芽胞杆菌对香蕉枯萎病的防效评价

Control Effect of Bacillus Against Banana Fusarium Wilt

为有效评价生防菌对香蕉尖孢镰刀菌古巴转化型（Fusarium oxysporum f.sp.cubense,FOC4）B2的防病能力,通过对收集的生防菌资源进行抗性筛选,对249个测试菌中筛选到的3株拮抗菌A5-6、D7-16和CL7进行了抑菌观察、抗病谱测定、土壤抑菌能力监测及盆栽苗拮抗能力测定,并对测试菌进行了形态观察和16S r DNA测序鉴定。显微观察显示：3个拮抗菌会导致病原菌B2的菌丝发育畸形、膨胀、胞壁增厚、部分形成泡状、内容物外渗生长以及抑制孢子的萌发。抑菌谱测试表明,菌株对包括FOC4以内的其他真菌性病害抑菌率在60%以上,但对尖孢镰刀菌其他专化型抑菌率较低,仅在40%~50%之间。土壤拮抗性能评价结果表明：拮抗菌单独处理对土壤中FOC数量的控制有限,只能降低1个数量级,但对处理盆栽苗中土壤FOC数量的控制能下降到2个数量级。盆栽实验表明,菌株A5-6以72.3%的防病效果较D7-16（45.4%）、CL7（50.0%）的防效之间差异达到了极显著。3个菌株经形态学和16S r DNA序列鉴定表明D7-16为短短芽胞杆菌（Brevibacillus brevis）,A5-6和CL7也属于芽胞杆菌,3个菌株都是香蕉镰刀菌枯萎病潜在的良好生防资源,可作为生防菌做进一步的开发性研究。

To effectively evaluate the effect of biocontrol bacterium against Fusarium oxysporum f. sp. cubense, which causes banana fusarium wilt, 3 antagonistic strains AS-6, D7-16 and CL7 were selected from 249 testing isolates. The antibacterial ability of the 3 strains was observed, and resistant spectrum tests and bacteriostatic ability monitoring in soil and potted seedlings were conducted. Then morphological characteristics of the 3 strains were observed and identification of the 3 strains was conducted using 16S rDNA sequence. Microscopic observation showed that the pathogen hyphae growth and spores germination were inhibited by A5-6, DT-16 and CL7. Resistance spectrum tests showed that the 3 strains had relatively high resistant rate to FOC4 （60%） and relatively low resistant rate to other specializations of Fusarium oxysporum（40%-50%）. The population of FOC4 in the soil of potted seedlings was smaller than that in the soil without potted seedlings under the control of the 3 strains. Pot experiment showed that A5-6 had better disease control ability （72.3%） than that of D7-16 （45.4%） and CL7 （50.0%）. The morphological characteristics and 16S rDNA sequence analysis showed that the 3 strains were all Bacillus sp., and D7-16 was Brevibacillus brevis. All the 3 strains should be used as bio-control bacterium to control banana fusarium wilt and further developmental research should be conducted.