The antagonistic MYB paralogs RH1 and RH2 govern anthocyanin leaf markings in Medicago truncatula

Chongnan Wang, Wenkai Ji, Yucheng Liu, Peng Zhou, Yingying Meng, Pengcheng Zhang, Jiangqi Wen, Kirankumar S. Mysore, Jixian Zhai, Nevin D. Young, Zhixi Tian, Lifang Niu, Hao Lin

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Patterned leaf coloration in plants generates remarkable diversity in nature, but the underlying mechanisms remain largely unclear. Here, using Medicago truncatula leaf marking as a model, we show that the classic M. truncatula leaf anthocyanin spot trait depends on two R2R3 MYB paralogous regulators, RED HEART1 (RH1) and RH2. RH1 mainly functions as an anthocyanin biosynthesis activator that specifically determines leaf marking formation depending on its C-terminal activation motif. RH1 physically interacts with the M. truncatula bHLH protein MtTT8 and the WDR family member MtWD40-1, and this interaction facilitates RH1 function in leaf anthocyanin marking formation. RH2 has lost transcriptional activation activity, due to a divergent C-terminal domain, but retains the ability to interact with the same partners, MtTT8 and MtWD40-1, as RH1, thereby acting as a competitor in the regulatory complex and exerting opposite effects. Moreover, our results demonstrate that RH1 can activate its own expression and that RH2-mediated competition can repress RH1 expression. Our findings reveal the molecular mechanism of the antagonistic gene paralogs RH1 and RH2 in determining anthocyanin leaf markings in M. truncatula, providing a multidimensional paralogous–antagonistic regulatory paradigm for fine-tuning patterned pigmentation.

Original languageEnglish (US)
Pages (from-to)3330-3344
Number of pages15
JournalNew Phytologist
Volume229
Issue number6
DOIs
StatePublished - Nov 22 2020

Bibliographical note

Funding Information:
We thank Prof. Richard Dixon for providing p2GW7 and pRLC plasmids, Dr Yuhong Tang and Dr Guifen Li for assistance with histological analysis. This work was supported by grants from the National Natural Science Foundation of China (32070554 and 32071864), Agricultural Science and Technology Innovation Program of CAAS (CAAS‐ZDRW202009 and CAAS‐ZDXT2019004), and Fundamental Research Funds for Central Non‐profit Scientific Institution (Y2020YJ12 and No. 1610392020005). The development of Tnt1 insertion lines was supported by the US National Science Foundation (DBI 0703285 and IOS‐1127155) and Noble Research Institute LLC. The authors declare no competing financial interests. M. truncatula

Funding Information:
We thank Prof. Richard Dixon for providing p2GW7 and pRLC plasmids, Dr Yuhong Tang and Dr Guifen Li for assistance with histological analysis. This work was supported by grants from the National Natural Science Foundation of China (32070554 and 32071864), Agricultural Science and Technology Innovation Program of CAAS (CAAS-ZDRW202009 and CAAS-ZDXT2019004), and Fundamental Research Funds for Central Non-profit Scientific Institution (Y2020YJ12 and No. 1610392020005). The development of M.?truncatula Tnt1 insertion lines was supported by the US National Science Foundation (DBI 0703285 and IOS-1127155) and Noble Research Institute LLC. The authors declare no competing financial interests.

Publisher Copyright:
© 2020 The Authors New Phytologist © 2020 New Phytologist Foundation

Keywords

  • MYB regulator
  • Medicago truncatula
  • anthocyanin leaf marking
  • paralog antagonism
  • patterned pigmentation

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