Genome-Wide Association Studies Reveal the Genetic Architecture of Ionomic Variation in Grains of Tartary Buckwheat.

Tartary buckwheat (Fagopyrum tataricum) is esteemed as a medicinal crop due to its high nutritional and health value. However, the genetic basis for the variations in Tartary buckwheat grain ionome remains inadequately understood. Through genome-wide association studies (GWAS) on grain ionome, 52 genetic loci are identified associated with 10 elements undergoing selection. Molecular experiments have shown that the variation in FtACA13's promoter (an auto-inhibited Ca(2+)-ATPase) is accountable for grain sodium concentration and salt tolerance, which underwent selection during domestication. FtYPQ1 (a vacuolar amino acid transporter) exhibits zinc transport activity, enhancing tolerance to excessive zinc stress and raising zinc accumulation. Additionally, FtNHX2 (a Na(+)/H(+) exchanger) positively regulates arsenic content. Further genomic comparative analysis of "20A1" (wild accession) and "Pinku" (cultivated accession) unveiled structural variants in key genes involved in ion uptake and transport that may result in considerable changes in their functions. This research establishes the initial comprehensive grain ionome atlas in Tartary buckwheat, which will significantly aid in genetic improvement for nutrient biofortification.