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Summary: Rutin, a flavonoid rich in buckwheat, is important for human health and plant resistance to external stresses. The hydrolysis of rutin to quercetin underlies the bitter taste of Tartary buckwheat. In order to identify rutin hydrolysis genes, a 200 genotypes mini‐core Tartary buckwheat germplasm resource was re‐sequenced with 30‐fold coverage depth. By combining the content of the intermediate metabolites of rutin metabolism with genome resequencing data, metabolite genome‐wide association analyses (GWAS) eventually identified a glycosyl hydrolase gene FtGH1, which could hydrolyse rutin to quercetin. This function was validated both in Tartary buckwheat overexpression hairy roots and in vitro enzyme activity assays. Mutation of the two key active sites, which were determined by molecular docking and experimentally verified via overexpression in hairy roots and transient expression in tobacco leaves, exhibited abnormal subcellular localization, suggesting functional changes. Sequence analysis revealed that mutation of the FtGH1 promoter in accessions of two haplotypes might be necessary for enzymatic activity. Co‐expression analysis and GWAS revealed that FtbHLH165 not only repressed FtGH1 expression, but also increased seed length. This work reveals a potential mechanism behind rutin metabolism, which should provide both theoretical support in the study of flavonoid metabolism and in the molecular breeding of Tartary buckwheat. [ABSTRACT FROM AUTHOR]

The transcription factor (TFs) BES1, which mediates brassinosteroid (BR) signaling, regulates plant growth and development. However, BES1 genes have not yet been reported in Tartary buckwheat. Here, ten FtBES1 genes were identified in the Tartary buckwheat genome, and they were named FtBES1-1 to FtBES1-10. These genes were divided into four groups according to the classification in Arabidopsis thaliana. Multiple sequence alignment indicated that all BES1 gene members contained the BES1_N structural domain. Phylogenetic relationship FtBES1 genes in the same group had similar gene structures and motifs. An analysis of cis-acting elements demonstrated that the BES1 TFs contains many light-responsive, hormonal, and abiotic stress-responsive elements, etc. The 10 FtBES1 genes were located on four chromosomes of Tartary buckwheat, and gene distribution and synteny analysis revealed that segmental duplications have played important roles in FtBES1 gene family expansion. Tissue specificity revealed that all of the ten FtBES1 members expressed highly in two periods, and relatively high expression levels were observed in mature leaves. Gene expression profiles under different hormone treatments demonstrated that FtBES1 gene family participated in the hormone stress response. This study enriches our knowledge of the Tartary buckwheat BES1 gene family and provides a theoretical basis for analyzing the biological functions and stress tolerance mechanisms of the Tartary buckwheat BES1 transcription factors. [ABSTRACT FROM AUTHOR]

We aimed to elucidate the physiological and biochemical mechanism by which exogenous hydrogen peroxide (H2O2) alleviates salt stress toxicity in Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn). Tartary buckwheat "Chuanqiao-2" under 150 mmol·L−1 salt (NaCl) stress was treated with 5 or 10 mmol·L−1 H2O2, and seedling growth, physiology and biochemistry, and related gene expression were studied. Treatment with 5 mmol·L−1 H2O2 significantly increased plant height (PH), fresh and dry weights of shoots (SFWs/SDWs) and roots (RFWs/RDWs), leaf length (LL) and area (LA), and relative water content (LRWC); increased chlorophyll a (Chl a) and b (Chl b) contents; improved fluorescence parameters; enhanced antioxidant enzyme activity and content; and reduced malondialdehyde (MDA) content. Expressions of all stress-related and enzyme-related genes were up-regulated. The F3′H gene (flavonoid synthesis pathway) exhibited similar up-regulation under 10 mmol·L−1 H2O2 treatment. Correlation and principal component analyses showed that 5 mmol·L−1 H2O2 could significantly alleviate the toxic effect of salt stress on Tartary buckwheat. Our results show that exogenous 5 mmol·L−1 H2O2 can alleviate the inhibitory or toxic effects of 150 mmol·L−1 NaCl stress on Tartary buckwheat by promoting growth, enhancing photosynthesis, improving enzymatic reactions, reducing membrane lipid peroxidation, and inducing the expression of related genes. [ABSTRACT FROM AUTHOR]