Germinating rice seeds shape rhizospheric bacteria via releasing benzaldehyde

Abstract

Plants are not passively exposed to microbes during their life cycles, but rather shape the microbiome in their own way. However, little information is available about when and how plants recruit their microbes in the life cycles. We scrutinized the recruitment of soil microbes by rice (Oryza sativa) at the seed germination stage. Bacteria of Enterobacteria and Weeksellaceae were the most preferentially recruited by the germinating seeds, despite of many other bacteria in the soil. The seedlings that recruited Enterobacteria and Weeksellaceae bacteria notably outperformed those without these microbes in leaf length (by 54.21%), root length (by 188.11%) and biomass (by 88.65%). Further, we detected benzaldehyde, a plant-specific volatile metabolite, in the exudates of germinating seeds. Addition of benzaldehyde to the soil resulted in enrichment of Enterobacteria bacteria, suggesting that seed-released benzaldehyde could be a cue to recruit beneficial bacteria. Taken together, our results demonstrated that plants could recruit beneficial bacteria from the soil at the very early life stage of seed germination via releasing specific metabolites.