低温胁迫对紫花苜蓿根系呼吸作用的影响

Effect of low temperature stress on respiration of root in Medicago sativa

摘要:

呼吸作用是没有叶绿体的苜蓿根系唯一的能量来源,以新牧4号为试验材料,分别在26℃、12℃和4℃温度处理后,研究了低温对苜蓿根系呼吸作用的影响。结果表明:低温显著抑制苜蓿根系的生长,其中4℃处理后苜蓿根系生长受抑程度最大。随着处理温度的下降,根系细胞脯氨酸含量和电导率显著上升,这表明虽然苜蓿根系通过自身渗透调节作用抵御低温胁迫,但4℃低温仍旧破坏了根系细胞膜结构。与对照相比,12℃和4℃低温处理后,苜蓿根系细胞总呼吸、细胞色素途径(COX)和交替氧化酶途径(AOX)呼吸速率及ATP含量呈现不同程度的下降,4℃处理后下降程度最显著。这表明,低温胁迫显著抑制根系呼吸代谢,导致根系细胞能量供应不足。此外,不同温度低温处理后根系细胞AOX呼吸的比率逐渐增加,但H₂O₂含量也显著增加,这表明4℃低温下根系AOX的上调不足以清除活性氧对细胞的伤害。

Abstract:

Respiration is the only source of energy for the alfalfa roots without chloroplasts.In this experiment,Xinmu No.4 was used to study the effect of low temperature on the respiration in the alfalfa roots after the treatment at different temperature,26℃,12℃ and 4℃.The results showed that low temperature significantly inhibited the growth of alfalfa roots,and the maximum degree of inhibition occurred under 4℃ treatment.With the decline of treatment temperature,the proline content and conductivity of root cells increased significantly,which indicated that although self-osmotic regulation could resist low temperature stress,the membrane structure of root cells was still destroyed by the low temperature,especially under 4℃ treatment.ATP content and the respiratory rate of total respiratory,cytochrome C oxidase (COX) pathway,and alternate oxidase (AOX) pathway,in alfalfa root cells decreased significantly in different degrees under both 12℃ and 4°C treatment ,and the most significant decline was found under 4℃ treatment,indicating that low temperature stress significantly inhibited root respiratory metabolism,and resulted in insufficient energy supply to root cells.In addition,the ratio of AOX respiration to total respiratory in root cells increased gradually after different low temperature treatment,but the H₂O₂ content also increased significantly,which indicated that the increase in the ratio of AOX respiration to the total respiration in root cells at 4℃ is not enough to eliminate the damage of reactive oxygen species to cells.