不同温度下AOX和COX途径对苜蓿种子萌发和幼根生长的影响

Effects of the Alternative Oxidase and Cytochrome Oxidase Pathways on the Germination of Seeds and Growth of Roots of Alfalfa Seedlings Under Different Temperatures

为了研究不同温度下交替氧化酶(Alternative oxidase,AOX)和细胞色素氧化酶(Cytochrome oxidase,COX)呼吸途径在紫花苜蓿(Medicago sativa L.)种子萌发过程中的作用,本研究以‘新牧4号’和‘甘农5号’紫花苜蓿为试验材料,采用呼吸电子传递链专一性抑制剂水杨基氧肟酸(Salicylhydroxamic acid,SHAM)和氰化钠(Sodium cyanide,NaCN)部分抑制AOX和COX途径,研究了低温(10℃)、对照(25℃)、高温(40℃)下AOX和COX呼吸途径对紫花苜蓿种子萌发和幼根生长的影响。结果表明,高、低温均明显抑制了2种紫花苜蓿种子的萌发;2种呼吸途径在种子萌发中具有不可替代的作用,且2条途径对种子萌发的作用会受到温度的影响,其中AOX途径在高温条件下的贡献大,COX途径在低温条件下的贡献大。不同温度下AOX和COX呼吸途径对幼根生长有积极的促进作用,且AOX途径对幼根生长的作用大于COX途径。以上结果表明不同的呼吸途径对紫花苜蓿种子的发芽以及后期幼根生长的影响不同。此外,不同温度下AOX和COX途径对种子萌发的作用在2种紫花苜蓿间无显著差异。

In order to study the role of the alternative oxidase(AOX)and cytochrome oxidase(COX)respiratory pathways in the germination of alfalfa seeds at different temperatures,‘Xinmu No.4’(Medicago sativa L.‘Xinmu No.4’)and‘Gannong No.5’(Medicago sativa L.‘Gannong No.5’)were taken as experimental materials.The respiratory electron transport chain specific inhibitors salicylhydroxamic acid(SHAM)and sodium cyanide(NaCN)were used to study the effect of the AOX and COX respiratory pathway on seed germination and radicle growth of alfalfa,under low temperature(10℃),control(25℃),and high temperature(40℃),respectively.The results showed that both high temperature and low temperature obviously inhibited the germination of the two varieties of alfalfa seeds;the AOX and COX pathways played an irreplaceable role in seed germination,and the effects of the two pathways on seed germination are affected by temperature.Among them,the COX pathway had a greater contribution to the germination of alfalfa seeds under low temperature,while the AOX pathway had a greater effect on the germination of alfalfa seeds under high temperature.The AOX and COX respiratory pathways had a positive effect on the growth of radicle under different temperatures,and the AOX pathway had a greater effect on the growth of radicle than the COX pathway.The above results indicated that different respiratory pathways had different effects on the germination of alfalfa seeds and the growth of seedling roots in later stages.In addition,the contribution of the AOX and COX pathways to the seed germination of the two alfalfa varieties seeds was similar under different temperatures.