5种拮抗菌复合发酵对致病疫霉的抑制及离体防病作用研究

Exploration of compound fermentation of 5 species antagonistic bacteria on Phytophthora infestans growth inhibition and in vitro disease prevention

为了克服单一拮抗菌抑菌活性不够稳定、防病效果较差等不足,采用对峙培养法对HT-6、SR13-2、W-7、ST-1和Sy11这5株拮抗菌进行复合发酵的可行性进行了探讨,在此基础上比较了复合发酵菌液I(4株拮抗菌)和复合发酵菌液Ⅱ(5株拮抗菌)在抑菌活性、菌丝体致畸、离体组织防病等方面的差异。结果显示,5株拮抗菌之间无明显拮抗作用,可进行复合发酵;在与致病疫霉同时对峙培养至第11天时,与5株菌中抑菌活性最强的HT-6相比,复合发酵菌液Ⅱ的抑菌作用较强,抑菌率为83.77%,与复合发酵菌液I有显著性差异(P<0.05);在致病疫霉预先生长1d后再对峙培养,发现复合发酵菌液Ⅱ的抑菌作用在对峙培养的第7天和第9天也显著优于复合发酵菌液I和HT-6,并与复合发酵菌液I达到显著性差异(P<0.05)。另外,镜检发现复合发酵菌液Ⅱ处理的病菌菌丝体畸变率最高(73.96%),其次是HT-6菌液,畸变率为49.47%;预先以菌液处理马铃薯块茎切片2d后接种致病疫霉,发现至接种后第9天,复合发酵菌液Ⅱ处理的块茎切片只出现轻微褐变,未出现或仅出现少量菌丝体,病情指数最低(28.13),与复合发酵菌液I有显著性差异(P<0.05),保护率达63.83%。这表明复合发酵菌液Ⅱ防治马铃薯晚疫病的潜力明显优于复合发酵菌液I。

To overcome disadvantages of single antagonistic bacterium in inhibiting Phytophthora infestans and in vitro disease prevention,dual-culture method was used for detecting the feasibility of compound fermentation of 5 species of antagonists to the pathogen.And compound fermentation bacterial fluid I(CFBF-I)containing 4 species of bacteria and compound fermentation bacterial fluid II(CFBF-II)containing 5 species of bacteria were compared in activity of suppressing growth,deforming mycelia,and preventing disease on potato tuber slices.The results showed that there was no obvious antagonism among 5 species of bacteria and they could be co-cultured for compound fermentation.Prohibition of CFBF-II against P.infestans mycelia growth was the strongest in comparison with CFBF-I and HT-6 after simultaneous dual culture 11 d on Rye medium,the inhibitory rate reached 83.77%and existed significant differences compared with CFBF-I(P<0.05).It was also found that restraint of CFBF-II to P.infestans was obvious better than that of CFBF-I and HT-6 culturing 7 d and 9 d after pre-culture P.infestans 1 d,and there was evident difference between CFBF-II and CFBF-I(P<0.05).In addition,mycelial aberration rate of P.infestans caused by CFBF-II was the highest(73.96%),followed by HT-6 treatment(49.47%).Potato tuber slices after pre-treated with CFBF-II for 2 d were inoculated by agar disk containing P.infestans.Only slight brown stain and no or little mycelia were observed on tuber slices 9 d after inoculation.The disease index was 28.13 and significant lower than that of CFBF-I and HT-6 treatments.There was marked difference(P<0.05)between CFBF-II and CFBF-I.The protective efficiency of CFBF-II on tuber slices against late blight reached 63.83%.These results indicate that CFBF-II might have the greater potential than CFBF-I in control potato late blight in future.