Abstract: Helminthosporium gramineum Rabenh f. sp.echinochloae (HGE), a promising fungus for controlling barnyardgrass, was evaluated for biocontrol of sheath blight in rice caused by Rhizoctonia solani Kuhn. On a PDA plate, the antagonistic result showed that the inhibitory activity of HGE strain against the mycelial growth of R. solani was 83.5%. Culture filtrate of HGE strain showed strong inhibitory activity against R. solani with a relative inhibitory rate of 84.1% at the 5-fold diluted filtrate. On PDA plate, mycelial growth of R. solani was completely inhibited by crude toxins (ethyl acetate extract of culture filtrate and mycelia of HGE) produced by HGE strain at 200 μg/mL. One compound with high inhibitory activity against the growth of R. solani was isolated from the extracts of culture filtrate and mycelia of HGE. The bioactive compound was identified as Ophiobolin A through detailed analysis of NMR and MS data of the compound and the comparison with the reported spectra data. The relative inhibitory rate of Ophiobolin A against R. solani was 100% and 70.2% at 25 μg/mL and 1 μg/mL, respectively. These results indicated that HGE strain and its metabolite Ophiobolin A could be potentially developed as a natural fungicide for the control of rice sheath blight.

Key words: Helminthosporium gramineum f. sp. echinochloae, metabolite, Ophiobolin A, rice sheath blight, biocontrol, barnyardgrass

摘要： 为充分利用已有杂草生防菌菌种资源，进行了稗草生防菌禾长蠕孢菌(Helminthosporium gramineum Rabenh f. sp.echinochloae，HGE）防治水稻纹枯病的初步研究。菌落对峙实验结果表明HGE对纹枯病菌菌丝生长有较强的抑制作用。HGE菌株的发酵液对纹枯病菌的生长有较强的抑制活性，稀释5倍的发酵液24 h的抑菌率为84.1％。发酵液及菌丝的乙酸乙酯提取粗毒素在200 μg/mL浓度下100％抑制纹枯病菌的生长。从粗毒素中分离纯化的有很强抑菌活性的化合物经过NMR及MS波谱分析鉴定为Ophiobolin A。Ophiobolin A在25 μg/mL浓度下即100％抑制纹枯病菌的生长，浓度1 μg/mL时的抑菌率为70.2%。实验结果显示HGE菌及其代谢物Ophiobolin A具有开发成水稻纹枯病生物杀菌剂的潜力。

关键词: 禾长蠕孢菌, 代谢产物, Ophiobolin A, 水稻纹枯病, 生物防治, 稗草