Impact of Transgenic Genotypes and Subdivision on Diversity within Elite North American Soybean Germplasm
- Clay H. Sneller *
There are several recent trends in North American soybean [Glycine max (L.) Merr.] breeding that call for a new evaluation of the pedigree structure of this population. These are the introduction of Roundup Ready (RR) soybean and restricted exchange of germplasm between breeding programs. The objectives of this study were to assess the genetic structure of the current elite North American soybean population and the current and potential affect of RR soybean and crossing restrictions on this population. This study used coefficient of parentage (CP) analysis of 312 current RR and conventional lines. The RR trait was initially backcrossed into elite lines from a total of 30 different recurrent parents. Many of the intermediates of the backcrossing were also crossed to other elite lines and it is from such crosses that many of the current RR lines derive. Only 1% of the total variation in CP among lines from the northern or southern regions was accounted for by differences between conventional lines, RR lines, and the recurrent parents used to initiate RR breeding programs. The advent of RR cultivars has had little impact on diversity because of the wide use of this technology by many programs and its incorporation into many lines. In contrast, 19% of the variation in CP among northern lines, and 14% among southern lines, was due to difference between lines from different companies and institutions. Diversity was limited among elite lines from some companies. The restricted diversity within some companies coupled with limited exchange of germplasm could affect the soybean industry if marketplace shifts favor one company. Public programs can work to ensure and expand diversity.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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