低温胁迫对核桃枝条活性氧代谢的影响

以抗寒性不同的香玲和鲁果12号核桃品种为试材,在-15、-20、-25、-30、-35℃低温梯度胁迫下,分别测定了离体枝条的质膜相对透性、MDA和H2O2含量、O2-·产生速率、SOD和CAT保护酶活性等指标,分析了低温胁迫对核桃枝条活性氧代谢的影响,结果表明:低温胁迫显著增加了核桃枝条的膜透性、O2-·产生速率、MDA和H2O2含量,但耐寒品种鲁果12号的增幅低于香玲品种;2个品种的SOD酶活性均呈现"升—降—升—降"的趋势,CAT酶活性则先升高后降低,但不同品种之间的变化幅度较大;由此可知,鲁果12号在低温胁迫期间可有效地增加保护酶活性,抑制H2O2的积累,从而降低活性氧对核桃的伤害,这可能是其抗寒性较强的重要原因之一。

Effects of Low Temperature Stress on Active Oxygen Metabolism of Walnut Branches

Two walnut cultivars ＂Luguo No. 12＂ （most cold -resistant cultivar） and ＂Xiangling＂ （more cold -resistant culti- var） were taken as test materials, they were stressed and treated at -15, -20, -25, -30 and -35 ℃, the plasma membrane relative permeability, contents of MDA and H2O2, producing rate of O2-· , and activities of protective enzymes （SOD and CAT） in their isolated braches were determined, and the effects of low temperature stress on the active oxygen metabolism of walnut bran- ches were analyzed. The results indicated that the plasma membrane permeability, producing rate of O2-· , and contents of MDA and H2 02 in the branches of two walnut cultivars were significantly increased by low teniperature stress, but their increment in ＂Lu- gno No. 12＂ was lower than that in ＂Xiangling＂. The SOD activity in two cuhivars all presented the trend of ＂ascend ＂- descend - ascend - descend＂, while the CAT activity increased firstly and then decreased Under low temperature stress. It was concluded that ＂Lugno No. 12＂ could effectively enhance the activities of protective enzymes, further inhibit the accumulation of H202 during low temperature stress, therefore reduce the damage of active oxygen to walnut. This might be one of important reasons for higher cold - resistance of ＂Luguo No. 12＂.