外源NO和SA对盐胁迫下番茄幼苗叶片膜脂过氧化及AsA-GSH循环的影响

以番茄(Lycopersicon esculentum Mill.)品种‘秦丰保冠’为试材,在水培条件下研究单独和复配施用一氧化氮(NO)供体硝普钠(SNP)、水杨酸(SA)对100 mmol/L NaCl胁迫下番茄幼苗的生长、叶片光合作用、膜脂过氧化及抗坏血酸-谷胱甘肽(AsA-GSH)循环的影响。结果显示,盐胁迫能显著影响番茄幼苗的生长、光合作用和活性氧代谢系统的相关指标。单独或复配施用SNP、SA均能有效缓解番茄幼苗的盐渍伤害,并以SNP和SA复配处理效果最好。处理3~7 d时,叶片PSⅡ最大光化学效率(Fv/Fm)、净光合速率(Pn)、APX、GR、DHAR的活性、AsA和GSH含量分别较胁迫处理有不同程度的提高;而H2O2、MDA、DHA、GSSG的含量和电解质渗漏率分别较胁迫处理有不同程度的降低。研究结果表明盐胁迫下外源NO、SA单独或复配处理均能通过维持或协调作用促进番茄相关抗氧化酶活性的提高和抑制抗氧化剂含量的降低,起到维持AsA-GSH循环高效运转、减轻膜脂过氧化、促进光合作用、改善植株生长发育和提高幼苗盐渍抗性的作用,且NO和SA复配处理时具有协同增效的作用。

Effects of exogenous nitric oxide and salicylic acid on membrane peroxidation and the ascorbate-glutathione cycle in leaves of Lycopersicon esculentum seedlings under NaCl stress

A hydroponics experiment was conducted to study the effects of single and compound application of nitric oxide (NO) donor sodium nitroprusside (SNP) and salicylic acid (SA) on plant growth, photosynthetic parameters, membrane lipid peroxidation and the ascorbate-glutathione cycle (AsA-GSH cycle) in tomato cultivar (‘Qinfeng Baoguan’) seedling leaves under 100 mmol/L NaCl stress. Results showed that salt stress had significant effects on the growth, photosynthetic rate, and related indicators of reactive oxygen metabolism. Single or combined application of SNP and SA effectively alleviated the salinity damage of tomato seedlings, and the strongest effect was observed after applying a combination of SNP and SA. After 3-7 days of stress treatment, the PSⅡ maximal photochemistry efficiency (F_v/F_m), net photosynthetic rate (P_n), activities of ascorbate peroxidase (APX), glutathione reductase (GR) and droascorbic acid reductase (DHAR), and contents of reductive-form abscisic acid (AsA) and reduced glutathione (GSH) in leaves increased by 9.5%-15.3%, 25.5%-94.9%, 38.8%-67.5%, 15.2%-30.6%, 7.9%-41%, 4.4%-45.7%, and 13.8%-21.5%, respectively. Furthermore, the contents of H₂O₂, malondialdehyde (MDA), dehydroascorbic acid (DHA), oxidized glutathione (GSSG) and electrolyte leakage in leaves were reduced by 18.4%-40.4%, 35.2%-52.4%, 4.6%-26.3%, 14.8%-20.7%, and 23.1%-29.3%, respectively, compared with stress treatment. In conclusion, single or combined application of SNP and SA not only played a role in the stable operation of the AsA-GSH cycle, but also reduced membrane lipid peroxidation, promoted photosynthesis, enhanced plant growth and development, and improved seedling resistance by maintaining and coordinating the increase in related antioxidant enzyme activities and inhibiting the decrease in antioxidant content. Thus, a synergistic effect was observed after applying both SNP and SA.