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Evaluation of the Genetic Diversity of Xylella fastidiosa Strains from Citrus and Coffee Hosts by Single-Nucleotide Polymorphism Markers

First and third authors: Microorganism and Plant Biochemistry Laboratory, Department of Technology, School of Agricultural and Veterinary Sciences, University of the State of São Paulo (UNESP), Jaboticabal, SP, Brazil; and second author: Biotechnology Laboratory, APTA Citrus/IAC, State of São Paulo, Cordeirópolis, SP, Brazil.

The aim of this study was to obtain information about genetic diversity and make some inferences about the relationship of 27 strains of Xylella fastidiosa from different hosts and distinct geographical areas. Single-nucleotide polymorphism (SNP) molecular markers were identified in DNA sequences from 16 distinct regions of the genome of 24 strains of X. fastidiosa from coffee and citrus plants. Among the Brazilian strains, coffee-dependent strains have a greater number of SNPs (10 to 24 SNPs) than the citrus-based strains (2 to 12 SNPs); all the strains were compared with the sequenced strain 9a5c. The identified SNP markers were able to distinguish, for the first time, strains from citrus plants and coffee and showed that strains from coffee present higher genetic diversity than the others. These markers also have proven to be efficient for discriminating strains from the same host obtained from different geographic regions. X. fastidiosa, the causal agent of citrus variegated chlorosis, possesses genetic diversity, and the SNP markers were highly efficient for discriminating genetically close organisms.