根癌农杆菌感染对甘薯外植体生理生化特性的影响

Effects of Agrobacterium tumefaciens on the Physiological and Biochemical Properties in Sweetpotato Explants

【目的】研究根癌农杆菌(Agrobacterium tumefaciens)菌株N9-1侵染甘薯外植体后其生理生化特性的变化规律。【方法】用根癌农杆菌菌株N9-1侵染甘薯品种"新大紫"的茎段、叶片和叶柄为外植体,分别在共培养0、1、3、5d后取样,测定根癌农杆菌感染甘薯外植体后的生理生化特性变化。【结果】根癌农杆菌感染甘薯茎段、叶片和叶柄外植体后,可溶性蛋白质含量随共培养天数的增加而逐渐下降。在感染初期,由于逆境的出现,消耗了外植体内大量的POD和SOD,从而使其POD活性和SOD活性下降。感染后期由于植物抗病机制的作用使POD和SOD活性升高。感染后的甘薯外植体中的内源ABA和GA3含量均表现为先增加后减少的变化趋势,但内源iPAs的含量变化趋势却正相反。在甘薯茎段处于最佳感受态区段时(3d左右),POD活性增高减缓,SOD活性、内源GA3和iPAs含量处于相对低值阶段,内源ABA含量处于高值区。【结论】与其它逆境条件下表现出的变化趋势一致,根癌农杆菌感染甘薯外植体后可溶性蛋白质含量降低,POD和SOD酶活性升高,内源GA3含量增加,这些生理生化指标的变化可以反映甘薯外植体对根癌农杆菌侵染的感受状况。

【Objective】The effect of Agrobacterium tumefaciens strain N9-1 on physiological and biochemical properties of sweetpotato explants were studied in this paper. 【Method】 The stem,lamina and petiole explants of sweetpotato cv. Xindazi infected by A. tumefaciens strain N9-1 were taken after 0,1,3,5 days of cocultivation respectively and the changes on physiological and biochemical properties were investigated. 【Result】 The changes of the contents of soluble protein in stem,lamina and petiole explants infected by A. tumefaciens were showed a tendency to decrease gradually since the increasing of co-culture time. During the primary period of infection,a lot of POD and SOD in the explants would be used up due to the occurrence of stress. So the activities of POD and SOD would decrease at this period. In the later stage of infection,the reason why the activities of POD and SOD would increase may be that the mechanism of disease resistance in plant had functioned. The change tendencies in contents of endogenous hormones ABA and GA3 in the infected stem,petiole and lamina explants were showed increasing first and then decreasing,while the contents of iPAs in them showed a tendency on the contrary. During the suitable co-culture time of the stem explants （about 3 days）,the activities of POD increased gently,while the activities of SOD,the contents of endogenous hormones GA3 and iPAs were in the relatively lower range,and the content of ABA was in the higher range. 【Conclusion】 During the period of infection,the contents of soluble protein,the activities of POD and SOD,the contents of endogenous hormones in explants infected by A. tumefaciens were changed due to the occurrence of stress. All of these change tendencies in explants infected by A. tumefaciens were similar to those in plants infected by other bacterium in field.