稻曲病菌菌核降解微生物的筛选与作用机制分析

Screening of Biocontrol Fungi against Sclerotia of Villosiclava virens and Their Mechanisms

菌核是稻曲病菌天然的越冬菌源和来年病害发生的重要初侵染源,控制田间菌核越冬数量能够从源头上遏制和减轻稻曲病的发生。为此,本研究对来自稻田土壤、菌核表面、以及青海高原的能够降解菌核的真菌进行了筛选,得到了6个有较好降解作用的生防菌株。在实验室条件下它们能够在30~70 d内彻底降解稻曲病菌菌核。真菌形态特征和r DNA-ITS序列分析表明,这些菌株分别为淡色生赤壳菌Bionectria ochroleuca、粘鞭霉Gliomastix polychroma、烟曲霉Aspergillus fumigatus、草酸青霉Penicillium oxalicum、粉红粘帚霉Gliocladium spp.和疣孢漆斑菌Myrothecium verrucaria。进一步超微结构观察发现,不同生防菌对菌核的降解机制可分为以重寄生作用和直接降解为主2种基本模式。春季田间撒施试验表明,其中2种生防菌的防治效果可达33.9%和46.8%。

Sclerotia of Villosiclava virens, the pathogen of rice false smut, can overwinter and germinate in the next year to produce ascospores as the primary inocula of rice, so the measures decreasing the sclerotial number in paddy field will be practically useful in control of the disease. We screened sclerotium-degrading fungi against V. virens from paddy field soil, the sclerotium-attached fungi, and the fungi from Tibetan plateau. Tests indicated that Bionectria ochroleuca, Gliomastix polychroma, Aspergillus fumigates, Penicillium oxalicum, Gliocladium roseum, and Myrothecium verrucaria could degrade completely the sclerotia within 30-70 d. Ultrastructural examinations showed that the degradation mechanisms included myco-parasitism and saprophytic modes, respectively. Two of the fungi spreading in paddy field in the spring could decrease the false smut balls by 33.9% and 48.6%, respectively.