Metabolite Changes on Cold Response in Tartary Buckwheat (Fagopyrum tataricum)
Background : Plants live in restricted spaces that are constantly exposed to various environmental stresses. Under these stressful conditions, plants lead to biosynthesize specialized metabolites to adapt to environmental stresses. Here we investigate the effects of cold on the metabolome of tartaty buckwheat, focusing the flavonoid biosynthetic pathway. Methods and Results : From the metabolic profiling based on the GC-TOF-MS analysis, we identified the effect of cold on forty-four metabolites, including sugars, amino acids, and organic acids. Most of sugars and sugar derivatives remain nearly unchanged or slightly decreased in the plants grown at 25 ºC, whereas sugar and sugar derivative contents of cold-treated plants significantly increased, excepting galactose. Some of amino acid and amino acid derivatives contents decrease in cold-treated plants, whereas organic acid derived from tricarboxylic acid (TCA) cycle were increased the cold-treated plants compared with the plants grown at 25 ºC. Particularly, the contents of two anthocyanins, cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside, were significantly increased by cold treatment. Proanthocyanidins such as epicatechin and catechin were also significantly affected by cold. The expression of most flavonoid biosynthetic genes were significantly upregulated in cold-treated buckwheat seedling. Among the flavonoid biosynthetic genes, the expression of FtANS was notably upregulated in response to cold. Conclusion : By analyzing both primary metabolites and secondary metabolites of tartary buchwheat without or with cold, we showed that cold play a critical role in the modulation of the primary metabolites and flavonoid synthesis pathway in tartary buchwheat. Particularly, anthocyanin and proanthocyanidin biosynthetic pathways are strongly up-regulated in response to cold.