桉树木栓形成层脱落期间抗氧化物酶活性与DNA动态分析

以桉树品种‘3229’和‘U6’的木栓形成层为材料,比较分析了其从形成到脱落期间,3种抗氧化物酶(POD、SOD、APX)和LOX的活性,以及叶绿素、MDA、H2O2和DNA含量的动态变化.结果显示:随着2个品种木栓形成层衰老的加剧,叶绿素的含量均下降,但MDA含量、H2O2含量和LOX活力均增加.品种‘3229’木栓形成层成熟期的SOD活性显著高于形成期和脱落期,但形成期与脱落期的酶活性却无显著差异;品种‘U6’木栓形成层成熟期SOD的活性也为最高,但各时期间的SOD活性差异不显著.品种‘3229’和‘U6’的木栓形成层从形成期到成熟期APX活性均呈显著增加趋势,但成熟期后活性均又呈下降趋势.品种‘3229’木栓形成层的POD活性在成熟期到脱落期期间显著增加,而品种‘U6’却在形成期到成熟期显著增加.两品种DNA的动态分析电泳结果表明,桉树木栓形成层的脱落很可能包括细胞程序化死亡过程(PCD).

Detection of Antioxidant Enzymes and DNA Dynamic Changes during Senescence of Eucalyptuses Phellogen Zone

During the period of senescence of eucalyptuses(Eucalyptus grandis×E.urophylla) cultivars ’3229’ and ’U6’ phellogen,a comparative study on changes of antioxidant enzymes,chlorophyll content,the contents of malondialdehyde(MDA),hydrogen peroxide(H2O2),activities of lipoxygenase(LOX) and DNA dynamic changes were conducted.Data showed that chlorophyll content decreased,but the contents of MDA and H2O2 and activity of LOX increased in both cultivars ’3229’ and ’U6’.In ’3229’,the sample collected at the ripe stage of new phellogen formation(NPF) showed significantly high superoxide dismutase(SOD) activity compared to that collected at the early and detached stage of NPF,while the latter two had no significant difference in enzyme activity.In ’U6’,however,no significant difference was found among the samplings for different batches,although the sample of the ripe stage of NPF displayed the highest SOD activity.Activity of ascorbate peroxidase(APX) significantly increased from the early to ripe stage of NPF and thereafter,declined.In ’3229’,peroxidase(POD) activity significantly increased between the ripe and detached stage of NPF,but in ’U6’,it did between the early and ripe stage of NPF.DNA ladders were also observed in the eucalyptuses phellogen.The results suggested that senescence in eucalyptuses phellogen could involve programmed cell death(PCD),reduced antioxidant activity and increased H2O2.