Genetic separation of southern and northern soybean breeding programs in North America and their associated allelic variation at four maturity loci

Authors: Goettel, Herbert; An, Yong-Qiang - Charles

Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2016
Publication Date: 1/11/2017
Publication URL: https://handle.nal.usda.gov/10113/5695425
Citation: Goettel, H.W., An, Y. 2017. Genetic separation of southern and northern soybean breeding programs in North America and their associated allelic variation at four maturity loci. Molecular Breeding. 37(1):8. doi:10.1007/s11032-016-0611-7.

Interpretive Summary: Soybean maturity is an important agronomic trait. It directly affects the yield and growth acreage for each soybean cultivar. Soybean has only 90 years of breeding history in North America. During the short period, soybean breeders have successfully developed a large set of elite cultivars each with distinct maturity to maximize seed yield at specific ecological environments. To understand molecular and genetic basis underlying their diverse soybean maturity and their associated soybean breeding history in US, we analyzed a total of 75 major ancestry landraces and elite cultivars representing the 90-year soybean breeding history in North America. We showed that ancestry landraces were introduced from the locations at a wide range of latitudes from East Asia, and were used to develop many elite cultivars at similar attitudes in North America. We analyzed and visualized their pedigree relationships using networking approaches, and revealed a clear separation of southern and northern breeding programs in North America, suggesting that there is little genetic exchange between northern genotypes (Maturity group 0-IV) and north genotypes (Maturity Group V-VIII). Having analyzed variation of four soybean maturity genes (E1-4), we showed E1 had the predominant and most effective allele in northern cultivars, followed by E2 and E3 genes. We did not observe any E4 variation. However, the variation found in these genes is not sufficient to fully explain the maturity difference present in the cultivars, suggesting that additional genes are involved in regulating maturity of those cultivars. The knowledge gained from the study should help breeders to design an effective strategy to integrate superior gene pools of southern and northern cultivars to develop soybean cultivars suitable for a broader agricultural region.

Technical Abstract: Soybean has only 90 years of breeding history in North America. During the short breeding period, soybean breeders have successfully developed a large collection of elite cultivars with diverse maturity groups. To understand the molecular and genetic basis underlying the diverse soybean maturity, and its association with the soybean breeding history, we analyzed a total of 75 major ancestry landraces and elite cultivars representing soybean breeding history in North America. The ancestry landraces originated at diverse locations in East Asia, and were introduced at similar attitudes in North America to develop those elite cultivars. Network analysis and visualization of their pedigree relationships revealed that a clear separation of southern and northern soybean breeding programs in North America, suggesting that there is little genetic exchange between northern cultivars (Maturity group 0-IV) and north cultivars (Maturity Group V-VIII). Having analyzed allelic variation at four soybean maturity loci (E1-4), we showed e1 mutant allele is predominately in northern genotypes, followed by e2 and e3 mutant alleles. We did not observe e4 allelic variation. However, the variation of the alleles and their allelic combinations is not sufficient to fully explain their maturity diversity, suggesting that allelic variation at additional genes/loci is likely involved in regulating maturity of those genotypes.