Title: Identification of positive yield QTL alleles from exotic soybean germplasm in two backcross populations Authors
Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 8, 2012
Publication Date: August 7, 2012
Citation: Kim, K., Diers, B., Hyten, D., Mian, R.M., Shannon, J., Nelson, R.L. 2012. Identification of positive yield QTL alleles from exotic soybean germplasm in two backcross populations. Journal of Theoretical and Applied Genetics. 125(6):1353-1369. Interpretive Summary: Increasing seed yield is the most important soybean breeding goal. Less then 1% of the available soybean lines in the USDA Soybean Germplasm Collection contribute to current commercial varieties. Utilizing more of this available genetic diversity is important to increasing the rate of the soybean yield improvement. The objective of this research was to identify specific chromosomal regions from two lines from the USDA Soybean Germplasm Collection that can increase the yield of U.S. varieties. One is a variety (Tie feng No. 8) released in China in 1970 and the second (PI 90566-1) was introduced into the U.S. from China in 1930. Experimental lines developed by crossing these exotic lines with U.S. varieties yielded significantly more than the U.S. variety demonstrating the positive contribution to yield from the introduced germplasm. We identified regions on chromosomes 4 and 16 from Tie feng No. 8 that contributed to the yield increase of the variety Elgin and a region on chromosome 3 from PI 90566-1 that contributed to the yield increase of the variety Williams 82. This is first time that yield enhancing genes have been reported in these chromosomal regions. These results can be used by soybean breeders to help increase yield of commercial varieties.
Technical Abstract: Increasing seed yield is an important breeding goal of soybean [Glycine max (L.) Merr.] improvement efforts. Due to the small number of ancestors and subsequent breeding and selection, the genetic base of current soybean cultivars in North America is narrow. The objective of this study was to map quantitative trait loci (QTL) in two backcross populations developed using soybean plant introductions (PIs) as donor parents. The first population included 116 BC2F3-derived lines developed using “Elgin” as the recurrent parent and PI 436684 as the donor parent (E population). The second population included 93 BC3F3-derived lines developed with “Williams 82” as the recurrent parent and PI 90566-1 as the donor parent (W population). The two populations were evaluated with 1,536 SNP markers and during two years for seed yield and other agronomic traits. Genotypic and phenotypic data were analyzed using the programs MapQTL and QTLNetwork to identify major QTL and epistatic QTL. In the E population, two yield QTL were identified by both MapQTL and QTLNetwork, and the PI 436684 alleles were associated with yield increases. In the W population, a QTL allele from PI 90566-1 was associated with a 30% yield increase, however, the PI region also was associated with later maturity and shorter plant height. No epistasis for seed yield was identified in either population. No yield QTL were previously reported at the regions where these QTL map indicating that exotic germplasm can be a source of new alleles that can improve soybean yield.