Microsatellite fingerprinting in the International Cocoa Genebank, Trinidad: accession and plot homogeneity information for germplasm management

Abstract

The International Cocoa Genebank, Trinidad, is the largest field genebank collection of cacao (Theobroma cacaoL.) in the public domain and the correct identity of each tree is crucial for germplasm movement, evaluation and phenotypic characterization. Nine microsatellite loci were used to assess the identity of 1477 trees from 486 cacao accessions representing approximately 16.9% of the trees and 29.2% of the accessions within the genebank. Heterogeneous plots (plots containing more than one genotype group) averaged 25.1% in The International Cocoa Genebank, Trinidad, with maximal admixture (32.6%) being recorded in Field 5B. The error rate did not differ significantly among different fields. Mislabeling error could be affected by accession grouping with an average error rate of 27.4% for accession groups in the genebank. Synonymous accessions were estimated to account for 14.4% of the field genebank. The results of the present study provide essential information for the management and utilization of the germplasm collection. Single-tree genotyping of every tree in this collection is strongly recommended.