Jia Ke, Gao Yu-Han, Huang Xiao-Qin, Guo Rong-Jun, Li Shi-Dong
Key Laboratory of Pest Management in Crops of the Ministry of Agriculture, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100081, P. R. China.
Institute of Plant Protection, Sichuan Academy of Agricultural Sciences, Chengdu 610066, P. R. China.
Plant Pathol J. 2015 Jun;31(2):140-51. doi: 10.5423/PPJ.OA.10.2014.0113. Epub 2015 Jun 30.
Bacillus subtilis B006 strain effectively suppresses the cucumber fusarium wilt caused by Fusarium oxysporum f. sp. cucumerinum (Foc). The population dynamics of Foc, strain B006 and its surfactin over-producing mutant B841 and surfactin-deficient mutant B1020, in the rhizosphere were determined under greenhouse conditions to elucidate the importance of the lipopeptides excreted by these strains in suppressing Foc. Results showed that B. subtilis strain B006 effectively suppressed the disease in natural soil by 42.9%, five weeks after transplanting, whereas B841 and B1020 suppressed the disease by only 22.6% and 7.1%, respectively. Quantitative PCR assays showed that effective colonization of strain B006 in the rhizosphere suppressed Foc propagation by more than 10 times both in nursery substrate and in field-infected soil. Reduction of Foc population at the cucumber stems in a range of 0.96 log10 ng/g to 2.39 log10 ng/g was attained at the third and the fifth weeks of B006 treatment in nursery substrate. In field-infected soil, all three treatments with B. subtilis suppressed Foc infection, indicated by the reduction of Foc population at a range of 2.91 log10 ng/g to 3.36 log10 ng/g at the stem base, one week after transplanting. This study reveals that the suppression of fusarium wilt disease is affected by the effective colonization of the surfactin-producing B. subtilis strain in the rhizosphere. These results improved our understanding of the biocontrol mechanism of the B. subtilis strain B006 in the natural soil and facilitate its application as biocontrol agent in the field.
枯草芽孢杆菌B006菌株能有效抑制由尖孢镰刀菌黄瓜专化型（Foc）引起的黄瓜枯萎病。在温室条件下测定了Foc、B006菌株及其表面活性素高产突变体B841和表面活性素缺陷突变体B1020在根际的种群动态，以阐明这些菌株分泌的脂肽在抑制Foc中的重要性。结果表明，枯草芽孢杆菌B006菌株在移栽五周后能有效抑制自然土壤中的病害，抑制率达42.9%，而B841和B1020对病害的抑制率分别仅为22.6%和7.1%。定量PCR分析表明，B006菌株在根际的有效定殖在育苗基质和田间感染土壤中均能使Foc繁殖抑制10倍以上。在育苗基质中，B006处理的第三周和第五周，黄瓜茎部的Foc种群数量减少了0.96 log10 ng/g至2.39 log10 ng/g。在田间感染土壤中，枯草芽孢杆菌的所有三种处理均抑制了Foc感染，移栽一周后，茎基部的Foc种群数量减少了2.91 log10 ng/g至3.36 log10 ng/g。本研究表明，枯萎病的抑制受产表面活性素的枯草芽孢杆菌菌株在根际有效定殖的影响。这些结果增进了我们对枯草芽孢杆菌B006菌株在自然土壤中生物防治机制的理解，并促进了其在田间作为生物防治剂的应用。
