Phenotypic and Genetic Diversity of Xanthomonads Isolated from Pepper ( spp.) in Taiwan from 1989 to 2019.

Bacterial spot caused by spp. is an economically important disease of pepper causing significant yield losses in Taiwan. Monitoring the pathogen population on a continuous basis is necessary for developing disease management strategies. We analyzed a collection of xanthomonad strains isolated from pepper in Taiwan between 1989 and 2019. Among the sequenced genomes, 65 were identified as , and 10 were . Thirty-five and 10 strains were copper tolerant, whereas only four and none of the strains were tolerant to streptomycin. Nine strains were amylolytic, which is considered an unusual characteristic for . Bayesian analysis of the population structure based on core gene single-nucleotide polymorphisms clustered the strains into five clusters for and three clusters for . One cluster, designated as TP-2019, appears to be a novel genetic cluster based on core genes, accessory gene content, and effector profile. This knowledge of pathogen diversity with whole genomic information will be useful in future comparative studies and in improving breeding programs to develop disease-resistant cultivars and other disease management options.