Unraveling the Mechanism of Purple Leaf Formation in Brassica napus by Integrated Metabolome and Transcriptome Analyses

Abstract

Brassica napus as both oilseed and vegetable, is widely cultivated in China. The purple leaf of B. napus is rich in anthocyanins and can provide valuable nutrients. Although several high-anthocyanin cultivars have been reported, the molecular mechanism underlying anthocyanin biosynthesis in B. napus remains lesser-known. Therefore, in this study, we conducted integrative metabolome and transcriptome analyses in three B. napus cultivars with different leaf colors. Overall, 39 flavonoids were identified (including 35 anthocyanins), and 22 anthocyanins were differentially accumulated in the leaves, contributing to the different leaf colors. Cyanidin-3,5,3’-O-triglucoside was confirmed as the main contributor of the purple leaf phenotype. Meanwhile, other anthocyanins may play important roles in deepening the color of B. napus leaves. A total of 5,069 differentially expressed genes (DEGs) and 32 overlapping DEGs were identified by RNA-sequencing; hence, the correlation between anthocyanin content and DEG expression levels was explored. Two structural genes (DFR and ANS), three GSTs (homologous to TT19), and 68 differentially expressed transcription factors (TFs), especially MYB-related TFs and WRKY44, were identified in three B. napus varieties characterized by different leaf color, thereby indicating that these genes may contribute to anthocyanin biosynthesis, transport, or accumulation in B. napus leaves. The findings of study provide important insights that may contribute to gaining a better understanding of the transcriptional regulation of anthocyanin metabolism in B. napus.

Metabolome and Transcriptome Reveal Chlorophyll, Carotenoid, and Anthocyanin Jointly Regulate the Color Formation of Triadica sebifera

“…The role of anthocyanin biosynthesis in the development of purple colouration has been extensively studied in multiple plant species, including tomato (Wang et al 2019), Tetrastigma hemsleyanum (Yan et al 2020a), Brassica (Heng et al 2020, Li et al 2022a, Zhao et al 2022c), tea (Song et al 2022), and wheat (Liu et al 2023).…”

Transcriptomic analysis reveals biosynthesis genes and transcription factors related to leaf anthocyanin biosynthesis in Aglaonema commutatum

“…‘Royalty’ [ 38 ]. Through metabolome analyses, cyanidin was proved to be the main contributor of the purple leaf phenotype in Brassica napus [ 39 ]. In the present study, cyanidin was found to be the major anthocyanin in the leaves of A. commutatum ; however, the composition and proportion of anthocyanin monomers did not significantly affect the leaf color of A. commutatum .…”

“…'Royalty' [38]. Through metabolome analyses, cyanidin was proved to be the main contributor of the purple leaf phenotype in Brassica napus [39].…”

An R3-MYB repressor, BnCPC forms a feedback regulation with MBW complex to modulate anthocyanin biosynthesis in Brassica napus

“…Due to the genome complexity compared with Arabidopsis, the regulation mechanism of anthocyanin biosynthesis in B. napus is more complicate and it has not been fully elucidated yet. Although many differentially expressed genes (DEGs) have been reported among rapeseed materials with different seed, leaf, or flower colors [50][51][52]. Hitherto, the functionally reported genes affecting anthocyanin biosynthesis in B. napus are structural genes (e.g., DFR, FLS, and LDOX) [52,53] and transcription regulatory factors (PAP2.A7, BnGL3-1, and WRKY41-1) [54][55][56][57].…”