Combinatorial Regulation of Stilbene Synthase Genes by WRKY and MYB Transcription Factors in Grapevine (Vitis vinifera L.)

Abstract

Stilbene synthase (STS) is the key enzyme leading to the biosynthesis of resveratrol. Recently we reported two R2R3-MYB transcription factor (TF) genes that regulate the stilbene biosynthetic pathway in grapevine: VviMYB14 and VviMYB15. These genes are strongly co-expressed with STS genes under a range of stress and developmental conditions, in agreement with the specific activation of STS promoters by these TFs. Genome-wide gene co-expression analysis using two separate transcriptome compendia based on microarray and RNA sequencing data revealed that WRKY TFs were the top TF family correlated with STS genes. On the basis of correlation frequency, four WRKY genes, namely VviWRKY03, VviWRKY24, VviWRKY43 and VviWRKY53, were further shortlisted and functionally validated. Expression analyses under both unstressed and stressed conditions, together with promoter-luciferase reporter assays, suggested different hierarchies for these TFs in the regulation of the stilbene biosynthetic pathway. In particular, VviWRKY24 seems to act as a singular effector in the activation of the VviSTS29 promoter, while VviWRKY03 acts through a combinatorial effect with VviMYB14, suggesting that these two regulators may interact at the protein level as previously reported in other species.

VpSTS29/STS2 enhances fungal tolerance in grapevine through a positive feedback loop

“…Activated WRKYs and MYBs showing strong coexpression with 21 STS genes suggest that WRKYs interact with MYBs to regulate the stilbene synthesis pathway (Vannozzi et al, 2018). These observations confirm "cross talk" by the SA signalling molecule to activate STS expressions Fung et al, 2008;Jiao et al, 2016;Xu et al, 2011).…”

“…Under artificial inoculation with U. necator , SA signalling pathway activation induces transcriptional reprogramming of pathogen responsive genes, such as WRKYs , MYBs , and PR proteins, to strengthen pathogen defences in VpSTS29/STS2 mutants (Figure and Table ). Activated WRKYs and MYBs showing strong coexpression with 21 STS genes suggest that WRKYs interact with MYBs to regulate the stilbene synthesis pathway (Vannozzi et al, ). These observations confirm “cross talk” by the SA signalling molecule to activate STS expressions (Duan et al, ; Fung et al, ; Jiao et al, ; Xu et al, ).…”

The ethylene response factor VaERF092 from Amur grape regulates the transcription factor VaWRKY33, improving cold tolerance

“…In grapevine, systems biology approaches holds great promise in advancing our understanding of the molecular mechanisms underpinning the regulation of key secondary metabolism pathways (Wong and Matus, ; Vannozzi et al ., ) and responses to the environment (Loyola et al ., ; Sun et al ., ). To elucidate the regulatory mechanisms exerted by VaERF092 and VaWRKY33 , we performed a systems‐oriented study encompassing: (i) GCNs of multiple species and platforms and (ii) network‐driven transcriptional analysis of cold stress responses and promoter CRE architecture.…”

“…Grapevine GCNs were constructed as previously described (Vannozzi et al ., ; Wong et al ., ) using r (http://www.r-project.org), with two separate transcriptome compendia consisting of RMA‐normalized microarray (29K NimbleGen Grape whole‐genome platform) and FPKM(log 2 )‐normalized RNA‐seq data sets. All biological replicates were averaged in the microarray and RNA‐seq expression matrix, resulting in 356 and 236 columns (experiments), respectively, representing numerous and diverse experimental conditions.…”

A specific allele of MYB14 in grapevine correlates with high stilbene inducibility triggered by Al3+ and UV-C radiation

“…A close functional association between MYB and WRKY TFs has been demonstrated, and they have been reported to act combinatorially and synergistically to regulate grapevine STS genes (Vannozzi et al 2018). For instance, VviWRKY03 itself does not activate STS29, but in combination with VviMYB14 significantly increases STS promoter activity.…”