Concurrent Session
Johan Bastien Quilbe
Assistant Professor
Aarhus University
Aarhus, DENMARK
Troels W. Mouritzen
Aarhus University
Aarhus, Midtjylland, Denmark
Turgut Akyol
Aarhus University
Aarhus, Midtjylland, Denmark
Yusdar Mustamin
Tohoku University
Sendai, Miyagi, Japan
Masaru Bamba
Tohoku University
Sendai, Miyagi, Japan
Shusei Sato
Tohoku University
Sendai, Miyagi, Japan
Stig U. Andersen
Aarhus University
Aarhus, Midtjylland, Denmark
Plant roots interact dynamically with diverse soil microbes, yet the mechanisms regulating bacterial colonization remain poorly understood. In this study, we leveraged a panel of Lotus japonicus accessions and a synthetic bacterial community, LjSPHERE, to identify host genes influencing rhizosphere colonization. Genome-wide association analysis revealed significant signals in 36 loci, among which an uncharacterized gene, which we named ROOT MICROBIOME ESTABLISHMENT 1 (ROOMIE1). Disruption of ROOMIE1 resulted in drastic alterations in root microbiome composition, both under LjSPHERE inoculation and in native Japanese soil. Given the complex haplotype structure around the ROOMIE1 locus, we explored the genomic context of multiple microbiome GWAS hits. Traditional population genetics tools failed to fully capture this complexity, prompting the development of a novel metric, HAPk, to quantify haplotype diversity across genomic windows. Strikingly, GWAS hits exhibited a significant skew toward high HAPk scores, indicating elevated haplotype complexity and signatures of balancing selection. These findings suggest that microbial communities exert selective pressure on plant genomes, shaping host genetic adaptation to the rhizosphere microbiome.