亚精胺浸种对渗透胁迫下白三叶种子萌发及淀粉代谢的影响

Effects of Seed-Soaking with Spermidine on Seed Germination and Starch Metabolism of White Clover(Trifolium repens L.) under Osmotic Stress

以‘拉丁诺'白三叶为材料,用0、10%、15%、20%(W/V)的聚乙二醇(PEG-6000)溶液模拟干旱条件,研究亚精胺(Spd)浸种对渗透胁迫下白三叶种子萌发和淀粉代谢的影响。结果表明,在PEG渗透胁迫下,白三叶种子的发芽率、发芽势、发芽指数、胚芽及胚根鲜重和胚根长度均显著(P<0.05)降低,淀粉水解为糖类的速率减慢;与蒸馏水浸种相比,0.05mmol·L^(-1)Spd浸种处理显著(P<0.05)提高了在渗透胁迫条件下种子的发芽率、发芽势、发芽指数、胚芽及胚根鲜重、干重和胚根长度,同时大幅提高了α-淀粉酶、β-淀粉酶及(α+β)-淀粉酶总活性,降低了淀粉含量,增加了还原糖和葡萄糖含量。说明Spd浸种提高了白三叶种子在渗透胁迫下的萌发能力和幼苗生长的环境适应性,这可能与增强种子体内淀粉酶活性,加速淀粉水解为还原糖和葡萄糖,为种子萌发和幼苗早期生长及时提供充足能量有关。

The effects of seed-soaking with spermidine （Spd） on seed germination and starch metabolism were investigated under osmotic stress induced by 0, 10%, 15% and 20% aqueous solutions of polyethylene glycol 6000 （PEG-6000） in white clover （Trifolium repens cv. ＇Ladino＇）. The results showed that germination rate, germination vigor, germination index, fresh weight of plumule and radicle, and radicle length of white clover seeds were significantly （P〈0.05） reduced, as well as the transformation rate of starch into reducing sugar and glucose were suppressed in the process of seed germination trader osmotic stress. Compared with seed-soaking with distilled water, seed-soaking with 0.05 mmol.L-1 Spd significantly （P〈0.05） improved seed germination rate, germination vigor, germination index, fresh and dry weight of radicle and plumule, and radicle length under the same osmotic stress. At the same time, seed-soaking with Spd showed significantly higher activities of α-amylase, β-amylase and （α＋β）-total amylase, and higher contents of reducing sugar and glucose, but lower content of starch than those in seed-soaking with distilled water. In conclusion, the above results indicated that the ability of seed germination and environmental adaptability of white clover seedlings was improved by seed- soaking with Spd under osmotic stress, which could be related to timely supply of sufficient energy resulted from accelerating transformation starch into sugars by Spd activating amylase activities during seed germination and early growth of seedlings.