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Browsing by Author "Potnis, Neha"

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    Comparative genomics reveals diversity among xanthomonads infecting tomato and pepper
    Potnis, Neha; Krasileva, Ksenia V.; Chow, Virginia; Almeida, Nalvo F.; Patil, Prabhu B.; Ryan, Robert P.; Sharlach, Molly; Behlau, Franklin; Dow, J. Max; Momol, M. T.; White, Frank F.; Preston, James F.; Vinatzer, Boris A.; Koebnik, Ralf; Setubal, João C.; Norman, David J.; Staskawicz, Brian J.; Jones, Jeffrey B. (2011-03-11)
    Background Bacterial spot of tomato and pepper is caused by four Xanthomonas species and is a major plant disease in warm humid climates. The four species are distinct from each other based on physiological and molecular characteristics. The genome sequence of strain 85-10, a member of one of the species, Xanthomonas euvesicatoria (Xcv) has been previously reported. To determine the relationship of the four species at the genome level and to investigate the molecular basis of their virulence and differing host ranges, draft genomic sequences of members of the other three species were determined and compared to strain 85-10. Results We sequenced the genomes of X. vesicatoria (Xv) strain 1111 (ATCC 35937), X. perforans (Xp) strain 91-118 and X. gardneri (Xg) strain 101 (ATCC 19865). The genomes were compared with each other and with the previously sequenced Xcv strain 85-10. In addition, the molecular features were predicted that may be required for pathogenicity including the type III secretion apparatus, type III effectors, other secretion systems, quorum sensing systems, adhesins, extracellular polysaccharide, and lipopolysaccharide determinants. Several novel type III effectors from Xg strain 101 and Xv strain 1111 genomes were computationally identified and their translocation was validated using a reporter gene assay. A homolog to Ax21, the elicitor of XA21-mediated resistance in rice, and a functional Ax21 sulfation system were identified in Xcv. Genes encoding proteins with functions mediated by type II and type IV secretion systems have also been compared, including enzymes involved in cell wall deconstruction, as contributors to pathogenicity. Conclusions Comparative genomic analyses revealed considerable diversity among bacterial spot pathogens, providing new insights into differences and similarities that may explain the diverse nature of these strains. Genes specific to pepper pathogens, such as the O-antigen of the lipopolysaccharide cluster, and genes unique to individual strains, such as novel type III effectors and bacteriocin genes, have been identified providing new clues for our understanding of pathogen virulence, aggressiveness, and host preference. These analyses will aid in efforts towards breeding for broad and durable resistance in economically important tomato and pepper cultivars.
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    Novel insights into the genomic basis of citrus canker based on the genome sequences of two strains of Xanthomonas fuscans subsp aurantifolii
    Moreira, Leandro M.; Almeida, Nalvo F.; Potnis, Neha; Digiampietri, Luciano A.; Adi, Said S.; Bortolossi, Julio C.; da Silva, Ana C.; da Silva, Aline M.; de Moraes, Fabrício E.; de Oliveira, Julio C.; de Souza, Robson F.; Facincani, Agda P.; Ferraz, André L.; Ferro, Maria I.; Furlan, Luiz R.; Gimenez, Daniele F.; Jones, Jeffrey B.; Kitajima, Elliot W.; Laia, Marcelo L.; Leite, Rui P., Jr; Nishiyama, Milton Y.; Rodrigues Neto, Julio; Nociti, Letícia A.; Norman, David J.; Ostroski, Eric H.; Pereira, Haroldo A. Jr.; Staskawicz, Brian J.; Tezza, Renata I.; Ferro, Jesus A.; Vinatzer, Boris A.; Setubal, João C. (Biomed Central, 2010-04-13)
    Background Citrus canker is a disease that has severe economic impact on the citrus industry worldwide. There are three types of canker, called A, B, and C. The three types have different phenotypes and affect different citrus species. The causative agent for type A is Xanthomonas citri subsp. citri, whose genome sequence was made available in 2002. Xanthomonas fuscans subsp. aurantifolii strain B causes canker B and Xanthomonas fuscans subsp. aurantifolii strain C causes canker C. Results We have sequenced the genomes of strains B and C to draft status. We have compared their genomic content to X. citri subsp. citri and to other Xanthomonas genomes, with special emphasis on type III secreted effector repertoires. In addition to pthA, already known to be present in all three citrus canker strains, two additional effector genes, xopE3 and xopAI, are also present in all three strains and are both located on the same putative genomic island. These two effector genes, along with one other effector-like gene in the same region, are thus good candidates for being pathogenicity factors on citrus. Numerous gene content differences also exist between the three cankers strains, which can be correlated with their different virulence and host range. Particular attention was placed on the analysis of genes involved in biofilm formation and quorum sensing, type IV secretion, flagellum synthesis and motility, lipopolysacharide synthesis, and on the gene xacPNP, which codes for a natriuretic protein. Conclusion We have uncovered numerous commonalities and differences in gene content between the genomes of the pathogenic agents causing citrus canker A, B, and C and other Xanthomonas genomes. Molecular genetics can now be employed to determine the role of these genes in plant-microbe interactions. The gained knowledge will be instrumental for improving citrus canker control.