Xanthomonas protegenssp. nov., a rice seed-associated probiotic and taxonomic outlier species ofXanthomonas sontii

Abstract

AbstractRice seed microbiota play a vital role throughout their growth and developmental stages.Xanthomonas sontiiis known as an abundant, core-vertically transmitted rice seed endophyte with probiotic properties. Studies reveal a less explored world of non-pathogenicXanthomonas(NPX) species likeX. sontiiandX. indicathat are associated with healthy rice seeds. The present study reports the isolation, biochemical characterization, and in-depth taxonogenomic evidence for a third NPX species,X. protegens, from rice seeds, a taxonomic outlier ofX. sontii. It also highlights the importance of using multiple taxonogenomic indices to identify taxonomic outlier species. Similar to the other two NPX species, the new member species is also non-pathogenic and providesin vivoprotection to rice plants fromXanthomonas oryzaepv.oryzaeupon leaf clip inoculation. The pangenome investigation suggested a set of unique genes to the novel species that might be important in adaptation to rice plants and differentiate it from other NPX species. The study will allow the design of markers for the identification of these NPX members, targeted culturomics of a particular NPX species and in the discovery of other novel NPX species from healthy rice seed microbiome for further exploitation in rice health.