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Title: Local genetic diversity of Xanthomonas citri subsp. citri in citrus orchards in northwest Paraná state, Brazil

Author
item GONCALVES-ZULIANI, ALINE - University Of Maringa
item ZANUTTO, CARLOS - University Of Maringa
item BELASQUE JR., JOSE - Universidad De Sao Paulo
item NOCCHI, PAULA - University Of Maringa
item SOARES, L.S. - University Of Maringa
item HASHIGUTI, HERALDO - University Of Maringa
item Bock, Clive
item NUNES, WILLIAM - University Of Maringa

Submitted to: Phytopathologia Mediterranea
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2016
Publication Date: 5/10/2017
Citation: Goncalves-Zuliani, A.M., Zanutto, C.A., Belasque Jr., J., Nocchi, P.T., Soares, L., Hashiguti, H.T., Bock, C.H., Nunes, W.M. 2017. Local genetic diversity of Xanthomonas citri subsp. citri in citrus orchards in northwest Paraná state, Brazil. Phytopathologia Mediterranea. 56:40-49.

Interpretive Summary: Asiatic citrus canker (Xanthomonas citri subsp. citri) is an important pathogen of citrus in Brazil and elsewhere, including the US. The genetic diversity of X. citri subsp. citri pathtype ‘A’ has not been studied at a local scale. A total of 40 isolates were collected from lesions of ACC on citrus in three orchards (commercial and experimental) in Paraná state, Brazil. There was substantial polymorphism but an analysis of molecular variance among populations showed that 98% of the variance was accounted for within the populations, and only 2% was accounted for among populations. Consequently differences among populations was not significant, and genetic identity was comparable among populations with no association between physical distance and genetic distance. The uniform genetic diversity among isolates and low degree of spatial differentiation between populations of X. citri subsp. citri suggests that the populations found in Paraná state possess similar origins and have historically strong epidemiological links.

Technical Abstract: Xanthomonas citri subsp. citri, causal agent of Asiatic citrus canker, is an important pathogen of citrus in Brazil and elsewhere. The genetic diversity of X. citri subsp. citri pathtype ‘A’ has not been studied in Brazil at a local scale (up to 300 km). A total of 40 isolates were collected from lesions of ACC on citrus in three orchards (commercial and experimental) in Paraná state, Brazil. Twelve minisatellite markers were used to characterize the genetic diversity of the isolates. A UPGMA analysis separately identified each isolate as a unique multi locus haplotype, but there was no tendency to differentiate isolates by source location. A type isolate of X. citri subsp. citri pathotype ‘A’ was genetically similar to the other isolates sampled. There was substantial polymorphism (mean number of different alleles per locus = 3.33). An analysis of molecular variance among populations showed that 98% of the variance was accounted for within the populations, and only 2% was accounted for among populations. Differences among populations was not significant (' = 0.018, P-value = 0.2). Genetic identity was comparable among populations (Nei’s genetic identity = 0.657-0.828), and was no association between physical distance (log km) and genetic distance. The uniform genetic diversity among isolates and low degree of spatial differentiation between populations of X. citri subsp. citri suggests that the populations found in Paraná state may possess similar origins and have historically strong epidemiological links.