Pepper SUMO E3 ligase CaDSIZ1 enhances drought tolerance by stabilizing the transcription factor CaDRHB1

通讯单位：韩国中央大学

背景回顾：SUMOylation is a reversible post-translational modification associated with protein stability and activity and modulates hormone signaling and stress responses in plants. Previously, we reported that the pepper homeobox domain transcription factor CaDRHB1 acts as a positive modulator of drought response.

SUMOylation是一种调控蛋白质稳定性以及活性的可逆的翻译后修饰，它参与了植物激素信号转导以及逆境响应过程。作者前期在胡椒中发现了一个homeobox domain transcription factor CaDRHB1正调控植物对干旱胁迫的耐受性。

Here, we show that CaDRHB1 protein stability is enhanced by SUMO E3 ligase CaDSIZ1-mediated SUMOylation in response to drought, thereby positively modulating ABA signaling and drought responses. Substituting lysine (K) 138 of CaDRHB1 with arginine reduced CaDSIZ1-mediated SUMOylation, indicating that K138 is the principal site for SUMO conjugation. • Virus-induced silencing of CaDSIZ1 promoted CaDRHB1 degradation, suggesting that CaDSIZ1 is involved in drought-induced SUMOylation of CaDRHB1. CaDSIZ1 interacted with and facilitated SUMO conjugation of CaDRHB1. CaDRHB1, mainly localized in the nucleus, was localized in both the nucleus and the cytoplasm in the SUMOylation mimic state, suggesting that SUMOylation of CaDRHB1 promotes its nuclear export, leading to cytoplasmic accumulation. • Moreover, CaDSIZ1-silenced pepper plants were less sensitive to ABA and considerably sensitive to drought stress, whereas CaDSIZ1-overexpressing plants displayed ABA-hypersensitive and drought-tolerant phenotypes. Collectively, our data indicate that CaDSIZ1-mediated SUMOylation of CaDRHB1 functions in ABA-mediated drought tolerance.

研究作者证实CaDRHB1蛋白稳定性在干旱胁迫条件下受到SUMO E3 ligase CaDSIZ1-mediated SUMOylation的正调控，从而激活ABA信号转导过程，最终提高了植物对旱胁迫的耐受性。分析显示，转录因子CaDRHB1的第138位的赖氨酸是被修饰的位点，当该位点被精氨酸取代后导致CaDRHB1的SUMOylation修饰水平下降。沉默CaDSIZ1导致CaDRHB1被降解，这进一步证实了CaDSIZ1参与了干旱胁迫条件下对CaDRHB1的SUMOylation修饰。在蛋白水平上CaDSIZ1与CaDRHB1存在相互作用。被SUMOylation修饰的CaDRHB1可以存在于细胞核以及细胞质中，说明SUMOylation修饰促进了该基因从细胞核中的输出过程，导致其在细胞质中的累积。最后作者证实CaDSIZ1的沉默株系对ABA的敏感度降低，对旱胁迫的耐受性下降，而过表达株系则恰恰相反。

原文链接：https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.18300

Journal:New Phytologist

Published date:  June 07, 2022