大麦幼苗抗氧化酶系统对低高温胁迫的差异响应

Differential Responses of Antioxidant Enzyme System in Barley Seedlings to Low and High Temperatures

为探究低高温胁迫下大麦(Hordeum vulgare L.)幼苗抗氧化酶系统的差异响应,以鄂啤2号为试验材料,采用人工模拟低温[14℃(昼)/10℃(夜)]与高温[38℃(昼)/34℃(夜)],以最适温度[22℃(昼)/18℃(夜)]为对照处理大麦幼苗。测定大麦幼苗叶片的活性氧分子[ROS:超氧阴离子(O_(2)^(÷))、过氧化氢(H_(2)O_(2))]、丙二醛(MDA)含量和超氧化物歧化酶(SOD)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)、过氧化氢酶(CAT)、谷胱甘肽还原酶(GR)的活性及相关基因表达量。结果表明,低温与高温胁迫降低了H_(2)O_(2)含量,诱导了O_(2)^(÷)、MDA含量的显著上升,抗氧化酶(SOD、POD、CAT等)的活性及相关基因(HvSOD、HvPOD、HvCAT2等)的表达量也均显著上升(P<0.05)且高温下上升幅度更大。随着处理时间的延长,低温处理下MDA含量及SOD、POD、CAT活性与对照差异逐渐减小,而高温处理下始终处于较高水平。综上,低温与高温显著诱导了抗氧化酶活性及相关基因表达的上升。高温下大麦幼苗氧化损伤程度较低温更深,同时诱导了较低温更高的抗氧化酶活性及基因的转录水平。

The current research was undertaken to clarify the differential responses of antioxidant enzyme system in barley(Hordeum vulgare L.)seedlings to varying temperatures,using the barley variety Epi No.2 as the experimental material.The artificially simulated low temperature[14℃(day)/10℃(night)]and high temperature[38℃(day)/34℃(night)]were set to treat barley seedlings,with the optimum temperature[22℃(day)/18℃(night)]serving as the control.The physiological responses of barley seedlings to these temperatures in different treatments were determined by measuring the contents of ROS(O_(2)^(÷),H_(2)O_(2))and MDA;the activities of SOD,POD,CAT,APX,and GR;and the expression of related genes.The results showed that the low and high temperature stresses reduced H_(2)O_(2)content,but induced significant increases in O_(2)^(÷)and MDA contents.In addition,the activities of antioxidant enzymes(SOD,POD,CAT,etc.)and the expression levels of related genes(HvSOD,HvPOD,HvCAT2,etc.)also all increased significantly(P<0.05),and the increases were greater at the high temperature than at the low temperature.With the prolongation of treatment time,the differences between the low temperature treatment and the control gradually decreased in MDA content and the activities of SOD,POD,CAT and other enzymes,while these parameters remained higher in the high temperature treatment.In conclusion,the low and high temperature stresses significantly stimulated the activities of antioxidant enzymes and related gene expression;compared with the low temperature treatment,the high temperature treatment led to more severe oxidative damage and higher antioxidant enzyme activities and gene transcription levels in barley seedlings.