外源过氧化氢提高燕麦耐盐性的生理机制

摘要

Soil salinity is a major limiting factor for plant growth and productivity globally.Hydrogen peroxide (H2 O2 )is an important signaling molecule in plants that regulates many important physiological and biochemi-cal processes and induces tolerance to different stresses,including salt stress.A study has been undertaken in order to further understand the operation of these regulatory mechanisms in oat seedlings (Avena nuda ).A new oat cultivar,‘Dingyou No.6’,was selected to investigate,using greenhouse nutrient solution cultivation, the effects of exogenous H2 O2 on plant growth,osmotic adjustment substances accumulation and active oxygen metabolism in seedlings under salt stress.The results showed that 150 mmol/L NaCl exposure significantly in-hibited seedling growth.It enhanced the production of free amino acid and proline and decreased the contents of glutathione (GSH)and soluble sugar in leaves.Foliar spraying of 0.010 mmol/L H2 O2 significantly alleviated the inhibitory effect of NaCl stress on seedling growth.Exogenous H2 O2 increased the contents of soluble pro-tein,soluble sugar and proline,and decreased free amino acid content in leaves.Under 150 mmol/L NaCl stress,superoxide dismutase (SOD),catalase (CAT),peroxidase (POD)and ascorbate peroxidase (APX)ac-tivities all increased,along with excessive production of O2 ·- ,H2 O2 and malondialdehyde (MDA)in seedling leaves.Spraying the stressed seedlings with 0.010 mmol/L H2 O2 treatments significantly increased the activi-ties of SOD,CAT,POD and APX and GSH content,but decreased O2 ·- production rate and the contents of H2 O2 and MDA in leaves.These results indicate that exogenous H2 O2 could enhance anti-oxidative ability and decrease membrane lipid peroxidation injury in oat seedlings under NaCl stress.Exogenous H2 O2 enhanced seedlings’salinity tolerance by regulating osmotic adjustment substances accumulation and active oxygen me-tabolism in plant leaves.%以燕麦品种‘定莜6号’为材料，采用水培法，研究喷施过氧化氢（H2 O2）对盐胁迫下燕麦幼苗生长、渗透调节物质积累和活性氧代谢的影响。结果表明：1）150 mmol／L NaCl 胁迫显著抑制燕麦幼苗生长，提高叶片游离氨基酸和脯氨酸水平，降低谷胱甘肽（GSH）和可溶性糖含量；喷施0．01 mmol／L H2 O2对 NaCl 胁迫引起的生长抑制有明显的缓解作用，并提高了幼苗叶片可溶性蛋白质、可溶性糖和脯氨酸含量，降低了游离氨基酸含量。2）NaCl 胁迫下，虽然燕麦叶片超氧化物歧化酶、过氧化氢酶、过氧化物酶和抗坏血酸过氧化物酶活性提高，但 O2·－、H2 O2和丙二醛（MDA）积累；喷施 H2 O2进一步提高了 NaCl 胁迫下燕麦的上述抗氧化酶活性和 GSH 含量，却降低了O2·－产生速率及 H2 O2和 MDA 含量，说明外施 H2 O2能够增强盐胁迫燕麦的抗氧化能力，减轻氧化伤害。以上结果表明，外源 H2 O2可通过调控渗透调节物质积累和活性氧代谢提高燕麦耐盐性。