西瓜枯萎病生防菌的分离鉴定及其生防潜力研究

The Study on Screening,Identification and Its Potential Application of Biocontrol Agents against Fusarium oxysporum f.sp.niveum

为筛选获得高效防治西瓜枯萎病菌的生防菌株,本研究以胶体几丁质为唯一碳源的培养基,从广东珠海红树林根际土分离的1000余株细菌中筛选到32株具有高几丁质酶活性菌株,采用平板对峙法进行复筛,最终获得10株综合效果好的菌株。温室结果表明,这10株菌株均具有促生及防病效果,其中菌株PL-29处理组相对于对照组防病效果最好,防治效果为63.11%,促生效果同样显著。经形态学、生理生化特征和16S rDNA系统发育分析,最终将菌株PL-29鉴定为黄三素链霉菌Streptomyces flavotricini。此外,抑菌谱试验结果表明,该菌株对辣椒疫霉Phytophthora capsici、灰葡萄孢Botrytis cinerea、立枯丝核菌Rhizoctonia solani等多种病原菌都具有拮抗能力。对菌株PL-29的抑菌作用进一步研究表明,菌株PL-29能抑制尖孢镰刀菌孢子的产生及萌发,从而抑制病原菌的生长。此外,还可以破坏尖孢镰刀菌质膜完整性,诱导ROS积累。综合上述结果表明,黄三素链霉菌S. flavotricini PL-29在防治西瓜枯萎病方面具有较高的潜在应用价值。

To obtain biocontrol strains with high control efficacy against watermelon Fusarium wilt,32 strains with high chitinase activity were screened in this study,by using colloidal chitin as the only carbon source,from more than 1000 strains isolated from mangrove rhizosphere soil in Zhuhai,Guangdong province.Furthermore,10 strains with high efficacy were obtained by using plate antagonism assay.The greenhouse results showed that the 10 strains had various growth promotion and disease prevention effects,among which the strain PL-29 treatment showed the best control efficacy of watermelon Fusarium wilt compared with the control.The control efficacy of strain PL-29 was 63.11%,and its growth promotion effect was also significant.The strain PL-29 was identified as Streptomyces flavotricini by morphological,physiological and biochemical characteristics and 16S rDNA phylogenetic analysis.In addition,the result of antagonism spectrum assay showed that the strain had antagonistic ability against Phytophthora capsici,Botrytis cinerea,Rhizoctonia solani and other pathogens.Further study on the inhibitory effect of strain PL-29 on Fusarium oxysporum showed that strain PL-29 could inhibit the formation and germination of F.oxysporum spores,and thus inhibit the growth of the pathogen.In addition,it can impair the integrity of the plasma membrane of F.oxysporum and induce ROS accumulation.These results indicate that S.flavotricini PL-29 has high potential application value in the control of watermelon Fusarium wilt.