蓝花楹内生拮抗细菌筛选及对茎腐病的防治研究

【目的】筛选蓝花楹茎腐病的内生拮抗细菌,并探讨其生物防治作用。【方法】采用稀释平板法从健康蓝花楹根茎分离内生菌株;以蓝花楹茎腐病原菌(Fusarium chlamydosporum)作为供测菌,用5点对峙法进行拮抗作用初筛、平板扩散法复筛获得拮抗菌株,经形态学和16Sr DNA序列比对,对其进行鉴定。采用温室盆栽和田间试验检测拮抗菌的生防效果。【结果】分离获得24株内生菌株,其中zhu66抑菌率达到97.8%,鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens),Gen Bank序列登录号为JF899258。盆栽试验结果表明,解淀粉芽孢杆菌能有效预防和治疗蓝花楹茎腐病。在一定浓度下,浓度越高防效越好,以107cfu/m L浓度最佳。灭菌土防效优于自然土;生防菌先于病原菌施入防效优于生防菌与病原菌同时接种,病原菌先于生防菌接种方式防效较低。菌株能显著促进蓝花楹地径、苗高与冠幅生长,浓度越高,促生效果越好。田间试验进一步验证,蓝花楹茎腐病不同发病程度的生防效果有显著差异,无病区预防作用十分显著,不发生茎腐;重度发生区几乎没有效果,轻度发生区防效明显,防效达74.1%,中度发生区有一定效果,且随着时间延长,防效增加。【结论】解淀粉芽孢杆菌zhu66对蓝花楹茎腐病有良好的生防潜力。

Screening for endophytic antagonistic bacterium of Jacaranda acutifolia and biocontrol effect against stem rot

Objective]This study was aimed at screening antagonistic endophytic strains against stem rot in Jacaranda acutifolia, and investigating the antagonistic activity. Method] Endophytic bacteria were isolated by dilution plating. F. chlamydosporum served as the test fungus, and antagonistic strains was obtained firstly by the five-point confrontation method and secondly by plate diffusion. Strains were identified by analyses of morphology and 16S rDNA sequence. Bio-control effect was analyzed by greenhouse and field experiments. Results]The number of endophytic strains obtained was 24;the strain zhu66 with an inhibition rate of 97.8% was screened from the 24 strains. It was identified as Bacillus amyloliquefaciens by the 16S rDNA sequence analysis. Its GenBank accession number was JF899258. The greenhouse pot experiment showed that B. amyloliquefaciens could effectively prevent and treat stem rot in J. acutifolia. At a certain con-centration, the higher the concentration, the better the anti-effect, and 107 cfu/mL was at the optimal concentration.The control effect of sterilized soil was stronger than that of the natural soil. The control effect of the biocontrol strain inocula-ted before pathogen inoculation was stronger than that of the biocontrol strain and pathogen inoculated simultaneously;the control effect of pathogen inoculated before biocontrol strain inoculation was weak. It could promote growth of stems, and increase height and crown diameter of J. acutifolia. The higher the concentration, the stronger the effect. The field experiment further verified that the biocontrol effect on stem rot in J. acutifolia at different degrees showed remarkable differences. The preventive effect in the uneffective region was remarkably considerable,which had no stem rot. There was virtually no effect in the severely affected areas, although obvious control effect was observed in the mildly affected areas reaching 74.1%. There was a certain effect in the moderately affected areas, and with time, the control effect was enhanced.Conclusion]B. amyloliquefaciens zhu66 strain could potentially serve as a biocontrol agent against stem rot.