Detection Of Dimethomorph And Asoxystrobin Resistant Isolates Of Plasmopara Viticola From Main Grapevine Areas In China

Grape downy mildew,which is caused by Plasmopara viticola,is one of the most serious diseases on grapevine and can cause devastating damage.Though there are many effective methods but chemical applicatiuons are the most important to control grape downy mildew in vineyards.Among chemicals that were applied on grapevine in China,Carboxylic acid amide(CAA)fungicides and strobilurin fungicides are the main agents.Frequent applictions of chemical have the risk of resistance.So detection of resistance level is the scientific basis for chemical application.In this study,a molecular method —Taqman-MGB Technologies were developed to detect resistance for isolates of P.viticola to dimethomorph and Azoxystrobin.By the molecular methods,we detected the resistance level of P.viticola from some important grapevine areas in China,which are Beizhen in Liaoning Province,Qingxu in Shanxi Province,Binchuan and Yongning in Yunnan Province,Weixian in Hebei Province,Gongan in Hubei Province,Penglai in Shandong Province and Huaihua in Hunan Province.The main results are as follows: 1.Method by Taqman-MGB Technology was established to detect dimethomorph-resistance andasoxystrobin-resistance of isolates of P.viticolaThe dimethomorph-resistance of isolates was related to the mutation of the 1105 codon of the cellulose synthase gene of P.viticola The asoxystrobin-resistance of isolates was related to the mutation of the 143 codon of the cytochrome oxidase B gene of P.viticola.Depending on the technology,the sample which the content of DNA is 0.00126 ng can be detected.Compared with Tetra-primers ARMS PCR detection technology,this method is specific,false positive is lower.2.Detection of the dimethomorph-resistance level of P.viticola in 2016 by Taqman-MGBSamples of grape downy mildew are collected in 8 grapevine areas in China,including Beizhen,Liaoning Province;Qingxu,Shanxi Province;Weixian,Hebei Province;Penglai,Shandong Province;Gongan,Hubei Province;Huaihua,Hunan Province;Binchuan,Yunnan Province;Yongren,Yunnan province,and 2127 isolates were obtained.Detection of the dimethomorph-resistance level were carried out by Taqman-MGB.The results showed that the total of resistant strains was 1087 and 1040 strains were sensitive,the total resistance frequency is 51.1%,while,P.viticola from Beizhen,Penglai and Weixian have high dimethomorph-resistance frequency,which is more than 80%,while the isolates from Qingxu,Binchuan,Huaihua is low,less than 20%.3.Detection of the asoxystrobin-resistance level of P.viticola in 2016 by Taqman-MGBSamples of grape downy mildew are collected in 8 grapevine areas in China,including Beizhen,Liaoning Province;Qingxu,Shanxi Province;Weixian,Hebei Province;Penglai,Shandong Province;Gongan,Hubei Province;Huaihua,Hunan Province;Binchuan,Yunnan Province;Yongren,Yunnan province,and 2373 isolates were obtained.Detection of the dimethomorph-resistance level were carried out by Taqman-MGB.The results showed that the total of resistant strains was 1567 and 806 strains were sensitive,the total resistance frequency is 66%,while,P.viticola from Weixian,Yongren,binchua,Huaihua and Beizhen have high asoxystrobin-resistance frequency,which is more than 80%,while the isolates from Qingxu,Penglai is low,less than 10%.4.Suggestions about application of dimethomorph and asoxystrobin were discussedBased on the results of detection of dimethomorph-resistance and asoxystrobin-resistance of isolates of P.viticola,we discussed and supplied suggestions about application of dimethomorph and asoxystrobin in the areas related.