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Article|01 Jun 2019|OPEN
The MdWRKY31 transcription factor binds to the MdRAV1 promoter to mediate ABA sensitivity
Xian-Yan Zhao1 , Chen-Hui Qi2 , Han Jiang1 , Chun-Xiang You2 , Qing-Mei Guan1 , Feng-Wang Ma1 , Yuan-Yuan Li2 , and Yu-Jin Hao,2 ,
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, China
2National Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China
*Corresponding author. E-mail: liyy0912@163.com,haoyujin@sdau.edu.cn

Horticulture Research 6,
Article number: 66 (2019)
doi: https://doi.org/10.1038/s41438-019-0147-1
Views: 1063

Received: 29 Dec 2018
Revised: 29 Mar 2019
Accepted: 31 Mar 2019
Published online: 01 Jun 2019

Abstract

The phytohormone abscisic acid (ABA) is a major element involved in apple (Malus domestica) production because of its role in seed germination and early seedling development. The WRKY family, which is one of the largest families of transcription factors, plays an important role in ABA signaling in plants. However, the underlying molecular mechanisms of WRKY-mediated ABA sensitivity in apple are poorly understood. A genome-wide transcriptome analysis indicated that MdWRKY31 is a key factor induced by ABA. Quantitative real-time PCR showed that MdWRKY31 is induced by ABA in response to PEG4000, which is used to simulate drought. As a transcription factor, MdWRKY31 is localized in the nucleus. Ectopic expression of MdWRKY31 in Arabidopsis and Nicotiana benthamiana enhanced plant sensitivity to ABA. Overexpression of MdWRKY31 in apple roots and apple calli increased sensitivity to ABA, whereas repression of MdWRKY31 reduced sensitivity to ABA in the roots of ‘Royal Gala’. Electrophoretic mobility shift assays, chromatin immunoprecipitation PCR, and yeast one-hybrid assays indicated that MdWRKY31 directly binds to the promoter of MdRAV1. Expression analyses of transgenic apple calli containing MdWRKY31 and pMdRAV1::GUS implied that MdWRKY31 represses the expression of MdRAV1. We also found that MdRAV1 binds directly to the promoters of MdABI3 and MdABI4 and repressed their expression. Our findings reveal a new important regulatory mechanism of MdWRKY31-MdRAV1-MdABIs in the ABA signaling pathway in apple.