低温胁迫对豆科牧草圆叶决明苗期植株C、N代谢的影响

Effect of chilling stress on carbon and nitrogen metabolism of leguminous Cassia rotundifolia seedlings

选择豆科牧草圆叶决明进行5,10和15℃的低温胁迫,以25℃为对照(CK),在5℃下进行24,48,72,96和120 h的胁迫,来探讨低温胁迫下圆叶决明苗期植株叶片游离氨基酸、可溶性蛋白质和糖含量的变化与抗寒性的关系。15,10和5℃胁迫下的可溶性糖含量分别比对照提高83.21%,224.02%和257.94%,游离氨基酸总量分别比对照提高26.51%,128.11%和324.43%,水解氨基酸总量分别比对照下降10.75%,39.57%和43.60%,可溶性蛋白质含量分别比对照提高3.37%,4.92%和8.11%。5℃处理24,48,72,96和120 h后,可溶性糖含量分别较对照提高239.07%,243.64%,248.05%,252.70%和257.94%,可溶性蛋白质含量分别较对照提高2.73%,3.37%,6.07%,6.99%和8.11%。在低温胁迫下可诱导圆叶决明植株体内启动抗寒机制,可溶性糖、游离氨基酸和可溶性蛋白质含量提高;植物体内可溶性糖和游离氨基酸含量的提高可以增加细胞液的浓度,对原生质具有保护作用;而可溶性蛋白质具有强的吸水性,其含量的增加可以加强细胞的持水力,以减少原生质内结冰而伤害致死的机会,从而增强了圆叶决明植株的抗寒性。

The changes of free amino acids, soluble protein and sugar contents in leaves of C. rotundifolia seedlings and the relation between them and cold resistance under chilling stress were discussed by modeling differ-ent chilling stress grades as 15, 10 and 5℃ in comparison with 25℃ in this paper. The chilling stress lasted 24 h, 48 h, 72 h, 96 h, and 120 h under 5℃, respectively. Compared with the CK （25℃）, the soluble sugar con-tents in the leaves under 15, 10 and 5℃ stress increased by 83.21%, 224.02% and 257.94% respectively while the gross free amino acids increased by 26.51%, 128.11% and 324.43%, hydrolyzed amino acids decreased by 10.75%, 39.57% and 43.60%, and soluble protein content increased by 3. 37%, 4.92% and 8.11%. After 24, 48, 72, 96 and 120 hours ＇ treatment with 5℃ chilling stress, the soluble sugar content increased by 239.07%, 243.64%, 248.05%, 252.70% and 257.94% more than the CK（25℃）, and the soluble protein content increased by 2.73%, 3. 37%, 6.07%, 6.99% and 8. 11%, respectively. The cold resistance mechanism increased the soluble sugars, the free amino acids and the soluble protein contents under chilling stress. The enhanced contents of soluble sugars and free amino acids might increase the cell sap concentration, which proteeted the protoplasm. The soluble proteins had strong water-absorbing capacities which strengthened the cold resistances of the seedlings and their increases could enhance the water retaining capacities of the cells thereby reducing the chances of seedling deaths due to the icing of protoplasm.