Li Changxia, Lu Xuefang, Liu Yunzhi, Xu Junrong, Yu Wenjin
College of Agriculture, Guangxi University, Nanning 530004, China.
Antioxidants (Basel). 2023 May 4;12(5):1043. doi: 10.3390/antiox12051043.
Strigolactones (SLs), as a new phytohormone, regulate various physiological and biochemical processes, and a number of stress responses, in plants. In this study, cucumber 'Xinchun NO. 4' is used to study the roles of SLs in seed germination under salt stress. The results show that the seed germination significantly decreases with the increase in the NaCl concentrations (0, 1, 10, 50, and 100 mM), and 50 mM NaCl as a moderate stress is used for further analysis. The different concentrations of SLs synthetic analogs GR24 (1, 5, 10, and 20 μM) significantly promote cucumber seed germination under NaCl stress, with a maximal biological response at 10 μM. An inhibitor of strigolactone (SL) synthesis TIS108 suppresses the positive roles of GR24 in cucumber seed germination under salt stress, suggesting that SL can alleviate the inhibition of seed germination caused by salt stress. To explore the regulatory mechanism of SL-alleviated salt stress, some contents, activities, and genes related to the antioxidant system are measured. The malondialdehyde (MDA), HO, O, and proline contents are increased, and the levels of ascorbic acid (AsA) and glutathione (GSH) are decreased under salt stress conditions, while GR24 treatment reduces MDA, HO, O, and proline contents, and increases AsA and GSH contents during seed germination under salt stress. Meanwhile, GR24 treatment enhances the decrease in the activities of antioxidant enzymes caused by salt stress [superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX)], following which antioxidant-related genes , , , , and are up-regulated by GR24 under salt stress. However, TIS108 reversed the positive effects of GR24 on cucumber seed germination under salt stress. Together, the results of this study revealed that GR24 regulates the expression levels of genes related to antioxidants and, therefore, regulates enzymatic activity and non-enzymatic substances and enhances antioxidant capacity, alleviating salt toxicity during seed germination in cucumber.
独脚金内酯（SLs）作为一种新型植物激素，可调节植物体内多种生理生化过程以及一些应激反应。在本研究中，以黄瓜‘新春四号’为材料，研究SLs在盐胁迫下对种子萌发的作用。结果表明，随着NaCl浓度（0、1、10、50和100 mM）的升高，种子萌发率显著降低，选取50 mM NaCl作为中度胁迫用于进一步分析。不同浓度的SLs合成类似物GR24（1、5、10和20 μM）能显著促进盐胁迫下黄瓜种子的萌发，在10 μM时生物响应最大。独脚金内酯（SL）合成抑制剂TIS108抑制了GR24在盐胁迫下对黄瓜种子萌发的积极作用，表明SL可以缓解盐胁迫对种子萌发的抑制。为探究SL缓解盐胁迫的调控机制，测定了一些与抗氧化系统相关的含量、活性及基因。盐胁迫条件下，丙二醛（MDA）、HO、O和脯氨酸含量增加，抗坏血酸（AsA）和谷胱甘肽（GSH）水平降低，而GR24处理在盐胁迫下种子萌发过程中降低了MDA、HO、O和脯氨酸含量，并增加了AsA和GSH含量。同时，GR24处理增强了盐胁迫导致的抗氧化酶[超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）]活性的降低，盐胁迫下GR24上调了抗氧化相关基因、、、、和的表达。然而，TIS108逆转了GR24在盐胁迫下对黄瓜种子萌发的积极影响。总之，本研究结果表明，GR24调节抗氧化相关基因的表达水平，进而调节酶活性和非酶物质，增强抗氧化能力，缓解黄瓜种子萌发过程中的盐毒害。
