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用弯孢菌粗毒素诱导处理抗病和感病玉米品种沈试 2 9和掖单 13后 ,结果发现 ,相同浓度毒素处理不同时间后和不同浓度毒素处理相同时间后 ,抗、感品种防御酶系中的苯丙氨酸解氨酶 (PAL)、过氧化物酶 (PO)和超氧化物歧化酶 (SOD)的变化规律基本相同。病原菌毒素处理后 ,抗病品种的PAL和PO对毒素较感病品种敏感 ,诱导酶峰的临界毒素浓度低于感病品种 ,抗病品种酶峰出现时间提前或峰值大于感病品种。而SOD活性变化规律与上述两种酶不同 ,弯孢菌毒素能刺激感病品种SOD活性增加 ,而抑制了抗病品种的SOD活性。抗病品种SOD活性在处理初期下降 ,后期缓慢上升 ,而感病品种SOD活性快速上升 ,高于抗病品种。抗病品种SOD活性较低 ,有利于细胞内积累适量的超氧自由基 ,从而激发寄主抗性机制的表达 ;而毒素处理感病品种后SOD活性提高 ,有利于及时清除细胞内活性氧 ,使寄主因缺少活性氧而无法激发产生抗性
The results showed that after the same concentration of toxin was treated at different times and the same concentration of toxin at the same time, the resistant and susceptible varieties of defense enzymes The changes of phenylalanine ammonia lyase (PAL), peroxidase (PO) and superoxide dismutase (SOD) were basically the same. After pathogen toxin treatment, PAL and PO of resistant varieties were more sensitive to toxins than susceptible varieties, the critical toxin concentration of induced enzyme peak was lower than that of susceptible varieties, and the peak of enzyme peak appeared more or less than that of susceptible varieties. However, the change of SOD activity was different from that of the above two enzymes. Curculovirus toxin could stimulate the SOD activity of susceptible varieties and inhibit the SOD activity of the resistant varieties. SOD activity of disease-resistant cultivars decreased at the early stage of treatment and slowly increased at the late stage, while the SOD activity of susceptible cultivars increased rapidly, which was higher than that of resistant cultivars. The SOD activity of the resistant varieties was low, which was conducive to the accumulation of superoxide radicals in the cells, and thus stimulated the expression of the host resistance mechanism. However, the SOD activity was enhanced after the toxin treatment of susceptible cultivars, which was in favor of timely removal of intracellular reactive oxygen species Host due to the lack of reactive oxygen species can not stimulate the production of resistance