西洋参根腐病拮抗菌XT-25的生防作用研究OA北大核心CSTPCD

This study explored the application of biological control technology in managing the root rot disease of American ginseng.Fusarium solani and Ilyonectria mors-panacis,two major fungal pathogens causing root rot,were used as targets to screen antagonistic biocontrol bacteria from the rhizosphere soil of American ginseng.Through confrontation culture experiments,the antagonistic bacteria were screened based on their mycelial inhibition activity,bacteriostatic activity,effects on promoting biomass,and ability in controlling pathogen growth in the inoculation experiments in vitro.The results showed that a strain,XT-25 was isolated,which has a>55%inhibition rate against two species of American ginseng pathogens.Combining morphological characteristics and phylogenetic analysis of 16S rRNA,atpD and rpoB genes,strain XT-25 was identified as Streptomyces lavendulae.In addition to root rot inducing fungi,XT-25 showed a 59%～70%inhibitory effect against 6 other pathogens such as F.oxysporum f.sp.cucumerinum.Next,the antifungal mechanism of XT-25 on root rot of American ginseng were investigated.Notably,XT-25 has the ability to secrete enzymes such as protease,amylase and β-1,3 glucanase to inhibit the growth of fungi.It has the ability to dissolve organic phosphorus and inorganic phosphorus,produce ammonia,fix nitrogen,and secrete IAA and ACC deaminase,which may contribute to biomass promotion.Meanwhile,the volatile gas constituent of strain XT-25 showed a 9.04%inhibition rate against F.solani.It also induced deformity of F.solani and I.mors-panacis hyphae.For the in vitro American ginseng root inoculation experiments,XT-25 demonstrated 40.00%and 24.74%control effects on the root rot caused by F.solani and I.mors-panacis,respectively.In summary,the study of strain XT-25 can provide biocontrol materials and theoretical references for the prevention and treatment of Panax quinquefolium root rot caused by Fusarium and Ilyonectria.