title: Accurate determination of genetic identity for a single cacao bean, using molecular markers with a nanofluidic system, ensures cocoa authentication.
abstract: Cacao (Theobroma cacao L.), the source of cocoa, is an economically important tropical crop. One problem with the premium cacao market is contamination with off-types adulterating raw premium material. Accurate determination of the genetic identity of single cacao beans is essential for ensuring cocoa authentication. Using nanofluidic single nucleotide polymorphism (SNP) genotyping with 48 SNP markers, we generated SNP fingerprints for small quantities of DNA extracted from the seed coat of single cacao beans. On the basis of the SNP profiles, we identified an assumed adulterant variety, which was unambiguously distinguished from the authentic beans by multilocus matching. Assignment tests based on both Bayesian clustering analysis and allele frequency clearly separated all 30 authentic samples from the non-authentic samples. Distance-based principle coordinate analysis further supported these results. The nanofluidic SNP protocol, together with forensic statistical tools, is sufficiently robust to establish authentication and to verify gourmet cacao varieties. This method shows significant potential for practical application.
authors.affiliation: Sustainable Perennial Crops Laboratory (SPCL), Beltsville Agricultural Research Center (BARC), Agricultural Research Service (ARS), United States Department of Agriculture (USDA) , 10300 Baltimore Avenue, Building 001, Room 223, BARC-W, Beltsville, Maryland 20705, United States.
authors.forename: Wanping
authors.initials: W
authors.lastname: Fang
authors.forename: Lyndel W
authors.initials: LW
authors.lastname: Meinhardt
authors.forename: Sue
authors.initials: S
authors.lastname: Mischke
authors.forename: Cláudia M
authors.initials: CM
authors.lastname: Bellato
authors.forename: Lambert
authors.initials: L
authors.lastname: Motilal
authors.forename: Dapeng
authors.initials: D
authors.lastname: Zhang
mesh_terms: D002099:Cacao / Q000145:classification* / Q000235:genetics*; D016172:DNA Fingerprinting; D018744:DNA, Plant / Q000032:analysis; D005506:Food Contamination / Q000032:analysis*; D005787:Gene Frequency / Q000235:genetics; D005838:Genotype; D036103:Nanotechnology; D010568:Peru; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D012639:Seeds / Q000145:classification* / Q000235:genetics*
chemical_list: D018744:DNA, Plant
keywords: Theobroma cacao; authentication; chocolate; conservation; fair trade; fluidigm; food adulteration; food forensics; germplasm; gourmet food; molecular markers; traceability; tropical tree