| Potato common scab(PCS)is caused by the saprophytic filamentous Gram-positive Streptomyces scabieis and other pathogenic Streptomyces species.The disease is widespread and increases in the potato growing areas around the world.The development of the disease in potato growing areas in our country is becoming increasingly serious.At the same time,in the four major potato producing regions in China,the types of pathogenic bacteria are also different.It is necessary to investigate the pathogenic bacteria in various regions and propose corresponding prevention and control methods.At present,the biological control of potato scab at home and abroad mainly concentrates on the single strain,and there has been no report on the prevention and treatment of scab disease by compound fungicides.This study collected potato that infected common scab from four regions of Hohhot,Hulunbeier,Damaoqi and Duolun County,Inner Mongolia,and isolated actinomycetes from scab lesions.And pathogenicity test and system identification were used to determine the types of pathogens and major pathogenic bacteria types in the investigated area.Later,based on the laboratory research,the two strains that were separation and preservation in our laboratory were used to control the scab disease with the treatments including single strain and complex strains.During the period mainly obtained the following results:(1)A total of 127 strains of actinomycetes were isolated from the diseased parts of diseased plants collected in the four regions.We validated the strains with a series of methods such as pathogenic gene test and pot experiment.The results showed that 56 strains of Streptomyces had pathogenesis and the main pathogenic strains developed the typical scab lesion on potato tubers.(2)Using the two strains stored in the laboratory,through the compatibility measurement and co-cultivation methods,it was judged that the two strains did not inhibit each other and the inhibitory effect of the two strains was determined using a plate-to-tank method.(3)The pot experiment in spring,the biocontrol efficiency of two bacteria AMCC100018 and AMCC100179,showed that the control effect of the single strain on potato scab when used twice,reached 50.43% and 62.57%,respectively.and the application of two complex bacteria to control scab disease reached 67.30%.In autumn pot experiment,the control effect of the biocontrol bacteria AMCC100018 and AMCC100179 on scab disease reached 62.00% and 65.60% respectively,which was slightly better than that of the spring pot experiment,and the stability was better.When two complex bacteria were applied to the scab,the control effect reached 70.21%,forming a significant difference with a single strain.The results of pot experiments showed that the compound inoculants could significantly reduce the incidence and severe of potato scab,and had a good control efficiency.The two pot trials had a stable control effect.(4)The results showed that the supernatants of the biocontrol bacteria AMCC100018 and AMCC100179 had good inhibitory effects on other scab pathogens,and also had inhibitory effects on other plant pathogens.(5)The active substance produced by the biocontrol bacteria AMCC100018 was treated with different temperatures,pH,and different enzymes.The results showed that the activity decreased slightly with increasing temperature.The active substance was resistant to a wide range of acid and alkali.Enzymes had little effect on active substances.Antimicrobial substances produced by AMCC100179 still maintained a good antibacterial activity after being treated with different temperatures,pH,and different enzymes,indicating that the antibacterial substances produced by the two strains have good stability. |
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