were grown in liquid culture medium which secreted phytotoxic compounds of solanapyrone A, B, C and cytochalasin D. The same fungal metabolites were also recovered from extract of naturally blight stricken chickpea plants. Toxicity of purified solanapyrones as determined by cell bioassay was in the order of solanapyrone A>solanapyrone B>solanapyrone C. However, the specificity of all three compounds was dependent on the genetic identity of the chickpea cultivars. Seed treatment and foliar application of fungicides are commonly recommended for disease management, but further information on biology and survival of A. rabiei is needed to devise more effective management strategies. A short description of chickpea blight, geographical distribution, disease cycle, symptoms, losses, production of phytotoxins and disease management practices for the control of Ascochyta blight will be discussed in this review article.

  14. Genomic analysis of Xanthomonas translucens pathogenic on wheat and barley reveals cross-kingdom gene transfer events and diverse protein delivery systems.

    PubMed

    Gardiner, Donald M; Upadhyaya, Narayana M; Stiller, Jiri; Ellis, Jeff G; Dodds, Peter N; Kazan, Kemal; Manners, John M

    2014-01-01

    In comparison to dicot-infecting bacteria, only limited numbers of genome sequences are available for monocot-infecting and in particular cereal-infecting bacteria. Herein we report the characterisation and genome sequence of Xanthomonas translucens isolate DAR61454 pathogenic on wheat and barley. Based on phylogenetic analysis of the ATP synthase beta subunit (atpD) gene, DAR61454 is most closely related to other X. translucens strains and the sugarcane- and banana- infecting Xanthomonas strains, but shares a type III secretion system (T3SS) with X. translucens pv. graminis and more distantly related xanthomonads. Assays with an adenylate cyclase reporter protein demonstrate that DAR61454's T3SS is functional in delivering proteins to wheat cells. X. translucens DAR61454 also encodes two type VI secretion systems with one most closely related to those found in some strains of the rice infecting strain X. oryzae pv. oryzae but not other xanthomonads. Comparative analysis of 18 different Xanthomonas isolates revealed 84 proteins unique to cereal (i.e. rice) infecting isolates and the wheat/barley infecting DAR61454. Genes encoding 60 of these proteins are found in gene clusters in the X. translucens DAR61454 genome, suggesting cereal-specific pathogenicity islands. However, none of the cereal pathogen specific proteins were homologous to known Xanthomonas spp. effectors. Comparative analysis outside of the bacterial kingdom revealed a nucleoside triphosphate pyrophosphohydrolase encoding gene in DAR61454 also present in other bacteria as well as a number of pathogenic Fusarium species, suggesting that this gene may have been transmitted horizontally from bacteria to the Fusarium lineage of pathogenic fungi. This example further highlights the importance of horizontal gene acquisition from bacteria in the evolution of fungi.

  15. Community Analysis of Biofilters Using Fluorescence In Situ Hybridization Including a New Probe for the Xanthomonas Branch of the Class Proteobacteria

    PubMed Central

    Friedrich, Udo; Naismith, Michèle M.; Altendorf, Karlheinz; Lipski, André

    1999-01-01

    Domain-, class-, and subclass-specific rRNA-targeted probes were applied to investigate the microbial communities of three industrial and three laboratory-scale biofilters. The set of probes also included a new probe (named XAN818) specific for the Xanthomonas branch of the class Proteobacteria; this probe is described in this study. The members of the Xanthomonas branch do not hybridize with previously developed rRNA-targeted oligonucleotide probes for the α-, β-, and γ-Proteobacteria. Bacteria of the Xanthomonas branch accounted for up to 4.5% of total direct counts obtained with 4′,6-diamidino-2-phenylindole. In biofilter samples, the relative abundance of these bacteria was similar to that of the γ-Proteobacteria. Actinobacteria (gram-positive bacteria with a high G+C DNA content) and α-Proteobacteria were the most dominant groups. Detection rates obtained with probe EUB338 varied between about 40 and 70%. For samples with high contents of gram-positive bacteria, these percentages were substantially improved when the calculations were corrected for the reduced permeability of gram-positive bacteria when formaldehyde was used as a fixative. The set of applied bacterial class- and subclass-specific probes yielded, on average, 58.5% (± a standard deviation of 23.0%) of the corrected eubacterial detection rates, thus indicating the necessity of additional probes for studies of biofilter communities. The Xanthomonas-specific probe presented here may serve as an efficient tool for identifying potential phytopathogens. In situ hybridization proved to be a practical tool for microbiological studies of biofiltration systems. PMID:10427047

  16. Action of chitosan against Xanthomonas pathogenic bacteria isolated from Euphorbia pulcherrima.

    PubMed

    Wang, Yanli; Li, Liping; Li, Bin; Wu, Guoxing; Tang, Qiaomei; Ibrahim, Muhammad; Li, Hongye; Xie, Guanlin; Sun, Guochang

    2012-06-07

    The antibacterial activity and mechanism of two kinds of chitosan were investigated against twelve Xanthomonas strains recovered from Euphorbia pulcherrima. Results indicated that both chitosans markedly inhibited bacterial growth based on OD loss. Furthermore, the release of DNA and RNA from three selected strains was increased by both chitosans. However, the release of intracellular proteins was inhibited by both chitosans at different concentration and incubation times, except chitosan A at 0.1 mg/mL for 0.5 h incubation and 0.2 mg/mL for 2.0 h incubation increased the release of proteins, indicating the complexity of the interaction and cell membranes, which was affected by incubation time, bacterial species, chitosan type and concentration. Transmission electron microscopic observations revealed that chitosan caused changes in protoplast concentration and surface morphology. In some cells, the membranes and walls were badly distorted and disrupted, while other cells were enveloped by a thick and compact ribbon-like layer. The contrary influence on cell morphology may explain the differential effect in the release of material. In addition, scanning electron microscope and biofilm formation test revealed that both chitosans removed biofilm biomass. Overall, this study showed that membrane and biofilm play an important role in the antibacterial mechanism of chitosan.

  17. Insertion sequence- and tandem repeat-based genotyping techniques for Xanthomonas citri pv. mangiferaeindicae.

    PubMed

    Pruvost, O; Vernière, C; Vital, K; Guérin, F; Jouen, E; Chiroleu, F; Ah-You, N; Gagnevin, L

    2011-07-01

    Molecular fingerprinting techniques that have the potential to identify or subtype bacteria at the strain level are needed for improving diagnosis and understanding of the epidemiology of pathogens such as Xanthomonas citri pv. mangiferaeindicae, which causes mango bacterial canker disease. We developed a ligation-mediated polymerase chain reaction targeting the IS1595 insertion sequence as a means to differentiate pv. mangiferaeindicae from the closely related pv. anacardii (responsible for cashew bacterial spot), which has the potential to infect mango but not to cause significant disease. This technique produced weakly polymorphic fingerprints composed of ≈70 amplified fragments per strain for a worldwide collection of X. citri pv. mangiferaeindicae but produced no or very weak amplification for pv. anacardii strains. Together, 12 tandem repeat markers were able to subtype X. citri pv. mangiferaeindicae at the strain level, distinguishing 231 haplotypes from a worldwide collection of 299 strains. Multilocus variable number of tandem repeats analysis (MLVA), IS1595-ligation-mediated polymerase chain reaction, and amplified fragment length polymorphism showed differences in discriminatory power and were congruent in describing the diversity of this strain collection, suggesting low levels of recombination. The potential of the MLVA scheme for molecular epidemiology studies of X. citri pv. mangiferaeindicae is discussed.

  18. Solution structure of ApaG from Xanthomonas axonopodis pv. citri reveals a fibronectin-3 fold.

    PubMed

    Cicero, Daniel O; Contessa, Gian M; Pertinhez, Thelma A; Gallo, Mariana; Katsuyama, Angela M; Paci, Maurizio; Farah, Chuck S; Spisni, Alberto

    2007-05-01

    ApaG proteins are found in a wide variety of bacterial genomes but their function is as yet unknown. Some eukaryotic proteins involved in protein-protein interactions, such as the human polymerase delta-interacting protein (PDIP38) and the F Box A (FBA) proteins, contain ApaG homology domains. We have used NMR to determine the solution structure of ApaG protein from the plant pathogen Xanthomonas axonopodis pv. citri (ApaG(Xac)) with the aim to shed some light on its molecular function. ApaG(Xac) is characterized by seven antiparallel beta strands forming two beta sheets, one containing three strands (ABE) and the other four strands (GFCC'). Relaxation measurements indicate that the protein has a quite rigid structure. In spite of the presence of a putative GXGXXG pyrophosphate binding motif ApaG(Xac) does not bind ATP or GTP, in vitro. On the other hand, ApaG(Xac) adopts a fibronectin type III (Fn3) fold, which is consistent with the hypothesis that it is involved in mediating protein-protein interactions. The fact that the proteins of ApaG family do not display significant sequence similarity with the Fn3 domains found in other eukaryotic or bacterial proteins suggests that Fn3 domain may have arisen earlier in evolution than previously estimated.

  19. Linkage and mapping of resistance genes to Xanthomonas axonopodis pv. passiflorae in yellow passion fruit.

    PubMed

    Lopes, Ricardo; Lopes, Maria Teresa Gomes; Carneiro, Monalisa Sampaio; Matta, Frederico de Pina; Camargo, Luis Eduardo Aranha; Vieira, Maria Lucia Carneiro

    2006-01-01

    The cultivated passion fruit (Passiflora edulis f. flavicarpa) is a cross-pollinated species native to South America. In the current study, a segregating F1 population derived from a single cross between the clones IAPAR-06 and IAPAR-123 was used to construct AFLP-based linkage maps and to map resistance genes to bacterial spot caused by Xanthomonas axonopodis pv. passiflorae. Linkage analysis was performed by the 2-way pseudo-testcross mapping method using markers that segregated in a 1:1 ratio. The IAPAR-06 linkage map was constructed using 115 markers, 112 of which were allocated to 9 linkage groups (LG) covering 790.2 cM. The map of IAPAR-123 was constructed using 140 markers, 138 of which were allocated to 9 LG covering 488.9 cM. In both maps, clusters of markers were detected, indicating that the AFLP markers were not distributed at random. Bacterial resistance was assessed by measuring the diseased leaf area after wound-inoculating the leaves of F1 plants. Quantitative resistance loci (QRLs) mapping was carried out by composite interval mapping and 1 QRL was detected, which explained 15.8% of the total phenotypic variation. The possibility of considering these data for marker-assisted selection in passion fruit breeding programs is discussed.

  20. Inhibition of Xanthomonas fragariae, Causative Agent of Angular Leaf Spot of Strawberry, through Iron Deprivation

    PubMed Central

    Henry, Peter M.; Gebben, Samantha J.; Tech, Jan J.; Yip, Jennifer L.; Leveau, Johan H. J.

    2016-01-01

    In commercial production settings, few options exist to prevent or treat angular leaf spot (ALS) of strawberry, a disease of economic importance and caused by the bacterial pathogen Xanthomonas fragariae. In the process of isolating and identifying X. fragariae bacteria from symptomatic plants, we observed growth inhibition of X. fragariae by bacterial isolates from the same leaf macerates. Identified as species of Pseudomonas and Rhizobium, these isolates were confirmed to suppress growth of X. fragariae in agar overlay plates and in microtiter plate cultures, as did our reference strain Pseudomonas putida KT2440. Screening of a transposon mutant library of KT2440 revealed that disruption of the biosynthetic pathway for the siderophore pyoverdine resulted in complete loss of X. fragariae antagonism, suggesting iron competition as a mode of action. Antagonism could be replicated on plate and in culture by addition of purified pyoverdine or by addition of the chelating agents tannic acid and dipyridyl, while supplementing the medium with iron negated the inhibitory effects of pyoverdine, tannic acid and dipyridyl. When co-inoculated with tannic acid onto strawberry plants, X. fragariae’s ability to cause foliar symptoms was greatly reduced, suggesting a possible opportunity for iron-based management of ALS. We discuss our findings in the context of ‘nutritional immunity,’ the idea that plant hosts restrict pathogen access to iron, either directly, or indirectly through their associated microbiota. PMID:27790193

  1. Host Genotype and Hypersensitive Reaction Influence Population Levels of Xanthomonas campestris pv. vitians in Lettuce.

    PubMed

    Bull, Carolee T; Gebben, Samantha J; Goldman, Polly H; Trent, Mark; Hayes, Ryan J

    2015-03-01

    Dynamics of population sizes of Xanthomonas campestris pv. vitians inoculated onto or into lettuce leaves were monitored on susceptible and resistant cultivars. In general, population growth was greater for susceptible (Clemente, Salinas 88, Vista Verde) than resistant (Batavia Reine des Glaces, Iceberg, Little Gem) cultivars. When spray-inoculated or infiltrated, population levels of X. campestris pv. vitians were consistently significantly lower on Little Gem than on susceptible cultivars, while differences in the other resistant cultivars were not consistently statistically significant. Populations increased at an intermediate rate on cultivars Iceberg and Batavia Reine des Glaces. There were significant positive correlations between bacterial concentration applied and disease severity for all cultivars, but bacterial titer had a significantly greater influence on disease severity in the susceptible cultivars than in Little Gem and an intermediate influence in Iceberg and Batavia Reine des Glaces. Infiltration of X. campestris pv. vitians strains into leaves of Little Gem resulted in an incompatible reaction, whereas compatible reactions were observed in all other cultivars. It appears that the differences in the relationship between population dynamics for Little Gem and the other cultivars tested were due to the hypersensitive response in cultivar Little Gem. These findings have implications for disease management and lettuce breeding because X. campestris pv. vitians interacts differently with cultivars that differ for resistance mechanisms.

  2. pigB determines a diffusible factor needed for extracellular polysaccharide slime and xanthomonadin production in Xanthomonas campestris pv. campestris.

    PubMed Central

    Poplawsky, A R; Chun, W

    1997-01-01

    Seven xanthomonadin transcriptional units (pigA through pigG) were identified by transposon saturation mutagenesis within an 18.6-kbp portion of the previously identified 25.4-kbp pig region from Xanthomonas campestris pv. campestris (strain B-24). Since marker exchange mutant strains with insertions in one 3.7-kbp portion of pig could not be obtained, mutations in this region may be lethal to the bacterium. Complementation analyses with different insertion mutations further defined and confirmed the seven transcriptional units. Insertional inactivation of one of the transcriptional units, pigB, resulted in greatly reduced levels of both xanthomonadins and extracellular polysaccharide slime, and a pigB-encoding plasmid restored both traits to these strains. pigB mutant strains could also be restored extracellularly by growth adjacent to strains with insertion mutations in any of the other six xanthomonadin transcriptional units, the parent strain (B-24), or strains of five different species of Xanthomonas. Strain B-24 produced a nontransforming diffusible factor (DF), which could be restored to pigB mutants by the pigB-encoding plasmid. Several lines of evidence indicate that DF is a novel bacterial pheromone, different from the known signal molecules of Vibrio, Agrobacterium, Erwinia, Pseudomonas, and Burkholderia spp. PMID:8990296

  3. Investigating alternative strategies for managing bacterial angular leaf spot in strawberry nursery production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The focus of this article is to discuss some of the approaches we have tested for managing the bacterial pathogen Xanthomonas fragariae in infected strawberry nursery stock. X. fragariae causes angular leaf spot (ALS) in strawberry. The pathogen is transmitted to production fields almost exclusively...

