P-377 - Rice-microbiota interaction outcomes are governed by cultivar-specific inoculum preferences and host immune receptors

Deciphering how plant–microbiota interactions achieve beneficial outcomes for crops will provide innovative strategies for sustainable agriculture. Here, we investigated the rice-microbiota interactions in a tailored gnotobiotic bottle from dual perspectives. From the bacterial side, inoculation with native soil microbiota and a simplified synthetic community (SynCom) induced root growth promotion (RGP) and root growth inhibition (RGI) in different cultivars, suggesting that the function of microbial inocula has a cultivar-specific preference. Tracking of SynCom colonization and assessing the effect of individual strains revealed that the RGP and RGI outcomes were linked to imbalanced colonization of detrimental versus beneficial bacteria in rice roots. From the host side, we found that several receptor-like kinase (RLK) mutants disrupted the RGP function of soil microbiota, i.e., the same microbial inocula promoted root growth in wild-type rice but suppressed growth in these rlk mutants. Further analysis demonstrated that the rice extracellular immune receptor OsFLS2 played a critical role in microbiota-mediated root growth. The study reveals that the outcomes of rice–microbiota interactions are governed by both cultivar-specific preferences in bacterial inocula and host immune receptors, providing a framework for future rice microbiome engineering.