Relationship between Origin and Genetic Diversity in Chinese Soybean Germplasm

management and utilization of soybean germplasm. Knowing the range and distributionof the genetic diverThe soybean [Glycine max (L.) Merr. ] was domesticated in China. sity of a species can affect acquisition priorities for a Information about the amount and distribution of genetic diversity germplasm collection and sampling strategies for germinChinaiscriticaltoeffectivesoybeangermplasmmanagement.Inforplasm screening research or for establishing a core colmation is currently available from only a few provinces in China. The objectives of this research are to estimate the genetic variation within lection. It also allows breeders to better understand the and among four geographically diverse provinces (Zhejiang, Sichuan, evolutionary relationships among accessions and to deGansu,andHebei)inChinaandtodeterminetherelationshipbetween velop strategies to integrate useful diversity into their geographical origin and genetic diversity. Ten primitive cultivars from breeding programs (Bretting and Widrlechner, 1995). each province were characterized by random amplified polymorphic Several diversity studies in soybean have been conDNA(RAPD)fragmentsproducedfrom31selecteddecamerprimers. ducted using morphological characters, pedigree inforCNS, an important U.S. ancestral line, was also included as a control. mation, and biochemical variation (Nelson et al., 1987, Genetic variation was estimated by AMOVA analysis with 125 poly- 1988; Gizlice et al., 1994; Sneller, 1994; Bernard et al., morphic RAPD fragments. Genetic distances were calculated by means 1998). Although morphological and agronomic characof Jaccard’s coefficient and expressed as dissimilarity coefficients. Un- ters are useful in evaluating genetic diversity, collecting weighted paired group method using arithmetic averages (UPGMA), such data can be laborious and the phenotypic values Ward’s minimum-variance method, VARCLUS, and multidimensional are often strongly influenced by the environment. Bioscaling (MDS) were applied to define the genetic relationships. AMOVA chemical variants such as isozymes and electrophoresis identified significant genetic differences between all pairs of provinces patterns of storage proteins are less affected by the enexceptbetweenZhejiangandSichuan.Thegreatestdifferencewasobvironment but have limitedvariation. DNA markers are served between Hebei and Zhejiang. There was disagreement among an attractive alternative. They are nearly unlimited in the clustering methods, but each procedure identified clusters of acnumbers,presumablyselectivelyneutral,andcanbeorgacessions that originated from the same province. Based on data from all clustering procedures, six major clusters containing a total of 32 nized into linkage maps (Thormann and Osborn, 1992). accessions were defined with each cluster dominated by accessions There are several reports of using molecular markers from a single province. These data provide additional evidence that for evaluation of primitive soybean germplasm. RAPD primitive cultivars of China were generally genetically isolated in rel- markers have been shown to be a simple and effective atively small geographical areas.