Phylogenomic analysis of Paracidovorax citrulli strains reveals the presence of two lineages in Brazil.

Abstract

Paracidovorax citrulli is the causative agent of bacterial fruit blotch in melons and watermelons. This study used comparative genomic approaches of 17 Brazilian P. citrulli strains obtained from melons and watermelons to classify them into groups I and II and try to understand their genomic differences. The genomes of P. citrulli presented general characteristics similar to those shown for the genomes of the type strain of P. citrulli and reference strains of groups I and II. A phylogenomic analysis revealed two distinct groups of P. citrulli, in which most Brazilian P. citrulli strains were grouped with the strain representing group I. CRISPR-Cas analysis revealed the presence of two proteins, Cas3 and Cas10, in all Brazilian P. citrulli genomes. In addition, we observed the presence of two plasmids (pAMC6 and pAC53) in three Brazilian P. citrulli strains, all closely related to group I. The prediction of effector proteins revealed the XopE/AvrPphe protein as a differential between the strains of groups I and II. The present study will contribute to a more detailed understanding of aspects of host-pathogen interactions and will help improve the detection of strains from these groups, thus elucidating the population dynamics of Brazilian strains of P. citrulli.