| Verticillium dahliae Kleb.is the worldwide soil-borne fungus disease,which makes severe vascular wilt in more than 660 plants and causes heavy economic losses.The pathogenicity of Vdahliae has a high variability,and in the process of co-evolution with the host and the environment,it often appeared physiological differentiation.Therefore,monitoring the culture,genetic characteristics and pathogenicity of Verticillium dahliae is a long-term basic work.In order to explore the differentiation and regularity of V.dahliae and to provide the theoretical testimony for establishing disease control techniques,the culture characteristic,pathogenicity test,the pathogenic types,the carrying situation of avirulence gene Ave1 and mating type analysis of strains of V.dahliae collected from 7 provinces in China were studied and obtained the following research results.The culture characteristics,pathogenicity and genetic variation of V.dahliae,288 isolates were analyzed,which include the 301 isolates preserved in the laboratory and collected from cotton planting areas in Jiangsu Province in 2015-2016 and the other 258 ones preserved in the lab.Morphological observation showed that all the pathogens except four were identified as V.dahliae.According to the quantity of microsclerotia of the colonial morphology on PDA,the strains were divided into three cultural types;The sclerotium type,the hyphal type and the intermediate type accounted for 52.1%,23.6%and 24.3%respectively.Among them,178 strains of V.dahliae were isolated from the main cotton-planting areas in Jiangsu Province from 2002 to 2016,and 97 ones were sclerotium type,accounting for 54.5%;in 96 strains of the pathogen were isolated from diseased cotton in Jiangsu Province from 2011 to 2016,the sclerotium type accounting for 79.7%,the results indicated that the sclerotium type had become the dominant population of V dahliae in main cotton area of Jiangsu Province.We select representative strains to determine the pathogenicity of V.dahliae on cotton and eggplant plants,the results displayed that there was obvious differentiation of pathogenicity of V.dahliae on different crops.The pathogenic types of V.dahliae,the carrying situation of avirulence gene Ave1 and mating genotypes were detected by specific primers.Using specific primers D-1/D-2 and ND-1/ND-2 detected pathogenic type of 301 strains of V.dahliae through PCR technology.PCR results showed that 196 of the 262 samples are defoliating V.dahliae strains,accounted for 74.8%,the other 31 samples are nondefoliating V.dahliae strains and occupied 11.8%.And the last 35 strains,accounting for 13.4%,which were not grouped due to no amplifying.The proportion of defoliation pathotype strains was much greater than the other two strains,shows that the V.dahliae was still centralized by defoliation pathotype.The results of pathogenic types assay showed that 38 strains of V.dahliae isolated from eggplant and one strain from strawberry were nondefoliating.Using specific primer(VdAve1F/VdAve1R)detected whether carrying the avirulence gene Ave1 in V.dahliae,and V.dahliae strain 'JR2' from tomato was used as a positive control,the result was not found in any V.dahliae strain from cottons and eggplants employed in this study.Pairs of primers(VdMAT111F2/VdMAT111R3 and VdMAT12F/VdMAT12R)were designed for detection of the two mating-type genes,301 of single ascospore isolates were employed to detect mating-type genes based on PCR amplification in this study.The results indicated that the strains preserved in the laboratory were MAT1-2,and no MAT1-1 was found. |
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