Pedigree Analysis of Elite Soybean Lines
- Clay H. Sneller
The reported genetic diversity of North American soybean [Glycine max (L.) Merr.] cnitivars is low. Public and industry breeders have initiated programs to expand the diversity. This paper assesses the impact of diversification efforts on the extent and pattern of diversity among elite lines and estimates the impact of industry on diversity. Coefficient of parentage (CP) analyses were performed with 122 lines from the northern and southern regions of the USA. The average CP was 0.173: this value was 0.233 among northern lines, 0.261 among southern lines, and 0.100 between lines from different regions. These values, and an analysis of the number of ancestors and their contribution of parentage to the elite population, were similar to values in previous reports, thereby indicating that recent efforts of public and proprietary breeders have had little impact on diversity among current elite lines. Minor differences in genetic diversity were noted between lines from public or proprietary sources. Industry has affected diversity by introducing parentage from PI 257.435, and the development of ‘A3127’ has served as a genetic bridge between regions. Cluster analysis distinctly separated northern lines from Maturity Group V and V1 lines and suggested four clusters within each region. Principal component analyses interpreted the clusters as groups of lines with genetic similarity to recently developed parents that were used extensively to generate the elite population. Genetic diversity within and between regions could be exploited by crossing pairs of lines that have a low CP. The effectiveness of this approach could be enhanced by using cluster patterns to achieve a more thorough sampling of the genetic diversity.
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