Gentic Diversity Of Sclerotinia Sclerotiorum Isolate From Soybean And Variety Resistance

Soybean Sclerotinia sclerotiorum is one of the major diseases of Soybean production, it has occurred in Heilongjiang Province and Inner Mongolia provinces of china. The main purpose of this study is identifying morphology, vegetative compatibility and genetic diversity of diffrent regions and sources of Sclerotinia isolates to obtain the main specific differences between different sclerotiorum.This study has separated 233 isolates of soybean Sclerotinia sclerotiorum from Heilongjiang Province and evaluated the growth rate and sclerotia production of 88 Sclerotinia sclerotiorum isolates that cultured on PDA medium.The result shows generally that isolates colony formation are fast, most of the isolates can be touched the edge of the Petri dish in 3 day. colony growth rate of isolate averaged 2.486 cm/d. The average growth rate of isolate of Jianan Farm area was the lowest growth rate,no more than 2.000 cm/d, for the 1.686 cm/d. Isolates from different region were all highly significant difference on the number in the production of sclerotia, sclerotia fresh weight (P<0.001).Through nutrition-friendly pilot study,233 isolates of Sclerotinia sclerotiorum were divided into 39 vegetative compatibility groups.32 VCGs contained only one isolate, the percentage of 32VCGs among 39VCGs was 81.2%.34 isolates from Jianan Fram were divided into 22 VCGs, The percentage among 39VCGs was 54.6%,17 VCGs contained only one isolate. The results showed that the division of affinity groups related to geographical origin to a certain extent, but not absolute. One of the largest group even included sclerotinia sclerotiorum isolates from all geographical sources, but in the same plowland existed several different types of affinity groups.With six pairs of polymorphic SSR primers, genetic diversity of 180 isolates of sclerotinia sclerotiorum were analysed, and results showed that the genetic similarity of isolates were extremely high UPGMA cluster analysis was performed by soft NTYSIS-pc2.01, the clades formed 7 populations at the dice coefficient of 0.71.UPGMA Cluster analysis showed that most individuals from the same area gathered in the same group or adjacent group, but the isolates from same regions were found in different cluster groups.The result showed that after 7 day inoculating in cotyledons, all plants with white mycelia died 7 days later. Detached leaf assays bassically showed that white mycelia appeared in inoculation 3 days later, by the two methods currently were unable to find disease-resistant germplasm.