Origins and close relatives of a semi-domesticated neotropical fruit tree: Chrysophyllum cainito (Sapotaceae).

PREMISE OF THE STUDY

Understanding patterns and processes associated with domestication has implications for crop development and agricultural biodiversity conservation. Semi-domesticated crops provide excellent opportunities to examine the interplay of natural and anthropogenic influences on plant evolution. The domestication process has not been thoroughly examined in many tropical perennial crop species. Chrysophyllum cainito (Sapotaceae), the star apple or caimito, is a semi-domesticated species widely cultivated for its edible fruits. It is known to be native to the neotropics, but the precise geographic origins of wild and cultivated forms are unresolved.

METHODS

We used nuclear ribosomal ITS sequences to infer phylogenetic relationships among C. cainito and close relatives (section Chrysophyllum). We employed phylogeographic approaches using ITS and plastid sequence data to determine geographic origins and center(s) of domestication of caimito.

KEY RESULTS

ITS data suggest a close relationship between C. cainito and C. argenteum. Plastid haplotype networks reveal several haplotypes unique to individual taxa but fail to resolve distinct lineages for either C. cainito or C. argenteum. Caimito populations from northern Mesoamerica and the Antilles exhibit a subset of the genetic diversity found in southern Mesoamerica. In Panama, cultivated caimito retains high levels of the diversity seen in wild populations.

CONCLUSIONS

Chrysophyllum cainito is most closely related to a clade containing Central and South American C. argenteum, including subsp. panamense. We hypothesize that caimito is native to southern Mesoamerica and was domesticated from multiple wild populations in Panama. Subsequent migration into northern Mesoamerica and the Antilles was mediated by human cultivation.