Combining GWAS and RNA-seq approaches identifies the FtADH1 gene for drought resistance in Tartary buckwheat

Drought is one of the major environmental constraints that significantly affects seedling emergence, yield, and quality of Tartary buckwheat, thereby hindering the development of its industry. However, the molecular mechanisms underlying drought tolerance genes in Tartary buckwheat remain largely unexplored. Alcohol dehydrogenase (ADH), one of the essential plant proteins, plays a crucial role in growth, development, and stress responses, but its specific role in drought resistance is still unclear. In this study, we identified an ADH gene FtADH1 , using a membership function value of drought tolerance (MFVD) combined with a genome-wide association study (GWAS) and transcriptomic profiles that confers drought tolerance in Tartary buckwheat. Our findings demonstrated that the overexpression of FtADH1 in Arabidopsis and Tartary buckwheat hairy roots enhances drought tolerance by promoting root elongation and mitigating elevated levels of reactive oxygen species (ROS). Our findings demonstrated that FtADH1 can enhanced tolerance to drought stresses in both Tartary buckwheat and Arabidopsis . This study identifies the FtADH1 as a new player in affecting ROS level and the stress response of Tartary buckwheat by regulating protective enzyme activities at a high level to scavenge ROS and modulating root growth under drought stress. Further, we identified proteins interacting with FtADH1 through a prokaryotic expression pull-down assay combined with mass spectrometry, revealing that FtADH1 specifically interacts with the S-adenosyl-L-methionine (SAM) synthetase protein, FtSAMS1 . Overexpression of FtSAMS1 was found to enhance ADH enzymatic activity, leading to increased SAM content in overexpressing Tartary buckwheat hairy roots under water-deficit conditions. Additionally, FtSAMS1 overexpression induced a drought-resistant phenotype in Arabidopsis and Tartary buckwheat hairy roots under drought stress, revealing the biological function of FtADH1 . Evolutionary analysis indicates that ADH1 in Fagopyrum species has undergone significant evolutionary events, including duplication and purifying selection, which may contribute to functional diversification and adaptive advantages such as drought resistance in cultivated buckwheat. In summary, this study proposes that FtADH1 is a key contributor to drought tolerance, and its interaction with FtSAMS1 holds potential for the development of drought-resistant varieties in Tartary buckwheat and its relative species.