茉莉酸甲酯对棉花抗旱效果的影响
Effect of Methyl Jasmonate (MeJA) on Enhancing Drought Resistance of Cotton

为探讨茉莉酸甲酯（Methyl Jasmonate，MeJA）对棉花抗旱作用的影响，采用质量分数为2.5%聚乙二醇（PEG6000）模拟干旱胁迫处理，检测MeJA对干旱胁迫下棉花的含水量、光合作用、渗透胁迫和抗氧化损伤的生理生化指标。结果表明：2.5 μmol·L-1 MeJA处理能够使干旱胁迫下棉花的相对含水量和总叶绿素质量分数分别增加22.11%和40.58%，渗透调节性物质甜菜碱、可溶性糖和脯氨酸的质量分数均显著增加，但渗透势降低20.29%，抗坏血酸质量分数增加38.19%，超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性分别升高28.54%和46.19%，但O-·2、H2O2则分别降低43.71% 和84.85%,显著降低丙二醛（MDA）质量摩尔浓度和相对电导率。而加入MeJA的抑制剂水杨苷异羟肟酸（SHAM）后，消除了MeJA对棉花抗旱性的促进效应。说明MeJA通过调节渗透胁迫和氧化损伤提高棉花的抗旱性。MeJA能够在生产实践中用于提高棉花的抗旱性。
Methyl Jasmonate (MeJA) plays important roles in the regulation of plant growth and responses to abiotic stress. In order to explore the effects of MeJA on the drought resistance of cotton, cotton seedlings were treated with 2.5% polyethylene glycol (PEG6000) in the presence or absence of MeJA, photosynthesis, osmotic stress and oxidative damage in cotton seedling were analyzed. The results showed that the relative water mass fraction and total chlorophyll mass fraction were increased by 22.11% and 40.58%, respectively, in 2.5 μmol·L-1 MeJA treatment. The contents of betaine, soluble sugar and proline were also significantly increased， but the osmotic potential was reduced by 20.29% in the presence of 2.5 μmol·L-1 MeJA. Consistently, MeJA treatment increased the molality of ascorbic acid by 38.19%, enhanced the activity of superoxide dismutase (SOD) and catalase (CAT) by 28.54% and 46.19%, respectively. However, MeJA treatment decreased the content of O-·2 and H2O2 by 43.71% and 84.85%, and significantly reduced the malondialdehyde (MDA) and the relative conductivity. Further, the effect of MeJA on the enhancement of cotton drought resistance was abolished by the treatment of salicin hydroxamic acid (SHAM), an inhibitor of MeJA. The results indicated that MeJA can enhance the drought resistance of cotton through the regulation of osmotic stress and oxidative damage. MeJA might be used to improve the drought resistance of cotton in production practice.