樱桃叶斑病生防菌株萎缩芽孢杆菌菌株QH-588的筛选鉴定

Screening and identification of Bacillus atrophaeus QH-588 for biological control of cherry leaf spot

【目的】从枸杞根际土壤中分离可拮抗樱桃叶斑病菌的细菌菌株,为樱桃叶斑病防治提供生防资源。【方法】利用稀释平板法从枸杞根际土壤中分离可培养细菌,以平板对峙法测定分离菌株对樱桃叶斑病菌杨柳刺盘孢菌(Colletotrichum salicis)、链格孢菌(Alternaria alternaria)和细极链格孢菌(A.tenuissima)的拮抗效果,结合形态学、生理生化特性和基于16S rDNA、GyrA和GyrB基因序列的系统发育分析对拮抗菌株进行鉴定;通过显微镜观察拮抗菌株对靶标病原菌菌丝形态和孢子萌发的影响,选用樱桃离体叶片培养测定其对樱桃叶斑病的预防和防治效果。【结果】从枸杞根际土壤中共分离获得660株细菌,有10株细菌对供试靶标病原菌具有较强的拮抗效果,其中有4株细菌(QH-588、QH-668、QH-667和QH-664)的发酵液对靶标病原菌的抑制率超过50.00%,经鉴定,菌株QH-588为萎缩芽孢杆菌(Bacillus atrophaeus),菌株QH-664、QH-667和QH-668为枯草芽孢杆菌(B.subtilis)。通过显微观察发现,萎缩芽孢杆菌菌株QH-588可明显抑制靶标病原菌的菌丝生长和孢子萌发;生防效果测定结果表明,菌株QH-588发酵液在樱桃离体叶片上对靶标病原菌具有预防和防治作用。【结论】萎缩芽孢杆菌菌株QH-588具有防治樱桃叶斑病的生防潜力。

【Objective】Bacterial strains that could antagonize cherry leaf spot were isolated from the rhizosphere soil of Lycium barbarum,so as to provide biocontrol resources for the control of cherry leaf spot.【Method】The culturable bacteria were isolated from the rhizosphere soil of L.barbarum by dilution plate method.The antagonistic effect of the iso-lated strains against Colletotrichum salicis,Alternaria alternaria,A.tenuissima was determined by plate confrontation method.Combined with morphological,physiological and biochemical characteristics and phylogenetic analysis based on 16S rDNA,GyrA and GyrB genes sequences,antagonistic bacteriawere identified;the effects of antagonistic bacteria on the mycelial morphology and spores of target fungi were observed under microscope,and the in vitro leaf culture of cherry was selected to determine its prevention and control effect on cherry leaf spot.【Result】A total of 660 strains of bacteria were isolated from the rhizosphere soil of L.barbarum,of which 10 strains had strong antagonistic effect on the tested pathogens.Among them,the inhibition rate of fermentation broth of 4 strains of bacteria(QH-588,QH-668,QH-667 and QH-664)on the target pathogens exceeded 50.00%.After identification,strain QH-588 was Bacillus atrophaeus,strains QH-664,QH-667 and QH-668 were B.subtilis.Microscopic observation showed that B.atrophaeus strain QH-588 could inhibit the mycelial growth and spore germination of the target pathogen.The results of biological control showed that the fermentation broth of strain QH-588 could prevent and control the target pathogens on the isolated leaves of cherry.【Conclusion】B.atrophaeus strain QH-588 has the potential of biocontrol against cherry leaf spot.