Department of Plant Biology, University of Szeged, Szeged, Hungary.
Department of Biology, Biochemestry and Natural Sciences, Universitat Jaume I, Castello de la Plana, 12071, Spain.
Plant Physiol Biochem. 2023 Dec;205:108192. doi: 10.1016/j.plaphy.2023.108192. Epub 2023 Nov 18.
The endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) are highly dependent on phytohormones such as salicylic acid (SA). In this study, the effect of SA supplementation and the lack of endogenous SA on glutathione metabolism were investigated under ER stress in wild-type (WT) and transgenic SA-deficient NahG tomato (Solanum lycopersicum L.) plants. The expression of the UPR marker gene SlBiP was dependent on SA levels and remained lower in NahG plants. Exogenous application of the chemical chaperone 4-phenylbutyrate (PBA) also reduced tunicamycin (Tm)-induced SlBiP transcript accumulation. At the same time, Tm-induced superoxide and hydrogen peroxide production were independent of SA, whereas the accumulation of reduced form of glutathione (GSH) and the oxidised glutathione (GSSG) was regulated by SA. Tm increased the activity of glutathione reductase (GR; EC 1.6.4.2) independently of SA, but the activities of dehydroascorbate reductase (DHAR; EC 1.8.5.1) and glutathione S-transferases (GSTs; EC 2.5.1.18) were increased by Tm in a SA-dependent manner. SlGR2, SlGGT and SlGSTT2 expression was activated in a SA-dependent way upon Tm. Although expression of SlGSH1, SlGSTF2, SlGSTU5 and SlGTT3 did not change upon Tm treatment in leaves, SlGR1 and SlDHAR2 transcription decreased. PBA significantly increased the expression of SlGR1, SlGR2, SlGSTT2, and SlGSTT3, which contributed to the amelioration of Tm-induced ER stress based on the changes in lipid peroxidation and cell viability. Malondialdehyde accumulation and electrolyte leakage were significantly higher in WT as compared to NahG tomato leaves under ER stress, further confirming the key role of SA in this process.
内质网（ER）应激和未折叠蛋白反应（UPR）高度依赖于植物激素，如水杨酸（SA）。在这项研究中，研究了 ER 应激下 SA 补充和内源 SA 缺乏对野生型（WT）和转 SA 缺陷 NahG 番茄（Solanum lycopersicum L.）植物谷胱甘肽代谢的影响。UPR 标记基因 SlBiP 的表达依赖于 SA 水平，在 NahG 植物中仍保持较低水平。化学伴侣 4-苯丁酸（PBA）的外源应用也降低了衣霉素（Tm）诱导的 SlBiP 转录物积累。同时，Tm 诱导的超氧阴离子和过氧化氢的产生与 SA 无关，而还原型谷胱甘肽（GSH）和氧化型谷胱甘肽（GSSG）的积累受 SA 调节。Tm 独立于 SA 增加了谷胱甘肽还原酶（GR；EC 1.6.4.2）的活性，但脱氢抗坏血酸还原酶（DHAR；EC 1.8.5.1）和谷胱甘肽 S-转移酶（GSTs；EC 2.5.1.18）的活性在 SA 依赖性方式下被 Tm 增加。SlGR2、SlGGT 和 SlGSTT2 的表达在 Tm 作用下以 SA 依赖的方式被激活。尽管 SlGSH1、SlGSTF2、SlGSTU5 和 SlGTT3 的表达在叶片中没有因 Tm 处理而改变，但 SlGR1 和 SlDHAR2 的转录减少了。PBA 显著增加了 SlGR1、SlGR2、SlGSTT2 和 SlGSTT3 的表达，这有助于根据脂质过氧化和细胞活力的变化缓解 Tm 诱导的 ER 应激。与 NahG 番茄叶片相比，WT 叶片在 ER 应激下丙二醛积累和电解质泄漏显著增加，进一步证实了 SA 在该过程中的关键作用。
