Comparative transcriptome and iTRAQ-based proteome analysis in mature leaves of Brassica carinata provides insights into the purple leaf color diversity

Anthocyanins are the main pigments in leaves, flowers and fruits, performing diverse biological functions in plants and exhibiting benefits for human health. The purple-leaved accession of Brassicacarinata was used to study the biosynthetic mechanism of anthocyanins in this study. To elucidate the mechanisms of anthocyanin accumulation in the purple-leaved line, we employed comparative transcriptome and iTRAQ-based proteome technique to investigate the expression profile of the purple-leaved line (BC-P01) in comparison with that of the green-leaved line (BC-G01) in B. carinata. In total, 58,124 transcripts and 4,631 proteins were identified, of which 5,183 and 285 exhibited significant changes in abundance between BC-G01 and BC-P01. Joint transcriptome and proteome analysis reveal six candidate genes of UDP-glucosyl transferase 79B1 (UGT79B1) for synthesis of cyanidin 3-O-xylosyl(1->2)glucoside, UDP-glucosyl transferase 79C1 (UGT75C1) for synthesis of cyanidin 3-O-xylosyl(1->2)glucoside, chalcone isomerase (CHI) and chalcone synthase (CHS) for synthesis of chalcone, anthocyanidin 5-O-glucoside-6„-O-malonyltransferase (AT5MAT) for malonylation of anthocyanins, granule bound starch synthase 1 (GBSS1) for amylose starch biosynthetic, glutathione s-transferase f3 (GSTF3) for encoding glutathione transferase for anthocyanin transporting, respectively. The expression level of the transcriptome data was further verified by qRT-PCR method. The study can provide useful information for biosynthesis of total anthocyanin content (TAC) and molecular breeding in B. carinata and other species in Brassiceae.