Study On Genetic Diversity Of Chinese Resistant SCN Germplasm And The Conformation Of Resistant Gene Between Chinese And American Soybean

Soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) is the most destructive pest of soybean. Host plant resistance is the most cost-effective and environmentally friendly method of controlling SCN. Research on SCN had been emphasized in many countries. China was the original and the center of diversity of soybean. There were abundant gennplasm resistant to SCN, while research about diversity was seldom performed. The America soybeans were introduced from China mostly. There are special gennplasm and excellent resistant variety. However, there are few reporters about the relationship between American and Chinese resistant SCN germplasm. In this study, we analyzed the phenotypic diversity of Chinese resistant germplasm according to the Chinese Cultivated Soybean Database and 27 immune or high resistant accessions were select to construct the core collection for gennplasm resistant to SCN. Using SSR markers, we analyzed the genetic diversity of core collection. Simultaneously we compared the difference of the construction of the gene resistant to SCN between Chinese and American resistant germplasm by PCR-SSCP. The aim of this study was show the diversity of Chinese germplasm resistant to SCN and the difference between Chinese and American resistant germplasm.There are plenty of resistant SCN germplasm in China. The resistant are distributed in North Spring eco-region and HuangHuai Summer eco-region mainly. Examination of phenotypic diversity of Chinese germplasm resistant to SCN showed that the quantitative traits have more phenotypic diversity than qualitative traits. Among qualitative traits, hilum color, seed color, seed shape and leaf shape have more diverse information. The representation for phenotype between the core collection and the whole gennplasm was tested by Chi-square test of distribution of frequency of qualitative trait and F test of quantitative trait. The result shows that there is not obviously difference on phenotype between the core collection and the whole germplasm except crude oil and 100-seed weight. Using the phenotypic data and molecular data, we have the same cluster-analysis result among different populations from different eco-regions or provinces. The relationship between resistant character and polymorphism alleles was tested by X2. There is obviously difference frequency of alleles on 15 SSR loci between resistant and susceptible accessions and a total of 130 alleles were identified with an average of 8.7. The range of Shannon-weaver index is 0.744-1.855.In this study, some special primers were designed according to the sequences of rhgl and Rhg4. Using the PAGE gel and MDE gel as substratum, the technique of PCR-SSCP was operated. The SNPs (single nucleotide polymorphism) of resistant SCN germplasm between China and America was analyzed. The result shows that there are special resistant source that are not existed in America in China. The relationship between resistant character and polymorphism alleles was tested by X . There is obviously difference frequency of alleles on 4 loci between resistant and susceptible accessions and not difference among resistant accessions to different SCN races. On rhgl locus, there are 4 pairs of polymorphous primers, account for 44.4percent in total polymorphous primers. The America resistant accessions have the maximal similarity coefficient with breeding parents and the smaller with resistant core collection. That means there is special genetic material in Chinese resistant germplasm. These germplasm is very important for resistant SCN breeding. Our study detected the SNPs using MDE gel and showed that the MDE gel can detect the allele that can not be found in PAGE gel. That increases the efficiency to detect the SNPs.