The Ultraviolet Mutagenesis Of Antagonistic Streptomyces Sp.CC5 And Biocontrol Potential Against Potato Scab

Potato scab is a soil-borne disease of potato(Solanum tuberosum L.)that occurs in most potato production areas of the world.Recent years,with increased significantly potato acreage,the potato scab has developed into a major potato disease and become one of the· most important factors affecting the quality of potatoes.An antagonistic strain Streptomyces sp.CC5 was isolated from soils.In addition,the strain Streptomyces sp.CC5 has great inhibition to different plant pathogens in plates,such as Fusarium oxysporua cumebrinm Owen,Magnaporthe oryzae strain Guy11,Phytophthora capsici Leonian,Streptomyces scabies,Erwina carotovora subsp.earotovora(Jones)Bergeyetaz,Erwina.aroideae,Erwina carotovora subsp.EG.It also showed great inhibitionto nonpathogenic bacteria,such as Streptomyces sp.M30 and Streptomyces sp.P3.Theinhibitory diameter were from 5.8 mm to 12.5 mm.And the inhibitory diameter of Streptomyces scabies was 10.5 mm.Because Streptomyces scabies was the pathogenic bacteria of potato scab.So the strain Streptomyces sp.CC5 can be used as a kind of bio-control resource on the biocontrol of potato scab.Genetic instability and the low production of secondary metabolites is a common occurrence in Streptomyces.Streptomyces sp.CC5 was induced by physical mutagenesis method of UV And we used Streptomyces scabies(SC)which is the pathogen of potato scab as indicator.At last,63 strains of mutant culture are screened and 12 strains of high yield strains are verified.The positive mutation rate is 19.04%.And the activity of the highest yield strain CC5-6 is increased by 25%than the wild type strain.The results of genetic stability experiment showed that the mutant strain CC5-6 has a good genetic stability.In this study,The biological characteristics of strain SC under different conditions were studied,including temperature,pH and lethal temperature.The results showed that the optimal grow temperature and pH of SC was 30? and pH 6-8,respectively.The lethal temperature of SC was 65?.The small potatochips experiment was used to detect the pathogenicity of SC.The small potatochips infected by SC were cultured in 28? for four days.The results showed that the morbidity of small potatochips was 100%.In the potato pot experiment,the biocontrol effect of CC5-6 was 33.9%.