内生真菌DC-11的分离筛选及对致病疫霉的抑制作用

Screening of endophytic fungi DC-11 strain and its inhibition to Phytophthora infestans

为了获得对致病疫霉有拮抗作用的植物内生真菌,采用常规的分离方法从健康的芹菜及大葱植株中分离内生真菌,并以对峙培养法筛选对致病疫霉有较强抑制作用的菌株。结果显示:分离获得的41株内生真菌与致病疫霉对峙培养后,有11个菌株的抑制率达到50%以上,以QC-18的抑菌率最高(84.21%),其次是QC-13(79.90%);无菌体发酵液活性表明DC-11菌株的抑菌作用最强(84.6%),其次是DC-1(62%);进一步试验发现,经较高浓度(1.91mg/mL)DC-11菌株的发酵液处理后的致病疫霉菌不能恢复生长,在马铃薯块茎切片上也失去了致病能力;镜检发现在0.51mg/mL浓度处理下菌丝体形态明显发生畸变。这些结果表明DC-11菌株在未来防治马铃薯晚疫病方面有一定的应用潜力。

In order to acquire endophytic fungi against Phytophthora infestans, the routine separation method was used for isolation fungal strains from healthy celery （Apiurn graveo- lens） and onion （A. fistulosum） plants, and the mycelium growth rate method for screening antagonistic strains. The results showed that most of isolated 41 strains displayed evident suppression on mycelium growth of P. infestans. Among them, the inhibition rates （IR） of the 11 strains reached more than 50% and the strain QC-18 had the strongest effect （IR84. 21%）, and the stronger is QC-13（IR79.90%）. Activities detection of cell free fermentation liquid showed that the DC-11 strain exhibited the highest IR （84. 6%）. In addition, P. infestans mycelia treated with 1. 91 mg/mL cell free fermentation liquid of DC-11 could not recover growth on fresh Rye agar till 8 days, and lost the pathogenicity to potato tuber slices. The distortion of mycelia shape was observed under microscopy. These results indicated that DC-11 strain has a great potential in control potato late blight in future.