CHARACTERIZATION OF XANTHOMONAS CITRI subsp MALVACEARUM CAUSING COTTON ANGULAR LEAF SPOT IN BRAZIL
J.C. Oliveira, G.M.R. Albuquerque, A.S. Xavier, R.L.R. Mariano, N.D. Suassuna, E.B. Souza
The variability of a population of 100 strains of Xanthomonas citri subsp. malvacearum (Xcm) was analyzed based on phenotypic and genotypic characteristics. These strains were obtained from cotton plants showing symptoms of angular leaf spot in the states of Goiás, Mato Grosso, Mato Grosso do Sul, and Bahia (Brazil). Amylase, lipase, cellulase and levan were produced by all strains of Xcm, whereas caseinase was generated by only 20 strains. All strains induced a hypersensitivity response in tomato leaves, were sensitive to copper oxychloride, copper hydroxide, oxytetracycline, oxytetracycline plus tribasic copper sulphate, and oxytetracycline plus streptomycin sulfate, and were resistant to kasugamycin. Rep-PCR revealed at 78% the existence of two large clusters and three smaller size clusters of 2-6 strains, and some strains with isolated profiles. Strains from different cotton cultivars and diverse origins were found within the two major clusters and Xcm reference strain IBSBF1733 showed similarity to most of the analyzed strains. We conclude that the Brazilian population of Xcm has a low phenotypic and genotypic variability.