Bacillus species are core microbiota of highly resistant maize varieties that induce host metabolic defense against corn stalk rot

Abstract

Microbes colonizing each niche of terrestrial plants are indispensable for maintaining crop health. Although corn stalk rot (CSR) is a severe disease infecting maize (Zea mays) worldwide, the mechanisms underlying host–microbe interactions across vertical niches in maize plants, which exhibit heterogeneous CSR resistance, remain largely uncharacterized. Here, we investigated the microbial communities associated with CSR-resistant and -susceptible maize cultivars using multi-omics analysis coupled with experimental verification. Maize cultivars resistant to CSR reshaped the microbiota and recruited Bacillus species with three antagonistic phenotypes to alleviate pathogen stress. By inducing the expression of Tyrosine decarboxylase 1 (TYDC1), encoding an enzyme that catalyzes the production of tyramine and dopamine, Bacillus isolates that do not directly suppress pathogen infection facilitated the synthesis of berberine, an isoquinoline alkaloid that inhibits pathogen growth. These beneficial bacteria were recruited from the rhizosphere and transferred to the stems but not grains of the infected resistant plants. Our findings offer insight into how maize plants respond to and interact with their microbiome and provide valuable strategies for controlling soil-borne pathogens.