A plant biodiversity effect resolved to a single genetic locus

Despite pervasive evidence that biodiversity promotes plant community productivity, progress towards understanding the mechanistic basis of this effect remains slow, impeding the development of predictive ecological theory and agricultural applications. Here, we analysed non-additive interactions between divergent Arabidopsis accessions in experimental plant communities. By combining methods from ecology and genetics, we identified and mendelized a major effect locus that promotes complementarity amongst genotypes and productivity in mixed communities. Using plant-soil-feedback experiments, we demonstrate that this allelic diversity also causes genotype-specific soil legacy responses in a subsequent generation. This suggests that asymetric interactions of plants with soil-borne factors drive niche complementarity, and that the impacts of allelic diversity extends across generations. Our work shows that positive diversity effects can be linked to single Mendelian factors, and that complex community properties can have simple causes. This may pave the way to novel breeding strategies, focussing on phenotypic properties that manifest themselves beyond the individual, i.e. at a higher level of biological organisation.