In the Solanaceae, a hierarchy of bHLHs confer distinct target specificity to the anthocyanin regulatory complex

Montefiori, Mirco; Brendolise, Cyril; Dare, Andrew P.; Lin‐Wang, Kui; Davies, Kevin; Hellens, Roger P.; Allan, Andrew C.

doi:10.1093/jxb/eru494

Cited by 121 publications

(143 citation statements)

References 41 publications

(73 reference statements)

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“…Therefore, despite the HF2 induction by VvWRKY26, petals of the fully complemented 35S:VvWRKY26 petunia plants have a reddish color typical of the cyanidin-based anthocyanin profile of the R27 background. The microarray analysis of petunia petals expressing VvWRKY26 also revealed the weak induction of a bHLH regulator of the flavonoid pathway, JAF13 , whose precise role in the pigmentation of petunia corollas still has to be fully elucidated (Quattrocchio et al, 1998; Montefiori et al, 2015). …”

Section: Discussionmentioning

confidence: 99%

A Grapevine TTG2-Like WRKY Transcription Factor Is Involved in Regulating Vacuolar Transport and Flavonoid Biosynthesis

et al. 2017

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A small set of TTG2-like homolog proteins from different species belonging to the WRKY family of transcription factors were shown to share a similar mechanism of action and to control partially conserved biochemical/developmental processes in their native species. In particular, by activating P-ATPases residing on the tonoplast, PH3 from Petunia hybrida promotes vacuolar acidification in petal epidermal cells whereas TTG2 from Arabidopsis thaliana enables the accumulation of proanthocyanidins in the seed coat. In this work we functionally characterized VvWRKY26 identified as the closest grapevine homolog of PhPH3 and AtTTG2. When constitutively expressed in petunia ph3 mutant, VvWRKY26 can fulfill the PH3 function in the regulation of vacuolar pH and restores the wild type pigmentation phenotype. By a global correlation analysis of gene expression and by transient over-expression in Vitis vinifera, we showed transcriptomic relationships of VvWRKY26 with many genes related to vacuolar acidification and transport in grapevine. Moreover, our results indicate an involvement in flavonoid pathway possibly restricted to the control of proanthocyanidin biosynthesis that is consistent with its expression pattern in grape berry tissues. Overall, the results show that, in addition to regulative mechanisms and biological roles shared with TTG2-like orthologs, VvWRKY26 can play roles in fleshy fruit development that have not been previously reported in studies from dry fruit species. This study paves the way toward the comprehension of the regulatory network controlling vacuolar acidification and flavonoid accumulation mechanisms that contribute to the final berry quality traits in grapevine.

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Section: Discussionmentioning

confidence: 99%

A Grapevine TTG2-Like WRKY Transcription Factor Is Involved in Regulating Vacuolar Transport and Flavonoid Biosynthesis

et al. 2017

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“…In some species, such as Antirrhinum (Schwinn et al 2006), bHLHs of different clades appear to be interchangeable, while in others, e.g. the Solanaceae, it has been shown that AN1 is specifically required for activation of the anthocyanin biosynthetic pathway, while JAF13 regulates the anthocyanin pathway indirectly by regulating AN1 expression (Montefiori et al 2015). In kiwifruit, bHLH42 (belonging to clade B, AN1-like) appears to be slightly up-regulated during anthocyanin biosynthesis .…”

Section: Transcriptional Regulationmentioning

confidence: 99%

Genetics of Pigment Biosynthesis and Degradation

Montefiori

Pilkington

Davies

et al. 2016

Compendium of Plant Genomes

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Within the genus Actinidia, there is large variability in fruit skin and flesh colour. The most familiar kiwifruit, A. chinensis var. deliciosa 'Hayward', has flesh of bright emerald green. Although many species have live, coloured fruit skins, most commercial cultivars have a dead, brown fruit skin. Hidden underneath the skin is a diversity and range of flesh colours which are characteristic of the species or specific genotypes. From a commercial point of view, flesh colour has become a particularly important feature which distinguishes the fruit and new cultivars in the market. In today's market, there is a large number of cultivars with a range of flesh colours grouped into three main categories: green, yellow and red. The red-fleshed cultivars are a recent addition and have generated great interest throughout the industry worldwide. It is also the distinctive feature of the genotype used to build the reference genome for A. chinensis var. chinensis (Huang et al., 2013). Fruit ColourAnthocyanins, carotenoids and chlorophylls are responsible for almost all fruit coloration. Plant breeding and domestication have produced numerous fruit where the levels and distribution of pigments vary widely, changing during development and in response to the environment. The accumulation of pigments in fruit is an important indicator of ripeness, quality and value. These pigments also differentiate cultivars for consumers, as well as being implicated in the health attributes of our foods. A highly pigmented fruit has become perceived by consumers as conferring

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“…), PpMYBPA1 and PpMYB7 in peach (Ravaglia et al ., ; Zhou et al ., ) and MdMYB9 and MdMYB11 in apple (Gesell et al ., ; An et al ., ). Flavonoid‐related bHLH TFs can be divided into two clades, A and B (Montefiori et al ., ). Clade A includes GL3/EGL3 in Arabidopsi s, JAF13 in petunia and R in maize, whereas clade B consists of AN1 in petunia, TT8 in Arabidopsis and IN1 in maize.…”

Section: Introductionmentioning

confidence: 97%

Activator‐type R2R3‐MYB genes induce a repressor‐type R2R3‐MYB gene to balance anthocyanin and proanthocyanidin accumulation

et al. 2018

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Anthocyanin and proanthocyanidin (PA) accumulation is regulated by both myeloblastosis (MYB) activators and repressors, but little information is available on hierarchical interactions between the positive and negative regulators. Here, we report on a R2R3-MYB repressor in peach, designated PpMYB18, which acts as a negative regulator of anthocyanin and PA accumulation. PpMYB18 can be activated by both anthocyanin- and PA-related MYB activators, and is expressed both at fruit ripening and juvenile stages when anthocyanins or PAs, respectively, are being synthesized. The PpMYB18 protein competes with MYB activators for binding to basic Helix Loop Helixes (bHLHs), which develops a fine-tuning regulatory loop to balance PA and anthocyanin accumulation. In addition, the bHLH binding motif in the R3 domain and the C1 and C2 repression motifs in the C-terminus of PpMYB18 both confer repressive activity of PpMYB18. Our study also demonstrates a modifying negative feedback loop, which prevents cells from excess accumulation of anthocyanin and PAs, and serves as a model for balancing secondary metabolite accumulation at the transcriptional level.

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In the Solanaceae, a hierarchy of bHLHs confer distinct target specificity to the anthocyanin regulatory complex

Abstract: SummaryAnthocyanin biosynthesis is regulated by a transcription factor complex. Here, it is determined that the potential bHLH partners in this complex function in a hierarchy to control each other and the anthocyanin biosynthesis pathway.

Cited by 121 publications

References 41 publications

A Grapevine TTG2-Like WRKY Transcription Factor Is Involved in Regulating Vacuolar Transport and Flavonoid Biosynthesis

A Grapevine TTG2-Like WRKY Transcription Factor Is Involved in Regulating Vacuolar Transport and Flavonoid Biosynthesis

Genetics of Pigment Biosynthesis and Degradation

Activator‐type R2R3‐MYB genes induce a repressor‐type R2R3‐MYB gene to balance anthocyanin and proanthocyanidin accumulation

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