镧对酸雨胁迫下大豆萌发种子糖代谢的动态影响

为了探索La(Ⅲ)对酸雨胁迫下大豆萌发种子糖代谢的动态影响,以pH 2.5、4.5模拟酸雨和La(Ⅲ)(25 mg·L~(-1))处理大豆种子,测定La(Ⅲ)对不同酸雨强度胁迫下大豆萌发种子可溶性糖、还原性糖、蔗糖、淀粉及α,β-淀粉酶的影响.结果表明,与CK相比,各糖代谢指标对酸雨胁迫的响应随胁强增加呈增加趋势;pH2.5胁迫5 d后α-淀粉酶,6 d后β-淀粉酶酶活性无法向CK趋近,酸士雨胁迫对α,β-淀粉酶活性造成致命性伤害;La(Ⅲ)浸种在低酸雨胁迫下(pH>2.5)可缓解酸雨胁迫对大豆萌发种子各糖代谢指标的影响,而在高胁强胁时(pH=2.5)下则无法缓解.说明La(Ⅲ)可通过增强糖代谢来缓解酸雨,尤其是低强度酸雨(pH>2.5)对大豆萌发种子的伤害,增强种子抗酸雨能力,并且其缓解能力与酸雨胁迫强度呈负相关.

Dynamic Effects of Lanthanum on Sugar Metabolism of Soybean Seed Germination Under Acid Rain Stress

In order to explore the dynamic effects of La( Ⅲ ) on the sugar metabolism during the seed germination of soybean, the effect of La( Ⅲ ) on the contents of soluble sugar, reducing sugar, sucrose, starch and α,β-amylase activity were investigated during seed germination under acid rain stress. The two simulated acid rain(SAR) solutions with pH2.5 and 4.5, and the neutral solution(pH7.0) as control were used in the study. Seeds were pretreated with LaCl, at the optimum concentration (25 mg·L~(-1)) and placed in culture dishes with filter sheets to germinate in a culture container keeping at a constant temperature of 20 ℃. Each treatment group involved three dishes and each dish received 50 seeds. During germination, seeds were exposed to SAR with pH2.5 and 4.5, that was replaced everyday, for 7 d until the germination was over. The results showed that compared with the control (CK), the contents of soluble sugar, reducing sugar, sucrose and starch increased with increasing the stress strength of SAR. The activity of α-amylase could not approach that of CK when the soybean seeds were treated with SAR of pH2.5 for 5 d. The same phenomenon was observed in the activity of β-amylase of soybean seeds treated with SAR of pH2.5 for 6 d. Therefore, SAR stress could lead to the lethality damage to the activities of α, β-amylase. When soybean seeds were pretreated with La( Ⅲ ), the contents of soluble sugar, reducing sugar, sucrose, starch and α, β-amylase activity in soybean seeds under acid rain stress increased comparing with that of the treatment without La( Ⅲ ). The result indicated that the pretreatment of La( Ⅲ ) could alleviate the damage of acid rain with the high pH (pH>2.5) to the indexes of sugar metabolism during seed germination. However, the effect of La( Ⅲ ) mentioned above was not observed in the soybean seeds treated with pH=2.5. Theses results indicated that La( Ⅲ ) could alleviate the damage of acid rain to seed germination of soybean through increasing the sugar metabolism, especially the low strength of acid rain( pH>2.5), and then increase the ability of seeds to resist acid rain. Moreover, the alleviation effect of La( Ⅲ ) was negatively correlated with the stress strength of acid rain.