内生黑曲霉JS-1对稻瘟病的拮抗作用研究

利用平板对峙法和牛津杯法，从疏花水柏枝、金银花、秋华柳的内生菌中，筛选出1株对稻瘟病菌具有很强抑制作用的菌株JS-1。经生理生化实验和18S rDNAITS序列分析，确定该菌株为黑曲霉(Aspergillus niger)。实验结果表明，JS-1发酵液作用稻瘟病菌后，稻瘟病菌的菌丝变细，分支减少，菌丝基质颜色变浅，作用72 h后干重显著降低。进一步实验表明，该菌产生的活性物质位于其发酵液的乙酸乙酯酯相部位，对稻瘟病病菌抑制率高达96.1%。大田实验数据（天然接种圃）显示，添加该物质后，丰两优4号（中感）和广陆矮4号（易感）叶瘟病情指数分别只有16.25%和32.48%，对稻瘟病的防治取得了很好的效果，说明该菌株具有开发成高效生物农药的巨大潜能。

Antagonistic effect of endophytic Aspergillus niger JS-1 on rice blast

The strain JS-1 with strong inhibitory effect against Magnaporthe grisea was screened from the endophytic fungi of Myricaria laxiflora, Lonicera japonica Thunb, and Salix variegata Franch by the method of plate confrontation and Oxford cup. The strain was identified as Aspergillus niger by physiological and biochemical experiments and 18S rDNA ITS sequence analysis. The experimental results showed that after the JS-1 fermentation broth treating, Magnaporthe grisea mycelium became thinner, the branch decreased, and the color of the mycelial matrix became lighter. After 72 hours, the dry weight decreased significantly. Further experiments showed that the active substance produced by the fungus was located in the ethyl acetate ester phase of the fermentation broth, and the inhibition rate against rice blast disease was as high as 96.1%. Field experimental data (natural inoculation) showed that after adding this substance, the disease index of Fengliangyou 4 (moderate infection) and Guangluai 4 (susceptible) were only 16.25% and 32.48%, respectively, for rice blast. The prevention and treatment have achieved good results, indicating that the strain has great potential for development into high-efficiency biological pesticide.