NO 介导的 Ca2＋信号在干旱胁迫下紫花苜蓿种子萌发及抗氧化酶中的传导作用研究

本试验以紫花苜蓿种子为试验材料,添加外源一氧化氮供体硝普钠(SNP)、CaCl_2及抑制剂亚甲基蓝(methylene blue,MB)和LaCl_3,对种子进行浸种处理,以研究NO介导的Ca~(2+)信号在干旱胁迫下紫花苜蓿种子萌发及抗氧化酶中的传导作用。结果表明,15%PEG胁迫下紫花苜蓿种子萌发受到明显抑制,当外源添加NO或Ca~(2+)处理后萌发指标均有上升,外施0.1mmol/L SNP或10mmol/L CaCl_2都能有效缓解PEG对紫花苜蓿种子的胁迫伤害。干旱胁迫下NO+Ca~(2+)共处理时效果最为显著,萌发率较SNP处理提高了8.96%,较CaCl_2处理提高了19.67%。共处理时比SNP、CaCl_2处理时提高了种子淀粉酶活性、淀粉含量、可溶性糖、可溶性蛋白及脯氨酸含量,降低了MDA含量和超氧阴离子产生速率,显著提高了SOD,POD,CAT活性。其中淀粉酶活性、淀粉含量、可溶性蛋白、可溶性糖、脯氨酸含量以及POD活性的变化中,均表现出:NO和Ca~(2+)共处理下各指标变化要慢于单一处理。当添加外源NO的同时添加Ca~(2+)通道抑制剂La~(3+),NO的促进效果受到抑制,而添加外源Ca~(2+)的同时添加NO抑制剂亚甲基蓝,Ca~(2+)的促进效果受到抑制,表明NO经由Ca~(2+)信号通路调控干旱胁迫下紫花苜蓿的信号传导。

Investigation into the mechanism of Mo-mediated Ca2+ signaling during seed germination and antioxidation in Medicago sativa under drought stress

The Ca2 + transduction pathways have been implicated in mediating stress response and tolerance in plants.In order to investigate the mechanism of Ca2 + signaling mediated by nitric oxide (NO)during seed ger-mination and antioxidation in Medicago sativa under drought stress,sodium nitroprusside (SNP,nitric oxide donor),CaCl2 ,and methylene blue (NO blockers)and LaCl3 (Ca2 + channel blockers)were used in this study, and alfalfa seeds were pre-soaked with these solutions.An index of germination was markedly decreased under drought stress induced by 15% polyethylene glycol treatment,but this effect was reversed after treatments with SNP and Ca2 + .Moreover,0.1 mmol/L SNP or 10 mmol/L CaCl2 alleviated drought stress damage.Com-pared to SNP or CaCl2 treatment alone,germination rate significantly increased by 8.96% and 19.67% respec-tively when the seeds were treated with both SNP and Ca2 + .Furthermore,both SNP and CaCl2 treatments in-creased content of starch,soluble sugar,soluble protein and proline,and activities of amylase,superoxide dis-mutase,peroxidase and catalase,whereas malondialdehyde content decreased compared to that under SNP or CaCl2 treatment alone.The changes were slower for seeds receiving both NO and Ca2 + treatments than for NO or Ca2 + treatment alone.Interestingly,with added exogenous Ca2 + and methylene blue,the promotional effect of Ca2 + was inhibited.In addition,the promotional effect of NO was inhibited by La3 + .This indicates that NO mediated protein modifications in alfalfa seeds under drought stress through the Ca2 + signaling pathway.