Polymerphisms And Growth Influencing Factors Of Cotton Verticillium Dahliae In Xinjiang

Cotton is the important economy crop in Xinjiang . Verticillium wilt caused by Verticillium dahliae, is an important disease on cotton, which has become a factor limiting the yield and quality of cotton, made great economy losing. In Xinjiang, the diseased cotton plants showing leaf-defoliating (LD) symptoms were reported in a previous survey, implying that the genomic structure of the pathogen in Xinjiang may be changed. Therefore, it is necessary to study the genome of this pathogen in Xinjiang. Main results were obtained as follows:From main cotton-producing areas (Shihezi,Bole,Hutubi,Akesu) in Xinjiang, 22 isolates of V. dahliae were obtained and single conidium (SC) isolation was made to further purification for these parental isolates.The pathogenicity differences between the isolates were detected on the four cotton varieties. On each cotton variety, no difference in pathogenicity were observed between 22 isolates in Xinjiang and T9,V151 and VD8. The results of the pathogenicity tests also showed that Zhongmian 35 was more tolerant to V.dahliae than the other three cotton varieties.The similarity coefficient between the isolates evaluated on the basis of the amplified DNA fragments was 0.75-1.00. Cluster analysis revealed that four RAPD groups (RG) could be classified at 0.625 except the V. dahliae isolates in Jiangsu, there is a significant different between the genetic distance and the region distribution among all isolates, and there is also a signification difference in pathogenicity. All these maybe was caused by frequently introduction of cotton seed in Xinjiang cotton-producing areas and in other cotton-producing areas.Ten specific bands from 25 strains RAPD patterns were transformed and cloned into T vector, and the corresponding positive clones were obtained, but only four clones from the bands were successful sequenced. By the BLAST in Genebank, no gene was found similar with the four positive clones.In the preliminary comparison of the cotton field soils from Xinjiang and Hainan, bacteria isolates from soil in Hainan against Verticillium dahliae were up to the inhibiting ratio of 53.85-61.54%, higher than that in the soil in Xinjiang (36.36 -45.45%). P and N contents in soil were found having a greater impact on pathogen growth than k content in the soil. P level in medium over 30 ppm inhibited the growth of V. dahliae. The inceasing in N content promoted the growth of two pathogens. The K content from 10 ppm-100ppm had no significant changes in V. dahliae and Fusarium oxysporum f.sp. vansifectum growth .