Fine mapping of a seed protein QTL on soybean linkage group I and its correlated effects on agronomic traits

Soybean [Glycine max (L.) Merr.] is primarily grown as a source of protein and oil. A quantitative trait locus (QTL) controlling seed protein concentration was previously mapped to linkage group (LG) I of soybean. The objectives of this study were to fine map the QTL and to determine if additional recombination could reduce the inverse phenotypic relationship between seed protein concentration and yield and oil concentration. The fine mapping was done with two sets of backcross populations that were tested in the field and with genetic markers. These populations were developed by the introgression of a high protein allele from the Glycine soja Sieb and Zucc. plant introduction (PI) 468916 into the genetic background of the breeding line A81-356022. The first set (Set 1) included three populations of backcross-four (BC4) lines, and the second set (Set 2) included four populations of BC5 lines. The populations segregated for different segments of the genomic region where the QTL maps. Tests of the two sets of populations resulted in the localization of the QTL for protein and oil to a 3-cM interval between the simple sequence repeat (SSR) marker Satt239 and the amplified fragment length polymorphism (AFLP) marker ACG9b. The results from the agronomic trait evaluations were inconsistent, making it difficult to definitively conclude whether the protein QTL controls these other traits through pleiotropy.