  4. Antagonistic activity of Bacillus subtilis SB1 and its biocontrol effect on tomato bacterial wilt

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A potential biocontrol agent of bacterial wilt, Bacillus subtilis SB1, isolated from tomato roots, showed a broad-spectrum of antimicrobial activity in in vitro experiments. It inhibited the growth of many plant pathogens, including Ralstonia solanacearum, Xanthomonas oryzae pv. oryzae, Fusarium ox...

  5. Evaluation of Glyphosate-Resistant Soybean Cultivars for Resistance to Bacterial Pustule

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Xanthomonas axonopodis pv. glycines causes bacterial pustule of soybean, which is a common disease in many soybean-growing areas of the world and is controlled by a single recessive gene that was commonly found in many conventional glyphosate-sensitive soybean cultivars. Since glyphosate-resistant c...

  6. Inhibitory activity of monoacylglycerols on biofilm formation in Aeromonas hydrophila, Streptococcus mutans, Xanthomonas oryzae, and Yersinia enterocolitica.

    PubMed

    Ham, Youngseok; Kim, Tae-Jong

    2016-01-01

    Biofilm provides a bacterial hiding place by forming a physical barrier and causing physiological changes in cells. The elimination of biofilm is the main goal of hygiene. Chemicals that are inhibitory to biofilm formation have been developed for use in food, personal hygiene products, and medical instruments. Monoacylglycerols are recognized as safe and are used in food as emulsifiers. In this study, the inhibitory activity of monoacylglycerols on bacterial biofilm formation was evaluated systematically with four bacterial strains, Aeromonas hydrophila, Streptococcus mutans, Xanthomonas oryzae, and Yersinia enterocolitica. Monoacylglycerols with two specific lengths of fatty acid moiety, monolaurin and monobehenin, were found to have strong inhibitory activity toward bacterial biofilm formation of S. mutans, X. oryzae, and Y. enterocolitica in a strain specific manner. First, this result suggested that biofilm formation was not inhibited by the detergent characteristics of monoacylglycerols. This suggestion was supported by the inhibitory action of monolaurin on biofilm development but not on the initial cell attachment of Y. enterocolitica in flow cytometric observation. Second, it was also suggested that two distinct response mechanisms to monoacylglycerols existed in bacteria. The existence of these two inhibitory response mechanisms was bacterial strain specific.

  7. Xanthomonas and the TAL Effectors: Nature's Molecular Biologist.

    PubMed

    White, Frank

    2016-01-01

    Agrobacterium, due to the transfer of T-DNA to the host genome, is known as nature's genetic engineer. Once again, bacteria have led the way to newfound riches in biotechnology. Xanthomonas has emerged as nature's molecular biologist as the functional domains of the sequence-specific DNA transcription factors known as TAL effectors were characterized and associated with the cognate disease susceptibility and resistance genes of plants.

  8. Regulation of resistance to copper in Xanthomonas axonopodis pv. vesicatoria.

    PubMed

    Voloudakis, Andreas E; Reignier, Therese M; Cooksey, Donald A

    2005-02-01

    Copper-resistant strains of Xanthomonas axonopodis pv. vesicatoria were previously shown to carry plasmid-borne copper resistance genes related to the cop and pco operons of Pseudomonas syringae and Escherichia coli, respectively. However, instead of the two-component (copRS and pcoRS) systems determining copper-inducible expression of the operons in P. syringae and E. coli, a novel open reading frame, copL, was found to be required for copper-inducible expression of the downstream multicopper oxidase copA in X. axonopodis. copL encodes a predicted protein product of 122 amino acids that is rich in histidine and cysteine residues, suggesting a possible direct interaction with copper. Deletions or frameshift mutations within copL, as well as an amino acid substitution generated at the putative start codon of copL, caused a loss of copper-inducible transcriptional activation of copA. A nonpolar insertion of a kanamycin resistance gene in copL resulted in copper sensitivity in the wild-type strain. However, repeated attempts to complement copL mutations in trans failed. Analysis of the genomic sequence databases shows that there are copL homologs upstream of copAB genes in X. axonopodis pv. citri, X. campestris pv. campestris, and Xylella fastidiosa. The cloned promoter area upstream of copA in X. axonopodis pv. vesicatoria did not function in Pseudomonas syringae or in E. coli, nor did the P. syringae cop promoter function in Xanthomonas. However, a transcriptional fusion of the Xanthomonas cop promoter with the Pseudomonas copABCDRS was able to confer resistance to copper in Xanthomonas, showing divergence in the mechanisms of regulation of the resistance to copper in phytopathogenic bacteria.

  9. Structural-functional characterization and physiological significance of ferredoxin-NADP reductase from Xanthomonas axonopodis pv. citri.

    PubMed

    Tondo, María Laura; Musumeci, Matías A; Delprato, María Laura; Ceccarelli, Eduardo A; Orellano, Elena G

    2011-01-01

    Xanthomonas axonopodis pv. citri is a phytopathogen bacterium that causes severe citrus canker disease. Similar to other phytopathogens, after infection by this bacterium, plants trigger a defense mechanism that produces reactive oxygen species. Ferredoxin-NADP(+) reductases (FNRs) are redox flavoenzymes that participate in several metabolic functions, including the response to reactive oxygen species. Xanthomonas axonopodis pv. citri has a gene (fpr) that encodes for a FNR (Xac-FNR) that belongs to the subclass I bacterial FNRs. The aim of this work was to search for the physiological role of this enzyme and to characterize its structural and functional properties. The functionality of Xac-FNR was tested by cross-complementation of a FNR knockout Escherichia coli strain, which exhibit high susceptibility to agents that produce an abnormal accumulation of (•)O(2)(-). Xac-FNR was able to substitute for the FNR in E. coli in its antioxidant role. The expression of fpr in X. axonopodis pv. citri was assessed using semiquantitative RT-PCR and Western blot analysis. A 2.2-fold induction was observed in the presence of the superoxide-generating agents methyl viologen and 2,3-dimethoxy-1,4-naphthoquinone. Structural and functional studies showed that Xac-FNR displayed different functional features from other subclass I bacterial FNRs. Our analyses suggest that these differences may be due to the unusual carboxy-terminal region. We propose a further classification of subclass I bacterial FNRs, which is useful to determine the nature of their ferredoxin redox partners. Using sequence analysis, we identified a ferredoxin (XAC1762) as a potential substrate of Xac-FNR. The purified ferredoxin protein displayed the typical broad UV-visible spectrum of [4Fe-4S] clusters and was able to function as substrate of Xac-FNR in the cytochrome c reductase activity. Our results suggest that Xac-FNR is involved in the oxidative stress response of Xanthomonas axonopodis pv. citri and

  10. Flower biology and biologically-based integrated fire blight management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fire blight infection is generally initiated in flowers, and thus, research has been directed to the biology and microbial ecology of flowers as related to this disease. In addition to investigations involving apple and pear flowers, Manchurian crab apple (Malus manchurica), closely related to appl...

  11. Fire blight: applied genomic insights of the pathogen and host

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The enterobacterial phytopathogen, Erwinia amylovora, causes fire blight, an invasive disease that threatens a wide range of commercial and ornamental Rosaceae host plants. The response elicited by E. amylovora in its host during disease development is similar to the hypersensitive reaction that ty...

  12. Pseudomonas blight caused by Pseudomonas syringae on raspberry in California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plantings of red raspberry (Rubus idaeus var. strigosus) exhibited symptoms of a previously undocumented disease. Lesions were observable from both adaxial and abaxial leaf surfaces. As disease progressed, lesions enlarged and coalesced, resulting in significant dark brown to black blighting of the ...

  13. Towards Managing Stemphylium Blight of Lentil in the Pacific Northwest

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stemphylium blight of lentil, caused by the fungus Stemphylium botryosum, has recently emerged as a disease problem in the Pacific Northwest, particularly on the recently released lentil cultivar ‘Morena’. The first step toward managing the disease is to correctly identify early signs of the diseas...

  14. Exploring Fusarium head blight disease control by RNA interference

    Technology Transfer Automated Retrieval System (TEKTRAN)

    RNA interference (RNAi) technology provides a novel tool to study gene function and plant protection strategies. Fusarium graminearum is the causal agent of Fusarium head blight (FHB), which reduces crop yield and quality by producing trichothecene mycotoxins including 3-acetyl deoxynivalenol (3-ADO...

  15. Quince (Cydonia oblonga) emerges from the ashes of fire blight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The two-decade history of fire blight in Bulgaria revealed quince as one of the most frequently attacked hosts and its production on a large scale has almost been entirely eliminated. Nevertheless, this species will play an important epidemiological role as a permanent source of inoculum for other p...

  16. Three inoculation methods for evaluating Sclerotinia blight resistance in peanut

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Laboratory-based assays for screening germplasm for resistance to Sclerotinia blight in peanuts can be conducted year-round, and thus may accelerate progress in breeding for resistant plants. Three previously proposed inoculation methods (using main stems of intact plants, detached main stems, or de...

  17. Brassica cover cropping for management of sheath blight of rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sheath blight, caused by Rhizoctonia solani, is the most important disease limiting rice production in Texas and other rice-producing states. The fungal pathogen survives between crops as soilborne sclerotia and mycelium in infected plant debris. These sclerotia and colonized plant debris float on t...

  18. Genetic variability in the pistachio late blight fungus, Alternaria alternata

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genetic variation in the pistachio late blight fungus, Alternaria alternata, was investigated by restriction fragment length polymorphism (RFLP) in the rDNA region. Southern hybridization of EcoRI, HindIII, and Xbal digested fungal DNA with a RNA probe derived from Alt1, an rDNA clone isolated from ...

  19. Sheath-blight resistance QTLs and in japonica rice germplasm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sheath blight (SB), caused by Rhizoctonia solani, is one of the most serious diseases of cultivated rice (Oryza sativa L.) and genetic resistance is in demand by rice breeders. With the goal of resistance-QTL discovery in U. S. japonica breeding material, a set of 197 F1 doubled-haploid lines (DHLs)...

  20. Ascochyta blight and insect pests of chickpeas in the Palouse

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This newsletter article informs chickpea growers in the Palouse region about current disease and insect pest problems. Ascochyta blight appeared in many chickpea fields and was severe in some fields. Insect pests including loopers and armyworms were rampant. Appropriate management practices for t...

  1. Budagovsky 9 rootstock: uncovering a novel resistance to fire blight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Budagovsky 9 (B.9) apple rootstock, displayed a high level of susceptibility (similar to M.9 rootstock) to fire blight bacteria (Erwinia amylovora) when leaves of non-grafted B.9 plants were inoculated. However, when older B.9 rootstock tissue was inoculated directly with E. amylovora, rootstock tis...

  2. Field Susceptibility of Quince Hybrids to Fire Blight in Bulgaria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spread of fire blight in Bulgaria during the last 20 years has nearly eliminated commercial production of pear and quince. Damage has increased in both nurseries and orchards, yet susceptible cultivars continue to be planted. Quince is the host most frequently attacked by Erwinia amylovora in Bulgar...

  3. Integrated Control of Fire Blight with Antagonists and Oxytetracycline

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the Pacific Northwest of the United States, the antibiotic streptomycin provided excellent control of fire blight until resistant isolates of Erwinia amylovora arose. Oxytetracycline (Mycoshield) is now sprayed as an alternative antibiotic. We found that the duration of inhibitory activity of o...

  4. Prospects for advanced late blight resistance breeding in potato

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The potato late blight pathogen, Phytophthora infestans, is able to rapidly evolve to overcome resistance genes. The pathogen accomplishes this by secreting an arsenal of proteins, termed effectors, that function to modify host cells. Although hundreds of candidate effectors have been identified in ...

  5. Fusarium stalk blight and rot in sugar beet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fusarium stalk blight of sugar beet can cause reductions or complete loss of seed production. The causal agent is Fusarium oxysporum. In addition, Fusarium solani has been demonstrated to cause a rot of sugar beet seed stalk, and other species have been reported associated with sugar beet fruit, but...

  6. Expression, purification, crystallization and preliminary X-ray analysis of YaeQ (XAC2396) from Xanthomonas axonopodis pv. citri.

    PubMed

    Guzzo, Cristiane R; Nagem, Ronaldo A P; Galvão-Botton, Leonor M P; Guimarães, Beatriz G; Medrano, Francisco J; Barbosa, João A R G; Farah, Chuck S

    2005-05-01

    Xanthomonas axonopodis pv. citri YaeQ (XAC2396) is a member of a family of bacterial proteins conserved in several Gram-negative pathogens. Here, the cloning, expression, purification and crystallization of the 182-residue (20.6 kDa) YaeQ protein are described. Recombinant YaeQ containing selenomethionine was crystallized in space group P2(1) and crystals diffracted to 1.9 A resolution at a synchrotron source. The unit-cell parameters are a = 39.75, b = 91.88, c = 48.03 A, beta = 108.37 degrees. The calculated Matthews coefficient suggests the presence of two YaeQ molecules in the asymmetric unit. Initial experimental phases were calculated by the multiple-wavelength anomalous dispersion technique and an interpretable electron-density map was obtained.

  7. Antagonism of Gluconacetobacter diazotrophicus (a sugarcane endosymbiont) against Xanthomonas albilineans (pathogen) studied in alginate-immobilized sugarcane stalk tissues.

    PubMed

    Blanco, Yolanda; Blanch, María; Piñón, Dolores; Legaz, María-Estrella; Vicente, Carlos

    2005-04-01

    Xanthomonas albilineans, a pathogenic bacterium that produces leaf scald disease of sugarcane, secretes a xanthan-like gum that invades both xylem and phloem of the host. Xanthan production has been verified after experimental infection of stalk segments of healthy plants. Moreover, Gluconacetobacter diazotrophicus is a nitrogen-fixing endosymbiont of sugarcane plants that antagonizes with X. albilineans by impeding the production of the bacterial gum. The physiological basis of this antagonism has been studied using tissues of sugarcane stalks previously inoculated with the endosymbiont, then immobilized in calcium alginate and maintained in a culture medium for Gluconacetobacter. Under these conditions, bacteria infecting immobilized tissues are able to secrete to the medium a lysozyme-like bacteriocin that inhibits the growth of X. albilineans.

  8. Crystallization and X-ray diffraction data collection of topoisomerase IV ParE subunit from Xanthomonas oryzae pv. oryzae.

    PubMed

    Shin, Hye Jeong; Yun, Mirim; Song, Ju Yeon; Kim, Hyun Jeong; Heo, Yong Seok

    2009-06-01

    Topoisomerase IV is involved in topological changes in the bacterial genome using the free energy from ATP hydrolysis. Its functions are the decatenation of daughter chromosomes following replication by DNA relaxation and double-strand DNA breakage. In this study, the N-terminal fragment of the topoisomerase IV ParE subunit from Xanthomonas oryzae pv. oryzae was overexpressed in Escherichia coli, purified and crystallized. Diffraction data were collected to 2.15 A resolution using a synchrotron-radiation source. The crystal belonged to space group P4(2)2(1)2, with unit-cell parameters a = b = 105.30, c = 133.76 A. The asymmetric unit contains one molecule, with a corresponding V(M) of 4.21 A(3) Da(-1) and a solvent content of 69.6%.

