Luo Qiaoyu, Ma Yonggui, Chen Zhi, Xie Huichun, Wang Yanlong, Zhou Lianyu, Ma Yushou
School of Life Sciences, Qinghai Normal University, Xining, China.
Qinghai Provincial Key Laboratory of Medicinal Plant and Animal Resources of Qinghai-Tibet Plateau, Qinghai Normal University, Xining, China.
Front Plant Sci. 2022 Sep 26;13:987845. doi: 10.3389/fpls.2022.987845. eCollection 2022.
Plant growth and development are closely related to water availability. Water deficit and water excess are detrimental to plants, causing a series of damage to plant morphology, physiological and biochemical processes. In the long evolutionary process, plants have evolved an array of complex mechanisms to combat against stressful conditions. In the present study, the duration-dependent changes in ascorbate (AsA) and glutathione (GSH) contents and activities of enzymes involved in the AsA-GSH cycle in hairgrass () in response to water stress was investigated in a pot trial using a complete random block design. The treatments were as follows: (1) heavily waterlogging, (2) moderate waterlogging, (3) light waterlogging, (4) light drought, (5) moderate drought, (6) heavily drought, and (7) a control (CK) with plant be maintained at optimum water availability. The hairgrass plants were subjected to waterlogging or drought for 7, 14, 21 and 28 days and data were measured following treatment. Results revealed that hairgrass subjected to water stress can stimulate enzymatic activities of ascorbate peroxidase (APX), glutathione peroxidase (GPX), glutathione reductase (GR), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and L-galactono-1, 4-lactone dehydrogenase (GalLDH), switched on the ascorbate-glutathione (AsA-GSH) cycle and the L-galactose synthesis, up-regulated the contents of AsA and GSH, and maintained higher ratios of ascorbate to dehydroascorbate (AsA/DHA) and reduced glutathione to oxidized glutathione (GSH/GSSG) to alleviate potential oxidative damage. However, the light waterlogging did not induce hairgrass under stress to switch on the AsA-GSH pathway. In general, the critic substances and enzyme activities in AsA-GSH metabolic pathway increased as the increase of water stress intensity. As the increase of exposure duration, the critic antioxidant substances content and enzyme activities increased first and then maintained a relatively stable higher level. Our findings provide comprehensive information on biochemical responses of hairgrass to hydrological change, which would be a major step for accelerating ecological restoration of degradation alpine marshes in the Qinghai-Tibetan Plateau.
植物的生长发育与水分供应密切相关。水分亏缺和水分过多对植物都不利，会对植物的形态、生理和生化过程造成一系列损害。在漫长的进化过程中，植物进化出了一系列复杂的机制来抵御胁迫条件。在本研究中，采用完全随机区组设计进行盆栽试验，研究了毛草在水分胁迫下，抗坏血酸（AsA）和谷胱甘肽（GSH）含量以及抗坏血酸-谷胱甘肽循环中相关酶活性随时间的变化。处理如下：（1）重度涝渍，（2）中度涝渍，（3）轻度涝渍，（4）轻度干旱，（5）中度干旱，（6）重度干旱，（7）对照（CK），保持植物处于最佳水分供应状态。将毛草植株进行7、14、21和28天的涝渍或干旱处理，并在处理后测量数据。结果表明，遭受水分胁迫的毛草可刺激抗坏血酸过氧化物酶（APX）、谷胱甘肽过氧化物酶（GPX）、谷胱甘肽还原酶（GR）、脱氢抗坏血酸还原酶（DHAR）、单脱氢抗坏血酸还原酶（MDHAR）和L-半乳糖内酯脱氢酶（GalLDH）的酶活性，开启抗坏血酸-谷胱甘肽（AsA-GSH）循环和L-半乳糖合成，上调AsA和GSH的含量，并维持较高的抗坏血酸与脱氢抗坏血酸（AsA/DHA）以及还原型谷胱甘肽与氧化型谷胱甘肽（GSH/GSSG）的比值，以减轻潜在的氧化损伤。然而，轻度涝渍并未诱导胁迫下的毛草开启AsA-GSH途径。总体而言，AsA-GSH代谢途径中的关键物质和酶活性随着水分胁迫强度的增加而增加。随着暴露时间的增加，关键抗氧化物质的含量和酶活性先增加，然后维持在相对稳定的较高水平。我们的研究结果提供了毛草对水文变化的生化响应的全面信息，这将是加速青藏高原退化高寒沼泽生态恢复的重要一步。
