Plant & Animal Genomes XVIII Conference Plant & Animal Genomes XVIII ConferenceJanuary 9-13, 2010
Town & Country Convention Center
San Diego, CA
Raymond J. Schnell1 , J. Steven Brown1 , Cecile L. Tondo1 , David N. Kuhn1 , Wilbert Phillips2 , Freddy Amores3 , Carmen Suarez-Capello3 , Jemmy Takrama4 , Juan C. Motamayor5
Over the past 15 years a number of studies have produced genetic linkage maps using a variety of molecular markers and small populations (<200 individuals). A consensus linkage map has been developed that gives the most precise estimates of marker locations and distances. QTLs have been identified for resistance to black pod (BP), frosty pod (FP), and witches’ broom (WB) diseases and for 20 different growth, quality, and flavor characters. Fifteen different BP QTLs, four WB QTLs and three FP QTLs and over 80 horticultural QTLs have been reported. Two of the WB QTLs were used to characterize seedlings of a SCA 6 x SIAL 1 cross that had been evaluated for WB in Ecuador. Seedlings homozygous for the favorable alleles at the flanking markers had a significantly reduced broom number compared to seedlings heterozygous for the favorable allele, and seedlings lacking any favorable alleles were the most susceptible. In Ghana, 412 seedlings from five experimental families segregating for WB and BP resistance have been characterized for WB and BP QTLs. Ninety-six seedlings (23%) had the proper allelic configurations for WB resistance, 39 (9.5%) for BP resistance, and 15 (3%) for both. The major problem with utilizing these QTLs in cacao breeding is the distance between flanking markers. Over 280 thousand SNP markers have been developed from the cacao genome sequencing project and a subset of these will be used to identify markers more closely associated with QTL for disease resistance and horticultural traits.