Breeding Approaches for Introgressing Alleles From Wild Soybean (G. soja) Into Cultivated Soybean (G.max).

The amount of progress that can be made from breeding a crop species is directly related to the amount of genetic diversity present within the breeding program.  The amount of genetic diversity present in modern soybean [Glycine max (L.) Merr.] varieties currently grown in the United States has been shaped by three separate events: (i) the domestication of soybean from its progenitor species, wild soybean (Glycine soja), (ii) its initial introduction into the United States by way of only a few ancestral types, and (iii) through selection over the last 80 years of modern soybean breeding. This narrow genetic base can slow the amount of gains that can be made through conventional breeding methods.  One source of diversity that remains largely untapped is wild soybean. Past research has shown that G.soja contains alleles that can be used to improve seed composition, pest resistance, and tolerance to abiotic stress.  However, the use of G. soja in breeding efforts has remained minimal due to poor agronomic performance of the resulting progeny.  The focus of this research is to estimate the number of genes controlling a ‘Max-like’ phenotype using approximately 2,500 F2:3 lines derived from a single G.max by G.soja cross, as well as to evaluate the amount of diversity present in F4 derived lines developed from the cross of G. soja PI 366122 and the G. max variety ‘N7103,’ through field and molecular marker evaluation.  Two years of yield testing has revealed lines that are not significantly different from maturity checks in terms of agronomic performance that still yield within 75% of the G. max checks. Many of these lines still maintain characteristics of the G. soja parent. This research should offer guidelines on how to effectively manage G. soja in a soybean breeding program.