MeJA对盐胁迫下杠柳实生苗不同部位缓解机制研究

Study on the alleviation mechanism of MeJA on different parts of Periploca sepium Bunge seedlings under salt stress

关键词:  杠柳实生苗  盐胁迫  MeJA  光合指标  生理机制

Key words:  Periploca sepium seedlings  salt stress  MeJA  photosynthetic index  physiological mechanism

摘要:

[目的] 探究茉莉酸甲酯（MeJA）对盐胁迫下杠柳实生苗光合作用和生理的改善机制，明确MeJA改善浓度范围。[方法] 以培养30 d的杠柳实生苗为材料，用1 % NaCl 溶液进行盐胁迫处理，胁迫处理7 d后分别喷施不同浓度MeJA（50、200、500 μmol/L），测量喷施前后杠柳实生苗光合指标和生理指标，非盐胁迫组作为空白对照。[结果] 50~200 μmol/L的MeJA喷施效果较好，短期内即可表现出一定的改善作用。光合方面，50~200 μmol/L MeJA可减缓盐胁迫对叶绿素合成的抑制；提高实生苗净光合速率（Pn）、蒸腾速率（Tr）和气孔导度（Gs），同时降低胞间二氧化碳浓度（Ci）；生理方面，50~200 μmol/L MeJA的处理能够有效提高植物体内抗氧化酶的活性，促进黄酮、多酚等还原性成分的积累，以降低植物体内活性氧（ROS）积累，降低丙二醛（MDA）等脂膜代谢物的含量；同时，提高植物体内脯氨酸及可溶性糖等渗透调节物质的含量以提高植物体渗透压，减少生理干旱。[结论] MeJA可以在一定程度上改善盐胁迫导致的胁迫损伤，在50~200 μmol/L的MeJA喷施效果较好，但过高浓度MeJA（500 μmol/L）会对植物体产生一定毒害作用。

Abstract:

[Objective] To investigate the ameliorative mechanism of methyl jasmonate(MeJA) on photosynthesis and physiology in Periploca sepium seedlings under salt stress and to define the effective concentration range of MeJA.[Methods] Thirty-day-old P. sepium seedlings were subjected to salt stress using a 1% NaCl solution. After 7 days of stress treatment,different concentrations of MeJA(50,200,and 500 μmol/L) were sprayed. Photosynthetic and physiological indices of the seedlings were measured before and after spraying,with a non-salt stress group serving as the blank control.[Results] MeJA at 50-200 μmol/L showed good efficacy,demonstrating improvement effects within a short period. Photosynthetically,50-200 μmol/L MeJA alleviated the salt stress-induced inhibition of chlorophyll synthesis;increased the net photosynthetic rate(Pn),transpiration rate(Tr),and stomatal conductance(Gs) of the seedlings;and reduced the intercellular carbon dioxide concentration(Ci). Physiologically,treatment with 50-200 μmol/L MeJA effectively enhanced the activity of antioxidant enzymes and promoted the accumulation of reductive components,such as flavonoids and polyphenols,thereby reducing the accumulation of reactive oxygen species(ROS) and the content of lipid membrane metabolites like malondialdehyde(MDA). It also increased the content of osmotic regulators,such as proline and soluble sugars,to elevate osmotic pressure and mitigate physiological drought.[Conclusion] MeJA can partially alleviate salt stress-induced damage,with 50-200 μmol/L being the optimal concentration range. However,a high concentration of MeJA(500 μmol/L) may cause toxic effects on plants.