CaHSL1 Acts as a Positive Regulator of Pepper Thermotolerance Under High Humidity and Is Transcriptionally Modulated by CaWRKY40
CaHSL1 Acts as a Positive Regulator of Pepper Thermotolerance Under High Humidity and Is Transcriptionally Modulated by CaWRKY40
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CaHSL1 在高湿度下作为辣椒耐热性的正调节因子并受 CaWRKY40 转录调节
DOI：
10.3389/fpls.2018.01802
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发表时间：
2018-12-07
影响因子：
5.6
通讯作者：
He, Shuilin
中科院分区：
文献类型：
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作者：
Guan, Deyi;Yang, Feng;He, Shuilin
辣椒(Capsicum Annuum)是一种重要的经济作物，高温胁迫会严重影响辣椒的生长发育和产量。因此，了解辣椒耐热性的分子机制很重要，但仍然难以捉摸。在本研究中，我们研究了编码类HAESA(HSL)受体样蛋白激酶(RLK)的CaHSL1在辣椒对高温高湿(HTHH)反应过程中的功能。CaHSL1具有精氨酸-天冬氨酸RLK的典型结构特征。CaHSL1在烟草叶肉细胞中的瞬时过表达表明，CaHSL1定位于整个细胞，包括质膜、细胞质和细胞核。接种HTHH或外源脱落酸可显著上调CaHSL1的表达，但青枯菌接种不能显著上调CaHSL1的表达。然而，CaHSL1被外源水杨酸、茉莉酸甲酯或乙烯利下调。通过病毒诱导的基因沉默显著降低了对HTHH的耐受性，并下调了相关基因CaHSP24的转录水平。相反，CaHSL1的瞬时过表达增加了CaHSP24的转录丰度，提高了对HTHH的耐受性，表现为光系统II在黑暗中的最佳/最大光化学效率(Fv/Fm)和光系统II在光下的实际光化学效率。此外，CaWRKY40针对CaHSL1的启动子，在HTHH过程中诱导转录，但对青枯病菌没有反应。这些结果表明，CaHSL1在转录水平上受到CaWRKY40的直接调控，在辣椒对HTHH的反应中起着正向调节作用。
Pepper (Capsicum annuum) is an economically important vegetable and heat stress can severely impair pepper growth, development, and productivity. The molecular mechanisms underlying pepper thermotolerance are therefore important to understand but remain elusive. In the present study, we characterized the function of CaHSL1, encoding a HAESA-LIKE (HSL) receptor-like protein kinase (RLK), during the response of pepper to high temperature and high humidity (HTHH). CaHSL1 exhibits the typical structural features of an arginine-aspartate RLK. Transient overexpression of CaHSL1 in the mesophyll cells of Nicotiana benthamiana showed that CaHSL1 localizes throughout the cell, including the plasma membrane, cytoplasm, and the nucleus. CaHSL1 was significantly upregulated by HTHH or the exogenous application of abscisic acid but not by R. solanacearum inoculation. However, CaHSL1 was downregulated by exogenously applied salicylic acid, methyl jasmonate, or ethephon. Silencing of CaHSL1 by virus-induced gene silencing significantly was reduced tolerance to HTHH and downregulated transcript levels of an associated gene CaHSP24. In contrast, transient overexpression of CaHSL1 enhanced the transcript abundance of CaHSP24 and increased tolerance to HTHH, as manifested by enhanced optimal/maximal photochemical efficiency of photosystem II in the dark (Fv/Fm) and actual photochemical efficiency of photosystem II in the light. In addition, CaWRKY40 targeted the promoter of CaHSL1 and induced transcription during HTHH but not in response to R. solanacearum. All of these results suggest that CaHSL1 is directly modulated at the transcriptional level by CaWRKY40 and functions as a positive regulator in the response of pepper to HTHH.