冷处理后桉树POD活性、同工酶及基因转录变化分析

Analysis on the Activity,Isoenzyme and Gene Transcription of Peroxidase in Three Eucalyptus Species being Cold Treatment

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 discussed the correlation between peroxidase expression and cold tolerance of Eucalyptus species, Half-year-old saplings of three Eucalyptus species（Eucalyptus wetarensis×Eucalyptus dunnii, Eucalyptus dunnii xiangdeng, Eucalyptus dunnii） with different cold tolerance were used for cold treatment. After the Eucal-%yptus species were cultured at 26℃ for two weeks, then cultured 5℃ for 24 h. The leaves of the Eucalyptus species were used to detected the peroxidase activity, isozymes and transcription levels of 4 peroxidase genes. In comparison to that the peroxidase activity of E. wetarensis ×E. dunnii did not show significantly difference. However, the expression of higher molecular weight isozymes increased and the expression of lower molecular weight isozymes decreased. The peroxidase activity of Eucalyptus dunnii decreased sharply and all isozymes showed expression reduced. The peroxidase activity of Eucalyptus dunnii xiangdeng increased markedly. Except Line 4 and 5, the other lines showed expression increased. Transcription level of the same POD gene at 26℃ was normalized to 1.Transcription level of POD3 and POD4 in E. wetarensis ×E. dunnii rose to 1.31 and 1.92, respectively. Transcription level of POD2, POD3 and POD4 in E. dunnii declined to 0.44, 0.066 and 0.66, respectively. Transcription level of POD1, POD2, POD3 and POD4 in E. dunnii xiangdeng declined to 0.79, 0.29, 0.19 and 0.20, respectively.The results indicated there was negative correlation between cold tolerance of Eucalyptus species and gene transcription level of POD2, POD3 and POD4. The results also provided a reference for the breeding of eucalyptus varieties with cold resistance.