Application of osmoprotectant enhance tolerance to drought stress in rice and trigger changes in root microbial composition

Drought stress triggers changes in the composition of microbes associated with roots. In this study, we performed metagenomic analysis to assess microbial abundance in the roots of two rice cultivars, Merah Pari Eja (MPE: tolerant) and Putih Payo (PP: susceptible), under different drought conditions: FTSW 1 (control) and FTSW 2 (severe drought). Additionally, we investigated the impact of exogenous osmoprotectant treatment at three levels: 0 (control), 50 (medium), and 100 (high). Based on the results of the metagenomic analysis, the Shannon diversity index across all treatment groups fell within the range of 4.01 to 5.40, indicating a high relative abundance of microbes in each group. As drought severity decreased, there was a notable increase in the relative abundance of Streptomyces, Actinosynema, and Nonomura, all of which play pivotal roles in synthesizing compatible solutes. Furthermore, in both MPE and PP cultivars, a decrease in the relative abundance of Cyanobacteria and Bacteroidetes phyla was noted alongside elevated concentrations of exogenous osmoprotectants in both drought stress groups. These findings suggest that the application of osmoprotectants enhances rice’s tolerance to drought by influencing the root microbial composition. Observations of morphophysiological characteristics revealed a concurrent increase in chlorophyll and carotenoid content, proline levels, and antioxidant activity, aligning with the increasing concentrations of exogenous osmoprotectants across all cultivars under drought led to producing more resilient phenotypic traits. Specific microbial groups within each drought stress treatment group or under exogenous osmoprotectant treatment induce physiological and biochemical changes within the cells, underscoring the intricate interplay between microbial communities and plant responses to environmental stress. These findings have practical implications for rice cultivation under drought conditions, suggesting a potential strategy for improving rice resilience in the face of climate change. © The Author(s), under exclusive licence to Society for Plant Biochemistry and Biotechnology 2024.