GhWRKY21 regulates ABA-mediated drought tolerance by fine-tuning the expression of GhHAB in cotton
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ORIGINAL ARTICLE
GhWRKY21 regulates ABA‑mediated drought tolerance by fine‑tuning the expression of GhHAB in cotton Jiayu Wang1 · Lijun Wang1 · Yan Yan1 · Shuxin Zhang1 · Han Li1 · Zheng Gao1 · Chen Wang1 · Xingqi Guo1 Received: 26 June 2020 / Accepted: 26 August 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Key message We report that GhWRKY21, a WRKY transcription factor, plays essential roles in regulating the intensity of the drought-induced ABA signalling pathway by facilitating the expression of GhHAB in cotton (Gossypium hirsutum). Abstract Abscisic acid (ABA) is one of the most important plant hormones in response to abiotic stress. However, activation of the ABA signalling pathway often leads to growth inhibition. The mechanisms that regulate the intensity of ABA signals are poorly understood. Here, we isolated and analysed the cotton group IId WRKY transcription factor (TF) gene GhWRKY21. Functional analysis indicated that GhWRKY21 plays a negative role in the drought response of cotton. Silencing of GhWRKY21 in cotton dramatically increased drought tolerance, whereas ectopic GhWRKY21 overexpression in Nicotiana benthamiana decreased drought tolerance. Furthermore, the GhWRKY21-mediated drought tolerance was ABA dependent. To clarify the mechanism underlying the GhWRKY21-mediated regulation of drought tolerance, 17 clade-A-type type 2C protein phosphatase (PP2C) genes, which are negative regulators of ABA signalling, were identified in cotton. Notably, GhWRKY21 interacted specifically with the W-box element within the promoter of GhHAB and regulated its expression. Silencing of GhHAB in cotton yielded a phenotype similar to that of GhWRKY21-silenced cotton. These results suggest that GhWRKY21 regulates the intensity of ABA signals by facilitating the expression of GhHAB. In summary, these findings dramatically improve our understanding of the function of WRKY TFs and provide insights into the mechanism of ABAmediated drought tolerance. Keywords Gossypium hirsutum · WRKY transcription factor · GhWRKY21 · ABA-mediated drought tolerance · PP2Cs · GhHAB
Introduction
Communicated by Neal Stewart. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00299-020-02590-4) contains supplementary material, which is available to authorized users. * Chen Wang [email protected] * Xingqi Guo [email protected] 1
State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian 271018, Shandong, People’s Republic of China
To accommodate dynamic growth environments, plants employ complex regulatory mechanisms to quickly optimize their response to environmental stress (Li et al. 2013). Phytohormones are key signals that regulate a series of plant physiological processes in response to various environmental stresses (Fujita et al. 2006; Yang et al. 2017). Abscisic acid (ABA) is a crucial phytohormone that is largely involved in response to abiotic stress, such as high salinity, extreme temperature and d
