Comparative Study On The Biological Characteristics And Pathogenicity Of MAT1-1 And MAT1-2 Of Verticillium Dahliae

V.dahliae is a soil-borne,broad host-range,plant pathogen that invades hundreds of dicotyledonous plant species but is generally considered an asexually(clonal)reproducing fungus.Although two mating types MAT1-1 and MAT1-2 have been found in V.dahlia,most of the research information about V.dahlia,including biology,pathology and genomics and genetics,comes from the research on the mating type MAT1-2.Therefore,there is little information in the literature about the V.dahlia strain of mating type MAT1-1.In this experiment,we first collected disease samples and isolated Pathogen from sunflowers and potatoes in different years and locations,and isolated a large amount of V.dahlia strains from sunflower seeds,stems,potato plants and tubers.Based on isolation,purification and molecular identification,after mating type identification of all V.strains,The difference in growth of MAT1-1 and MAT1-2 of V.dahliae strains were compared under different temperatures,p H,light,darkness,carbon sources and different stresses conditions.At the same time,after obtaining the heterologous expression strains of the two mating strains,the differences in biological characteristics and pathogenicity were also analyzed.The results were as follows:1.A total of 374 V.dahliae strains were isolated from diseased potato and sunflower strains,sunflower seeds and potato tubers using tissue isolation method.2.The results of mating type identification showed that there are two mating types of MAT1-1 and MAT1-2 for both potato and V.dahliae.However,MAT1-1 is the dominant mating type of V.dahliae of sunflower and MAT1-2 is the dominant mating type of V.dahliae of potato.The conidia and conidiophores of the two different mating-type strains have the same morphology,that is,the conidia are ovoid and transparent,while the conidiophores are typically verticillate.3.The analysis of biological characteristics shows that the MAT1-2 strain has a faster growth rate than the MAT1-1 strain and can produce more melanin.In addition,the MAT1-2 strain also has a higher ability to decompose polysaccharides,such as starch,pectin and cellulose.Therefore,compared with the MAT1-1 strain,the MAT1-2 strain not only has a stronger ability to adapt to the environment and the host,but also has a stronger pathogenicity.4.The results of the biological characteristics of the strains expressing different mating genes showed that the positive strains obtained after heterologous expression grew slower than the wild type;but under the same growth conditions,there was no significant difference in the growth rate between the heterologous expression strains.The shape is basically the same.Under different carbon source conditions,the utilization of carbon source by heterologous expression strains was significantly higher than that of wild-type strains,especially the strains with heterologous expression of MAT1-1-1 gene,and the utilization of carbon source was significantly improved.5.The results of pathogenic differentiation on different hosts showed that the pathogenicity of MAT1-2 strain P50 in its isolated host potato was significantly higher than that of sunflower;however,the MAT1-1 strain P48 was pathogenic on two different hosts.The difference in pathogenicity is not significant;however,the heterologous expression of different mating type genes in the above-mentioned strains can significantly increase the pathogenicity of MAT1-1 strain P48 on potatoes,but it reduces the pathogenicity of MAT1-2 strain P50.The pathogenicity of the above-mentioned heterologous expression strains on sunflowers is completely opposite to that on potatos.