An Integrated Analysis of Transcriptome and Metabolism Reveals an Inhibitory Effect of Low Light on Anthocyanin Biosynthesis in Purple cai-tai (Brassicarapa L. var. purpurea)

Abstract

Low light caused by industrial development and environment change has become a limitation in crop production. This condition inhibits the petiole anthocyanin synthesis and even its tastes in purple cai-tai (Brassicarapa L. var. purpurea); however, the molecular basis of the inhibitory effects by low light on anthocyanin synthesis in purple cai-tai petiole is less reported. In this study, we performed an integrated analysis of transcriptomes and metabolisms to decipher key genes and/or metabolites that responsible for low light acclimation in a purple cai-tai cultivar, XH1. Results shows that anthocyanin is obviously repressed by low light treatment, and consistently the structural genes related to the anthocyanin biosynthesis pathway is significantly enriched in the list of differentially expressed genes according to both GO and KEGG analysis. Furthermore, the amounts of some metabolites related to anthocyanin are dramatically decreased under low light treatment, such as cyanindin 3-O-glucoside chloride, cyanindin O-syringic acid, and cyanidin 3-O-rutinoside. In addition, we found that five transcription factors in TCP gene family especially BrTCP15 is substantially downregulated by low light treatments. The expression pattern of BrTCP15 in response to low light treatment was further confirmed by qPCR. This study reports the inhibitory effects of the anthocyanin biosynthesis pathway and BrTCP15 by low light treatments, and extends our knowledge on regulatory mechanism of the anthocyanin biosynthetic pathway in response to low light in B. rapa L.