ARS | Publication request: A GENOMIC PERSPECTIVE ON THE SOYBEAN PROTEIN(+)/OIL(-)YIELD(-)ENIGMA

Submitted to: Cellular and Molecular Biology of Soybean Biennial Conference
Publication Type: Proceedings/Symposium
Publication Acceptance Date: August 31, 2002
Publication Date: August 20, 2002
Citation: SPECHT, J.E., NELSON, R.L., WEBSTER, R., NAIDU, S., AINSWORTH, E., ORT, D.R. A GENOMIC PERSPECTIVE ON THE SOYBEAN PROTEIN(+)/OIL(-)YIELD(-)ENIGMA. CELLULAR AND MOLECULAR BIOLOGY OF SOYBEAN BIENNIAL CONFERENCE. 2002. p. 202.

Technical Abstract: The soybeans [Glycine max(L>) Merrill] seed protein is negatively correlated with seed oil and yield. A number of QTL mapping studies have been conducted to date involving matings of a high-protein (less than 48 percent) low-yield parents with high-yield parents exhibiting ordinary protein (less than 42 percent). A QTL with a major effect on protein/oil/yield has been repeatedly detected on LG-I, and we recently mapped it to a small genomic segment (0.84-cM) flanked by Satt700/496 and Satt239. In populations segregating for the parental alleles at this QTL, regression of protein and oil on the yield revealed respective coefficients of -2.6 and +1.6 percentage points per kg ha**-1 (i.e., a protein/oil exchange ratio of -1.6). The additive effect of the high protein parental allele on seed protein and oil was a respective +1.0 and -0.6 percentage points (a protein/oil ratio of -1.6), and its effect on the yield was -154 kg ha**-1. A graph of seed protein and oil on the yield of the 475, released cultivars in the soybean germplasm collection, reveals a similar relationship. Given that the genic-based protein/oil exchange ratio is 1.6, and that the calorific-based oil/protein ratio is theorized to be 2.0, one might expect the remaining 0.4 units of carbon and/or energy to be available for enhanced (other) seed dry maters. However, both oil and yield invariably fall when seed protein is genetically enhanced, suggesting that protein synthesis and its deposition in the seed in energetically more costly to the plant than physiologists have commonly assumed.