内生细菌B3-7 的运动性参与其在小麦根系的内生定殖和对小麦全蚀病的生物防治

 蜡样芽孢杆菌(Bacillus cereus)B3-7 是一株对于小麦全蚀病具有有效生防作用的小麦内生细菌。为了研究B3-7 在小麦根内的定殖机制,本研究将含有转座子TnYLB-1 和温度敏感型复制子的质粒pMarB 转化B3-7 菌株,高温处理后TnYLB-1 插入细菌基因组中,构建转座子插入突变体库。通过筛选,获得1 株在小麦根内定殖能力显著降低的突变体B3-7-458。利用反向PCR 方法分离转座子插入位点的侧翼序列并分析其特征,发现转座子插入导致细菌鞭毛运动性相关基因mota 失活,同时发现mota 失活菌株对于小麦全蚀病的生防能力降低。通过构建互补载体对突变基因mota 进行互补分析,发现互补菌株的运动性、在小麦根系内部的定殖能力以及对于小麦全蚀病的生防能力得以恢复。本研究证明了生防菌蜡样芽孢杆菌B3-7 的mota 基因参与该菌株在小麦根系的内生定殖,也参与了该菌株对于小麦全蚀病的生物防治。

Motility of endophytic bacteria strain B3-7 involved in endophytic colonization of wheat roots and biological control of wheat take-all

Bacillus cereus strain B3-7 isolated from wheat roots is an endophytic bacteria,and has biological control activity against take-all of wheat incited by Gaeumannomyces graminis var.tritici.To elucidate colonization mechanism of B3-7 within wheat roots,transposon TnYLB-1 was introduced into genome of B3-7 and a transposon insertion mutant library was constructed.Mutants with altered colonization numbers within wheat roots were then screened and one mutant designated as B3-7-458 with low root colonization abi...