Analysis of genetic diversity of Xanthomonas citri subsp citri strains. Characterization of a new isolate which triggers a host-specific response

SICILIANO FLORENCIA; CHIESA MARÍA AMALIA; ORNELLA, L.; PINO DELGADO, NATALIA; FAVARO, ALEJANDRA; SENDÍN LORENA; ROESCHLIN, ROXANA; ORCE, INGRID; PLOPER, DANIEL; VOJNOV ADRIAN; FILIPPONE PAULA; CASTAGNARO ATILIO; MARANO MARÍA ROSA

Congreso; XII Iternational Citrus Congress. Books of abstracts; 2012

Citrus is an economically important fruit crop that is severely afflicted by Asiatic Citrus Bacterial Canker (CBC), a disease caused by Xanthomonas citri subsp. citri (XC). Argentina is one of the world´s largest citrus producers, accounting for 17% of global lemon supply, with the majority of production concentrated in the northwestern province of Tucuman. To gain insight into the genetic diversity of Xanthomonas causing CBC in Tucuman, a total of 42 Xanthomonas isolates were collected from different citrus species across seventeen different orchards and subjected to molecular, biochemical and pathogenical tests. Analysis of genomespecific XC markers and DNA polymorphism based on rep-PCRs showed that all isolates belonged to XC. Thirty-eight haplotypes with relatively high genomic inter-relationship compared to XC reference strains were discriminated. Pathogenicity tests showed that one isolate, named XCT44, which shares 91% genetic similarity to the reference strain XCT, has specific host range. XCT44, induces a hypersensitive-like response in Citrus limon and Citrus paradisi leaves and weak canker lesions in Citrus aurantifolia and Citrus clementina leaves. Although XCT44 produces less exopolysaccharides than the reference strain XCT, this deficiency is not involved in the phenotype observed in C. limon leaves. This study constitutes the first report on the characterization of XC in the northwest of Argentina.