马铃薯致病疫霉及其拮抗菌的筛选与鉴定

采用组织分离法分离鉴定马铃薯致病疫霉,同时比较3株拮抗菌对马铃薯致病疫霉的抗菌效果,以期获得1株更具有生防潜力的拮抗细菌,并加以鉴定。用涂布分离法得到3株拮抗菌,通过形态学和分子生物学鉴定马铃薯致病疫霉和这3株拮抗菌。同时比较这些拮抗菌对马铃薯致病疫霉游动孢子释放、休止孢萌发和孢子囊直接萌发的抑制效果,分析菌液对马铃薯晚疫病的预防效果。结果鉴定出1株马铃薯致病疫霉PLB-2 Phytophthora infestans和1株具有明显抑制效果的拮抗细菌WZ-502 Brachybacterium sp.。菌株WZ-502的菌液对马铃薯致病疫霉游动孢子释放、孢子囊直接萌发和休止孢萌发有较好的抑制效果。菌株WZ-502菌液浓度为3.65×10⁷ CFU·mL^-1、稀释度为10^-2~10^-3时,对马铃薯致病疫霉的抑制效果均明显,稀释度为10^-3时,马铃薯致病疫霉孢子囊萌发率和释放率均在40%以下。因此,菌株WZ-502对马铃薯致病疫霉抗菌效果显著,具有一定的生防潜力。

Screening,identification of Phytophthora infestans and its antagonistic bacterial strain

Phytophthora infestans was identified from potato via tissue isolation method and the antibacterial effects of three antagonistic bacterium to it were compared in order to get the potential one. They were isolated by coating method and identified by morphology and molecular biology method. The inhibitory effects of Phytophthora infestans were studied including the release of zoospore, germination of resting spore and germination of sporangium. The preventive effect of the bacterial solution was also analyzed. The results showed that a PLB-2 Phytophthora infestans and a WZ-502 Brachybacterium sp. of potato were separated and identified. The strain WZ-502 had significant inhibitory effect on the release of zoospores, direct germination of sporangium and germination of resting spores. The strain WZ-502 (concentration was 3.65×10⁷ CFU·mL^-1) at dilutions grade of 10^-2-10^-3 was effective, and the rates of sporangium germination and the release of Phytophthora infestans were both below 40% when the dilution was 10^-3. The strain WZ-502 had a good antibacterial effect on Phytophthora infestans.