The Inheritance of High Protein

Soybean is a high protein crop. An average variety of soybean grown in Nebraska will have 30 to 36 percent protein in the seed. In contrast, corn has only 9% protein in the seed. If soybean is grown as a protein source for animals, raising the percentage of protein in the seed could improve this crop. Therefore, Dr. Graef has used several crossing strategies to develop high protein soybean varieties for Nebraska.

One improvement method used by Dr. Graef was to cross a soybean line that has a high protein plant introduction (PI) with a high yielding soybean line. The high protein PI had about 50% protein in the bean and the high yielding line had about 34% protein. The dozen or so F1 seeds generated from the cross could have their protein percentage determined by a near infrared analyzer (NIR) that nondestructively measures the seed’s protein content. The F1 seeds varied between 40 and 44% protein. On average, they had an intermediate protein level of about 42%. Based on this result, what hypothesis could we propose as to the control of seed protein in this cross?