Multilevel regulation of anthocyanin-promoting R2R3-MYB transcription factors in plants

Abstract

Anthocyanins are common secondary metabolites in plants that confer red, blue, and purple colorations in plants and are highly desired by consumers for their visual appearance and nutritional quality. In the last two decades, the anthocyanin biosynthetic pathway and transcriptional regulation of anthocyanin biosynthetic genes (ABGs) have been well characterized in many plants. From numerous studies on model plants and horticultural crops, many signaling regulators have been found to control anthocyanin accumulation via regulation of anthocyanin-promoting R2R3-MYB transcription factors (so-called R2R3-MYB activators). The regulatory mechanism of R2R3-MYB activators is mediated by multiple environmental factors (e.g., light, temperature) and internal signals (e.g., sugar, ethylene, and JA) in complicated interactions at multiple levels. Here, we summarize the transcriptional control of R2R3-MYB activators as a result of natural variations in the promoter of their encoding genes, upstream transcription factors and epigenetics, and posttranslational modifications of R2R3-MYB that determine color variations of horticultural plants. In addition, we focus on progress in elucidating the integrated regulatory network of anthocyanin biosynthesis mediated by R2R3-MYB activators in response to multiple signals. We also highlight a few gene cascade modules involved in the regulation of anthocyanin-related R2R3-MYB to provide insights into anthocyanin production in horticultural plants.

Genome-Wide Comparative Analysis of the R2R3-MYB Gene Family in Six Ipomoea Species and the Identification of Anthocyanin-Related Members in Sweet Potatoes

“…R2R3-MYBs are the major determinant regulators of the MBW(MYB-bHLH-WD40) complex, which fine-tune the spatial and temporal localization of anthocyanins by regulat-ing the expression level of flavonoid biosynthesis pathway genes [17,73].…”

“…Plant R2R3-MYB genes perform crucial roles in various biological processes, including plant growth and development, cell differentiation, specialized secondary metabolism, and biotic and abiotic stress responses [14,15]. In particular, many R2R3-MYB genes have been thoroughly investigated and verified to regulate tissue-specific anthocyanin accumulation in various plants [16][17][18]. For example, the first R3R3-MYB plant gene, COLORED1 (C1), which was isolated from maize, encodes a regulatory protein to control anthocyanin pigment production in the aleurone layer of the endosperm [19,20].…”

Metabolomics combined with transcriptomics analyses of mechanism regulating testa pigmentation in peanut

“…MYB30, MYB80, MYB86, MYB102) and an ANR (arahy.IK60LM) were found to be hub genes involved in anthocyanin and proanthocyanin metabolism by WGCNA. Previous study showed that R2R3-MYB transcription factor and ANR were important regulatory genes that confer pigment accumulation in plant tissues (Yang et al, 2022). A major gene (AhTc1) controlling peanut purple testa was characterized to be encoding a R2R3-MYB transcription factor using QTL-seq method together with transcriptome analysis and gene expression profiling.…”

PsERF1B-PsMYB10.1-PsbHLH3 module enhances anthocyanin biosynthesis in the flesh-reddening of amber-fleshed plum (cv. Friar) fruit in response to cold storage

“…MYB-mediated anthocyanin biosynthetic pathway of fruit can be affected by a variety of elements, including light, low temperature, and hormone signal transduction pathways [ 21 ]. Earlier studies showed that relevant TFs and structural genes associated with the anthocyanin biosynthesis are activated to express in plants in response to low temperature [ 22 , 23 ].…”

“…Earlier studies showed that relevant TFs and structural genes associated with the anthocyanin biosynthesis are activated to express in plants in response to low temperature [ 22 , 23 ]. Cold-activated MBW complexes are created through the up-regulation of critical positive genes of anthocyanin biosynthesis [ 21 ]. In addition, various TFs can interact with the MBW complex in the regulation of anthocyanin biosynthesis.…”