  9. Crystallization and preliminary X-ray crystallographic analysis of DNA gyrase GyrB subunit from Xanthomonas oryzae pv. oryzae.

    PubMed

    Jung, Ha Yun; Lee, Ki Jeung; Kim, Kyung Ha; Hyoung, Ji Hye; Han, Mi Ra; Kim, Hyun Kyoung; Kang, Lin-Woo; Ahn, Yeh-Jin; Heo, Yong-Seok

    2010-01-01

    DNA gyrase is a type II topoisomerase that is essential for chromosome segregation and cell division owing to its ability to modify the topological forms of bacterial DNA. In this study, the N-terminal fragment of the GyrB subunit of DNA gyrase from Xanthomonas oryzae pv. oryzae was overexpressed in Escherichia coli, purified and crystallized. Diffraction data were collected to 2.10 A resolution using a synchrotron-radiation source. The crystal belonged to space group I4(1), with unit-cell parameters a = b = 110.27, c = 70.75 A. The asymmetric unit contained one molecule, with a V(M) of 2.57 A(3) Da(-1) and a solvent content of 50.2%.

  10. Contribution of a harpin protein from Xanthomonas axonopodis pv. citri to pathogen virulence.

    PubMed

    Sgro, Germán G; Ficarra, Florencia A; Dunger, Germán; Scarpeci, Telma E; Valle, Estela M; Cortadi, Adriana; Orellano, Elena G; Gottig, Natalia; Ottado, Jorgelina

    2012-12-01

    Xanthomonas axonopodis pv. citri (Xac), the bacterium that causes citrus canker, contains a gene in the hrp [for hypersensitive response (HR) and pathogenicity] cluster that encodes a harpin protein called Hpa1. Hpa1 produced HR in the nonhost plants tobacco, pepper and Arabidopsis, whereas, in the host plant citrus, it elicited a weak defence response with no visible phenotype. Co-infiltrations of Xac with or without the recombinant Hpa1 protein in citrus leaves produced a larger number of cankers in the presence of the protein. To characterize the effect of Hpa1 during the disease, an XacΔhpa1 mutant was constructed, and infiltration of this mutant caused a smaller number of cankers. In addition, the lack of Hpa1 hindered bacterial aggregation both in solution and in planta. Analysis of citrus leaves infiltrated with Hpa1 revealed alterations in mesophyll morphology caused by the presence of cavitations and crystal idioblasts, suggesting the binding of the harpin to plant membranes and the elicitation of signalling cascades. Overall, these results suggest that, even though Hpa1 elicits the defence response in nonhost plants and, to a lesser extent, in host plants, its main roles in citrus canker are to alter leaf mesophyll structure and to aggregate bacterial cells, and thus increase virulence and pathogen fitness. We expressed the N-terminal and C-terminal regions and found that, although both regions elicited HR in nonhost plants, only the N-terminal region showed increased virulence and bacterial aggregation, supporting the role of this region of the protein as the main active domain.

  11. Amplification of DNA of Xanthomonas axonopodis pv. citri from historic citrus canker herbarium specimens.

    PubMed

    Li, Wenbin; Brlansky, Ronald H; Hartung, John S

    2006-05-01

    Herbaria are important resources for the study of the origins and dispersal of plant pathogens, particularly bacterial plant pathogens that incite local lesions in which large numbers of pathogen genomes are concentrated. Xanthomonas axonopodis pv. citri (Xac), the causal agent of citrus bacterial canker disease, is a notable example of such a pathogen. The appearance of novel strains of the pathogen in Florida and elsewhere make it increasingly important to understand the relationships among strains of this pathogen. USDA-ARS at Beltsville, Maryland maintains approximately 700 herbarium specimens with citrus canker disease lesions up to 90 years old, originally collected from all over the world, and so is an important resource for phytogeographic studies of this bacterium. Unfortunately, DNA in herbarium specimens is degraded and may contain high levels of inhibitors of PCR. In this study, we compared a total of 23 DNA isolation techniques in combination with 31 novel primer pairs in order to develop an efficient protocol for the analysis of Xac DNA in herbarium specimens. We identified the most reliable extraction method, identified in terms of successful amplification by our panel of 31 primer pairs. We also identified the most robust primer pairs, identified as successful in the largest number of extracts prepared by different methods. We amplified Xac genomic sequences up to 542 bp long from herbarium samples up to 89 years old. Primers varied in effectiveness, with some primer pairs amplifying Xac DNA from a 1/10,000 dilution of extract from a single lesion from a citrus canker herbarium specimen. Our methodology will be useful to identify pathogens and perform molecular analyses of bacterial and possibly fungal genomes from herbarium specimens.

  12. Comparative ultrastructure of nonwounded Mexican lime and Yuzu leaves infected with the citrus canker bacterium Xanthomonas citri pv. citri.

    PubMed

    Lee, In Jung; Kim, Ki Woo; Hyun, Jae Wook; Lee, Yong Hoon; Park, Eun Woo

    2009-07-01

    Ultrastructural aspects of citrus canker development were investigated in nonwounded leaves of citrus species by transmission electron microscopy (TEM). A susceptible species Mexican lime and a resistant species Yuzu were spray-inoculated with a virulent strain of Xanthomonas citri pv. citri. Initial symptoms occurred on Mexican lime approximately 9 days after inoculation, whereas they appeared on Yuzu mostly 11 days after inoculation. In Mexican lime leaves, the bacterial invasion was usually accompanied by host cell wall dissolution and cellular disruption. Fibrillar materials from degenerated cell walls were usually found in intercellular spaces. Damaged host cells with necrotic cytoplasm showed the localized separation of plasma membrane from the cell wall. Bacterial multiplication and electron-transparent capsule-like structures around bacteria were commonly observed. Meanwhile, cell wall protuberances were prominent outside host cell walls in response to bacterial invasion in Yuzu leaves. Occlusion of intercellular spaces was also formed by the fusion of two or more individual cell wall protuberances originated from two adjacent host cells. Papillae-like materials accumulated locally within host cells in close proximity to bacteria. Some bacteria were found to be undergoing degeneration in xylem vessels. Also, the shrunken, inactive bacteria were surrounded by electron-translucent fibrillar materials in intercellular spaces, implying bacterial immobilization. These cellular responses are thought to be the consequences of defense responses of Yuzu leaves to invading bacteria. In both citrus species, X. citri pv. citri contained polyphosphate bodies showing electron-dense and elliptical structures in cytoplasm.

  13. Copper chloride induces antioxidant gene expression but reduces ability to mediate H2O2 toxicity in Xanthomonas campestris.

    PubMed

    Sornchuer, Phornphan; Namchaiw, Poommaree; Kerdwong, Jarunee; Charoenlap, Nisanart; Mongkolsuk, Skorn; Vattanaviboon, Paiboon

    2014-02-01

    Copper (Cu)-based biocides are currently used as control measures for both fungal and bacterial diseases in agricultural fields. In this communication, we show that exposure of the bacterial plant pathogen Xanthomonas campestris to nonlethal concentrations of Cu(2+) ions (75 µM) enhanced expression of genes in OxyR, OhrR and IscR regulons. High levels of catalase, Ohr peroxidase and superoxide dismutase diminished Cu(2+)-induced gene expression, suggesting that the production of hydrogen peroxide (H2O2) and organic hydroperoxides is responsible for Cu(2+)-induced gene expression. Despite high expression of antioxidant genes, the CuCl2-treated cells were more susceptible to H2O2 killing treatment than the uninduced cells. This phenotype arose from lowered catalase activity in the CuCl2-pretreated cells. Thus, exposure to a nonlethal dose of Cu(2+) renders X. campestris vulnerable to H2O2, even when various genes for peroxide-metabolizing enzymes are highly expressed. Moreover, CuCl2-pretreated cells are sensitive to treatment with the redox cycling drug, menadione. No physiological cross-protection response was observed in CuCl2-treated cells in a subsequent challenge with killing concentrations of an organic hydroperoxide. As H2O2 production is an important initial plant immune response, defects in H2O2 protection are likely to reduce bacterial survival in plant hosts and enhance the usefulness of copper biocides in controlling bacterial pathogens.

  14. Evaluation of kasugamycin for fire blight management, effect on nontarget bacteria, and assessment of kasugamycin resistance potential in Erwinia amylovora.

    PubMed

    McGhee, Gayle C; Sundin, George W

    2011-02-01

    The emergence and spread of streptomycin-resistant strains of Erwinia amylovora in Michigan has necessitated the evaluation of new compounds effective for fire blight control. The aminoglycoside antibiotic kasugamycin (Ks) targets the bacterial ribosome and is particularly active against E. amylovora. The efficacy of Ks formulated as Kasumin 2L for control of fire blight was evaluated in six experiments conducted over four field seasons in our experimental orchards in East Lansing, MI. Blossom blight control was statistically equivalent to the industry standard streptomycin in all experiments. E. amylovora populations remained constant on apple flower stigmas pretreated with Kasumin and were ≈100-fold lower than on stigmas treated with water. Kasumin applied to apple trees in the field also resulted in a 100-fold reduced total culturable bacterial population compared with trees treated with water. We performed a prospective analysis of the potential for kasugamycin resistance (Ks(R)) development in E. amylovora which focused on spontaneous resistance development and acquisition of a transferrable Ks(R) gene. In replicated lab experiments, the development of spontaneous resistance in E. amylovora to Ks at 250 or 500 ppm was not observed when cells were directly plated on medium containing high concentrations of the antibiotic. However, exposure to increasing concentrations of Ks in media (initial concentration 25 μg ml(-1)) resulted in the selection of Ks resistance (at 150 μg ml(-1)) in the E. amylovora strains Ea110, Ea273, and Ea1189. Analysis of mutants indicated that they harbored mutations in the kasugamycin target ksgA gene and that all mutants were impacted in relative fitness observable through a reduced growth rate in vitro and decreased virulence in immature pear fruit. The possible occurrence of a reservoir of Ks(R) genes in orchard environments was also examined. Culturable gram-negative bacteria were surveyed from six experimental apple orchards

  15. A LOV protein modulates the physiological attributes of Xanthomonas axonopodis pv. citri relevant for host plant colonization.

    PubMed

    Kraiselburd, Ivana; Alet, Analía I; Tondo, María Laura; Petrocelli, Silvana; Daurelio, Lucas D; Monzón, Jesica; Ruiz, Oscar A; Losi, Aba; Orellano, Elena G

    2012-01-01

    Recent studies have demonstrated that an appropriate light environment is required for the establishment of efficient vegetal resistance responses in several plant-pathogen interactions. The photoreceptors implicated in such responses are mainly those belonging to the phytochrome family. Data obtained from bacterial genome sequences revealed the presence of photosensory proteins of the BLUF (Blue Light sensing Using FAD), LOV (Light, Oxygen, Voltage) and phytochrome families with no known functions. Xanthomonas axonopodis pv. citri is a Gram-negative bacterium responsible for citrus canker. The in silico analysis of the X. axonopodis pv. citri genome sequence revealed the presence of a gene encoding a putative LOV photoreceptor, in addition to two genes encoding BLUF proteins. This suggests that blue light sensing could play a role in X. axonopodis pv. citri physiology. We obtained the recombinant Xac-LOV protein by expression in Escherichia coli and performed a spectroscopic analysis of the purified protein, which demonstrated that it has a canonical LOV photochemistry. We also constructed a mutant strain of X. axonopodis pv. citri lacking the LOV protein and found that the loss of this protein altered bacterial motility, exopolysaccharide production and biofilm formation. Moreover, we observed that the adhesion of the mutant strain to abiotic and biotic surfaces was significantly diminished compared to the wild-type. Finally, inoculation of orange (Citrus sinensis) leaves with the mutant strain of X. axonopodis pv. citri resulted in marked differences in the development of symptoms in plant tissues relative to the wild-type, suggesting a role for the Xac-LOV protein in the pathogenic process. Altogether, these results suggest the novel involvement of a photosensory system in the regulation of physiological attributes of a phytopathogenic bacterium. A functional blue light receptor in Xanthomonas spp. has been described for the first time, showing an important

  16. A Novel Periplasmic Protein, VrpA, Contributes to Efficient Protein Secretion by the Type III Secretion System in Xanthomonas spp.

    PubMed

    Zhou, Xiaofeng; Hu, Xiufang; Li, Jinyun; Wang, Nian

    2015-02-01

    Efficient secretion of type III effector proteins from the bacterial cytoplasm to host cell cytosol via a type III secretion system (T3SS) is crucial for virulence of plant-pathogenic bacterium. Our previous study revealed a conserved hypothetical protein, virulence-related periplasm protein A (VrpA), which was identified as a critical virulence factor for Xanthomonas citri subsp. citri. In this study, we demonstrate that mutation of vrpA compromises X. citri subsp. citri virulence and hypersensitive response induction. This deficiency is also observed in the X. campestris pv. campestris strain, suggesting a functional conservation of VrpA in Xanthomonas spp. Our study indicates that VrpA is required for efficient protein secretion via T3SS, which is supported by multiple lines of evidence. A CyaA reporter assay shows that VrpA is involved in type III effector secretion; quantitative reverse-transcription polymerase chain reaction analysis suggests that the vrpA mutant fails to activate citrus-canker-susceptible gene CsLOB1, which is transcriptionally activated by transcription activator-like effector PthA4; in vitro secretion study reveals that VrpA plays an important role in secretion of T3SS pilus, translocon, and effector proteins. Our data also indicate that VrpA in X. citri subsp. citri localizes to bacterial periplasmic space and the periplasmic localization is required for full function of VrpA and X. citri subsp. citri virulence. Protein-protein interaction studies show that VrpA physically interacts with periplasmic T3SS components HrcJ and HrcC. However, the mutation of VrpA does not affect T3SS gene expression. Additionally, VrpA is involved in X. citri subsp. citri tolerance of oxidative stress. Our data contribute to the mechanical understanding of an important periplasmic protein VrpA in Xanthomonas spp.

