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对串珠镰刀菌(Fusarium moniliforme)侵染引起玉米穗粒腐病的防御酶活性变化和病原菌侵染过程进行研究。采用人工接菌的方法,分别对抗(Bt-1)、感(掖478)玉米材料进行接种,取抗、感材料间隔24 h的6个时间段接菌部位的苞叶组织,分析玉米植株感病后部分防御酶、同工酶谱的动态变化,并用扫描电镜对病原菌入侵植株过程进行组织病理学观察。扫描电镜观察发现,菌丝首先要经过1~3 d生长后,大约在72 h左右开始侵入气孔,并且随着时间的推移,侵入气孔的菌丝量逐渐增多。这说明病原菌是直接通过气孔侵入寄主苞叶组织。同时,玉米受串珠镰刀菌侵染后,苯丙氨酸解氨酶(PAL)和过氧化物酶(POD)的活性都是先上升后下降,在感病材料Ye478中PAL的活性要比抗病材料Bt-1中增加的更快、更高;同样对于POD来说,在感病材料Ye478中的活性要比抗病材料Bt-1中的高,但变化趋势在2个材料中相似;而丙二醛(MDA)的含量则相反,在感病材料Ye478中的活性要比抗病材料Bt-1中的低;对POD同工酶酶谱分析,2个材料都增加了3~4个条带,没有明显的区别,这说明玉米感病后会通过增加POD的活性来抵御外源病菌的侵入。总体而言PAL和POD活性水平与材料抗性呈负相关;MDA与材料抗性呈正相关关系。对玉米植株感病后防御酶活性变化的分析和病原菌入侵寄主的电镜观察结果,可为深入研究玉米穗粒腐病抗病机制和抗病育种提供参考。
The change of defensive enzyme activity and pathogen infection caused by Fusarium moniliforme infection were studied. The methods of artificial inoculation were used to inoculate corn (Bt-1) and tuck (478) maize respectively, and the husk tissues of the inoculation site in six time intervals with resistance and sensory material were separated for 24 h. After the disease part of the defensive enzymes, isoenzyme zymogram changes, and scanning electron microscopy of pathogens invade the plant process histopathological observations. Scanning electron microscopy showed that the mycelium began to invade the stomata about 72 h after 1 ~ 3 d of growth, and the amount of mycelial invaded stomata gradually increased with time. This indicates that the pathogen directly invades the host bract tissue through the stomata. At the same time, the activity of PAL and POD increased first and then decreased after infected by Fusarium moniliforme, and the activity of PAL in susceptible material Ye478 was higher than that of resistant The disease material Bt-1 increased faster and higher; also for POD, the activity of the susceptible material Ye478 was higher than that of the disease-resistant material Bt-1, but the trend was similar among the two materials; On the contrary, the content of malondialdehyde (MDA) was lower in the susceptible material Ye478 than that in the resistant material Bt-1. For the analysis of POD isozymes, both materials increased by 3 ~ 4 There is no obvious difference between the bands, which indicates that corn will resist the invasion of exogenous pathogens by increasing the activity of POD. Overall, PAL and POD activity levels were negatively correlated with material resistance; MDA was positively correlated with material resistance. Analysis of the change of defense enzyme activity in susceptible maize plants and the electron microscopic observation of pathogens invaded host could provide reference for further study on the disease resistance mechanism and disease-resistant breeding of maize ear rot.