Abstract
The majority of the world's cacao for chocolate manufacture is produced in West Africa. Cocoa breeding programs in West Africa need genetic markers to reduce the time needed for improving cocoa by screening seedlings for the presence of the markers rather than mature plants for the phenotypic traits (i.e., marker-assisted selection [MAS]). For MAS to be successful, the breeder must have both access to markers linked to desired traits and a convenient marker-assay system that can be performed locally. In this study, microsatellite markers that flanked disease resistance quantitative trait loci (QTL) but could not be assayed conveniently in West Africa were converted using a genome walking method into single nucleotide polymorphism (SNP) markers that could be assayed locally. The SNP and microsatellite markers were equally effective in identifying off-types in two different mapping populations of cacao. Also, SNPs cast doubt on whether all microsatellite markers are identical by descent.
Acknowledgments
This work was supported by the USDA-ARS Subtropical Horticulture Research Station (SHRS) Project 6631-21000-017-26 Genetic Improvement of Cacao, which is a Mars Inc. trust to the USDA. Abu Dadzie was also supported by the World Cocoa Foundation and the Norman Borlaug fellowship program. We thank Eric Brenyah and Clement Aryee of the Physiology/Biochemistry Division of CRIG for technical assistance. We also want to thank all staff of SHRS for their support and assistance, especially Cecile Tondo, Kathleen Cariaga, Barbie Freeman, Dr. Stefan Royaert, and Wilber Quintanilla.
Notes
*Contributed equally to research and writing of manuscript.
This work is published with permission of the executive director of CRIG.