  17. treA Codifies for a Trehalase with Involvement in Xanthomonas citri subsp. citri Pathogenicity

    PubMed Central

    Alexandrino, André Vessoni; Goto, Leandro Seiji; Novo-Mansur, Maria Teresa Marques

    2016-01-01

    Citrus canker, caused by the bacterium Xanthomonas citri subsp. citri (Xcc), is a severe disease of citrus. Xcc presents broad spectrum of citrus hosts including economically important species whereas X. fuscans subsp. aurantifolii–type C (XauC) causes a milder disease and only infects Citrus aurantifolia. Trehalase catalyzes hydrolysis of the disaccharide trehalose, a sugar that has been reported to be related to Xcc pathogenicity. We expressed the recombinant gene product and assessed Xcc trehalase structural and kinetics data. The recombinant protein presented 42.7% of secondary structures in α-helix and 13% in β-sheets, no quaternary structure in solution, and Michaelis-Menten constant (KM) of 0.077 mM and Vmax 55.308 μMol glucose.min-1.mg protein-1 for trehalose. A Xcc mutant strain (XccΔtreA) was produced by gene deletion from Xcc genome. Enzymatic activity of trehalase was determined in Xcc, XauC and XccΔtreA cellular lysates, showing the highest values for XauC in in vitro infective condition and no activity for XccΔtreA. Finally, leaves of Citrus aurantifolia infected with XccΔtreA showed much more drenching and necrosis than those infected by wild type Xcc. We concluded that trehalase contributes to alleviate bacterial virulence and that inability for trehalose hydrolysis may promote higher Xcc infectivity. PMID:27611974

  18. Pathogenic Interactions Between Xanthomonas axonopodis pv. citri and Cultivars of Pummelo (Citrus grandis).

    PubMed

    Shiotani, H; Ozaki, K; Tsuyumu, S

    2000-12-01

    ABSTRACT The aggressiveness of strains of Xanthomonas axonopodis pv. citri on seven Citrus species, including Citrus sinensis (navel orange), C. paradisi (grapefruit), C. unshiu (Satsuma mandarin), C. junos (Yuzu), C. aurantifolia ('Mexican' lime), C. tachibana (Tachibana), and C. grandis (pummelo: 'Otachibana', 'Banpeiyu', and 'Anseikan'), were assessed by comparing lesion expansion and growth in planta, using a prick inoculation method. The existence of two groups distinct in aggressiveness was demonstrated on the pummelo cultivars, whereas the remaining species tested were uniformly susceptible. The two groups of strains were distinct in lesion expansion and growth in planta; however, both caused canker lesions on the 'Otachibana' pummelo. The sensitivity of the bacterial strains to phages Cp1 and Cp2 was associated with differences in aggressiveness. Namely, all the strains sensitive to Cp2 but resistant to Cp1 were aggressive to 'Otachibana', whereas all the strains sensitive to Cp1 but resistant to Cp2 were weakly aggressive. When a repetitive sequence-based polymerase chain reaction amplification was carried out by enterobacterial repetitive intergeneric consensus (ERIC) sequences (ERIC1R and ERIC2) as the primers, these two groups were also distinguishable by the presence or absence of a 1.8-kb DNA fragment among otherwise identical fragments. The 1.8-kb fragment was amplified only from the strains aggressive to C. grandis.

  19. Ectopic accumulation of linalool confers resistance to Xanthomonas citri subsp. citri in transgenic sweet orange plants.

    PubMed

    Shimada, Takehiko; Endo, Tomoko; Rodríguez, Ana; Fujii, Hiroshi; Goto, Shingo; Matsuura, Takakazu; Hojo, Yuko; Ikeda, Yoko; Mori, Izumi C; Fujikawa, Takashi; Peña, Leandro; Omura, Mitsuo

    2017-01-27

    In order to clarify whether high linalool content in citrus leaves alone induces strong field resistance to citrus canker caused by Xanthomonas citri subsp. citri (Xcc), and to assess whether this trait can be transferred to a citrus type highly sensitive to the bacterium, transgenic 'Hamlin' sweet orange (Citrus sinensis L. Osbeck) plants over-expressing a linalool synthase gene (CuSTS3-1) were generated. Transgenic lines (LIL) with the highest linalool content showed strong resistance to citrus canker when spray inoculated with the bacterium. In LIL plants inoculated by wounding (multiple-needle inoculation), the linalool level was correlated with the repression of the bacterial titer and up-regulation of defense-related genes. The exogenous application of salicylic acid, methyl jasmonate or linalool triggered responses similar to those constitutively induced in LIL plants. The linalool content in Ponkan mandarin leaves was significantly higher than that of leaves from six other representative citrus genotypes with different susceptibilities to Xcc We propose that linalool-mediated resistance might be unique to citrus tissues accumulating large amounts of volatile organic compounds in oil cells. Linalool might act not only as a direct antibacterial agent, but also as a signal molecule involved in triggering a non-host resistance response against Xcc.

  20. A new function of graphene oxide emerges: inactivating phytopathogenic bacterium Xanthomonas oryzae pv. Oryzae

    NASA Astrophysics Data System (ADS)

    Chen, Juanni; Wang, Xiuping; Han, Heyou

    2013-05-01

    Xanthomonas oryzae pv. oryzae ( Xoo) is one representative phytopathogenic bacterium causing bacteria infections in rice. The antibacterial activity of graphene suspended in different dispersants against Xoo was first investigated. Bacteriological test data, fluorescence microscope and transmission electron microscopy images are provided, which yield insight into the antibacterial action of the nanoscale materials. Surprisingly, the results showed graphene oxide (GO) exhibits superior bactericidal effect even at extremely low dose in water (250 μg/mL), almost killing 94.48 % cells, in comparison to common bactericide bismerthiazol with only 13.3 % mortality. The high efficiency in inactivating the bacteria on account of considerable changes in the cell membranes caused by the extremely sharp edges of graphene oxide and generation of reactive oxygen species, which may be the fatal factor for bacterial inactivation. Given the superior antibacterial effect of GO and the fact that GO can be mass-produced with low cost, we expect a new application could be developed as bactericide for controlling plant disease, which may be a matter of great importance for agricultural development.

  1. Molecular and functional characterization of a unique sucrose hydrolase from Xanthomonas axonopodis pv. glycines.

    PubMed

    Kim, Hong-Suk; Park, Hyoung-Joon; Heu, Sunggi; Jung, Jin

    2004-01-01

    A novel sucrose hydrolase (SUH) from Xanthomonas axonopodis pv. glycines, a causative agent of bacterial pustule disease on soybeans, was studied at the functional and molecular levels. SUH was shown to act rather specifically on sucrose (K(m) = 2.5 mM) but not on sucrose-6-phosphate. Protein analysis of purified SUH revealed that, in this monomeric enzyme with an estimated molecular mass of 70,223 +/- 12 Da, amino acid sequences determined for several segments have corresponding nucleotide sequences in XAC3490, a protein-coding gene found in the genome of X. axonopodis pv. citri. Based on this information, the SUH gene, consisting of an open reading frame of 1,935 bp, was cloned by screening a genomic library of X. axonopodis pv. glycines 8ra. Database searches and sequence comparison revealed that SUH has significant homology to some family 13 enzymes, with all of the crucial invariant residues involved in the catalytic mechanism conserved, but it shows no similarity to known invertases belonging to family 32. suh expression in X. axonopodis pv. glycines requires sucrose induction, and insertional mutagenesis resulted in an absence of sucrose-inducible sucrose hydrolase activity in crude protein extracts and a sucrose-negative phenotype. Recombinant SUH, overproduced in Escherichia coli and purified, was shown to have the same enzymatic characteristics in terms of kinetic parameters.

  2. Biofilm formation, epiphytic fitness, and canker development in Xanthomonas axonopodis pv. citri.

    PubMed

    Rigano, Luciano A; Siciliano, Florencia; Enrique, Ramón; Sendín, Lorena; Filippone, Paula; Torres, Pablo S; Qüesta, Julia; Dow, J Maxwell; Castagnaro, Atilio P; Vojnov, Adrián A; Marano, María Rosa

    2007-10-01

    The phytopathogenic bacterium Xanthomonas axonopodis pv. citri is responsible for the canker disease affecting citrus plants throughout the world. Here, we have evaluated the role of bacterial attachment and biofilm formation in leaf colonization during canker development on lemon leaves. Crystal violet staining and confocal laser scanning microscopy analysis of X. axonopodis pv. citri strains expressing the green fluorescent protein were used to evaluate attachment and biofilm formation on abiotic and biotic (leaf) surfaces. Wild-type X. axonopodis pv. citri attached to and formed a complex, structured biofilm on glass in minimal medium containing glucose. Similar attachment and structured biofilm formation also were seen on lemon leaves. An X. axonopodis pv. citri gumB mutant strain, defective in production of the extracellular polysaccharide xanthan, did not form a structured biofilm on either abiotic or biotic surfaces. In addition, the X. axonopodis pv. citri gumB showed reduced growth and survival on leaf surfaces and reduced disease symptoms. These findings suggest an important role for formation of biofilms in the epiphytic survival of X. axonopodis pv. citri prior to development of canker disease.

  3. Site-directed gene replacement of the phytopathogen Xanthomonas axonopodis pv. citri.

    PubMed

    Oshiro, Elisa E; Nepomuceno, Roberto S L; Faria, Juarez B; Ferreira, Luís C S; Ferreira, Rita C C

    2006-04-01

    In this work we defined experimental conditions for site-directed gene replacement of the Xanthomonas axonopodis pv. citri (Xac), an economically relevant pathogen of citrus plants. The procedure involved, first, optimizing the electrotransformation conditions of the Xac 306 strain and, second, constructing non-replicative suicide vectors carrying knockout copies of the target gene. Using specific experimental conditions, transformation efficiencies of Xac were at least 100 fold higher than those achieved with electroporation protocols previously designed for X. campestris transformation. Successful gene replacement events were achieved with a suicide vector derived from R6K plasmid (pWR-SS) but not with those with ColE1 replication origin. We have chosen the oppA as a target gene, encoding the binding component (OppA) of the major oligopeptide uptake system found in the genome of the Xac 306 strain, although not in X. campestris pv. campestris (Xcc). Defining the experimental conditions, which allow for the specific mutagenesis of the Xac 306 strain, represents a step in the understanding of both genetics and physiology of this economically important bacterial species.

  4. An ent-kaurene-derived diterpenoid virulence factor from Xanthomonas oryzae pv. oryzicola.

    PubMed

    Lu, Xuan; Hershey, David M; Wang, Li; Bogdanove, Adam J; Peters, Reuben J

    2015-04-01

    Both plants and fungi produce ent-kaurene as a precursor to the gibberellin plant hormones. A number of rhizobia contain functionally conserved, sequentially acting ent-copalyl diphosphate and ent-kaurene synthases (CPS and KS, respectively), which are found within a well-conserved operon that may lead to the production of gibberellins. Intriguingly, the rice bacterial leaf streak pathogen Xanthomonas oryzae pv. oryzicola (Xoc) contains a homologous operon. Here, we report biochemical characterization of the encoded CPS and KS, and the impact of insertional mutagenesis on virulence and the plant defense response for these genes, as well as that for one of the cytochromes P450 (CYP112) found in the operon. Activity of the CPS and KS found in this phytopathogen was verified - that is, Xoc is capable of producing ent-kaurene. Moreover, knocking out CPS, KS or CYP112 led to mutant Xoc that exhibited reduced virulence. Investigation of the effect on marker gene transcript levels suggests that the Xoc diterpenoid affects the plant defense response, most directly that mediated by jasmonic acid (JA). Xoc produces an ent-kaurene-derived diterpenoid as a virulence factor, potentially a gibberellin phytohormone, which is antagonistic to JA, consistent with the recent recognition of opposing effects for these phytohormones on the microbial defense response.

  5. Characterization of genes encoding proteins containing HD-related output domain in Xanthomonas campestris pv. campestris.

    PubMed

    Lee, Hsien-Ming; Liao, Chao-Tsai; Chiang, Ying-Chuan; Chang, Yu-Yin; Yeh, Yu-Tzu; Du, Shin-Chiao; Hsiao, Yi-Min

    2016-04-01

    The Gram-negative plant pathogen Xanthomonas campestris pv. campestris (Xcc) is the causative agent of black rot in crucifers. The production of Xcc virulence factors is regulated by Clp and RpfF. HD-related output domain (HDOD) is a protein domain of unknown biochemical function. The genome of Xcc encodes three proteins (GsmR, HdpA, and HdpB) with an HDOD. The GsmR has been reported to play a role in the general stress response and cell motility and its expression is positively regulated by Clp. Here, the function and transcription of hdpA and hdpB were characterized. Mutation of hdpA resulted in enhanced bacterial attachment. In addition, the expression of hdpA was positively regulated by RpfF but not by Clp, subject to catabolite repression and affected by several stress conditions. However, mutational analysis and reporter assay showed that hdpB had no effect on the production of a range of virulence factors and its expression was independent of Clp and RpfF. The results shown here not only extend the previous work on RpfF regulation to show that it influences the expression of hdpA in Xcc, but also expand knowledge of the function of the HDOD containing proteins in bacteria.

  6. Association mapping of quantitative trait loci responsible for resistance to Bacterial Leaf Streak and Spot Blotch in spring wheat landraces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial leaf streak (BLS), caused by Xanthomonas translucens pv. undulosa, and spot blotch (SB), caused by Cochliobolus sativus are two major diseases of wheat (Triticum aestivum L.). Planting resistant cultivars is the best approach to manage these diseases and identifying new sources of resistan...

  7. In vitro control of plant pathogenic Xanthomonas spp. using Poncirus trifoliata Rafin.

    PubMed

    Rahman, Atiqur; Islam, Rafiquel; Al-Reza, Sharif M; Kang, Sun Chul

    2014-01-01

    The secondary metabolites such as essential oil and pure compounds (limonin and imperatorin) from Poncirus trifoliata Rafin were tested for in vitro control of phytopathogenic bacteria of Xanthomonas spp. In vitro studies showed that the oil had inhibitory effect on Xanthomonas campestris pv. compestris KC94-17-XCC, Xanthomonas campestris pv. vesicatoria YK93-4-XCV, Xanthomonas oryzae pv. oryzae KX019-XCO and Xanthomonas sp. SK12 with their inhibition zones and minimum inhibitory concentration (MIC) values ranging from 13.1~22.1 mm and 62.5~125 μg/ml, respectively. Limonin and imperatorin also had in vitro antibacterial potential (MIC: 15.62~62.5 μg/ml) against all the tested Xanthomonas spp. Furthermore, the SEM studies demonstrated that limonin and imperatorin caused morphological changes of Xanthomonas sp. SK12 at the minimum inhibitory concentration (15.62 μg/ml). These results of this study support the possible use of essential oil and natural compounds from P. Trifoliata in agriculture and agro-industries to control plant pathogenic microorganisms.

  8. In vitro control of plant pathogenic Xanthomonas spp. using Poncirus trifoliata Rafin

    PubMed Central

    Rahman, Atiqur; Islam, Rafiquel; Al-Reza, Sharif M.; Kang, Sun Chul

    2014-01-01

    The secondary metabolites such as essential oil and pure compounds (limonin and imperatorin) from Poncirus trifoliata Rafin were tested for in vitro control of phytopathogenic bacteria of Xanthomonas spp. In vitro studies showed that the oil had inhibitory effect on Xanthomonas campestris pv. compestris KC94-17-XCC, Xanthomonas campestris pv. vesicatoria YK93-4-XCV, Xanthomonas oryzae pv. oryzae KX019-XCO and Xanthomonas sp. SK12 with their inhibition zones and minimum inhibitory concentration (MIC) values ranging from 13.1~22.1 mm and 62.5~125 μg/ml, respectively. Limonin and imperatorin also had in vitro antibacterial potential (MIC: 15.62~62.5 μg/ml) against all the tested Xanthomonas spp. Furthermore, the SEM studies demonstrated that limonin and imperatorin caused morphological changes of Xanthomonas sp. SK12 at the minimum inhibitory concentration (15.62 μg/ml). These results of this study support the possible use of essential oil and natural compounds from P. Trifoliata in agriculture and agro-industries to control plant pathogenic microorganisms. PMID:26417325

  9. Pathogenomics of Xanthomonas: understanding bacterium-plant interactions.

    PubMed

    Ryan, Robert P; Vorhölter, Frank-Jörg; Potnis, Neha; Jones, Jeffrey B; Van Sluys, Marie-Anne; Bogdanove, Adam J; Dow, J Maxwell

    2011-05-01

    Xanthomonas is a large genus of Gram-negative bacteria that cause disease in hundreds of plant hosts, including many economically important crops. Pathogenic species and pathovars within species show a high degree of host plant specificity and many exhibit tissue specificity, invading either the vascular system or the mesophyll tissue of the host. In this Review, we discuss the insights that functional and comparative genomic studies are providing into the adaptation of this group of bacteria to exploit the extraordinary diversity of plant hosts and different host tissues.

