Anthocyanin Fruit encodes an R2R3‐MYB transcription factor, SlAN2‐like, activating the transcription of SlMYBATV to fine‐tune anthocyanin content in tomato fruit

Abstract

Anthocyanin fruit (Aft) and atroviolacea (atv) were characterized in wild tomato and can enhance anthocyanin content in tomato fruit. However, the gene underlying the Aft locus and the mechanism by which Aft and atv act remain largely unknown.In this study, the Aft locus was fine-mapped to an approximately 145-kb interval on chromosome 10, excluding SlAN2 (Solyc10g086250), SlANT1 (Solyc10g086260) and SlANT1like (Solyc10g086270), which have previously been suggested as candidates. Thus, the R2R3-MYB transcription factor SlAN2-like (Solyc10g086290) was considered the best candidate gene for Aft.The CRISPR/Cas9-mediated SlAN2-like mutants show a much lower accumulation of anthocyanins associated with the downregulation of multiple anthocyanin-related genes compared to the wild-type tomato, indicating that SlAN2-like is responsible for the Aft phenotype. The repressive function of SlMYBATV also was confirmed through the CRISPR/Cas9 approach. A yeast-two-hybrid assay revealed that SlMYBATV interacts with the bHLH protein SlJAF13. Furthermore, yeast-one-hybrid and dual-luciferase transient expression assays showed that Aft directly binds to the SlMYBATV promoter and activates its expression.The results herein provide candidate genes to enhance anthocyanin content in tomato fruit. This research also provides insight into a mechanism involving the Aft-SlMYBATV pathway that fine-tunes anthocyanin accumulation in tomato fruit.

Ethylene‐activated PpERF105 induces the expression of the repressor‐type R2R3‐MYB gene PpMYB140 to inhibit anthocyanin biosynthesis in red pear fruit

“…For example, the expression of the peach ( Prunus persica ) R2R3‐MYB gene MYB18 is induced by R2R3‐MYB transcriptional activators to balance anthocyanin and proanthocyanidin accumulation (Zhou et al ., 2019). In tomato fruit, the SlAN2‐like R2R3‐MYB TF activates the transcription of SlMYBATV , which encodes a transcriptional repressor, to fine‐tune anthocyanin biosynthesis (Yan et al ., 2020). In the present study, we detected the upregulated expression of the R2R3‐MYB transcriptional repressor gene PpMYB140 in PpERF105 ‐OX pear calli (Figure S6).…”

“…A luciferase assay indicated that although PpMYB140 can directly inhibit PpANS expression, the transcriptional repression is enhanced by the interaction between PpMYB140 and bHLH3 (Figure 5c). In tomato ( Solanum lycopersicum ), SlMYBATV competes with the SlAN2‐like TF for the interaction with SlJAF13 (i.e., bHLH TF) (Yan et al ., 2020). In our study, a firefly luciferase complementation imaging assay and an examination of transiently transformed ‘Hongzaosu’ pear fruit verified that PpMYB140 competes with PpMYB114 for the binding to bHLH3 and inhibits anthocyanin biosynthesis (Figures 5d and 6).…”

A genome-wide association study uncovers a critical role of the RsPAP2 gene in red-skinned Raphanus sativus L.

“…To understand the mechanism leading to differential gene expression in red- and white-skinned genotypes, the coding and promoter sequences of the RsPAP2 gene were compared among the different radish genotypes. It was found that there were three nonsynonymous SNPs in the coding region of RsPAP2 , but two of the SNPs were only identified in three genotypes with different skin colors, and one SNP was not located in a conserved domain, which similar to the situation of the SlAN2-like gene in tomato fruit 39 . However, a total of ten SNPs and four base deletions were found in the 948 bp promoter region, among which two of the base deletions (“T” at 849 bp and “A” at 850 bp) were consistently found among the red-skinned genotypes with the exception of one genotype, “NAU-123” (Table S3 ).…”

“…However, a total of ten SNPs and four base deletions were found in the 948 bp promoter region, among which two of the base deletions (“T” at 849 bp and “A” at 850 bp) were consistently found among the red-skinned genotypes with the exception of one genotype, “NAU-123” (Table S3 ). Cases of such insertions or deletions are also found in blood orange, apple, and tomato 39 – 41 . Although further experimental evidence is needed, this deletion in the promoter region might contribute to the differential expression of RsPAP2 and affect ATC biosynthesis in radish.…”

Quantitative dissection of color patterning in the foliar ornamental Coleus reveals underlying features driving aesthetic value

“…In these systems, an R2R3 Myb, bHLH, and WDR "MBW" transcriptional regulon has been identified as a central regulator for color patterning, controlling both orange carotenoid and purple/red anthocyanin deposition (Sagawa et al 2016;Ludwig et al 1989;Albert et al 2014). In contrast to floral systems, relatively little is known about the genetics of color patterning in vegetative organs; however, current knowledge including genetic mapping of pigmentation variants for leaves, roots, and fruits (Albert et al, 2015;Yan et al, 2020;Xu et al, 2020;Yu et al, 2020) and ectopic expression of floral regulators in vegetative tissue (Albert et al, 2020), indicates that the transcriptional MBW regulon is broadly involved in pigmentation patterning across diverse organs.…”