Tropical Plant Biology

, Volume 4, Issue 2, pp 106–116

Dissecting Genetic Structure in Farmer Selections of Theobroma Cacao in the Peruvian Amazon: Implications for on Farm Conservation and Rehabilitation

  • Dapeng Zhang
  • Enrique Arevalo Gardini
  • Lambert A. Motilal
  • Virupax Baligar
  • Bryan Bailey
  • Luiz Zuñiga-Cernades
  • Carlos E. Arevalo-Arevalo
  • Lyndel Meinhardt
Article

DOI: 10.1007/s12042-010-9064-z

Cite this article as:
Zhang, D., Gardini, E.A., Motilal, L.A. et al. Tropical Plant Biol. (2011) 4: 106. doi:10.1007/s12042-010-9064-z

Abstract

Knowledge of genetic diversity in farmers’ selections is essential for planning on-farm conservation and rehabilitation. Using 15 microsatellite loci, we analyzed parentage and population structure in 220 farmer selections of cacao from the Huallaga valley in Peruvian Amazon. A high level of allele richness and heterozygosity were detected in these selections. Coordination analysis showed that these farmer selections are mainly comprised of hybrids derived from Trinitario and Upper Amazon Forastero germplasm. Bayesian clustering analysis assigned 54 selections as Trinitario and 166 as Upper Amazon Forastero hybrids. Parentage analysis identified 15 international clones as probable parents for 96 farmer selections, which corresponded to a fraction of the known hybrid families disseminated in this region in the late 1980s. Combined analysis of demographic and molecular data revealed a significant spatial autocorrelation (r = 0.235; P = 0.006) at short geographical distances (<5.0 km). This patch-like distribution of spatial heterogeneity suggests a significant “neighborhood effects” in seeds distribution or variety adoption, where closely related hybrid progenies were adopted in the neighboring farms or villages. The outcomes of this study indicate that in spite of the introgressions of exotic germplasm in the past, Upper Amazon Forastero is still the dominant component in the Huallaga valley of Peru. The high level of on-farm diversity can offer needed variability for participatory selection of superior clones in this low input, small-scale production system, where adaptability to specific environment is more preferred than in a high input, large scale production system.

Keywords

CacaoFarmer selectionsHuallaga valleyPeruvian AmazonRehabilitationSpatial genetic correlation

Copyright information

© Springer Science+Business Media, LLC (outside the USA)  2011

Authors and Affiliations

  • Dapeng Zhang
    • 1
  • Enrique Arevalo Gardini
    • 2
  • Lambert A. Motilal
    • 3
  • Virupax Baligar
    • 1
  • Bryan Bailey
    • 1
  • Luiz Zuñiga-Cernades
    • 2
  • Carlos E. Arevalo-Arevalo
    • 2
  • Lyndel Meinhardt
    • 1
  1. 1.USDA ARS PSI SPCLBeltsvilleUSA
  2. 2.Intituto de Cultivos Tropicales (ICT)TarapotoPeru
  3. 3.Cocoa Research UnitThe University of the West IndiesSt. AugustineTrinidad and Tobago