  10. Control of litchi downy blight by zeamines produced by Dickeya zeae

    PubMed Central

    Liao, Lisheng; Zhou, Jianuan; Wang, Huishan; He, Fei; Liu, Shiyin; Jiang, Zide; Chen, Shaohua; Zhang, Lian-Hui

    2015-01-01

    Zeamines (ZMS), a class of polyamine-polyketide-nonribosomal peptide produced by bacterial isolate Dickeya zeae, were shown recently to be potent antibiotics against some bacterial pathogens. In this study, the results indicated that ZMS showed antifungal activity against Peronophythora litchii and other fungal pathogens. The activity of ZMS against the oomycete pathogen P. litchi, which causes the devastating litchi downy blight, was further investigated under in vitro and in vivo conditions. ZMS displayed potent inhibitory activity against the mycelial growth and sporangia germination of P. litchii. At a concentration of 2 μg/mL, about 99% of the sporangia germination was inhibited. Scanning electron microscopy and transmission electron microscopy analyses showed that treatment with ZMS could cause substantial damages to the oomycete endomembrane system. Furthermore, treatment of litchi fruits with ZMS solution significantly (P < 0.05) reduced the fruits decay and peel browning caused by P. litchii infection during storage at 28 °C. Taken together, our results provide useful clues on the antifungal mechanisms of ZMS, and highlight the promising potentials of ZMS as a fungicide, which in particular, may be useful for prevention and control of litchi fruits decay and browning caused by P. litchii infection during storage and transportation. PMID:26499339

  11. Defense-Related Responses in Fruit of the Nonhost Chili Pepper against Xanthomonas axonopodis pv. glycines Infection.

    PubMed

    Chang, Sung Pae; Jeon, Yong Ho; Kim, Young Ho

    2016-08-01

    Xanthomonas axonopodis pv. glycines (Xag ) is a necrotrophic bacterial pathogen of the soybean that causes bacterial pustules and is a nonhost pathogen of the chili pepper. In the current study, chili pepper fruit wound inoculated in planta with Xag 8ra formed necrotic lesions on the fruit surface and induced several structural and chemical barriers systemically in the fruit tissue. The initial defense response included programmed cell death of necrotizing and necrotized cells, which was characterized by nuclear DNA cleavage, as detected by TUNEL-confocal laser scanning microscopy (CLSM), and phosphatidylserine exposure on cell walls distal to the infection site, as detected by Annexin V FLUOS-CLSM. These two responses may facilitate cell killing and enhance transportation of cell wall materials used for cell wall thickening, respectively. The cells beneath the necrotic tissue were enlarged and divided to form periclinal cell walls, resulting in extensive formation of several parallel boundary layers at the later stages of infection, accompanying the deposition of wall fortification materials for strengthening structural defenses. These results suggest that nonhost resistance of chili pepper fruit against the nonhost necrotrophic pathogen Xag 8ra is activated systematically from the initial infection until termination of the infection cycle, resulting in complete inhibition of bacterial pathogenesis by utilizing organ-specific in situ physiological events governed by the expression of genes in the plant fruit organ.

  12. Metabolic Response of Strawberry (Fragaria x ananassa) Leaves Exposed to the Angular Leaf Spot Bacterium (Xanthomonas fragariae).

    PubMed

    Kim, Min-Sun; Jin, Jong Sung; Kwak, Youn-Sig; Hwang, Geum-Sook

    2016-03-09

    Plants have evolved various defense mechanisms against biotic stress. The most common mechanism involves the production of metabolites that act as defense compounds. Bacterial angular leaf spot disease (Xanthomonas fragariae) of the strawberry (Fragaria x ananassa) has become increasingly destructive to strawberry leaves and plant production. In this study, we examined metabolic changes associated with the establishment of long-term bacterial disease stress using UPLC-QTOF mass spectrometry. Infected leaves showed decreased levels of gallic acid derivatives and ellagitannins, which are related to the plant defense system. The levels of phenylalanine, tryptophan, and salicylic acid as precursors of aromatic secondary metabolites were increased in inoculated leaves, whereas levels of coumaric acid, quinic acid, and flavonoids were decreased in infected plants, which are involved in the phenylpropanoid pathway. In addition, phenylalanine ammonia-lyase (PAL) activity, a key enzyme in the phenylpropanoid pathway, was decreased following infection. These results suggest that long-term bacterial disease stress may lead to down-regulation of select molecules of the phenylpropanoid metabolic pathway in strawberry leaves. This approach could be applied to explore the metabolic pathway associated with plant protection/breeding in strawberry leaves.

  13. Defense-Related Responses in Fruit of the Nonhost Chili Pepper against Xanthomonas axonopodis pv. glycines Infection

    PubMed Central

    Chang, Sung Pae; Jeon, Yong Ho; Kim, Young Ho

    2016-01-01

    Xanthomonas axonopodis pv. glycines (Xag ) is a necrotrophic bacterial pathogen of the soybean that causes bacterial pustules and is a nonhost pathogen of the chili pepper. In the current study, chili pepper fruit wound inoculated in planta with Xag 8ra formed necrotic lesions on the fruit surface and induced several structural and chemical barriers systemically in the fruit tissue. The initial defense response included programmed cell death of necrotizing and necrotized cells, which was characterized by nuclear DNA cleavage, as detected by TUNEL-confocal laser scanning microscopy (CLSM), and phosphatidylserine exposure on cell walls distal to the infection site, as detected by Annexin V FLUOS-CLSM. These two responses may facilitate cell killing and enhance transportation of cell wall materials used for cell wall thickening, respectively. The cells beneath the necrotic tissue were enlarged and divided to form periclinal cell walls, resulting in extensive formation of several parallel boundary layers at the later stages of infection, accompanying the deposition of wall fortification materials for strengthening structural defenses. These results suggest that nonhost resistance of chili pepper fruit against the nonhost necrotrophic pathogen Xag 8ra is activated systematically from the initial infection until termination of the infection cycle, resulting in complete inhibition of bacterial pathogenesis by utilizing organ-specific in situ physiological events governed by the expression of genes in the plant fruit organ. PMID:27493606

  14. The crystallization of apo-form UMP kinase from Xanthomonas campestris is significantly improved in a strong magnetic field

    SciTech Connect

    Tu, Jhe-Le; Chin, Ko-Hsin; Wang, Andrew H.-J.; Chou, Shan-Ho

    2007-05-01

    A bacterial UMP kinase from the plant pathogen X. campestris pathovar campestris has been overexpressed in E. coli, purified and crystallized in a strong magnetic field. The crystals diffracted to 2.35 Å. Bacterial UMP kinases (UMPKs) are crucial enzymes that are responsible for microbial UTP biosynthesis. Interestingly, eukaryotic and prokaryotic cells use different enzymes for UMP-phosphorylation reactions. Prokaryotic UMPKs are thus believed to be potential targets for antimicrobial drug development. Here, the cloning, expression and crystallization of SeMet-substituted XC1936, a bacterial UMPK from Xanthomonas campestris pathovar campestris, are reported. The crystallization of the apo-form UMPK was found to be significantly improved in a strong magnetic field; the crystals diffracted to a resolution of 2.35 Å, a dramatic improvement over the original value of 3.6 Å. Preliminary structural analyses of apo-form XC1936 using crystals grown in a strong magnetic field clearly reveal well defined loop regions involved in substrate-analogue binding that were previously not visible. Crystallization in a strong magnetic field thus was found to be indispensable in determining the flexible region of the XC1936 UMPK structure.

  15. Analysis of apple (Malus) responses to bacterial pathogens using an oligo microarray

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fire blight is a devastating disease of apple (Malus x domestica) caused by the bacterial pathogen Erwinia amylovora (Ea). When infiltrated into host leaves, Ea induces reactions similar to a hypersensitive response (HR). Type III (T3SS) associated effectors, especially DspA/E, are suspected to ha...

  16. Identification of seven Xanthomonas oryzae pv. oryzicola genes potentially involved in pathogenesis in rice.

    PubMed

    Guo, Wei; Cui, Yi-Ping; Li, Yu-Rong; Che, Yi-Zhou; Yuan, Liang; Zou, Li-Fang; Zou, Hua-Song; Chen, Gong-You

    2012-02-01

    Xanthomonas oryzae pv. oryzicola (Xoc) causes bacterial leaf streak (BLS) in rice, an emerging and destructive disease worldwide. Identification of key virulence factors is a prerequisite for understanding the pathogenesis of Xoc. In this study, a Tn5-tagged mutant library of Xoc strain RS105 was screened on rice, and 27 Tn5 mutants were identified that were either non-pathogenic or showed reduced virulence in rice. Fourteen of the non-pathogenic mutants were also unable to elicit the hypersensitive response (HR) in tobacco and were designated Pth(-)/HR(-) mutants; 13 mutants showed attenuated virulence and were able to induce an HR (Vir(-)/HR(+)). Sequence analysis of the Tn5-tagged genes indicated that the 14 Pth(-)/HR(-) mutants included mutations in hrcC, hrcT, hrcV, hpaP, hrcQ, hrpF, hrpG and hrpX. The 13 Vir(-)/HR(+) mutants included tal-C10c-like (a transcriptional activator-like TAL effector), rpfC (regulator of pathogenicity factors), oxyR (oxidative stress transcriptional regulator), dsbC (disulfide isomerase), opgH (glucan biosynthesis glucosyltransferase H), rfbA (glucose-1-phosphate thymidylyltransferase), amtR (aminotransferase), purF (amidophosphoribosyltransferase), thrC (threonine synthase), trpA (tryptophan synthase alpha subunit) and three genes encoding hypothetical proteins (Xoryp_02235, Xoryp_00885 and Xoryp_22910). Collectively, the 27 Tn5 insertions are located in 21 different open reading frames. Bacterial growth and in planta virulence assays demonstrated that opgH, purF, thrC, trpA, Xoryp_02235, Xoryp_00885 and Xoryp_22910 are candidate virulence genes involved in Xoc pathogenesis. Reduced virulence in 13 mutants was restored to wild-type levels when the cognate gene was introduced in trans. Expression profiles demonstrated that the seven candidate virulence genes were significantly induced in planta, although their roles in Xoc pathogenesis remain unclear.

  17. Protein depletion using the arabinose promoter in Xanthomonas citri subsp. citri.

    PubMed

    Lacerda, Lilian A; Cavalca, Lucia B; Martins, Paula M M; Govone, José S; Bacci, Maurício; Ferreira, Henrique

    2017-03-23

    Xanthomonas citri subsp. citri (X. citri) is a plant pathogen and the etiological agent of citrus canker, a severe disease that affects all the commercially important citrus varieties, and has worldwide distribution. Citrus canker cannot be healed, and the best method known to control the spread of X. citri in the orchards is the eradication of symptomatic and asymptomatic plants in the field. However, in the state of São Paulo, Brazil, the main orange producing area in the world, control is evolving to an integrated management system (IMS) in which growers have to use less susceptible plants, windshields to prevent bacterial spread out and sprays of cupric bactericidal formulations. Our group has recently proposed alternative methods to control citrus canker, which are based on the use of chemical compounds able to disrupt vital cellular processes of X. citri. An important step in this approach is the genetic and biochemical characterization of genes/proteins that are the possible targets to be perturbed, a task not always simple when the gene/protein under investigation is essential for the organism. Here, we describe vectors carrying the arabinose promoter that enable controllable protein expression in X. citri. These vectors were used as complementation tools for the clean deletion of parB in X. citri, a widespread and conserved gene involved in the essential process of bacterial chromosome segregation. Overexpression or depletion of ParB led to increased cell size, which is probably a resultant of delayed chromosome segregation with subsequent retard of cell division. However, ParB is not essential in X. citri, and in its absence the bacterium was fully competent to colonize the host citrus and cause disease. The arabinose expression vectors described here are valuable tools for protein expression, and especially, to assist in the deletion of essential genes in X. citri.

  18. Identification of novel Xanthomonas euvesicatoria type III effector proteins by a machine-learning approach.

    PubMed

    Teper, Doron; Burstein, David; Salomon, Dor; Gershovitz, Michael; Pupko, Tal; Sessa, Guido

    2016-04-01

    The Gram-negative bacterium Xanthomonas euvesicatoria (Xcv) is the causal agent of bacterial spot disease in pepper and tomato. Xcv pathogenicity depends on a type III secretion (T3S) system that delivers effector proteins into host cells to suppress plant immunity and promote disease. The pool of known Xcv effectors includes approximately 30 proteins, most identified in the 85-10 strain by various experimental and computational techniques. To identify additional Xcv 85-10 effectors, we applied a genome-wide machine-learning approach, in which all open reading frames (ORFs) were scored according to their propensity to encode effectors. Scoring was based on a large set of features, including genomic organization, taxonomic dispersion, hypersensitive response and pathogenicity (hrp)-dependent expression, 5' regulatory sequences, amino acid composition bias and GC content. Thirty-six predicted effectors were tested for translocation into plant cells using the hypersensitive response (HR)-inducing domain of AvrBs2 as a reporter. Seven proteins (XopAU, XopAV, XopAW, XopAP, XopAX, XopAK and XopAD) harboured a functional translocation signal and their translocation relied on the HrpF translocon, indicating that they are bona fide T3S effectors. Remarkably, four belong to novel effector families. Inactivation of the xopAP gene reduced the severity of disease symptoms in infected plants. A decrease in cell death and chlorophyll content was observed in pepper leaves inoculated with the xopAP mutant when compared with the wild-type strain. However, populations of the xopAP mutant in infected leaves were similar in size to those of wild-type bacteria, suggesting that the reduction in virulence was not caused by impaired bacterial growth.

