Overexpression of a Bcl-2-associated athanogene SlBAG9 negatively regulates high-temperature response in tomato
Overexpression of a Bcl-2-associated athanogene SlBAG9 negatively regulates high-temperature response in tomato
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DOI：
10.1016/j.ijbiomac.2021.11.114
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发表时间：
2021-12-16
影响因子：
8.2
通讯作者：
Ge, Cailin
中科院分区：
文献类型：
--
作者：
Ding, Haidong;Qian, Lu;Ge, Cailin
BAG基因是一个多功能的辅伴侣调节基因家族，参与植物逆境胁迫的调控。我们前期的研究表明，高温诱导番茄（Solanum lycopersicum）的SlBAG 9基因在转录和蛋白水平上表达量较高，但其生物学功能尚不清楚。在这里，我们对SlBAG 9进行了深入的分析。SIBAG 9蛋白不定位于线粒体，而定位于细胞质和细胞核。SIBAG 9基因启动子区含有许多与植物逆境和激素反应有关的顺式作用元件，其中包括热激元件（HSE 1）。GUS组织化学分析表明，在非诱导条件下，SlBAG 9启动子可以驱动GUS基因在烟草瞬时转化叶片中表达，而HSE 1是HT诱导GUS活性的关键。SlBAG 9的转录在不同器官中表达，并受到高温、低温、干旱和盐胁迫以及外源脱落酸（阿坝）和H2 O2的调控。为了进一步阐明SlBAG 9响应HT的功能，开发了过表达SlBAG 9的转基因番茄植物。与野生型植物相比，SlBAG 9过表达植物表现出对HT胁迫的更敏感性，表现为燃烧症状、叶绿素降解和光合速率降低。此外，SlBAG 9-过表达株系表现出较高的脂质过氧化产物（MDA）和H2 O2的积累，但较低的超氧化物歧化酶，过氧化氢酶和过氧化物酶的活性。因此，推测SlBAG 9可能通过抑制抗氧化酶系统导致氧化损伤，从而加重HT引起的损伤表型而在耐热性中起负面作用。
The Bcl-2-associated athanogene (BAG) gene is a multi-functional family of co-chaperones regulator, modulating plant stress response. Our previous study revealed that the SlBAG9 of tomato (Solanum lycopersicum) had the higher expression level induced by high-temperature (HT) at the transcriptional and protein levels, but its biological function was still unclear. Here, we conducted an in-depth analysis of SlBAG9. SlBAG9 protein was not located in the mitochondria but in the cytoplasm and nucleus. Many cis-acting elements involved in plant stress and hormone responses were located in the promoter regions of SlBAG9 including heat-shock element (HSE1). The beta-glucuronidase (GUS) histochemical analysis showed that SlBAG9 promoter could drive GUS gene expression in transiently transformed Nicotiana tabacum leaves under non-inducing condition and HSE1 is critical for HT-induced GUS activity under HT. The transcription of SlBAG9 was expressed in different organs and was regulated by HT, cold, drought, and salt stresses as well as exogenous abscisic acid (ABA) and H2O2. To further elucidate SlBAG9 function in response to HT, the transgenic tomato plants overexpressing SlBAG9 were developed. Compared to the wild-type plants, SlBAG9-overexpressing plants exhibited more sensitivity to HT stress, reflected by the burning symptoms, the degradation of chlorophyll, and the reduction of photosynthetic rates. Additionally, SlBAG9-overexpressing lines showed higher accumulation of lipid peroxidation production (MDA) and H2O2, but lower activities of superoxide dismutase, catalase, and peroxidase. Therefore, it is speculated that SlBAG9 plays a negative role in thermotolerance probably by inhibition of antioxidant enzyme system leading to the oxidative damage, consequently aggravating the HT-caused injury phenotype.