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Article|01 Jul 2020|OPEN
Apple SERRATE negatively mediates drought resistance by regulating MdMYB88 and MdMYB124 and microRNA biogenesis
Xuewei Li1, Pengxiang Chen1, Yinpeng Xie1, Yan Yan1, Liping Wang1, Huan Dang1, Jing Zhang1, Lingfei Xu1, Fengwang Ma1 & Qingmei Guan1,
1State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling, 712100 Shaanxi, PR China

Horticulture Research 7,
Article number: 98 (2020)
doi: 10.1038/hortres.2020.98
Views: 458

Received: 07 Jan 2020
Revised: 03 Apr 2020
Accepted: 06 Apr 2020
Published online: 01 Jul 2020

Abstract

The function of serrate (SE) in miRNA biogenesis in Arabidopsis is well elucidated, whereas its role in plant drought resistance is largely unknown. In this study, we report that MdSE acts as a negative regulator of apple (Malus × domestica) drought resistance by regulating the expression levels of MdMYB88 and MdMYB124 and miRNAs, including mdm-miR156, mdm-miR166, mdm-miR172, mdm-miR319, and mdm-miR399. MdSE interacts with MdMYB88 and MdMYB124, two positive regulators of apple drought resistance. MdSE decreases the transcript and protein levels of MdMYB88 and MdMYB124, which directly regulate the expression of MdNCED3, a key enzyme in abscisic acid (ABA) biosynthesis. Furthermore, MdSE is enriched in the same region of the MdNECD3 promoter where MdMYB88/MdMYB124 binds. Consistently, MdSE RNAi transgenic plants are more sensitive to ABA-induced stomatal closure, whereas MdSE OE plants are less sensitive. In addition, under drought stress, MdSE is responsible for the biogenesis of mdm-miR399, a negative regulator of drought resistance, and negatively regulates miRNAs, including mdm-miR156, mdm-miR166, mdm-miR172, and mdm-miR319, which are positive regulators of drought resistance. Taken together, by revealing the negative role of MdSE, our results broaden our understanding of the apple drought response and provide a candidate gene for apple drought improvement through molecular breeding.