Purple Rehmannia: Investigation of the activation of R2R3‐MYB transcription factors involved in anthocyanin biosynthesis

Abstract

Engineering anthocyanin biosynthesis in herbs could provide health-promoting foods for improving human health. Rehmannia glutinosa is a popular medicinal herb in Asia, and was a health food for the emperors of the Han Dynasty (59 B.C.). In this study, we revealed the differences in anthocyanin composition and content between three Rehmannia species. On the 250, 235 and 206 identified MYBs in the respective species, six could regulate anthocyanin biosynthesis by activating the ANTHOCYANIDIN SYNTHASE (ANS) gene expression. Permanent overexpression of the Rehmannia MYB genes in tobacco strongly promoted anthocyanin content and expression levels of NtANS and other genes. A red appearance of leaves and tuberous/roots was observed, and the total anthocyanin content and the cyanidin-3-O-glucoside content were significantly higher in the lines overexpressing RgMYB41, RgMYB42, and RgMYB43 from R. glutinosa, as well as RcMYB1 and RcMYB3 in R. chingii and RhMYB1 from R. henryi plants. Knocking out of RcMYB3 by CRISPR/Cas9 gene editing resulted in the discoloration of the R. chingii corolla lobes, and decreased the content of anthocyanin. R. glutinosa overexpressing RcMYB3 displayed a distinct purple color in the whole plants, and the antioxidant activity of the transgenic plants was significantly enhanced compared to WT. These results indicate that Rehmannia MYBs can be used to engineer anthocyanin biosynthesis in herbs to improve their additional value, such as increased antioxidant contents.

Pigment Diversity in Leaves of Caladium × hortulanum Birdsey and Transcriptomic and Metabolic Comparisons between Red and White Leaves

“…In tobacco, CRISPR/Cas9-induced mutation in the RcMYB3 gene of Rubus chingii Hu. leads to the appearance of white petals [ 42 ]. In Syringa oblata Lindl., ERF plays an important role in the color transition period (from purple to light purple near white), while the MBW complex participates in the whole process of color change [ 43 ].…”

Comprehensive Analysis of the Complete Mitochondrial Genome of Rehmannia chingii: An Autotrophic Species in the Orobanchaceae Family

“…It is known for its effects of clearing heat and cooling blood, nourishing Yin and promoting fluid production, and tonifying the liver and kidneys [32]. In studies of R. chingii, the focuses were on plastid genome analyses [28,33], exploring the phylogeography of R. chingii using Internal Transcribed Spacer (ITS) sequences and Simple Sequence Repeat (SSR) molecular markers [30], as well as identifying the medicinal components of R. chingii [34,35]. However, there are no studies on the mitogenome evolution of R. chingii.…”