Metabolite accumulation and inhibition of hypocotyl elongation by blue light induction in Amaranthus tricolor L.

Red amaranth is an important fresh vegetable with valuable nutritional properties. Blue light is favorable for the accumulation of many metabolites and inhibits hypocotyl elongation in plants. However, the relation between metabolite induction and the inhibition of hypocotyl elongation by blue light in red amaranth is unclear. Here, we used LC-MS/MS-based widely targeted metabolomics to identify key compounds and to compare the metabolite composition of red amaranth under dark and blue light conditions. A total of 444 metabolites were identified, 37 of which differed between the two conditions. A pathway enrichment analysis also identified significant differences between the two conditions. Fifteen lipids, all up-regulated under the blue light, were significantly different. The amino acid content was lower under the blue light than under the dark condition. We found cyanidin chloride and anthocyanin 3-O-beta-D-glucoside which are the two components involved in the anthocyanin pathway. Our results verify the high nutritional quality of the red amaranth and suggest that blue light influences metabolite synthesis and hypocotyl elongation in the species.