香蕉枯萎病生防菌AF11的鉴定及其定殖研究

从健康大豆根系内分离出一株对香蕉枯萎病病原菌Fusarium oxysporum f.sp.cubense Race 4（FOC Race4）有强拮抗效果的内生细菌AF11。盆栽防病试验结果表明其对香蕉枯萎病的防效达71.5%。形态特征、生理生化测定和16S rDNA序列及其系统发育树分析初步确定该菌株为解淀粉芽孢杆菌Bacillus amyloliquefaciens。从菌株AF11中筛选出抗利福平（100μg.mL-1）且对FOC Race 4拮抗活性稳定的变异菌株AF11Rif,采用灌根接种方法,研究菌株AF11Rif在香蕉体内定殖分布规律。试验结果表明,菌株AF11Rif能定殖于香蕉根部和茎部,接种50 d后根部定殖量为118 cfu.mg-1,茎部为32 cfu.mg-1。

Identification and Colonization of Bacteria AFll Antagonistic against Fusarium oxysporum f. sp. cubense Race 4, the Pathogen of Banana Wilt Disease

Authors obtained an endophytic bacterial strain AFII from the root of healthy soybean plants. Pot experiments showed that AF11 reduced by 71.5% banana wilt disease caused byFusarium oxysporum f. sp. cubense Race 4 （FOC Race 4） as investigated at 30 days after treatment with pouring root at 106 cfu.mL-1. The strain was identified as Bacillus amyloliquefaciens based on its morphological and physiological properties and its 16S rRNA sequence. A mutant AF 11RJf resistant to Rifampicin at 100 μg-mL-1 was obtained by successive cultures on medium plates amended with increased concentration of Rifampicin. The mutant were stable in antagonism against FOC Race 4, and was used to inoculate banana by pouring root system. Re-isolation indicated that the strain AFllRif could colonize root and stem of banana by 118 cfumg-1 and 32 cfu.mg-1, respectively, at 50 d after inoculation.