Assemblage of root-associated microbiome contributes to disparate performance of two rice genotypes under aluminum...

Aluminum (Al) toxicity severely inhibits rice growth under acidic soils, posing a significant threat to food security. The assemblies of root-associated microbiomes throughout the lifecycle of rice are hypothesized to furnish a resilient reservoir of ecological functions for rice growth performance under Al stresses. However, the mechanisms that drive the assembly of root-associated microbiomes of rice are largely unknown. In this study, we chose two rice genotypes (including aluminum-tolerant (Al-T) and aluminum-sensitive (Al-S)) as model plants to investigate the microbial assemblage of root-associated microbiome and their potential roles on the plant growth performance under Al stress. The microbial community diversity (Shannon) and evenness (Chao1) in the endosphere of the Al-T genotype gradually decreased, converging towards levels observed in the Al-S genotype. In addition, the rhizosphere and endosphere microbiomes of Al-T genotype are primarily influenced by deterministic processes, while those of Al-S genotype are more influenced by stochastic processes. Compared to Al-S genotype, Al-T genotype exhibited higher complexity and stability in its rhizosphere and endosphere microbiomes, while the rhizoplane microbiome showed the opposite trend. In the rhizosphere microbiome of the Al-T genotype, we identified Gallionellales, Rhodobacterales, and Rhizobiales as keystone taxa. Their abundance was closely associated with microbial functions, including indole-3-acetic acid (IAA) synthesis, phosphorus solubilization, glutathione (GSH) metabolism, and 1-aminocyclopropane-1-carboxylate (ACC) metabolism. In the Al-S genotype, the keystone taxa included Actinomycetales and Burkholderiales. This study offers new insights into plant adaptation to abiotic stress and underscores the significance of the assemblage of root-associated microbiome in this process.