Genetic and Phenotypic Variation for Seed Protein Content In Advanced Backcross Derived Soybean Populations.

Soybean [Glycine max (L.) Merr.] occupies over half of the world’s oilseed production which can be attributed to the value of protein and oil found in the seed.  Increasing the amount of protein in soybean seed would expectantly lead to greater value of the commodity on the world market.  However, increasing seed protein, particularly in northern environments (i.e. Minnesota), has been a challenge.  The combination of a relatively short growing season and the lack of variation in the elite, adapted germplasm pool has hampered the development of high yielding, high protein genotypes.  A project was initiated in 1989 to characterize and introgress a high seed protein phenotype from the plant introduction (PI) 153296 (~46% protein) to cv. Evans (~36% protein), a historical Minnesota elite variety, using successive backcrossing (recurrent Evans).  At present, ~260 BC₄F₅ lines derived from the high protein donor and Evans have been developed.  The objective of this research was to evaluate these advanced backcross derived lines in replicated field trials in 2010 and 2011.  While protein levels in the BC₄F₅ lines did not reach that of the donor parent, protein increases of approximately 4 percentage points over Evans were observed (without yield penalty). Based on phenotypic data collected in 2010, a subset of 192 individuals was assayed with molecular markers for subsequent QTL analysis.  Ultimately, an agronomically sound, adapted soybean line with increased seed protein will be a valuable resource for future varietal development.