Metabolomics and related genes analysis revealed the distinct mechanism of drought resistance in novel buckwheat and cultivated species

Buckwheat (Fagopyrum tataricum), a crop with both food and medicinal applications, holds significant economic value particularly in regions with arid or barren land. In order to explore the physiological and metabolic mechanism of drought stress resistance in different varieties of buckwheat, we conducted analyses on morphophysiological indicators and metabolomes of two distinct drought-tolerant buckwheat varieties exposed to drought treatments of different durations. The results revealed that drought stress exacerbated cell membrane damage, reduced chlorophyll content, and impaired antioxidant enzyme activity in both buckwheat varieties. However, the novel species DK19 exhibited greater resistance to drought compared to cultivated buckwheat K33. Metabolomics approaches were employed to examine metabolite changes in DK19 and K33 during two critical periods (day 7 and day 11) of drought stress. As a result, 15 significantly altered metabolites were identified in different materials within the network of amino acid biosynthesis pathways. Furthermore, 16 significantly enriched metabolites in the phenylpropanoid biosynthesis pathway as well as 17 significantly enriched metabolites in flavonoids biosynthesis pathway were detected. Additionally, based on metabolite changes, we determined differential expression levels of six genes related to amino acid metabolism networks and 12 key genes highly associated with secondary metabolism. Moreover, we observed distinct accumulation patterns of secondary metabolites phenylpropanoids (including hydroxycinnamates and flavonoids) in the two materials, which may contribute to the improved drought resistance of the novel tartary buckwheat cultivars. These findings provide valuable clues for the breeding of perennial buckwheat and solid foundations for genetically improving the drought resistance of buckwheat in the future.