Genetic Tructure And Biological Characterization Of Fusarium Graminearum Populations In Major Wheat Regions Of China

Fusarium head blight(FHB)caused by Fusarium spp.is one of the most significant diseases of wheat concentrately occurring and prevailing in warm and humid areas around the world and is a major threat of wheat production and food safety in China.If occurred,FHB not only cause damage to wheat yield,but also produce a variety of trichothecenes toxins causing serious harm to human and animal health.In recent years,FHB has been moving and spreading to the north and west in China,causing increased degree of damage in a spreading range.Therefore,it is urgently necessary to study the genetic diversity and biological characteristics of the pathogens to provide a theoretical basis for the FHB control.FHB is caused by a variety of Fusarium spp.,of which Fusarium graminearum is the dominant.In order to clarify the dynamic changes of F.graminearum populations of the main wheat producing areas in China,and explore the genetic differences and selection effects among pathogenetic F.graminearum populations,we studied the population genetic diversity and biological characteristics of F.graminearum strains isolated from the main wheat producing areas in China.On this basis,the evolution direction and biological characteristics of different populations were elucidated combining analysis with the biological characteristics of pathogenicity,toxin produce,spore yield and growth rate among different populations.The main results of the study are as follows:1.The degree of genetic differentiation and heterozygosity of different genetic populations of F.graminearum from different wheat producing areas were clarified.The total 164 tested strains were mainly F.graminearum isolated from main wheat producing areas in China in 2018,together with some strains from the Huanghuai wheat producing area in2008,the Southwest wheat producing area in 2008 and Hungary.The genetic structure of the tested F.graminearum population was analyzed by VNTR markers.The F.graminearum population in different wheat producing areas was divided into three POPs by structural heterozygosity analysis,linkage disequilibrium analysis and genotype diversity analysis.The results showed that POP1 and POP2 were genetically closest related.Among them,POP1 showed a low level of linkage disequilibrium,less internal communication and low population fusion.POP2 is a large random mating population with the lowest linkage coefficient reaching linkage balance,which means high intra-group fusion and frequent sexual reproduction.Showing high level linkage disequilibrium,the POP3 population has not been fully integrated with the local population.2.The expansion trend of F.graminearum population of different regions of the main wheat producing areas in China in different years was determined F.graminearum for test is divided into seven groups according to different years and wheat producing areas.Among these groups,the genetic relationship between Huanghuai18 and Southwest08 is the closest,and the linkage disequilibrium coefficients of Huanghuai18 and Sichuan18 groups were both higher than those of the groups of 2008.Groups of Hungary and Neimonggol showed linkage balance,which means high degree of internal integration and frequent sexual reproduction.The MLYR group showed linkage disequilibrium,indicating low sexual reproduction frequency.3.The biological characteristics of different populations of F.graminearum of the main wheat producing areas in China were clarified.There was no significant difference among different genetics populations according to the biological characteristics analysis.Among the groups divided by years and areas,the pathogenicity of Huanghuai08 and Huanghuai18 was significantly higher than that of Southwest18,while there was no significant difference between other populations or other biological characteristics.This indicates that the biological characteristics of F.graminearum of different wheat producing areas tend to be similar,which may be the result of the difference-reduced overall condition came from the planting models in different regions all tends to be large-scale and standardized with same variety selection.This study is conducive to strengthening the dynamic monitoring of key and potential pathogens and FHB occurrence,and lays a solid foundation for the study of the disease control.