  19. Draft genome sequence of Xanthomonas axonopodis pathovar vasculorum NCPPB 900.

    PubMed

    Harrison, James; Studholme, David J

    2014-11-01

    Xanthomonas axonopodis pathovar vasculorum strain NCPPB 900 was isolated from sugarcane on Reunion island in 1960. Consistent with its belonging to fatty-acid type D, multi-locus sequence analysis confirmed that NCPPB 900 falls within the species X. axonopodis. This genome harbours sequences similar to plasmids pXCV183 from X. campestris pv. vesicatoria 85-10 and pPHB194 from Burkholderia pseudomallei. Its repertoire of predicted effectors includes homologues of XopAA, XopAD, XopAE, XopB, XopD, XopV, XopZ, XopC and XopI and transcriptional activator-like effectors and it is predicted to encode a novel phosphonate natural product also encoded by the genome of the phylogenetically distant X. vasicola pv. vasculorum. Availability of this novel genome sequence may facilitate the study of interactions between xanthomonads and sugarcane, a host-pathogen system that appears to have evolved several times independently within the genus Xanthomonas and may also provide a source of target sequences for molecular detection and diagnostics

  20. RNA-seq pinpoints a Xanthomonas TAL-effector activated resistance gene in a large-crop genome.

    PubMed

    Strauss, Tina; van Poecke, Remco M P; Strauss, Annett; Römer, Patrick; Minsavage, Gerald V; Singh, Sylvia; Wolf, Christina; Strauss, Axel; Kim, Seungill; Lee, Hyun-Ah; Yeom, Seon-In; Parniske, Martin; Stall, Robert E; Jones, Jeffrey B; Choi, Doil; Prins, Marcel; Lahaye, Thomas

    2012-11-20

    Transcription activator-like effector (TALE) proteins of the plant pathogenic bacterial genus Xanthomonas bind to and transcriptionally activate host susceptibility genes, promoting disease. Plant immune systems have taken advantage of this mechanism by evolving TALE binding sites upstream of resistance (R) genes. For example, the pepper Bs3 and rice Xa27 genes are hypersensitive reaction plant R genes that are transcriptionally activated by corresponding TALEs. Both R genes have a hallmark expression pattern in which their transcripts are detectable only in the presence and not the absence of the corresponding TALE. By transcriptome profiling using next-generation sequencing (RNA-seq), we tested whether we could avoid laborious positional cloning for the isolation of TALE-induced R genes. In a proof-of-principle experiment, RNA-seq was used to identify a candidate for Bs4C, an R gene from pepper that mediates recognition of the Xanthomonas TALE protein AvrBs4. We identified one major Bs4C candidate transcript by RNA-seq that was expressed exclusively in the presence of AvrBs4. Complementation studies confirmed that the candidate corresponds to the Bs4C gene and that an AvrBs4 binding site in the Bs4C promoter directs its transcriptional activation. Comparison of Bs4C with a nonfunctional allele that is unable to recognize AvrBs4 revealed a 2-bp polymorphism within the TALE binding site of the Bs4C promoter. Bs4C encodes a structurally unique R protein and Bs4C-like genes that are present in many solanaceous genomes seem to be as tightly regulated as pepper Bs4C. These findings demonstrate that TALE-specific R genes can be cloned from large-genome crops with a highly efficient RNA-seq approach.

  1. Structural and Physiological Analyses of the Alkanesulphonate-Binding Protein (SsuA) of the Citrus Pathogen Xanthomonas citri

    PubMed Central

    Tófoli de Araújo, Fabiano; Bolanos-Garcia, Victor M.; Pereira, Cristiane T.; Sanches, Mario; Oshiro, Elisa E.; Ferreira, Rita C. C.; Chigardze, Dimitri Y.; Barbosa, João Alexandre Gonçalves; de Souza Ferreira, Luís Carlos; Benedetti, Celso E.; Blundell, Tom L.; Balan, Andrea

    2013-01-01

    Background The uptake of sulphur-containing compounds plays a pivotal role in the physiology of bacteria that live in aerobic soils where organosulfur compounds such as sulphonates and sulphate esters represent more than 95% of the available sulphur. Until now, no information has been available on the uptake of sulphonates by bacterial plant pathogens, particularly those of the Xanthomonas genus, which encompasses several pathogenic species. In the present study, we characterised the alkanesulphonate uptake system (Ssu) of Xanthomonas axonopodis pv. citri 306 strain (X. citri), the etiological agent of citrus canker. Methodology/Principal Findings A single operon-like gene cluster (ssuEDACB) that encodes both the sulphur uptake system and enzymes involved in desulphurisation was detected in the genomes of X. citri and of the closely related species. We characterised X. citri SsuA protein, a periplasmic alkanesulphonate-binding protein that, together with SsuC and SsuB, defines the alkanesulphonate uptake system. The crystal structure of SsuA bound to MOPS, MES and HEPES, which is herein described for the first time, provides evidence for the importance of a conserved dipole in sulphate group coordination, identifies specific amino acids interacting with the sulphate group and shows the presence of a rather large binding pocket that explains the rather wide range of molecules recognised by the protein. Isolation of an isogenic ssuA-knockout derivative of the X. citri 306 strain showed that disruption of alkanesulphonate uptake affects both xanthan gum production and generation of canker lesions in sweet orange leaves. Conclusions/Significance The present study unravels unique structural and functional features of the X. citri SsuA protein and provides the first experimental evidence that an ABC uptake system affects the virulence of this phytopathogen. PMID:24282519

  2. Genetic and pathogenic variability of Indian strains of Xanthomonas campestris pv. campestris causing black rot disease in crucifers.

    PubMed

    Singh, Dinesh; Dhar, Shri; Yadava, D K

    2011-12-01

    Xanthomonas campestris pv. campestris (Pammel) Dowson (Xcc) causing black rot of crucifers is a serious disease in India and causes >50% crop losses in favorable environmental conditions. Pathogenic variability of Xcc, X. oryzae pv. oryzae (Xoo), and X. axonopodis pv. citri (Xac) were tested on 19 cultivars of cruciferae including seven Brassica spp. viz., B. campestris, B. carinata, B. juncea, B. napus, B. nigra, B. oleracea and B. rapa, and Raphanus sativus for two consecutive years viz., 2007-2008 and 2008-2009 under field conditions at Indian Agricultural Research Institute, New Delhi. Xcc (22 strains) and other species of Xanthomonas (2 strains), they formed three distinct groups of pathogenic variability i.e., Group 1, 2, and 3 under 50% minimum similarity coefficient. All strains of Xcc clustered under Groupl except Xcc-C20. The strains of Xcc further clustered in 6 subgroups viz., A, B, C, D, E, and F based on diseases reaction on host. Genetic variability of 22 strains of Xcc was studied by using Rep-PCR (REP-, BOX- and ERIC-PCR) and 10 strains for hrp (hypersensitive reaction and pathogenecity) gene sequence analysis. Xcc strains comprised in cluster 1, Xac under cluster 2, while Xoo formed separate cluster 3 based on >50% similarity coefficient. Cluster 1 was further divided into 8 subgroups viz., A, B, C, D, E, F, G, and H at 75% similarity coefficient. The hrpF gene sequence analysis also showed distinctness of Xcc strains from other Xanthomonads. In this study, genetic and pathogenic variability in Indian strains of Xcc were established, which will be of immense use in the development of resistant genotypes against this bacterial pathogen.

  3. Phylogenetic structure of Xanthomonas determined by comparison of gyrB sequences.

    PubMed

    Parkinson, Neil; Cowie, Claire; Heeney, John; Stead, David

    2009-02-01

    Previously, we have produced a phylogeny of species type strains from the plant-pathogenic genus Xanthomonas based on gyrB sequences. To evaluate this locus further for species and infraspecies identification, we sequenced an additional 203 strains comprising all the pathovar reference strains (which have defined plant hosts), 67 poorly characterized pathovars, currently classified as Xanthomonas campestris, and 59 unidentified xanthomonads. The well-characterized pathovars grouped either in clades containing their respective species type strain or in clades containing species related to Xanthomonas axonopodis. The Xanthomonas euvesicatoria, Xanthomonas perforans and Xanthomonas alfalfae species complex, Xanthomonas fuscans and Xanthomonas citri were discriminated as X. axonopodis-related clades and comprised a large proportion of unidentified strains as well as 80 pathovars representing all the X. axonopodis pathovars and many poorly characterized pathovars, greatly increasing the plant host ranges of the constituent species. Most xanthomonads from these three large clades were isolated from a taxonomically diverse range of plant hosts, including many weed species, from field systems in India, suggesting that these lineages became established and diversified in agricultural areas in this region. The majority of these xanthomonads had minimal sequence diversity, consistent with rapid and highly extensive pathovar diversification that has occurred in relatively recent times. Low-intensity farming practices may have provided conditions conducive to pathovar development, and evidence for pathovar diversification within other regional angiosperm floras is discussed. The gyrB locus was sufficiently discriminating to identify diversity within many species. Seven branches or clades were sufficiently distinct to be considered as potential novel species. This study has provided a comprehensive xanthomonad classification framework and has firmly established gyrB sequencing

  4. A MLVA genotyping scheme for global surveillance of the citrus pathogen Xanthomonas citri pv. citri suggests a worldwide geographical expansion of a single genetic lineage.

    PubMed

    Pruvost, Olivier; Magne, Maxime; Boyer, Karine; Leduc, Alice; Tourterel, Christophe; Drevet, Christine; Ravigné, Virginie; Gagnevin, Lionel; Guérin, Fabien; Chiroleu, Frédéric; Koebnik, Ralf; Verdier, Valérie; Vernière, Christian

    2014-01-01

    MultiLocus Variable number of tandem repeat Analysis (MLVA) has been extensively used to examine epidemiological and evolutionary issues on monomorphic human pathogenic bacteria, but not on bacterial plant pathogens of agricultural importance albeit such tools would improve our understanding of their epidemiology, as well as of the history of epidemics on a global scale. Xanthomonas citri pv. citri is a quarantine organism in several countries and a major threat for the citrus industry worldwide. We screened the genomes of Xanthomonas citri pv. citri strain IAPAR 306 and of phylogenetically related xanthomonads for tandem repeats. From these in silico data, an optimized MLVA scheme was developed to assess the global diversity of this monomorphic bacterium. Thirty-one minisatellite loci (MLVA-31) were selected to assess the genetic structure of 129 strains representative of the worldwide pathological and genetic diversity of X. citri pv. citri. Based on Discriminant Analysis of Principal Components (DAPC), four pathotype-specific clusters were defined. DAPC cluster 1 comprised strains that were implicated in the major geographical expansion of X. citri pv. citri during the 20th century. A subset of 12 loci (MLVA-12) resolved 89% of the total diversity and matched the genetic structure revealed by MLVA-31. MLVA-12 is proposed for routine epidemiological identification of X. citri pv. citri, whereas MLVA-31 is proposed for phylogenetic and population genetics studies. MLVA-31 represents an opportunity for international X. citri pv. citri genotyping and data sharing. The MLVA-31 data generated in this study was deposited in the Xanthomonas citri genotyping database (http://www.biopred.net/MLVA/).

  5. Development of an Efficient Real-Time Quantitative PCR Protocol for Detection of Xanthomonas arboricola pv. pruni in Prunus Species ▿ †

    PubMed Central

    Palacio-Bielsa, Ana; Cubero, Jaime; Cambra, Miguel A.; Collados, Raquel; Berruete, Isabel M.; López, María M.

    2011-01-01

    Xanthomonas arboricola pv. pruni, the causal agent of bacterial spot disease of stone fruit, is considered a quarantine organism by the European Union and the European and Mediterranean Plant Protection Organization (EPPO). The bacterium can undergo an epiphytic phase and/or be latent and can be transmitted by plant material, but currently, only visual inspections are used to certify plants as being X. arboricola pv. pruni free. A novel and highly sensitive real-time TaqMan PCR detection protocol was designed based on a sequence of a gene for a putative protein related to an ABC transporter ATP-binding system in X. arboricola pv. pruni. Pathogen detection can be completed within a few hours with a sensitivity of 102 CFU ml−1, thus surpassing the sensitivity of the existing conventional PCR. Specificity was assessed for X. arboricola pv. pruni strains from different origins as well as for closely related Xanthomonas species, non-Xanthomonas species, saprophytic bacteria, and healthy Prunus samples. The efficiency of the developed protocol was evaluated with field samples of 14 Prunus species and rootstocks. For symptomatic leaf samples, the protocol was very efficient even when washed tissues of the leaves were directly amplified without any previous DNA extraction. For samples of 117 asymptomatic leaves and 285 buds, the protocol was more efficient after a simple DNA extraction, and X. arboricola pv. pruni was detected in 9.4% and 9.1% of the 402 samples analyzed, respectively, demonstrating its frequent epiphytic or endophytic phase. This newly developed real-time PCR protocol can be used as a quantitative assay, offers a reliable and sensitive test for X. arboricola pv. pruni, and is suitable as a screening test for symptomatic as well as asymptomatic plant material. PMID:21037298

  6. A Statistical Comparison of the Blossom Blight Forecasts of MARYBLYT and Cougarblight with Receiver Operating Characteristic Curve Analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Blossom blight forecasting is an important aspect of fire blight, caused by Erwinia amylovora, management for both apple and pear. A comparison of the forecast accuracy of two common fire blight forecasters, MARYBLYT and Cougarblight, was performed with receiver operating characteristic (ROC) curve ...

  7. Breeding for resistance to early blight in potato (Solanum tuberosum L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Early blight of potato (Solanum tuberosum L.), caused by Alternaria solani, is a major cause of economic losses in many potato growing regions. We have identified two early blight resistant clones EB24-24 and EB24-3, which are hybrids between the cultivated (S. tuberosum) potato clone US-W4 (2x=24) ...

  8. Responses of high O/L peanut cultivars to fungicide for control of Sclerotinia blight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sclerotinia blight, caused by Sclerotinia minor, remains an important disease of peanuts in Oklahoma where it causes severe damage when prolonged periods of wet weather occur during mid to late season. Progress has been made in increasing the resistance of peanut cultivars to Sclerotinia blight. S...

  9. Botryosphaeria Stem Blight on Blueberries: Effect of Vaccinium Cultivar, Botryosphaeriaceae Species and Temperature

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Botryosphaeria stem blight is a destructive disease of blueberries grown in the southern United States. Historically stem blight has been reported to be caused by the fungus Botryosphaeria dothidea. Recently, other genera in the Botryosphaeriaceae family have been identified as causal pathogens of ...

  10. Botryosphaeria stem blight of southern blueberries: effect of fertilization, temperature, and Botryosphaeriaceae species on lesion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Botryosphaeria stem blight is a destructive disease of highbush, rabbiteye, and southern highbush blueberries in the southeastern U.S. The disease has been observed to be more severe on vigorous plants than on slower growing plants. Historically stem blight has been reported to be caused by the fu...

  11. Site-specific risk factors for ray blight in Tasmanian pyrethrum fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ray blight of pyrethrum, caused by Phoma ligulicola var. inoxydablis can cause significant reductions in crop growth and pyrethrin yield. Weather and site-specific disease risk factors for ray blight have not been identified or quantified in terms of relative risk, which has limited the efficiency ...

  12. Candidate fire blight resistance genes in Malus identified with the use of genomic tools and approaches

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The goal of this research is to utilize current advances in Rosaceae genomics to identify DNA markers for use in marker-assisted selection of durable resistance to fire blight. Candidate fire blight resistance genes were selected and ranked based upon differential expression after inoculation with ...

  13. Fusarium Head Blight resistance QTL in the NC-Neuse / AGS2000 recombinant inbred population

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Breeding for resistance to Fusarium Head Blight is of major importance as the disease can have serious negative impacts on wheat production in warm and humid regions of the world, including the state of North Carolina. Fusarium Head Blight can cause significant grain yield reduction, but also severe...

  14. The 2009 late blight pandemic in eastern USA – causes and results

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The tomato late blight pandemic of 2009 made late blight into a household term in much of the Eastern United States. Many home gardeners and organic producers lost most if not all of their tomato crop, and their experiences were reported in the mainstream press. Some CSAs (Community Supported Agricu...

  15. Effect of nitrogen fertilization and fungicides on Botryosphaeria stem blight lesion development on detached blueberry stems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Botryosphaeria stem blight is a destructive disease of blueberries. Field observations indicate stem blight is more severe on vigorous plants than on slower growing plants. Two studies compared the effect of two types of fertilizers applied at four rates and nine fungicides on lesion development fo...

