Integration of Molecular Markers and Double Haploid Technology into CIMMYT Global Maize Breeding Program for Accelerating Genetic Gains

Maize is the most important staple food for over 300 million people in SSA. However, the average yields are very low compared to the average yield of maize in developed and developing countries due to biotic and abiotic stresses. The International Maize and Wheat Improvement Center (CIMMYT) Maize program has effectively integrated doubled haploid (DH) and molecular marker technologies in product development pipeline. The DH technology shortens the breeding cycle significantly by developing parental lines of maize hybrids within 2-3 seasons compared to conventional breeding that takes at least 7-8 crops seasons to develop similar parental lines. This is a significant reduction of time, labor and important resources in breeding to deal with a host of stresses like the maize lethal necrosis. More than 92,000 DH lines have been developed and evaluated in preliminary and advanced stage trials across locations under optimum, drought and low nitrogen conditions. A total of 32 DH based hybrids were released for commercialization in Kenya, Uganda, Tanzania, and South Africa and Mozambique. In addition. We have conducted the largest Marker Assisted Recurrent Selection (MARS) and Genomic Selection (GS) projects to develop stress-resilient maize germplasm for SSA. Completed three cycles of MARS and GS on 34 tropical maize populations, finalized genetic gain studies to compare gain on grain yield from MARS and GS with pedigree selection, and nominated several superior hybrids derived using parental lines developed through both MARS and GS for commercialization.