内生菌XG-1对西瓜枯萎病诱导抗性的研究

以苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)、多酚氧化酶(PPO)、过氧化氢酶(CAT)4种防御酶的活性变化以及丙二醛(MDA)的含量变化作为指标,研究内生菌XG-1对西瓜枯萎病的诱导抗性,为阐明XG-1的作用机制及其开发应用提供理论依据。结果表明:经内生菌XG-1菌悬液处理后,西瓜苗叶片的PAL、POD、PPO及CAT活性均高于清水对照。同时接种XG-1菌悬液和西瓜枯萎病菌(Fusarium oxysporumf.sp niveum,FON)的叶片,PAL活性在接种后第4天、第10天出现2次高峰,分别比对照增加1.86倍和1.52倍;POD和PPO活性均在第4天达到最高峰,分别比对照提高52.6%和57.1%;CAT活性在第5天时达到最高峰,比对照提高56.4%。同时接种XG-1菌悬液和枯萎病菌FON后,西瓜苗叶片的MDA含量呈先下降后逐渐上升趋势,第4天时达到最低值,比对照下降33.1%。由此可见,诱导抗病性是菌株XG-1防治西瓜枯萎病的重要作用机制之一。

Induced Resistance of Endophyte XG-1 against Fusarium Wilt of Watermelon

This experiment studied the induced resistance of endophytic bacterium XG-1 against Fusarium wilt of watermelon by taking the content variation of MDA and the activity variation of four defense enzymes including PAL,POD,PPO and CAT as the indexes.The results showed that the activities of the four defense enzymes in leaves of watermelon plants treated by bacterial suspension of endophyte XG-1 were all higher than the control.After the leaves were treated by XG-1 bacterial suspension and Fusarium oxysporum f.sp niveum(FON),the activity of PAL showed two peeks on the 4th day and the 10th day,1.86 and 1.52 times higher than the control,respectively;the activities of POD and PPO both exhibited the peek on the 4th day,increased by 52.6% and 57.1%,respectively;the activity of CAT exhibited the peek on the 5th day,increased by 56.4%;MDA content firstly descended and then gradually ascended,falling to the lowest on the 4th day,dropped by 33.1%.The results suggest that induced resistance is one of the important mechanisms by strain XG-1 in control of watermelon Fusarium wilt.