木霉对棉花枯萎病菌和黄萎病菌的作用机理

木霉对棉花枯萎病菌(Fumrium oxysporum f.sp.Vasinfectum)的幼菌丝具有强烈的寄生能力，对于老熟菌丝的寄生能力较弱。木霉能够产生琼脂扩散性和挥发性抑菌物质。绿色木霉LTR-2产生的挥发性抑菌物质能强烈抑制棉花枯萎病菌的菌丝生长。木霉生物防治作用的另外一种方式是与病原菌竞争营养物质，研究发现葡萄糖是竞争对象之一。木霉具有很强的β-1,3-葡聚糖酶和几丁质酶活性。培养液中添加几丁质、木霉菌或者棉花枯萎病菌菌丝干粉后培养木霉，培养液上清能够破坏枯萎病菌的菌丝尖端并导致原生质体的泄露，该现象主要与木霉的几丁质酶活性有关。木霉对棉花黄萎病菌具有相同的作用方式。

Mode of action of Trichoderma spp. against Fusarium oxysporum f. sp. vasinfectum and Verticillium dahliae

Trichoderma spp. parasitized the young mycelia of Fusarium oxysporum f. sp. vasinfectum (Fov) strongly, but older mycelia weakly. Trichoderma spp. produced both diffusable and volatile inhibitory substances; volatile inhibitors from T. viride LTR-2 inhibited the mycelium growth of Fov significantly. Competence for nutrition with the pathogen involving glucose was another mechanism of Trichoderma of biocontrol activity in Trichoderma.Trichoderma spp. showed strong β-1,3-glucanase and chitinase activity. Supernatant from T. viride LTR-2 liquid culturecontaining chitin, dry powder of mycelia of Trichoderma spp. and Fov respectively,damaged the tips of living Fov mycelium and induced leakage of protoplast,the hydrolytic activity responsible was mainly chitinase.Similar activity was found with Trichoderm spp.as antagonists of Verticillium dahliae.