Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2000
Publication Date: N/A
Citation: Interpretive Summary: Almost all of the ancestors of U.S. varieties originally came from China. Soybean breeders in China have released more than 650 soybean varieties over the past 75 years and most of the ancestors of these varieties originated in China. Although modern U.S. and Chinese varieties originated from ancestral lines from China, we don't know how closely related the ancestors of U.S. and Chinese varieties are. There are no pedigree records that we can use to relate these ancestral lines but we can estimate the genetic relatedness of these ancestors by comparing DNA patterns. DNA carries the genetic instructions for living organisms and the varieties with more similar DNA can be assumed to be more closely related. Our results showed that although many of the U.S. ancestral lines originated from the same regions as the Chinese ancestral lines, the U.S. ancestral lines were genetically very different from the Chinese ancestral lines. The greatest genetic differences were found between the ancestral lines from southern China and the U.S. ancestral lines. These results show that the two largest national soybean breeding programs in the world have very different genetic origins. By using Chinese-developed varieties as parents in their breeding programs, U.S. soybean breeders can tap into a source of potentially very useful, new genes for increasing yield.
Technical Abstract: Most of the U.S. soybean ancestral lines were introduced from China but nothing is known of the genetic relationships between the ancestors of modern U.S. and Chinese cultivars. The focus of this research is to determine the genetic relationships between 18 ancestral lines that contributed more than 85% of the genes found in modern U.S. soybean cultivars and 32 ancestral lines that are in the pedigrees of more than 75% of the modern Chinese cultivars. Genomic DNA from these lines was characterized using random amplified polymorphic DNA (RAPD) with 35 selected decamer primers. Based on the presence or absence of amplified DNA fragments, simple matching coefficients were used to calculate similarities between pairs of lines. Cluster analyses generally separated the ancestral gene pools of the U.S. and China. Clusters reflected the geographical origin of the lines. Large differences exist between northern U.S. and Chinese ancestral lines and central and southern Chinese ancestral lines. The pattern of diversity found within the U.S. and Chinese ancestors can aid breeders in selecting parental lines to more efficiently exploit the diversity found in these two major gene pools.