Metabolome and transcriptome sequencing analysis reveals anthocyanins in the red flowers of black locust (Robinia pseudoacacia L.)

Abstract

Black locust (Robinia pseudoacacia L.) flowers display a white or red color. The white flowers are a popular food in Chinese markets, while the red flowers have high ornamental value. In this study, combined analysis of the transcriptome and flavonoid metabolome was performed to investigate the key genes and metabolites involved in flower pigmentation in the red and white flowers of black locust. A total of 308 flavonoid metabolites were identified, and five anthocyanins were significantly higher in the red flowers compared to the white flowers. Transcriptome sequencing yielded about 66 Gb data, from which 53,992 unigenes were assembled. Compared with the white flowers, 1,394 unigenes were up-regulated and 1,201 unigenes were down-regulated in the red flowers. Three anthocyanin structural genes, F3'H, ANS, and 3GT, were significantly up-regulated in the red flowers, representing the key genes for anthocyanin accumulation in the red flowers. Nine MYB and four bHLH genes were up-regulated in the red flowers, representing the candidate genes regulating the anthocyanin pathway. These results provide a theoretical basis for the development of black locust flowers as a food and also provide a foundation for the study of anthocyanin regulation in black locust.

Keywords:
black locust; Robinia pseudoacacia L.; red flower; flavonoids; anthocyanins; metabolome; transcriptome