In Planta Colonization and Role of T6SS in Two Rice Endophytes.

Endophytes live inside plants and are often beneficial. is a novel bacterial genus that includes many diazotrophic plant-associated isolates. Plant-bacteria studies on two rice endophytic beneficial strains were performed, including comparative genomics, secretome profiling, in planta tests, and a field release trial. The strains are efficient rhizoplane and root endosphere colonizers and localized in the root cortex. Secretomics revealed 144 putative secreted proteins, including type VI secretory system (T6SS) proteins. A T6SS genomic knock-out mutant showed a significant decrease in rhizoplane and endosphere colonization ability. A field trial using rice seed inoculated with spp. showed no effect on plant growth promotion upon nitrogen stress and microbiome studies revealed that spp. were significantly more present in the inoculated rice. Comparative genomics indicated that several protein domains were enriched in plant-associated spp. This study highlights that is an important, recently classified genus involved in plant-bacteria interaction.