| Sclerotinia sclerotiorum (Lib.) De Bary is host widely and non-specific plant pathogenic fungi, and it is also the rape of china and other various economic crops’ important plant pathogenic bacteria. In this paper, strains of S.sclerotiorum from different areas of Sichuan Province were used to study the biological characteristics, pathogenic differentiation and genetic differentiation, so as to get whether there are differences in pathogenicity and genetic diversity between strains of S.sclerotiorum from different areas, and whether there are relationships under the different environmental conditions between them. The results of the study will deepen the people to the disease regulation in their understanding of S.sclerotiorum, which have the important instruction meaning. Test results are as follows:1、Sclerotial samples collected from different regions in Sichuan province, and then after separation and purification of bacterial strains to gain41strains of S.sclerotiorum. Through the determination of the growth speed of hypha of bacteria strains and morphological characteristics, it showed that there were significant differences of the different regions and strains in the colony morphology, growth speed of hypha, sclerotial formation, the number, size and weight of Sclerotium, matrix color, etc. After training various strains in the PDA, the cultivatable matrix can be divided into four differences, white, light brown, brown and green;41bacteria strains basically could be divided into12colonies form; the growth speed of hypha’s range were0.55cm/d-4.02cm/d; Sclerotium spit water time focused on4～6d, sclerotium forming time most concentrated in6～7d; Their fresh weight and dry weight of the range were0.10g～1.13g and0.06g-0.77g; The number and single weight of sclerotium of the range were respectively7-118and5.51～136.25mg. Analysing the relationship of the morphological properties in the strains of hypha growth speed, their spit water time, forming time, weight (dry weight and fresh weight), number and size, etc, the results showed that the indexes of different morphology characteristics are markedly different. Through the analysis of the characteristics of biology,30bacteria strains of S.sclerotiorum were screened as the selected material for the late experiment. 2、30isolates of S.sclerotiorum and2rape varieties were used to measure the lesions to evaluate the pathogenicity of the isolates by applying vitro blade inoculation and toothpick stalks inoculation,The results show that the pathogenicity of S.sclerotiorum from different area was difference, these differences aggressiveness of S.sclerotiorum might be closely related to geographical origins and the resistance level of rapeseed varieties. The correlation analysis of lesion diameter by the same inoculation method on two rape varieties proved that there were significant differences in vitro blade inoculation and toothpick stalks inoculation, respectively r=0.74**and r=0.73**(p≤0.01), the results on two rape varieties were same on the whole, only was lesion diameter different. The correlation analysis of hypha growth speed and different inoculation method showed that there was positively relationship between the growth speed of hypha and toothpick stalks inoculation, but not seriously, and the relationship between the growth speed of hypha and vitro blade inoculation was significant positively difference, which showed that the hypha growth speed faster, the pathogenicity of S.sclerotiorum stronger.3、30rapeseed varieties were inoculated with a same strain of S.sclerotiorum by stalk toothpick inoculation method. SRAP markers was used to analysis the genetic differentiation of30isolates of S.sclerotiorum. A total of467scorable fragments were identified with ten SRAP primer combinations; among them409were polymorphic loci proportion of polymorphic bands was87.58%.UPGMA (Unweighted Pair Group Method with Arithmetic Mean) indicated that the dendrogram consisted of five groups, when the genetic similarity coefficient was0.73. This study is divided into seven geographical sources in different areas, AMOVA (Analysis of Molecular Variance) revealed that the percentage of variation within the group and between groups among populations differed by different regions level(85.22%,14.78%,P<0.007). And on the basis of POPGENE analysis show that genetic differentiation coefficient is0.1492, which show that the genetic variation between groups was14.92%,and Gene flow is2.8512. The result with AMOVA analysis results are basically the same. One of the most significant results in this study was that S. sclerotiorum isolates from different regions are genetic differentiate between strains, and that genetic differentiation was closely related to geographical origins. |
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