Introgression of a high protein allele into an elite soybean variety results in a high-protein near-isogenic line with yield parity

Authors: PRENGER, ELIZABETH - University Of Georgia; Mian, Rouf; BUCKLEY, BLAIR - Louisiana State University; LI, ZENGLU - University Of Georgia

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2019
Publication Date: 10/17/2019
Citation: Prenger, E.M., Mian, R.M., Buckley, B., Li, Z. 2019. Introgression of a high protein allele into an elite soybean variety results in a high-protein near-isogenic line with yield parity. Crop Science. 59:2498-2508.

Interpretive Summary: The percent of crude protein in soybean seed and soybean meal of the U.S. elite cultivars have been steadily declining over several decades. This is a major concern of the soybean producers, processors and end users. Soybean meal is the largest source of protein meal worldwide. However, soybean seed protein content is negatively correlated with both yield and oil content, complicating the simultaneous improvement of seed protein and selection for high yield. A major protein QTL on chromosome (Chr) 20 has been identified in genome-wide association (GWA) and bi-parental population mapping studies. The effects of various sources of Chr 20 high-protein alleles have been studied in several Maturity Group (MG) II soybean genetic backgrounds. The high-protein allele is often associated with a significant increase in protein and decreases in oil and yield. The Chr 20 high-protein allele from a Korean cultivar, Danbaekkong (PI 619083), was introgressed into an elite MG VII cultivar, Benning (PI 595645), at the University of Georgia. A near-isogenic line (NIL), Benning HP, was developed through backcrossing and yield-tested in 2015 and 2017. Results from eight environments revealed yield parity between the recurrent parent, Benning, and the NIL, despite a 41 g kg-1 increase in protein in the NIL, but it contained 19 g kg-1 less oil than Benning. The results of this research should help soybean breeders to develop high yielding soybean lines with high seed protein.

Technical Abstract: Soybean [Glycine max (L.) Merr.] meal is the largest source of protein meal worldwide. The soybean meal is a highly desirable high-protein product with essential amino acids for animal growth and development. Soybean seed protein content is negatively correlated with both yield and oil content, complicating the simultaneous improvement of seed protein and selection for high yield. A major protein QTL on chromosome (Chr) 20 has been identified in genome-wide association (GWA) and bi-parental population mapping studies. The effects of various sources of Chr 20 high-protein alleles have been studied in several Maturity Group (MG) II soybean genetic backgrounds. The high-protein allele is often associated with a significant increase in protein and decreases in oil and yield. The Chr 20 high-protein allele from a Korean cultivar, Danbaekkong (PI 619083), was introgressed into an elite MG VII cultivar, Benning (PI 595645), at the University of Georgia. A near-isogenic line (NIL), Benning HP, was developed through backcrossing and yield-tested in 2015 and 2017. Results from eight environments revealed yield parity between the recurrent parent, Benning, and the NIL, despite a 41 g kg-1 increase in protein in the NIL, but it contained 19 g kg-1 less oil than Benning. This NIL may be used to develop high protein, high-yielding soybean varieties for the Southern U.S.