NEW GENES FROM XANTHOMONAS CITRI SUBSP. CITRI INVOLVED IN BACTERIAL EPIPHYTIC SURVIVAL

BARCAROLO MV; OTTADO J; GOTTIG N; GARAVAGLIA BS

Cordoba

Congreso; LII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2016

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Xanthomonas citri subsp. citri (Xcc) is the causal agent of citrus canker.In this work we analyzed genes from Xcc with unknown functionpresent in several plant pathogens, such as XAC0100 and XAC4007.Expression of these genes in bacteria grown in XVM2, a minimalmedium that simulates conditions of the intercellular apoplast of leaves,was analyzed by RT-qPCR and the expression of both genes showed aninduction compared to bacteria grown in rich medium. Moreover, RNAwas obtained from Xcc recovered from citrus leaves at 0, 3 and 6 dayspost infection (dpi) and after RT-qPCR, results revealed that both geneswere induced at 6 dpi. These results suggest that these genes have a rolein plant-pathogen interaction. To characterize the function of XAC0100and XAC4007 during disease development, we constructed non-polarXcc mutants in these genes generated by double cross-over events. Theresulting ΔXAC0100 and ΔXAC4007 mutant strains were tested fortheir ability to trigger disease in citrus leaves and hypersensitiveresponse in non-host pepper leaves. No differences were observed inhost and non-host interactions. However, ΔXAC0100 and ΔXAC4007mutants displayed impaired epiphytic survival on citrus leaves,indicating that these genes were required to maintain bacteria on thehost plant tissue.