生防菌JNC2对柱花草炭疽病的生防效果及其机理作用

Biocontrol Effects and Mechanism of Antagonistic Bacterial Strain JNC2 against Colletotrichum gloeosporioides on Stylosanthes

由胶孢炭疽菌(Colletotrichum gloeosporioides)引起的柱花草炭疽病是热带和亚热带牧草豆科植物柱花草可持续生产的严重制约因素,对广泛使用杀菌剂以维持饲料高质量的担忧导致要求采用更安全的控制替代品。为获得对柱花草炭疽病菌有良好拮抗效果的生防菌株,经组织分离法从坚尼草叶片上分离获得一株对柱花草炭疽菌有拮抗作用的JNC2菌株。以该菌株基因组DNA为模板,通过形态学观察、生理生化特性、16S rDNA和gyrA基因序列分析,鉴定JNC2菌株为Bacillus amyloliquefaciens。对峙培养结果表明,经JNC2菌株处理后病原菌的菌丝生长呈现受抑制的现象,菌丝中的原生质凝集,肿胀膨大且出现不同程度的縊缩,凸起变形。利用特异性引物对JNC2基因组脂肽类抗生素合成有关基因进行检测,从该菌的基因组DNA中扩增获得bacA、ituA、ituD、Ipa-14、fenD、bmyB、mycB、sfp、Hag和tasA等脂肽类抗生素合成酶基因。离体叶片试验结果表明JNC2菌株能够明显抑制柱花草炭疽病病菌的扩展,对柱花草叶斑病的防效达到66%以上。本研究为柱花草炭疽病的生物防治提供菌种资源和理论依据。

Anthracnose of Stylosanthes(Stylo),caused by Collectotrichum gloeosporioides,remains a serious constraint to the sustainable production of tropical and subtropical pasture legume Stylosanthes.Concerns over the widespread use of fungicides to maintain high fodder quality have led to calls for the adoption of safer control alternatives.To obtain a Biocontrol Strain with good antagonism against Colletotrichum gloeosporioides,The JNC2 strain isolated from Panicum maximum leaf tissue,exhibited strong antagonistic activity on C.gloeosporioides,and was identified as Bacillus amyloliquefaciens based on its morphological,physiological and biochemical characteristics as well as the analysis of 16 S rDNA and gyrA gene sequences.The results of plate confrontation method showed that the mycelial growth of C.gloeosporioides treatment with JNC2 strain was inhibited.The protoplasts in the mycelium was agglutinate,swollen,constricted and deformed to varying degrees.The lipopeptide synthesis-related genes were detected by using specific primers,and bacA,ituA,ituD,Ipa-14,feuD,bmyB,mycB,sfp,Hag and tasA were amplified from the genomic DNA of strain JNC2.In vitro leaf test showed that JNC2 can significantly inhibit the expansion of Stylosanthes anthracnose,and the control effect on Stylosanthes leaf spot was more than 66%.This study provides further insight on the potentials of antagonistic bacterial resources as suitable biocontrol tools against anthracnose of Stylosanthes.