P-282 - Genetic Determinants and Regulatory Mechanisms Governing Rhizosphere Microbiome Assembly in Maize

The host-associated microbiome is crucial for plant fitness, yet how host genetic variation shapes microbiome assembly and impacts plant phenotypes remains unclear. Here, we investigate the genetic basis and regulatory mechanisms governing root development and rhizosphere microbiome assembly in maize using a Multi-parent Advanced Generation Inter-Cross (MAGIC) population of 248 genotypes from eight Mexican landraces. Through 16S rRNA amplicon sequencing of 1,001 rhizosphere samples, we identified key microbial taxa significantly associated with maize biomass, potentially contributing to secondary metabolism and nutrient cycling. In parallel, 979 root transcriptomes were analyzed using TWAS and WGCNA, revealing key host genes linked to biomass and microbiome composition. WGCNA identified functional modules related to hormone signaling and nutrient metabolism, while GWAS quantified microbial trait heritability and identified host loci associated with microbial communities and biomass. To validate these findings, we isolated 563 amplicon sequence variants (ASVs) from maize roots and plan to use the BonnMu mutant library for functional validation of candidate genes and microbial interactions. This population-scaled multi-omics approach provides insights into how host genetic variation and gene regulation modulate root development and microbiome assembly, advancing our understanding of plant-microbe interactions.