Segregation and Monogenic Characters
The decisions the wheat breeding team will make are based on a high level of confidence in the predictable inheritance of the genes that control ALS resistance. This confidence comes from a past discovery by a biologist named Gregor Mendel, who explained the inheritance of trait variation using the idea of monogenic traits.
Monogenic characters are controlled by the following biological principles:
- Living things have genes in their cells that encode the information to control a single character. These genes are stable and passed on from cell to cell without changing.
- The genes are in pairs in somatic cells. When these cells divide to form gametes, the pair of genes is divided. One gene from the pair goes into a gamete.
- Male gametes (pollen) combine with female gametes (eggs) in the wheat flower pistil and fuse to form the next generation (zygote). Gamete union is random.
- The zygote, again, has two copies of each gene. As the zygote grows into a multicellular seed and the seed grows into a plant, the same two gene copies are found in every cell.
Wheat geneticists who concentrated on understanding the inheritance of ALS resistance found evidence that in many wheat families, this character is monogenic.
This is the nature of most of the work that scientists complete. Like Dr. Baenziger, most scientists determine if a new situation can be explained by a previously discovered and well established principle. If it can, the science transitions to a technology that allows scientists to make reliable predictions. If the new situation is not explained by established principles, they need to propose new hypotheses. Baenziger and his breeding team believed that they could work with the inheritance of ALS resistance as a predictable trait and provide the farmer with a reliable technology for weed control. Let’s take a short genetics history lesson to understand their confidence.