  16. Effect of nitrogen fertilization and fungicides on Botryosphaeria stem blight lesion development on detached stems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    : Botryosphaeria stem blight is a destructive disease of blueberries that has not been well managed with fungicides. Field observations showed that stem blight is more severe on vigorously growing plants than on slower growing plants. Detached stem assays were used to compare the effect of fertil...

  17. Greenhouse-based inoculation methods for Sclerotinia blight resistance in peanut

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Greenhouse-based assays for screening germplasm for resistance to Sclerotinia blight in peanuts can be conducted year-round, and thus may accelerate progress in breeding for resistant plants. Several techniques for assaying Sclerotinia blight resistance in the greenhouse have been proposed including...

  18. Development and characterization of RiceCAP QTL mapping population for sheath blight resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    RiceCAP is a USDA CSREES funded project that has as one of its main objectives developing genetic markers associated with sheath blight resistance. Sheath blight, caused by Rhizoctonia solani, is an important disease of rice in the southern US. Tolerance to the disease is quantitatively inherited an...

  19. Using functional genomics to identify molecular markers for fire blight resistance (Erwinia amylovora) in apple (Malus)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fire blight, caused by Erwinia amylovora (Ea), is a destructive disease of apple (Malus), pear (Pyrus) and some woody ornamentals in the rose family (Rosaceae). The goal of this project is to use a functional genomics approach to develop tools to breed fire blight resistant apples. Six hundred fifty...

  20. Survival potential of Phytophthora infestans in relation to environmental factors and late blight occurrence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Potato is an important crop globally and late blight (Phytophthora infestans) often results in severe crop loss. The cost for late blight control can be in excess of $210 million in the United States. We utilized a non-parametric density distribution analysis of local temperature (Temp) and relative...

  1. Late blight-resistant tuber-bearing Solanum species in field and laboratory trials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Late blight, caused by Phytophthora infestans, is the most disastrous and widespread disease of potato. One of the most effective means of controlling late blight is through the use of resistant cultivars, but newly developed resistant cultivars often lose their resistance after a few years of comm...

  2. Xanthomonas campestris atcc 31601 and process for use

    SciTech Connect

    Weisrock, W.P.; McCarthy, E.F.

    1983-11-29

    A degenerative-resistant strain of Xanthomonas campestris has been developed and a process for using this strain to effectively overcome the problems of continuous xanthan production. This strain of X. campestris, designated X. campestris XCP-19 ATCC 31601, is capable of continuously producing xanthan at high specific productivities, i.e., 0.24 to 0.32 gm xanthan/gm cells/hr, for several hundred hours without culture degeneration from inexpensive aqueous nutrient media such as, for example, a minimal medium consisting primarily of inorganic salts, glucose, and NH4Cl. The medium may or may not also contain a yeast extract or yeast autolysate as a supplemental nitrogen source. Any medium having assimilable sources of carbon, nitrogen, and inorganic substances will serve satisfactorily for use with this new organism. 14 claims.

  3. Association analysis of bacterial leaf spot resistance and SNP markers derived from expressed sequence tags (ESTs) in lettuce (Lactuca sativa L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial leaf spot of lettuce, caused by Xanthomonas campestris pv. vitians, is a devastating disease of lettuce worldwide. Since there are no chemicals available for effective control of the disease, host-plant resistance is highly desirable to protect lettuce production. A total of 179 lettuce ge...

  4. Molecular Mechanisms Associated with Xylan Degradation by Xanthomonas Plant Pathogens*

    PubMed Central

    Santos, Camila Ramos; Hoffmam, Zaira Bruna; de Matos Martins, Vanesa Peixoto; Zanphorlin, Leticia Maria; de Paula Assis, Leandro Henrique; Honorato, Rodrigo Vargas; Lopes de Oliveira, Paulo Sérgio; Ruller, Roberto; Murakami, Mario Tyago

    2014-01-01

    Xanthomonas pathogens attack a variety of economically relevant plants, and their xylan CUT system (carbohydrate utilization with TonB-dependent outer membrane transporter system) contains two major xylanase-related genes, xynA and xynB, which influence biofilm formation and virulence by molecular mechanisms that are still elusive. Herein, we demonstrated that XynA is a rare reducing end xylose-releasing exo-oligoxylanase and not an endo-β-1,4-xylanase as predicted. Structural analysis revealed that an insertion in the β7-α7 loop induces dimerization and promotes a physical barrier at the +2 subsite conferring this unique mode of action within the GH10 family. A single mutation that impaired dimerization became XynA active against xylan, and high endolytic activity was achieved when this loop was tailored to match a canonical sequence of endo-β-1,4-xylanases, supporting our mechanistic model. On the other hand, the divergent XynB proved to be a classical endo-β-1,4-xylanase, despite the low sequence similarity to characterized GH10 xylanases. Interestingly, this enzyme contains a calcium ion bound nearby to the glycone-binding region, which is required for catalytic activity and structural stability. These results shed light on the molecular basis for xylan degradation by Xanthomonas and suggest how these enzymes synergistically assist infection and pathogenesis. Our findings indicate that XynB contributes to breach the plant cell wall barrier, providing nutrients and facilitating the translocation of effector molecules, whereas the exo-oligoxylanase XynA possibly participates in the suppression of oligosaccharide-induced immune responses. PMID:25266726

  5. Molecular mechanisms associated with xylan degradation by Xanthomonas plant pathogens.

    PubMed

    Santos, Camila Ramos; Hoffmam, Zaira Bruna; de Matos Martins, Vanesa Peixoto; Zanphorlin, Leticia Maria; de Paula Assis, Leandro Henrique; Honorato, Rodrigo Vargas; Lopes de Oliveira, Paulo Sérgio; Ruller, Roberto; Murakami, Mario Tyago

    2014-11-14

    Xanthomonas pathogens attack a variety of economically relevant plants, and their xylan CUT system (carbohydrate utilization with TonB-dependent outer membrane transporter system) contains two major xylanase-related genes, xynA and xynB, which influence biofilm formation and virulence by molecular mechanisms that are still elusive. Herein, we demonstrated that XynA is a rare reducing end xylose-releasing exo-oligoxylanase and not an endo-β-1,4-xylanase as predicted. Structural analysis revealed that an insertion in the β7-α7 loop induces dimerization and promotes a physical barrier at the +2 subsite conferring this unique mode of action within the GH10 family. A single mutation that impaired dimerization became XynA active against xylan, and high endolytic activity was achieved when this loop was tailored to match a canonical sequence of endo-β-1,4-xylanases, supporting our mechanistic model. On the other hand, the divergent XynB proved to be a classical endo-β-1,4-xylanase, despite the low sequence similarity to characterized GH10 xylanases. Interestingly, this enzyme contains a calcium ion bound nearby to the glycone-binding region, which is required for catalytic activity and structural stability. These results shed light on the molecular basis for xylan degradation by Xanthomonas and suggest how these enzymes synergistically assist infection and pathogenesis. Our findings indicate that XynB contributes to breach the plant cell wall barrier, providing nutrients and facilitating the translocation of effector molecules, whereas the exo-oligoxylanase XynA possibly participates in the suppression of oligosaccharide-induced immune responses.

  6. Proteomic analysis of the regulatory function of DSF-dependent quorum sensing in Xanthomonas oryzae pv. oryzicola.

    PubMed

    Zhao, Yancun; Qian, Guoliang; Yin, Fangqun; Fan, Jiaqin; Zhai, Zhongwei; Liu, Chunhui; Hu, Baishi; Liu, Fengquan

    2011-01-01

    Xanthomonas oryzae pv. oryzicola (Xoc), which caused bacterial leaf streak in rice, is a bacterial pathogen limited to the apoplast of the mesophyll tissue. The rpfF that encodes diffusible signal factor (DSF) synthase, played a key role in the virulence of many plant pathogenic bacteria. In this study, the rpf gene cluster was cloned, and the rpfF was deleted in Xoc. It was observed that the rpfF mutant lost the ability to produce DSF molecular, and exhibited a significant reduction of virulence in rice compared to the wild-type strain. Furthermore, the mutation of rpfF impaired EPS production, and led to Xoc cell aggregation. To analyze the differences of proteome expression between Xoc wild type and rpfF mutant, a comparative proteome analysis was performed by two-dimensional gel electrophoresis (2-DE). The results clearly revealed that 48 protein spots were differentially expressed above the threshold ratio of 1.5. Among them, 18 proteins were identified by MS, which were involved in nitrogen transfer, protein folding, elimination of superoxide radicals and flagellar formation. Our results indicated that DSF might play an important role in virulence and growth of Xoc by mediating expression of proteins.

  7. Construction of EGFP-labeling system for visualizing the infection process of Xanthomonas axonopodis pv. citri in planta.

    PubMed

    Liu, Li-Ping; Deng, Zi-Niu; Qu, Jin-Wang; Yan, Jia-Wen; Catara, Vittoria; Li, Da-Zhi; Long, Gui-You; Li, Na

    2012-09-01

    Xanthomonas axonopodis pv. citri (Xac) is the causal agent of citrus bacterial canker, an economically important disease to world citrus industry. To monitor the infection process of Xac in different citrus plants, the enhanced green florescent protein (EGFP) visualizing system was constructed to visualize the propagation and localization in planta. First, the wild-type Xac was isolated from the diseased leaves of susceptible 'Bingtang' sweet orange, and then the isolated Xac was labeled with EGFP by triparental mating. After PCR identification, the growth kinetics and pathogenicity of the transformants were analyzed in comparison with the wild-type Xac. The EGFP-labeled bacteria were inoculated by spraying on the surface and infiltration in the mesophyll of 'Bingtang' sweet orange leaves. The bacterial cell multiplication and diffusion processes were observed directly under confocal laser scanning microscope at different intervals after inoculation. The results indicated that the EGFP-labeled Xac releasing clear green fluorescence light under fluorescent microscope showed the infection process and had the same pathogenicity as the wild type to citrus. Consequently, the labeled Xac demonstrated the ability as an efficient tool to monitor the pathogen infection.

  8. Sugarcane glycoproteins may act as signals for the production of xanthan in the plant-associated bacterium Xanthomonas albilineans

    PubMed Central

    Legaz, María-Estrella; Blanch, María; Piñón, Dolores; Santiago, Rocío; Fontaniella, Blanca; Blanco, Yolanda; Solas, María-Teresa

    2011-01-01

    Visual symptoms of leaf scald necrosis in sugarcane (Saccharum officinarum) leaves develop in parallel to the accumulation of a fibrous material invading exocellular spaces and both xylem and phloem. These fibers are produced and secreted by the plant-associated bacterium Xanthomonas albilineans. Electron microscopy and specific staining methods for polysaccharides reveal the polysaccharidic nature of this material. These polysaccharides are not present in healthy leaves or in those from diseased plants without visual symptoms of leaf scald. Bacteria in several leaf tissues have been detected by immunogold labeling. The bacterial polysaccharide is not produced in axenic culture but it is actively synthesized when the microbes invade the host plant. This finding may be due to the production of plant glycoproteins, after bacteria infection which inhibit microbial proteases. In summary, our data are consistent with the existence of a positive feedback loop in which plant-produced glycoproteins act as a cell-to-bacteria signal that promotes xanthan production, by protecting some enzymes of xanthan biosynthesis against from bacterial proteolytic degradation. PMID:21791980

  9. Sugarcane glycoproteins may act as signals for the production of xanthan in the plant-associated bacterium Xanthomonas albilineans.

    PubMed

    Legaz, María-Estrella; Blanch, María; Piñón, Dolores; Santiago, Rocío; Fontaniella, Blanca; Blanco, Yolanda; Solas, María-Teresa; Vicente, Carlos

    2011-08-01

    Visual symptoms of leaf scald necrosis in sugarcane (Saccharum officinarum) leaves develop in parallel to the accumulation of a fibrous material invading exocellular spaces and both xylem and phloem. These fibers are produced and secreted by the plant-associated bacterium Xanthomonas albilineans. Electron microscopy and specific staining methods for polysaccharides reveal the polysaccharidic nature of this material. These polysaccharides are not present in healthy leaves or in those from diseased plants without visual symptoms of leaf scald. Bacteria in several leaf tissues have been detected by immunogold labelling. The bacterial polysaccharide is not produced in axenic culture but it is actively synthesized when the microbes invade the host plant. This finding may be due to the production of plant glycoproteins after bacteria infection, which inhibit microbial proteases. In summary, our data are consistent with the existence of a positive feedback loop in which plant-produced glycoproteins act as a cell-to-bacteria signal that promotes xanthan production, by protecting some enzymes of xanthan biosynthesis against from bacterial proteolytic degradation. 

  10. Nanotechnology in Plant Disease Management: DNA-Directed Silver Nanoparticles on Graphene Oxide as an Antibacterial Against Xanthomonas Perforans

    PubMed Central

    Ocsoy, Ismail; Paret, Mathews L.; Ocsoy, Muserref Arslan; Kunwar, Sanju; Chen, Tao; You, Mingxu; Tan, Weihong

    2013-01-01

    Bacterial spot caused by Xanthomonas perforans is a major disease of tomatoes, leading to reduction in production by 10–50%. While copper (Cu)-based bactericides have been used for disease management, most of the X. perforans strains isolated from tomatoes in Florida and other locations worldwide are Cu-resistant. We have developed DNA-directed silver (Ag) nanoparticles (NPs) grown on graphene oxide (GO). These Ag@dsDNA@GO composites effectively decrease X. perforans cell viability in culture and on plants. At the very low concentration of 16 ppm of Ag@dsDNA@GO, composites show excellent antibacterial capability in culture with significant advantages in improved stability, enhanced antibacterial activity and stronger adsorption properties. Application of Ag@dsDNA@GO at 100 ppm on tomato transplants in a greenhouse experiment significantly reduced the severity of bacterial spot disease compared to untreated plants, giving results similar to those of the current grower standard treatment, with no phytotoxicity. PMID:24016217

  11. Surface polysaccharides and quorum sensing are involved in the attachment and survival of Xanthomonas albilineans on sugarcane leaves.

    PubMed

    Mensi, Imene; Daugrois, Jean-Heinrich; Pieretti, Isabelle; Gargani, Daniel; Fleites, Laura A; Noell, Julie; Bonnot, Francois; Gabriel, Dean W; Rott, Philippe

    2016-02-01

    Xanthomonas albilineans, the causal agent of sugarcane leaf scald, is a bacterial plant pathogen that is mainly spread by infected cuttings and contaminated harvesting tools. However, some strains of this pathogen are known to be spread by aerial means and are able to colonize the phyllosphere of sugarcane before entering the host plant and causing disease. The objective of this study was to identify the molecular factors involved in the survival or growth of X. albilineans on sugarcane leaves. We developed a bioassay to test for the attachment of X. albilineans on sugarcane leaves using tissue-cultured plantlets grown in vitro. Six mutants of strain XaFL07-1 affected in surface polysaccharide production completely lost their capacity to survive on the sugarcane leaf surface. These mutants produced more biofilm in vitro and accumulated more cellular poly-β-hydroxybutyrate than the wild-type strain. A mutant affected in the production of small molecules (including potential biosurfactants) synthesized by non-ribosomal peptide synthetases (NRPSs) attached to the sugarcane leaves as well as the wild-type strain. Surprisingly, the attachment of bacteria on sugarcane leaves varied among mutants of the rpf gene cluster involved in bacterial quorum sensing. Therefore, quorum sensing may affect polysaccharide production, or both polysaccharides and quorum sensing may be involved in the survival or growth of X. albilineans on sugarcane leaves.

