Genetic factors explaining anthocyanin pigmentation differences

Abstract

Background: Anthocyanins represent one of the most abundant coloration factors found in plants. Biological functions of anthocyanins range from reproduction to protection against biotic and abiotic stressors. Owing to a clearly visible phenotype of mutants, the anthocyanin biosynthesis and its sophisticated regulation have been studied in numerous plant species. Genes encoding the anthocyanin biosynthesis enzymes are regulated by a transcription factor complex comprising MYB, bHLH and WD40 proteins. Results: A systematic comparison of anthocyanin-pigmented vs. non-pigmented varieties across flowering plant species was performed. Literature was screened for cases in which causal genes were previously identified. Transcriptomic data sets were processed to determine the genes most likely to be responsible for color variation based on their expression pattern. The contribution of different structural and regulatory genes to the pigmentation differences was quantified. Gene expression differences concerning transcription factors are by far the most frequent explanation for pigmentation differences observed between two varieties of the same species. Among the transcription factors in the analyzed cases, MYB genes are substantially more likely to explain pigmentation differences than bHLH or WD40 genes. Conclusions: These findings support previous assumptions about the plasticity of transcriptional regulation and its importance for the evolution of novel coloration phenotypes. The particular significance of MYBs and their apparent dominant role in the specificity of the MBW complex are underlined by our findings.

Genome-wide analysis of flavonoid biosynthetic genes in Musaceae (Ensete,Musella, andMusaspecies) reveals amplification of flavonoid 3’,5’-hydroxylase

“…Cenci et al (2019) suggested that the presence of the B genome was associated with increased expression of genes related to flavonoid biosynthesis. The extreme plasticity of transcriptional regulation, leading to novel colouration phenotypes (Nair et al, 2005), has been shown by Recinos and Pucker (2023), so variation in genes and regulation is likely to be more important than gene copy number. Nevertheless, the 5-to 10-fold increase in the copy number of F3'5'H genes in Zingiberales compared with that in Poaceae suggested the selection of multiple copies in monocots, as proven by the greater number of 4CL gene copies than other genes in the pathway.…”

Genome sequence and RNA-seq analysis reveal genetic basis of flower coloration in the giant water lilyVictoria cruziana

“…MYB transcription factors are able to bind DNA through a highly conserved DNA-binding repeat domain (Prouse & Campbell, 2012), while bHLHs can bind DNA with a stretch of basic amino acids (Voronova & Baltimore, 1990). MYBs can be divided into different groups based on the number of characteristic repeats with the R2R3-MYBs playing a predominant role in the control of the flavonoid biosynthesis (Baudry et al, 2004;Stracke et al, 2007;Gonzalez et al, 2008;Li, 2014;Marin & Pucker, 2023). Specific subgroups of these R2R3-MYBs have different and even opposing functions.…”

“…AtMYB123 and AtMYB5 belong to subgroup 5 and regulate proanthocyanidin biosynthesis in Arabidopsis thaliana (Baudry et al, 2004;Xu et al, 2014). MYBs assigned to subgroup 6 (AtMYB113, AtMYB114, AtMYB90, AtMYB75) are involved in controlling the anthocyanin biosynthesis in A. thaliana (Borevitz et al, 2000;Marin & Pucker, 2023) whereas AtMYB111, AtMYB12 and AtMYB11 (subgroup 7) are regulating the production of flavonols (Stracke et al, 2007;Dubos et al, 2010). Over the last years, various orthologous of the well characterized MYBs in A. thaliana have been identified across plant species which enables a broader understanding of regulatory mechanisms in the plant kingdom.…”