Jasmonic acid (JA) and its its methyl ester, methyl jasmonate (MeJA), are known to be important growth regulators which naturally occur in higher plants. They are also involved in incrcased plant resistance to different environmental stress, including abiotic stress such as mechanically damage, low temperature, drought, salinity etc., and biotic stress such as pathogen and insect damage. Seedlings of rice variety Zhong-Er-Ou-6 were exposed to four treatments including well-watered, drought, drought plus MeJA, drought plus MeJA and inhibitor of jasmonic acid signal pathways (SHAM) to determine effects of MeJA application on chlorophyll content, chlorophyll fluorescence and photosynthetic traits of rice seedling leaves. The results showed that MeJA application significantly increased leaf water potential, chlorophyll content, chlorophyll fluorescence parameter F_v/F_0 and F_v/F_m, transpi-ration rate, stomata conductance and CO_2 concentration in cell interval under drought conditions, while it reduced ABA content in rice leaves. SHAM application under drought plus MeJA effectively inhibited these effects and led to decreases in leaf water poten-tial, chlorophyll content, chlorophyll fluorescence parameter Fv/F0 and Fv/Fm and photosynthetic parameters, as well as increase in ABA content.%茉莉酸(JA)及茉莉酸甲酯(MeJA)是广泛存在于植物体内的与抗性关系密切的生长物质,能显著增强植物在机械伤害、低温、盐害、干旱等非生物环境胁迫和病虫害等生物胁迫中的抗性.以水稻品种中二欧6为实验材料,通过设置对照、干旱、干旱+MeJA、干旱+MeJA+水杨苷异羟肟酸(SHAM)四种处理,研究了干旱胁迫下施用MeJA及其代谢抑制剂SHAM对水稻幼苗的叶绿素荧光和光合作用特性的影响.研究结果表明,干旱胁迫下外源MeJA(0.25 μmol·L~(-1))处理可显著提高水稻幼苗的叶片水势、叶绿素含量、叶绿素荧光参数Fv/F_0和Fv/Fm值、蒸腾速率、叶片气孔导度、胞间CO_2浓度,降低ABA含量,从而提高水稻幼苗的抗旱性.然而,加入茉莉酸信号途径的抑制剂水杨苷异羟肟酸(SHAM)后MeJA诱导的水稻抗旱效应受到逆转,表现在水稻幼苗叶片水势、叶绿素荧光和光合作用参数等显著下降,ABA含量显著上升.
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