Study On Mating Type Distribution And Screening And Identification Of Antagonists Of Phytophthora Infestans From The West Of Inner Mongolia

Potatoes are one of the world's major food crops, due to recent occurrence of Phytophthora infestans, the potato industry to the harm caused by relatively large. The test of the 2008 Inner West of Main areas of different potato late blight of potato strains were isolated, and the mating type of Phytophthora infestans to metalaxyl sensitivity distribution and the level of the test, while analysis of P. infestans to Dimethomorph and silver Farley sensitivity of the two agents to the western region of Inner Mongolia for the future breeding and control of potato late blight of potato late blight fungus to provide the theoretical basis and foundation. The experiment also from the rhizosphere of potato late blight in selected bacteria against effective biocontrol strains, and gain a basic identification and prevention research to obtain new biological pesticides to lay a foundation. The main results are as follows:1. The mating type of the isolates of Phytophthora infestans were collected from the west of Inner Mongolia in 2008. Among 94 isolates tested, 82 isolates belonged to A1 mating type, accounting for 87.2 % ; 8 was A2 mating type, accounting for 8.5 %; 4 was A1A2 mating type, accounting for 4.3 %; 13 was self-fertil mating type, accounting for 13.8 %. A2 mating were found in Inner Mongolia region in western potatoes.2. The sensitivities to metalaxyl of 94 isolates were assayed and the results that among 94 isolates tested, 91.49 % were highly resistant, 8.51 % were intermediate resistant. No isolate resistant were sensitive.Also it was found that the vegetative growth of some re sistant isolates was stimulated by metalaxyl. The sensitivity of 14 isolates to dimethomorph and 28 isolates to silver power with different levels of metalaxyl resistance were determined. EC50 values ranged from 0.002μg/mL to 0.021μg/mL to dimethomorph, the mean EC50 values was 0.005μg/mL; EC50 values ranged from 0.081μg/mL to 0.192μg/mL to silver power, the mean EC50 values was 0.143μg/mL, and the resistance to metalaxyl did not correlate to the resistance to dimethomorph or silver power.3. 2870 stains isolated from potato soil plots in Inner Mongolia, after repetitive co-culture on plates and Biometrics,10 strains,which were screened for their stable antagonist toward Phytophthora infestans,those strains named108,158,162 and T6.Inhibitory effects of biocontrol 108,158,162 and T6 against Phytophthora infestans were tested at mycelial growth, zoospore release, zoospore germination, sporangium germination produce inhibition of germ tube.The results showed that the four biocontrol strongly inhibited the mycelia growth, release of zoospores from sporangia and germination of zoospores,including 158 strains most significant inhibitory effect on potato late blight, the largest of the hyphe growth bacteriostatic width can 18.3 mm, But to the germination of sporangia of the the P. infestans inhibitory effect is not strong.4. The strains 108,162 and 158 were identified as Pseudomonas aeruginosa and the strains T6 was identified as Enterococcus casseliflavus by morphological, biochemical, physiolofical characteristics, as well as the 16Sr DNA sequence analysis.