油菜素内酯浸种对盐胁迫番茄种子萌发的影响及其生理机制

为揭示油菜素甾醇类化合物提高作物耐盐的效应和机理，研究了10^-11、10^-10、10^-9、10^-8、10^-7、10^-6、10^-5 mol/L 2，4-表油菜素内酯（EBL）浸种处理对0、50、100、150、175 mmol/L NaCl胁迫7 d的番茄种子萌发、生长、溶质积累、抗氧化代谢的影响。结果显示：NaCl浓度越高的盐胁迫下，10^-9 mol/L EBL浸种可体现出越显著的促进番茄种子萌发的效应；在所有处理下，EBL浸种浓度过高，即10^-6、10^-5 mol/L EBL，均表现出对种子萌发的抑制效应。盐胁迫下种子萌发后，一定浓度的EBL浸种可表现出明显的增加种子胚根和下胚轴长，提高萌发种子鲜重和种子活力指数，其中10^-9 mol/L EBL浸种处理促进效果最适；EBL浸种浓度过高，则表现出抑制效应。150 mmol/L NaCl胁迫或非盐胁迫下，10^-9 mol/L EBL浸种均可降低萌发种子体内的O₂^·-、H₂O₂、丙二醛（MDA）和脯氨酸（Pro）含量；盐胁迫下，10^-9 mol/L EBL浸种可显著提高萌发种子可溶性糖（SS）和可溶性蛋白（SP）的含量。150 mmol/L NaCl胁迫或非盐胁迫下，10^-9 mol/L EBL处理可不同程度促进番茄种苗超氧化物歧化酶（SOD）和过氧化物酶（POD）活性的上升。综上所述，盐胁迫下，一定浓度范围内的EBL浸种可明显促进番茄种子萌发或成苗，其中以10^-9 mol/L EBL浸种的效果最好，主要是因为EBL施用可积极促进番茄种子萌发中物质转化，SS和SP等溶质积累增多，增强其渗透调节能力；同时SOD和POD酶活增强，缓解盐胁迫导致番茄种子萌发中的次生氧化胁迫。

Concentration effects and its physiological mechanism of soaking seeds with brassinolide on tomato seed germination under salt stress

The effects of seed soaking with 10^-11, 10^-10, 10^-9, 10^-8, 10^-7, 10^-6, and 10^-5 mol/L 2, 4-epibrassinolide (EBL) on the germination, growth, solute accumulation and antioxidant metabolism of tomato seeds under 0, 50, 100, 150, and 175 mmol/L NaCl stress for 7 days were studied to reveal the effect and mechanism of brassinosteroids on improving salt tolerance of crops. The results showed that 10^-9 mol/L EBL soaking seeds could significantly promote the germination of tomato seeds under comparative higher salt stress of NaCl concentration. Under all treatments, excessive high EBL concentrations (10^-6 and 10^-5 mol/L EBL) of soaking seeds showed inhibition effect on tomato seed germination. After seed germination under salt stress, seed soaking with a certain concentration of EBL could significantly increase the length of the seed radicle and hypocotyl, the fresh weight of seedlings and seed vigor index, among which 10^-9 mol/L EBL seed soaking treatment had the optimum promotion effect, while seed soaking treatments with excessive EBL concentration showed inhibition effect on them. Soaking seeds with 10^-9 mol/L EBL could decrease the content of O₂^·-, H₂O₂, malondialdehyde (MDA) and proline (Pro) in germinated seeds of tomato under both 150 mmol/L NaCl stress and non-salt stress. Soluble sugar (SS) and soluble protein (SP) in tomato seedlings were increased significantly under 150 mmol/L NaCl stress. The treatment of 10^-9 mol/L EBL significantly promoted the activities of superoxide dismutase (SOD) and peroxidase (POD) in tomato seedlings, especially under salt stress. In summary, EBL soaking in a certain concentration range can significantly promote the seed germination and its seedling formation, and the effect of soaking with 10^-9 mol/L EBL is the optimum treatment under salt stresses, mainly because the application of EBL can actively promote the transformation of substances in the germination of tomato seeds, increase the accumulation of solutes such as SS and SP, enhance the osmotic adjustment, and increase the activity of SOD and POD enzymes, and alleviate the oxidative stress in tomato seed germination caused by salinity.