Location: Sustainable Perennial Crops
Project Number: 8042-21000-267-00
Start Date: Mar 14, 2013
End Date: Mar 13, 2018
The project will first elucidate geospatial patterns of genetic diversity in the primary gene pool of T. cacao using research tools of genomics, spatial genetics and bioinformatics. Cacao germplasm that have been collected and maintained in various ex-situ genebanks will be characterized using single nucleotide polymorphism (SNP) markers. The generated SNP data, together with those previously obtained from the two international genebanks and other non-U.S. national collections, will be compiled and used for assessment of genetic diversity within and among collections. Completion of this work will allow ARS to have a clear understanding about the scope of existing wild germplasm and traditional varieties maintained in the non-U.S. national collections. It will also enable mapping of the geographical distribution of traditional varieties of T. cacao in the Americas using tools of spatial genetics. Second, diversity gaps in ex situ collections will be identified and filled through new collection expeditions, with emphasis on increasing representation from the geographical center of diversity. Based on the existing information, ARS collecting expeditions will focus on the Peruvian Amazon bordered by Brazil and Colombia, including Ríos Ucayali, Putumayo, Yavari, and their tributaries. In addition, landraces and traditional varieties which have a distinct genetic profile, specific regional distribution, and fine flavor, will be identified to support in situ/on-farm conservation. Resulting information will serve as a scientific baseline to support rational decision-making for future germplasm conservation and utilization. Finally, in collaboration with the curators of international and national collections, cacao germplasm will be evaluated for key agronomic traits, primarily disease resistance. Quantitative trait loci mapping, based on field evaluation, SNP genotyping, and genome-wide association mapping will be applied to discover new sources of resistance to major diseases. Approaches established and utilized in cacao will be applied to other tropical tree crops of major economic importance as they are identified and as conservation procedures are established.