广谱抗真菌枯草芽孢杆菌Bacillus subtilis菌株TR21在温室和大田对香蕉枯萎病具有较好的防效,其机制已证明与诱导香蕉产生系统抗性有关。本文以巴西蕉（Musa AAA Cavendish subgroup cv.Brazil）为材料,利用半定量RT-PCR法,以香蕉25S rRNA基因为内标,研究灌根接种菌株TR21后对香蕉根系4种抗病相关基因表达的影响。结果表明,PAL、POD、PR-3和PR-1基因在接种后表达水平均表现上调趋势,但PAL和POD基因的表达增幅明显高于PR-3和PR-1基因。PAL和POD基因在接种后12 h表达量最高,与TR21在香蕉根部的定殖规律表现出一致性。系统诱导抗性是枯草芽孢杆菌TR21防治香蕉枯萎病的机制之一。%Bacillus subtilis strain TR21 with broad-range antifungal activity has shown potential to control banana Fusarium wilt in greenhouse and fields.The mechanism through which strain TR21 confer resistance to the disease has previously been demonstrated to involve induced resistance.In this study,with Musa 25S rRNA gene as an internal control,the effect of strain TR21 on expression of four defense-related genes in roots of Musa AAA Cavendish subgroup cv.Brazil was investigated by semi-quantitative RT-PCR method.Results showed that the expression of PAL,POD,PR-3 and PR-1 was up-regulated after being inoculated with strain TR21,but PAL and POD had higher increase amplitude.The expression of PAL and POD reached the maximum in roots at 12 h after inoculation,which was in accordance with colonization of strain TR21 in roots of the plant.It suggested that induced systemic resistance was one of antagonistic mechanisms of the strain TR21 against banana Fusarium wilt.
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