Analysis Of Genetic Diversity And Drug Resistance Of Botrytis Ginseng

Panax ginseng C.A.Meyer is a perennial herb of Araliaceae family Panax genus.one of a traditional and precious Chinese herbal medicine in China.The damage of grey mould in ginseng production area of Northeast China is increasing year by year,which has becoming one of the most important factors influence the sustainable and healthy development of ginseng industry.In view of the severe situation of grey mold prevailing in ginseng producing areas,in the present work,following with the isolation and identification of Botrytis cinerea isolates from main ginseng producing areas locating at Liaoning-Jilin and Heilongjiang provinces,the fungicide resistance and pathogenicity of them were tested in the laboratory.Furthermore,genetic diversity analysis of B.cinerea isolates from different geographic distribution were carried out by ISSR molecular marker.Through above research,the current status of fungicide resistance of B.cinerea isolates in ginseng producing areas of China was clarified,the relationship of pathogenicity difference and genetic diversity of these isolates from different geographic regions was clearly explained.Results of the present work provided us important theoretical reference for scientific control of grey mold in ginseng producing areas,and the main results were summarized as follows:1)In total,102 isolates of B.cinerea were isolated from diseased leaves of P.ginseng cultivated in Liaoning,Jilin and Heilongjiang provinces of China.These isolates were identified as B.cinerea by colony morphological and molecular biological methods.2)The mean genetic diversity(Ht)of B.cinerea population is 0.3395,the mean genetic diversity(Hs)within geographical distributed B.cinerea population is 0.2937,the mean value of genetic diversity(Dst)between geographical distributed B.cinerea population is 0.0458,which indicates that B.cinereapopulationsfrom different geographical distribution is not as obvious as that within B.cinerea populations.The mean genetic differentiation coefficient(Gst)between B.cinerea populations is 0.1348.and the mean gene flow(Nm)is 3.2084,indicats that there no evident genetic differentiation among B.cinerea populations from ginseng producing areasin Northeast China,and the differentiation was mostly oringined from the inner of populations.Clustering results showed that the genetic similarity coefficients were ranged from 0.38 to 0.99,and isolates could be divided into four groups at the threshold of 0.52.When the threshold value is 0.65,the tested isolates can be divided into 13 groups(group A to group M),except for group A,group D,group E,group F and group J,the remaining groups contain only one strain.The results show that the genetic clustering of B.cinerea has nothing to do with geographical origin.3)According to the size of lesions on the leaves of P.ginseng,the pathogenicity of B.cinerea was divided into three grades:weak pathogenicity grade,medium pathogenicity grade and strong pathogenicity grade.Among them,the isolates with medium pathogenicity rank the most,accounting for 77.45%;the isolates with weak pathogenicity rank the next,accounting for 16.67%;the isolates with strong pathogenicity rank the least,accounting for 5.88%.The pathogenicity test results showed that there are significant pathogenic differentiation among P.ginseng isolates.4)The minimum inhibitory concentrations method was used to test the resistance of 102 B.cinerea isolates against commercial fungicide frequently used inginseng producing areas.Results showed that the resistance frequency of B.cinerea isolates against carbendazim(C),pyrimethanil(P),isocarbazide(I)and fludioxonil(F)were 100%,86.27%,73.53%and 30.39%,respectively.The fungicide resistance of B.cinerea isolates from Liaoning and Jilin provinces against pyrimethanil and isocarbazide were higher than the average level of the three provinces.According to the results of fungicide resistance test,all 102 isolates were divided into 7 resistance types,i.e.CRPRIRFR,CRPRIRFs,CRPRIsFR,CRPRIsFs,CRPsIRFs,CRPsIsFR and CRPsIsFs,which accounting for 26.47%,39.22%,4.90%,14.71%,5.88%,0.98%and 7.84%,respectively.No isolates imultaneously sensitive to four fungicides tested were found.