Genetic and biochemical differences in populations bred for extremes in maize grain methionine concentration.

Background: Methionine is an important nutrient in animal feed and several approaches have been developed to increase methionine concentration in maize (Zea mays L.) grain. One approach is through traditional breeding using recurrent selection.

Backcross breeding.

Backcross breeding enables breeders to transfer a desired trait such as a transgene from one variety (donor parent, DP) into the favored genetic background of another (recurrent parent, RP). If the trait of interest is produced by a dominant gene, this process involves four rounds of backcrossing within seven seasons. If the gene is recessive, this process requires more generations of selfing and thus nine or more seasons are needed.