【摘要】 芽孢杆菌BH1分离于大豆根际,在温室试验中表现出较好的防治效果。田间试验对尖孢镰刀菌引起的大豆根腐病防效达56.1%,增产7.6%。该菌株发酵无菌滤液对尖孢镰刀菌F3、茄孢镰刀菌W1和镰刀菌S1孢子萌发和菌丝生长有抑制作用;对热处理较稳定。对其抗利福平标记株B R+ 4与大豆根系的亲和性研究表明,BH1可定殖于无菌土和病土中生长的大豆根际,且动态变化趋势相似,但在无菌土中数量略高于病土。组织印记法表明:B R+ 4可在整个大豆根系生长。扫描电镜观察发现,BH1主要存在于根表凹陷处,在根尖或侧根处则很少。透射电镜观察,根细胞间隙内未检测到BH1。在大豆根际的定殖试验说明,B R+ 4与大豆根系有很好的亲和性,对营养和空间位点的竞争是其拮抗病原菌的主要机制。更多还原

【Abstract】 Strain BH1 (Bacillus sp.), isolated from soybean rhizosphere, is of potential in biocontrol of soybean root rot disease (SRRD) caused by Fusarium spp. based on greenhouse tests. In field trials, control efficacy of SRRD by BH1 was up to 561%. The mechanism of BH1 to suppress SRRD was conducted. The spores germination and hyphae growth of pathogens F3 (Fusarium oxysporum), W1 (F. solani) and S1 (F. sp.) were inhibited by BH1 fermentation filtrate. The affinity of BH1 with soybean roots was examined. BR+4, a mutant resistant to rifampicin, could colonize soybean rhizosphere when soybean were planted in sterilized soil or soil infested with F. oxysporum. The dynamics of BR+4 was similar in both infested and sterilized soils, but the amount of BR+4 was higher in sterilized soil than that in infested soil. The pressprinting examination showed that BR+4 had a high affinity with soybean roots, and could grow along with the roots. SEM observations indicated that BR+4 aggregated in the indented parts of the epidermal surface, few on root tip or lateral roots, and no in intracellular gap. The results indicate that competition for nutrition and space is an important mechanism for BH1 to suppress soybean root rot diseases caused by Fusarium spp. in soil.更多还原