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RESEARCH ARTICLE

Open Access

A WRKY transcription factor, TaWRKY42-B, facilitates initiation of leaf senescence by promoting jasmonic acid biosynthesis Ming-Ming Zhao1†, Xiao-Wen Zhang1†, Yong-Wei Liu2†, Ke Li1, Qi Tan1, Shuo Zhou2, Geng Wang1* Chun-Jiang Zhou1*

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Abstract Background: Leaf senescence comprises numerous cooperative events, integrates environmental signals with agedependent developmental cues, and coordinates the multifaceted deterioration and source-to-sink allocation of nutrients. In crops, leaf senescence has long been regarded as an essential developmental stage for productivity and quality, whereas functional characterization of candidate genes involved in the regulation of leaf senescence has, thus far, been limited in wheat. Results: In this study, we analyzed the expression profiles of 97 WRKY transcription factors (TFs) throughout the progression of leaf senescence in wheat and subsequently isolated a potential regulator of leaf senescence, TaWRKY42-B, for further functional investigation. By phenotypic and physiological analyses in TaWRKY42-Boverexpressing Arabidopsis plants and TaWRKY42-B-silenced wheat plants, we confirmed the positive role of TaWRKY42-B in the initiation of developmental and dark-induced leaf senescence. Furthermore, our results revealed that TaWRKY42-B promotes leaf senescence mainly by interacting with a JA biosynthesis gene, AtLOX3, and its ortholog, TaLOX3, which consequently contributes to the accumulation of JA content. In the present study, we also demonstrated that TaWRKY42-B was functionally conserved with AtWRKY53 in the initiation of age-dependent leaf senescence. Conclusion: Our results revealed a novel positive regulator of leaf senescence, TaWRKY42-B, which mediates JArelated leaf senescence via activation of JA biosynthesis and has the potential to be a target gene for molecular breeding in wheat. Keywords: Leaf senescence, WRKYs, JA, Transcriptional regulation, Wheat

* Correspondence: [email protected]; [email protected] † Ming-Ming Zhao, Xiao-Wen Zhang and Yong-Wei Liu contributed equally to this work. 1 Ministry of Education Key Laboratory of Molecular and Cell Biology, Hebei Collaboration Innovation Center for Cell Signaling, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, Hebei, China Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statu