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从小麦的叶片中筛选获得了一株抗赤霉病菌株XM5,经16S-23SrDNAITS序列的扩增比对,鉴定其为萎缩芽孢杆菌(Bacillusatrophaeus)。通过逐步提高抗生素浓度驯化,使该菌株获得了利福平和链霉素的双抗性标记,同时针对其ITS序列的特异性区段,设计了特异性引物L6SF、L6SR。采用抗抗生素和特异性PCR双重标记,研究了XM5在小麦中的内生定植状况,发现根施的XM5能长期定植于室内小麦苗和室外植株中,但定植菌的数量随时间呈递减趋势。为研究穗部的防治效果,分别以XM5的菌悬液和发酵液喷施幼穗,结果表明:10d后两个处理组在穗部表面残余的活菌数量均已不足起始量的5%,但在喷施菌悬液组,麦穗内部定植的XM5的数量不断增加,由5.2×103持续增加至4.8×104cfu·穗-1,其对赤霉病的防效在7d时可达到68.3%。
A strain of Fusarium graminearum XM5 was screened from the leaves of wheat and identified as Bacillusatrophaeus by amplification and alignment of 16S-23S rDNA ITS sequences. By gradually increasing the concentration of antibiotics domestication, the strain obtained dual resistance markers of rifampin and streptomycin, and specific primers L6SF and L6SR were designed according to the specific ITS sequences. Endophytic colonization of XM5 in wheat was studied by antibiotic-resistant and PCR-specific double labeling. It was found that XM5 was able to colonize in vitro wheat seedlings and outdoor plants for a long period of time, but the number of colonized bacteria decreased with time. In order to study the control effect of panicle, young spikes were sprayed with XM5 bacterial suspension and fermentation broth, respectively. The results showed that after 10 days, the number of viable cells remaining on the surface of panicles was less than 5% The number of XM5 colonized within the ears increased continuously from 5.2 × 103 to 4.8 × 104 cfu · spike-1, and its control effect on the disease was up to 68.3% on the 7th day.