  12. Xanthomonas citri ssp. citri requires the outer membrane porin OprB for maximal virulence and biofilm formation.

    PubMed

    Ficarra, Florencia A; Grandellis, Carolina; Galván, Estela M; Ielpi, Luis; Feil, Regina; Lunn, John E; Gottig, Natalia; Ottado, Jorgelina

    2016-05-25

    Xanthomonas citri ssp. citri (Xcc) causes canker disease in citrus, and biofilm formation is critical for the disease cycle. OprB (Outer membrane protein B) has been shown previously to be more abundant in Xcc biofilms compared with the planktonic state. In this work, we showed that the loss of OprB in an oprB mutant abolishes bacterial biofilm formation and adherence to the host, and also compromises virulence and efficient epiphytic survival of the bacteria. Moreover, the oprB mutant is impaired in bacterial stress resistance. OprB belongs to a family of carbohydrate transport proteins, and the uptake of glucose is decreased in the mutant strain, indicating that OprB transports glucose. Loss of OprB leads to increased production of xanthan exopolysaccharide, and the carbohydrate intermediates of xanthan biosynthesis are also elevated in the mutant. The xanthan produced by the mutant has a higher viscosity and, unlike wild-type xanthan, completely lacks pyruvylation. Overall, these results suggest that Xcc reprogrammes its carbon metabolism when it senses a shortage of glucose input. The participation of OprB in the process of biofilm formation and virulence, as well as in metabolic changes to redirect the carbon flux, is discussed. Our results demonstrate the importance of environmental nutrient supply and glucose uptake via OprB for Xcc virulence.

  13. Genetic and proteomic analyses of a Xanthomonas campestris pv. campestris purC mutant deficient in purine biosynthesis and virulence.

    PubMed

    Yuan, Zhihui; Wang, Li; Sun, Shutao; Wu, Yao; Qian, Wei

    2013-09-20

    Bacterial proliferation in hosts requires activation of a number of housekeeping pathways, including purine de novo biosynthesis. Although inactivation of purine biosynthesis genes can attenuate virulence, it is unclear which biochemical or virulence factors are associated with the purine biosynthesis pathway in vivo. We report that inactivation of purC, a gene encoding phosphoribosylaminoimidazole-succinocarboxamide synthase, caused complete loss of virulence in Xanthomonas campestris pv. campestris, the causal agent of black rot disease of cruciferous plants. The purC mutant was a purine auxotroph; it could not grow on minimal medium, whereas addition of purine derivatives, such as hypoxanthine or adenine plus guanine, restored growth of the mutant. The purC mutation also significantly enhanced the production of an unknown purine synthesis associated pigment and extracellular polysaccharides by the bacterium. In addition, comparative proteomic analyses of bacteria grown on rich and minimal media revealed that the purC mutation affected the expression levels of diverse proteins involved in purine and pyrimidine synthesis, carbon and energy metabolisms, iron uptake, proteolysis, protein secretion, and signal transduction. These results provided clues to understanding the contributions of purine synthesis to bacterial virulence and interactions with host immune systems.

  14. An adenosine kinase exists in Xanthomonas campestris pathovar campestris and is involved in extracellular polysaccharide production, cell motility, and virulence.

    PubMed

    Lu, Guang-Tao; Tang, Yong-Qin; Li, Cai-Yue; Li, Rui-Fang; An, Shi-Qi; Feng, Jia-Xun; He, Yong-Qiang; Jiang, Bo-Le; Tang, Dong-Jie; Tang, Ji-Liang

    2009-06-01

    Adenosine kinase (ADK) is a purine salvage enzyme and a typical housekeeping enzyme in eukaryotes which catalyzes the phosphorylation of adenosine to form AMP. Since prokaryotes synthesize purines de novo and no endogenous ADK activity is detectable in Escherichia coli, ADK has long been considered to be rare in bacteria. To date, only two prokaryotes, both of which are gram-positive bacteria, have been reported to contain ADK. Here we report that the gram-negative bacterium Xanthomonas campestris pathovar campestris, the causal agent of black rot of crucifers, possesses a gene (designated adk(Xcc)) encoding an ADK (named ADK(Xcc)), and we demonstrate genetically that the ADK(Xcc) is involved in extracellular polysaccharide (EPS) production, cell motility, and pathogenicity of X. campestris pv. campestris. adk(Xcc) was overexpressed as a His(6)-tagged protein in E. coli, and the purified His(6)-tagged protein exhibited ADK activity. Mutation of adk(Xcc) did not affect bacterial growth in rich and minimal media but led to an accumulation of intracellular adenosine and diminutions of intracellular ADK activity and ATP level, as well as EPS. The adk(Xcc) mutant displayed significant reductions in bacterial growth and virulence in the host plant.

  15. Development of a Species-specific PCR Assay for Three Xanthomonas Species, Causing Bulb and Flower Diseases, Based on Their Genome Sequences

    PubMed Central

    Back, Chang-Gi; Lee, Seung-Yeol; Lee, Boo-Ja; Yea, Mi-Chi; Kim, Sang-Mok; Kang, In-Kyu; Cha, Jae-Soon; Jung, Hee-Young

    2015-01-01

    In this study, we developed a species-specific PCR assay for rapid and accurate detection of three Xanthomonas species, X. axonopodis pv. poinsettiicola (XAP), X. hyacinthi (XH) and X. campestris pv. zantedeschiae (XCZ), based on their draft genome sequences. XAP, XH and XCZ genomes consist of single chromosomes that contain 5,221, 4,395 and 7,986 protein coding genes, respectively. Species-specific primers were designed from variable regions of the draft genome sequence data and assessed by a PCR-based detection method. These primers were also tested for specificity against 17 allied Xanthomonas species as well as against the host DNA and the microbial community of the host surface. Three primer sets were found to be very specific and no amplification product was obtained with the host DNA and the microbial community of the host surface. In addition, a detection limit of 1 pg/μl per PCR reaction was detected when these primer sets were used to amplify corresponding bacterial DNAs. Therefore, these primer sets and the developed species-specific PCR assay represent a valuable, sensitive, and rapid diagnostic tool that can be used to detect three specific pathogens at early stages of infection and may help control diseases. PMID:26361469

  16. The filamentous phage XacF1 causes loss of virulence in Xanthomonas axonopodis pv. citri, the causative agent of citrus canker disease.

    PubMed

    Ahmad, Abdelmonim Ali; Askora, Ahmed; Kawasaki, Takeru; Fujie, Makoto; Yamada, Takashi

    2014-01-01

    In this study, filamentous phage XacF1, which can infect Xanthomonas axonopodis pv. citri (Xac) strains, was isolated and characterized. Electron microscopy showed that XacF1 is a member of the family Inoviridae and is about 600 nm long. The genome of XacF1 is 7325 nucleotides in size, containing 13 predicted open reading frames (ORFs), some of which showed significant homology to Ff-like phage proteins such as ORF1 (pII), ORF2 (pV), ORF6 (pIII), and ORF8 (pVI). XacF1 showed a relatively wide host range, infecting seven out of 11 strains tested in this study. Frequently, XacF1 was found to be integrated into the genome of Xac strains. This integration occurred at the host dif site (attB) and was mediated by the host XerC/D recombination system. The attP sequence was identical to that of Xanthomonas phage Cf1c. Interestingly, infection by XacF1 phage caused several physiological changes to the bacterial host cells, including lower levels of extracellular polysaccharide production, reduced motility, slower growth rate, and a dramatic reduction in virulence. In particular, the reduction in virulence suggested possible utilization of XacF1 as a biological control agent against citrus canker disease.

  17. Xanthomonas campestris cell–cell signalling molecule DSF (diffusible signal factor) elicits innate immunity in plants and is suppressed by the exopolysaccharide xanthan

    PubMed Central

    Kakkar, Akanksha; Nizampatnam, Narasimha Rao; Kondreddy, Anil; Pradhan, Binod Bihari; Chatterjee, Subhadeep

    2015-01-01

    Several secreted and surface-associated conserved microbial molecules are recognized by the host to mount the defence response. One such evolutionarily well-conserved bacterial process is the production of cell–cell signalling molecules which regulate production of multiple virulence functions by a process known as quorum sensing. Here it is shown that a bacterial fatty acid cell–cell signalling molecule, DSF (diffusible signal factor), elicits innate immunity in plants. The DSF family of signalling molecules are highly conserved among many phytopathogenic bacteria belonging to the genus Xanthomonas as well as in opportunistic animal pathogens. Using Arabidopsis, Nicotiana benthamiana, and rice as model systems, it is shown that DSF induces a hypersensitivity reaction (HR)-like response, programmed cell death, the accumulation of autofluorescent compounds, hydrogen peroxide production, and the expression of the PATHOGENESIS-RELATED1 (PR-1) gene. Furthermore, production of the DSF signalling molecule in Pseudomonas syringae, a non-DSF-producing plant pathogen, induces the innate immune response in the N. benthamiana host plant and also affects pathogen growth. By pre- and co-inoculation of DSF, it was demonstrated that the DSF-induced plant defence reduces disease severity and pathogen growth in the host plant. In this study, it was further demonstrated that wild-type Xanthomonas campestris suppresses the DSF-induced innate immunity by secreting xanthan, the main component of extracellular polysaccharide. The results indicate that plants have evolved to recognize a widely conserved bacterial communication system and may have played a role in the co-evolution of host recognition of the pathogen and the communication machinery. PMID:26248667

  18. Xanthomonas campestris cell-cell signalling molecule DSF (diffusible signal factor) elicits innate immunity in plants and is suppressed by the exopolysaccharide xanthan.

    PubMed

    Kakkar, Akanksha; Nizampatnam, Narasimha Rao; Kondreddy, Anil; Pradhan, Binod Bihari; Chatterjee, Subhadeep

    2015-11-01

    Several secreted and surface-associated conserved microbial molecules are recognized by the host to mount the defence response. One such evolutionarily well-conserved bacterial process is the production of cell-cell signalling molecules which regulate production of multiple virulence functions by a process known as quorum sensing. Here it is shown that a bacterial fatty acid cell-cell signalling molecule, DSF (diffusible signal factor), elicits innate immunity in plants. The DSF family of signalling molecules are highly conserved among many phytopathogenic bacteria belonging to the genus Xanthomonas as well as in opportunistic animal pathogens. Using Arabidopsis, Nicotiana benthamiana, and rice as model systems, it is shown that DSF induces a hypersensitivity reaction (HR)-like response, programmed cell death, the accumulation of autofluorescent compounds, hydrogen peroxide production, and the expression of the PATHOGENESIS-RELATED1 (PR-1) gene. Furthermore, production of the DSF signalling molecule in Pseudomonas syringae, a non-DSF-producing plant pathogen, induces the innate immune response in the N. benthamiana host plant and also affects pathogen growth. By pre- and co-inoculation of DSF, it was demonstrated that the DSF-induced plant defence reduces disease severity and pathogen growth in the host plant. In this study, it was further demonstrated that wild-type Xanthomonas campestris suppresses the DSF-induced innate immunity by secreting xanthan, the main component of extracellular polysaccharide. The results indicate that plants have evolved to recognize a widely conserved bacterial communication system and may have played a role in the co-evolution of host recognition of the pathogen and the communication machinery.

  19. Domain structure of HrpE, the Hrp pilus subunit of Xanthomonas campestris pv. vesicatoria.

    PubMed

    Weber, Ernst; Koebnik, Ralf

    2005-09-01

    The plant-pathogenic bacterium Xanthomonas campestris pv. vesicatoria possesses a type III secretion (TTS) system necessary for pathogenicity in susceptible hosts and induction of the hypersensitive response in resistant plants. This specialized protein transport system is encoded by a 23-kb hrp (hypersensitive response and pathogenicity) gene cluster. X. campestris pv. vesicatoria produces filamentous structures, Hrp pili, at the cell surface under hrp-inducing conditions. The Hrp pilus acts as a cell surface appendage of the TTS system and serves as a conduit for the transfer of bacterial effector proteins into the plant cell cytosol. The major pilus component, the HrpE pilin, is unique to xanthomonads and is encoded within the hrp gene cluster. In this study, functional domains of HrpE were mapped by linker-scanning mutagenesis and by reporter protein fusions to an N-terminally truncated avirulence protein (AvrBs3Delta2). Thirteen five-amino-acid peptide insertion mutants were obtained and could be grouped into six phenotypic classes. Three permissive mutations were mapped in the N-terminal half of HrpE, which is weakly conserved within the HrpE protein family. Four dominant-negative peptide insertions in the strongly conserved C-terminal region suggest that this domain is critical for oligomerization of the pilus subunits. Reporter protein fusions revealed that the N-terminal 17 amino acid residues act as an efficient TTS signal. From these results, we postulate a three-domain structure of HrpE with an N-terminal secretion signal, a surface-exposed variable region of the N-terminal half, and a C-terminal polymerization domain. Comparisons with a mutant study of HrpA, the Hrp pilin from Pseudomonas syringae pv. tomato DC3000, and hydrophobicity plot analyses of several nonhomologous Hrp pilins suggest a common architecture of Hrp pilins of different plant-pathogenic bacteria.

  20. Xanthomonas campestris lipooligosaccharides trigger innate immunity and oxidative burst in Arabidopsis.

    PubMed

    Proietti, S; Giangrande, C; Amoresano, A; Pucci, P; Molinaro, A; Bertini, L; Caporale, C; Caruso, C

    2014-12-01

    Plants lack the adaptive immunity mechanisms of jawed vertebrates, so they rely on innate immune responses to defense themselves from pathogens. The plant immune system perceives the presence of pathogens by recognition of molecules known as pathogen-associated molecular patterns (PAMPs). PAMPs have several common characteristics, including highly conserved structures, essential for the microorganism but absent in host organisms. Plants can specifically recognize PAMPs using a large set of receptors and can respond with appropriate defenses by activating a multicomponent and multilayered response. Lipopolysaccharides (LPSs) and lipooligosaccharides (LOSs) are major components of the cell surface of Gram-negative bacteria with diverse roles in bacterial pathogenesis of animals and plants that include elicitation of host defenses. Little is known on the mechanisms of perception of these molecules by plants and the associated signal transduction pathways that trigger plant immunity.Here we addressed the question whether the defense signaling pathway in Arabidopsis thaliana was triggered by LOS from Xanthomonas campestris pv. campestris (Xcc), using proteomic and transcriptomic approaches. By using affinity capture strategies with immobilized LOS and LC-MS/MS analyses, we identified 8 putative LOS protein ligands. Further investigation of these interactors led to the definition that LOS challenge is able to activate a signal transduction pathway that uses nodal regulators in common with salicylic acid-mediated pathway. Moreover, we proved evidence that Xcc LOS are responsible for oxidative burst in Arabidopsis either in infiltrated or systemic leaves. In addition, gene expression studies highlighted the presence of gene network involved in reactive oxygen species transduction pathway.