Analysis Of Genetic Base And Establishment Of Core Collection For Chinese Soybean Cultivars

China released 749 cultivars from 1923 to 2000. However, their genetic relationship and diversity was not well characterized. The objective of this study was to quantity genetic diversity difference between Chinese ancestors and their offspring cultivars, and confirm a molecular pedigree method to access the genetic relationship for accessions related to each other, and establish Chinese cultivars core collection to obtain least diversiform resources for parents selection. The main results were summized as the following:1. Pedigree allele method could access genetic relationship of accessions related to each other, especially in the same pedigree branch. Estimates of genetic relationship among Zihua 4 and its offsprings were calculated from 18 SSR markers linked to important agricultural traits using pedigree allele method and common allele method, and expressed as similarity index. Genetic contribution from Zihua 4 to its offsprings by two methods was significantly different, and two similarity index matrixes were fit poorly. Analysis of Jinyuan and its offsprings proved pedigree allele method was more efficiently to access genetic accessions with kinship by using 60 SSR core primers on 20 soybean linkage groups.2. A total of 104 ancestors and cultivars were chosen as Chinese soybean cultivars core collection. Originally, primary 137 cultivars were selected, they were 28 core ancestors because of their fractional genetic contribution to cultivars, and milestone cultivars for their much area or important status in pedigree. According to their molecular dengdrogram, kinship among accessions, special allele and importance in pedigree were synthetically thought about, 100 accessions were reserved on the base of 403 alleles, diversity index 76.2% and similarity coefficient no significant difference to primary zccessions, 104 accessions were finished as core collection.3. Genetic base for cultivars was determinded. A set of 31 SSR core primers were used to analyze 12 excellent cultivars and their core ancestors, and detected 212 alleles with average 6.84 alleles per locus. Therefore, genetic base for cultivars trended narrow, but didn't reach significant level. lOScultivars in primary core collection were calculated for similarity coefficient and ancestors number, and it was indicated that genetic base of soybean cultivars was the worst in the 1960's, most abundant in the 1980's, and narrow lightly in 1990's. Other, there was no obvious correlationship between similarity coefficient and ancestors number among cultivars.