To adequately confront rapidly changing plant pests and diseases and safeguard food security for a growing population, breeders — in collaboration with their partners — have to keep testing and applying new breeding methods to deliver resilient seed varieties at a much faster rate using minimal resources. Molecular markers are essential in this regard and are helping to accelerate genetic gains and deliver better seed to smallholders across sub-Saharan Africa in a much shorter timeframe.
“There are three stages in the use of molecular markers: discovery, validation and deployment,” [maize molecular breeder Manje Gowda] explains. “At the discovery phase, the objective is to find molecular markers associated or tightly linked with the trait of interest, while also assessing whether the trait is more complex or easier to handle with few markers for selection.”
The molecular markers identified at the discovery stage are validated in independent bi-parental or backcross populations, and the marker trait associations — which are consistent across different genetic backgrounds and diverse environments — are then moved to the deployment stage.
CIMMYT scientists have discovered several marker trait associations for crop diseases including maize lethal necrosis (MLN), maize streak virus (MSV), corn rust and turcicum leaf blight. All these trait-associated markers have been validated in biparental populations.