Differential Assembly of Rhizosphere Microbiome and Metabolome in Rice with Contrasting Resistance to Blast Disease

Rice blast, caused by Magnaporthe oryzae, is one of the most devastating diseases threatening global rice production. Although host resistance represents a sustainable control strategy, the underlying mechanisms mediated by the rhizosphere microbiome remain poorly understood. In this study, we selected four rice varieties with varying resistance to blast and demonstrated, through an integrated approach of 16S rRNA/ITS amplicon sequencing, untargeted metabolomics, and soil physicochemical analysis, that the rice genotype reprograms the genotype-root exudate-rhizosphere microbiome system. Results showed that the resistant variety P104 significantly decreased the soil pH while increasing the contents of total nitrogen, ammonium nitrogen, and nitrate nitrogen. On the other hand, the susceptible variety P302 exhibited higher pH and available phosphorus content. Furthermore, the rhizosphere of P104 was enriched with specific beneficial microbes such as Desulfobacterota, Ascomycota, and Pseudeurotium, and activated defense-related metabolic pathways including cysteine and methionine metabolism and phenylpropanoid biosynthesis. In contrast, susceptible varieties showed reduced bacterial diversity and fostered a microecological environment more conducive to pathogen proliferation. Our findings indicate that blast-resistant rice genotypes are associated with a protective rhizosphere microbiome, potentially mediated by alterations in root metabolism, thereby suppressing pathogen establishment. These insights elucidate the underground mechanisms of blast resistance and highlight the potential of microbiome-assisted breeding for sustainable crop protection.