"Hot Spots" in Maize for Dry Regions in the Developing World

A new genomic map that applies to a wide range of maize breeding populations should help scientists develop maize more tolerant to drought.

Drought is second only to soil infertility as a constraint to maize production in developing countries, and probably reduces yields worldwide by more than 15 percent (more than 20 million tons) annually. Scientists at CIMMYT are seeking shared sections of the maize genome that contain genes for drought tolerance. Criteria include their being present in a wide range of tropical maize types and expressing themselves under diverse production conditions. A new consensus map of genes across maize populations may be the key to identifying such universal genetic, drought tolerance "hot spots" for maize.

Prior genomic maps for drought tolerance in tropical maize applied only to specific lines or populations. The CIMMYT team and partners have developed a single map that combines data from many experiments involving different tropical maize types in diverse environments. "Having all the QTL information integrated into a single map should allow us to identify the outstanding genomic regions involved in drought tolerance," says Jean-Marcel Ribaut, former CIMMYT molecular geneticist and now Director of the CGIAR's Generation Challenge Programme. The teams are linking field data for traits such as ear number, chlorophyll content, and carbohydrate content with DNA analyses for the same plants.

"This should allow maize breeders to select the right parents for drought tolerant maize by ensuring they have these important regions on their genome," says Ribaut.

With funding from the Rockefeller Foundation, members of the project team will give courses on this approach in to scientists in Kenya and China over coming months.

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