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为了探讨过氧化物酶(Peroxidase,POD)活性、同工酶及基因表达变化与桉树耐寒性间的相关性,选用耐寒性分别为弱、中、强的韦邓桉、邓恩桉和湘邓桉半年苗龄树苗作材料,先26℃培养两周,再5℃冷处理24 h后,剪取叶片检测3种桉树POD活性,同工酶酶谱和4个POD基因的转录变化。韦邓桉冷处理前后的POD活性无显著性差异,但冷处理后,分子量较大的同工酶表达量降低,分子量较小的同工酶表达量升高。冷处理后,邓恩桉POD活性显著降低,各条同工酶活性均有下降;湘邓桉POD活性升高明显,除L4和L5含量略有下降外,其他酶带活性均有增加。设26℃下相同树种的同种基因表达量为1,冷处理后,韦邓桉的POD1和POD2的表达略有下降,POD3和POD4的表达量分别升高到常温下的1.31和1.92倍;邓恩桉的POD1表达量没有改变,但POD2、POD3和POD4的表达量分别降低到常温下的0.44、0.66和0.66倍;湘邓桉的POD1、POD2、POD3和POD4的表达均有显著降低,分别为常温下的0.79、0.29、0.19和0.20倍。结果表明:冷处理后,POD2、POD3和POD4基因的表达变化与桉树抗寒性呈负相关关系。本研究可为桉树耐寒品种的选育提供参考。
In order to investigate the correlation between peroxidase (POD) activity, isoenzyme and gene expression and cold tolerance of Eucalyptus, we selected low, moderate and strong WeChat, Eucalyptus and Dunhuang Seedlings of seedling age were used as materials. After cultivated at 26 ℃ for two weeks and then cooled at 5 ℃ for 24 h, the activity of POD, the isozyme zymogram and the transcriptional changes of four POD genes were detected. There was no significant difference in POD activity between Cryptocarya sinica and Eucalyptus urophylla under cold treatment, but after cold treatment, the expression of isoenzyme with larger molecular weight decreased and the expression of isoenzyme with smaller molecular weight increased. After cold treatment, the POD activity of Dunn’s Eucalyptus significantly decreased and the isoenzyme activity decreased. The activity of POD increased obviously except for the slight decrease of L4 and L5 content. The expression of POD1 and POD2were slightly decreased and the expression of POD3 and POD4were increased to1.31and1.92times respectively at room temperature after cold treatment. POD1, POD3 and POD4 were decreased to 0.44, 0.66 and 0.66 times respectively at room temperature. The expression of POD1, POD2, POD3 and POD4 in Xiang-Deng Eucalyptus was significantly decreased, which were respectively at room temperature 0.79, 0.29, 0.19 and 0.20 times lower. The results showed that after cold treatment, the expression changes of POD2, POD3 and POD4 genes were negatively correlated with the cold resistance of Eucalyptus. This study can provide reference for the breeding of hardy varieties of Eucalyptus.