Preliminary Study On Pathogenicity Of Verticillium Dahliae And Its Vegetative Compatibility In Guanzhong Shaanxi

Verticillium dahliae kleb. is the worldwide fungus disease, which causes severe vascular wilt in many crops and heavy economic losses. The pathogenic differentiation of strains could be divided into three patho-types:TypeⅠ(a severe virulence), TypeⅡ(an intermediate one), TypeⅢ(a mild one). In order to Jingyang strain is the highest aggressiveness strain which come from the area of Shaanxi Guanzhong, We studies on Pathogenicity and vegetative compatibility tests for the strains of Verticillium dahliae to explicit the pathogenicity of Verticillium dahliae in the local area and to provide the theoretical testimony for the aberrance rule of pathogen. Therefore we are more scientific methods to control the disease.First of all,The cultural character of 27 representative strains of V. dahliae on the PDA substrate showed that there are three cultural type: black (sclerotium type), white (filamentous fungus) and middle. Furthermore, the white is all belong to TypeⅠ,part of TypeⅠalso have the black one;the middle are all belong to the TypeⅡ;the TypeⅢis the black.Foremore, The biological characteristic studies with 27representative strains show that the most appropriate temperature of grows for V. dahliae is 25℃,and a few strains can quickly grows in 20℃.In addition, the determination of pathogenicity in the seedling stage has also showed that difference exist among the 30 representative strains. According to the reaction types on 3 species cottons with different resistance, all strains can be classed into three pathogenic types: typeⅠ(16 strains, accounted for 53.3% of the total) was characterize by severe virulence, typeⅢ( 7 strains, accounted for 23.3%) showed mild virulence and typeⅡ( 7 strains, accounted for 23.3%), an intermediate type.Finally , in order to explicit the relationship about pathogenicity and vegetative compatibility(VGC) of Verticillium dahliae on shaanxi guangzhong, we have studyed vegetative compatibility of those 21 strains of Verticillium dahliae .Based on the formation of complementary heterokaryons, 364 Nitratenonutilizing (nit) mutants were obtained from 21 strains which induced on KPS media ,in which 289 mutants were Nit1,It accounted for 79.40% of the total;72 mutants were nitM, It accounted for 19.78% of the total; only three strain was Nit3.They also showed that 21 strains were assigned to three vegetative compatibility groups (VCGs): 17 representative strains of V. dahliae and the jing-yang strain were compatible with each other and classified into the VGC1,while the anyang strain was classified into the VGC2 and the xin-jiang strain was classified into the VGC3.