Working model of the VaMIEL1-VaMYB4a module in response to cold stress in grapevine. (IMAGE)
Caption
Image caption: Working model of the VaMIEL1-VaMYB4a module in response to cold stress in grapevine. Under normal temperature conditions (left panel), VaMIEL1 is highly expressed and promotes the degradation of VaMYB4a via the 26S proteasome pathway, leading to a suppression of CBF transcription. Consequently, the antioxidant enzyme levels (SOD, POD) remain at normal levels, and ROS are maintained at a steady state. Cold-responsive (COR) genes are not activated, and cold tolerance is not induced. Under cold stress conditions (right panel), VaMIEL1 expression is downregulated, reducing VaMYB4a ubiquitination and allowing its accumulation. The stabilized VaMYB4a binds to the CBF promoter, activating its expression. Increased CBF levels lead to the induction of downstream COR genes, enhancing cold tolerance. Additionally, the upregulation of SOD and POD contributes to ROS scavenging, further improving stress adaptation. The black arrows represent inducible expression, while flat-ended lines indicate inhibition. Red and blue arrows denote changes in enzyme activity and expression levels, respectively. The red ‘X’ indicates inhibited regulation, and Ub denotes ubiquitination modifications.
Image link: https://academic.oup.com/view-large/figure/521419406/uhaf093f8.tif
Credit
Horticulture Research
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CC BY