Complete genome and comparative analysis of Xanthomonas oryzae pv. oryzae isolated from northern Thailand

Rice (Oryza sativa L.) is a vital global crop with a predominant presence in Asia, including Thailand. However, it faces a significant threat from bacterial blight disease, primarily caused by Xanthomonas oryzae pv. oryzae (Xoo). This research aims to provide valuable insights into the genetic virulence factors and genomic variations of Xoo strains isolated in Thailand. Furthermore, we present the first complete genomic database of Thai Xoo, offering a comprehensive resource for studying pathogen diversity, tracking virulence evolution and supporting disease management strategies in rice production. Our phylogenetic analysis unveils that the 20 Thai strains align with the Asian strains, setting them apart from African and US strains. Remarkably, the average nt identity values, in comparison with Xanthomonas oryzae type strain 35933 (XO35933), consistently exceed 99%. These strains can be classified into three assigned ribosomal sequence types. Our investigation into the pangenome and the phylogenetic relationships of these 20 Xoo genomes reveals a diverse genetic landscape, with the pangenome comprising 11,872 orthologous gene clusters, of which roughly 30% form the core genome. Notably, all of these genomes exhibit a clustered regularly interspaced short palindromic repeats-Cas I-C array, indicative of their adaptive immune mechanisms. All strains belonged to BXO1 type LPS cassette with high identity. Furthermore, our analysis identifies two distinct types of plasmids, namely, Xanthomonas oryzae pv. oryzicola strain GX01 plasmid pXOCgx01 (A46, A57, A83, A112, D and E) and the X. oryzae strain AH28 plasmid pAH28 (A97). This genomic resource will be valuable for advancing research on surveillance, prevention, management and comparative studies of this critical pathogen in the future.