The Endophytic Plant Growth Promoting Methylobacterium oryzae CBMB20 Integrates and Persists into the Seed-Borne Endophytic Bacterial Community of Rice

Abstract

Endophytic persistence of inoculated plant growth promoting bacteria (PGPB) involves interaction with the host plant and the host’s indigenous endophytic bacterial communities. This study investigated the persistence of Methylobacterium oryzae CBMB20 into the rice endosphere together with the impact of inoculation on the diversity and community structure of the root and shoot bacterial endophytes in Oryza sativa L. spp. indica cv. IR29. Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis of the root and shoot showed that M. oryzae CBMB20 was able to integrate and persist in the rice endosphere without causing drastic shifts in bacterial endophytic diversity and community composition. The bacterial communities in the root and shoot are very similar to the seeds of IR29, suggesting that most of them are seed-borne. The root endosphere bacterial communities of inoculated and uninoculated IR29 plants are more diverse compared to the shoots in terms of richness and diversity indices. The dominant bacterial T-RFs of the root endosphere of IR29 belong to Microbacterium, Delftia, Pseudomonas, Xanthomonas and Stenotrophomonas, Herbaspirillum, Enterobacter, and Sphingomonas, as observed in the three restriction enzyme T-RFLP profiles. Bacterial clades identified as Curtobacterium, Enterobacter, Stenotrophomonas, and Xanthomonas were distinctly observed in both the root and shoot communities, and these bacterial groups are also the dominant endophytes of the shoot endosphere. This study showed that Methylobacterium oryzae CBMB20 could persist and incorporate into the endophytic bacterial community of the endosphere without causing long-term antagonistic interactions with its host plant and with the native microbiota.