The MYB Activator WHITE PETAL1 Associates with MtTT8 and MtWD40-1 to Regulate Carotenoid-Derived Flower Pigmentation in Medicago truncatula. Issue 11 (17th September 2019)

• Record Type: Journal Article
• Authors: Meng, Yingying; Wang, Zuoyi; Wang, Yiqin; Wang, Chongnan; Zhu, Butuo; Liu, Huan; Ji, Wenkai; Wen, Jiangqi; Chu, Chengcai; Tadege, Million; Niu, Lifang; Lin, Hao
• Is Part Of: The Plant Cell. Volume 31:Issue 11(2019)
• Page Start: 2751
• Page End: 2767
• Publication Date: 2019-09-17
• DOI: 10.1105/tpc.19.00480
• Languages: English
• ISSNs: 1040-4651

Abstract

Abstract : The R2R3 MYB activator WP1 associates with MtTT8 and MtWD40-1 and regulates floral carotenoid pigmentation by directly modulating carotenogenic gene expression in Medicago truncatula . Abstract: Carotenoids are a group of natural tetraterpenoid pigments with indispensable roles in the plant life cycle and the human diet. Although the carotenoid biosynthetic pathway has been well characterized, the regulatory mechanisms that control carotenoid metabolism, especially in floral organs, remain poorly understood. In this study, we identified an anthocyanin-related R2R3-MYB protein, WHITE PETAL1 (WP1), that plays a critical role in regulating floral carotenoid pigmentation in Medicago truncatula . Carotenoid analyses showed that the yellow petals of the wild-type M. truncatula contained high concentrations of carotenoids that largely consisted of esterified lutein and that disruption of WP1 function via Tnt1 insertion led to substantially reduced lutein accumulation. WP1 mainly functions as a transcriptional activator and directly regulates the expression of carotenoid biosynthetic genes including MtLYCe and MtLYCb through its C-terminal acidic activation motif. Further molecular and genetic analyses revealed that WP1 physically interacts with MtTT8 and MtWD40-1 proteins and that this interaction facilitates WP1's function in the transcriptional activation of both carotenoid and anthocyanin biosynthetic genes. Our findings demonstrate the molecular mechanism of WP1-mediated regulation of floral carotenoid pigmentation and suggest that the conserved MYB-basic-helix-loop-helix-WD40 regulatory module functions in carotenoid biosynthesis in M. truncatula, with specificity imposed by the MYB partner.