Ten polymorphic microsatellite primers in the tropical tree caimito, Chrysophyllum cainito (Sapotaceae)

The complete chloroplast genome sequence of Chrysophyllum cainito, a semidomesticated species

Chrysophyllum cainito is a semi-domesticated species widely cultivated in tropical regions, such as the Americas and Southeast Asia. In Yunnan, Guangdong, and Fujian Provinces, China, C. cainito is planted as an edible tropical fruit that was introduced from Southeast Asia. In this study, the chloroplast genome sequence of C. cainito was assembled and characterized using Illumina sequencing. The whole chloroplast genome of C. cainito is 158,841 bp long and consists of four regions: a large single-copy region (LSC, 88,256 bp), two inverted repeat regions (IRs, 25,958 bp), and a small single copy (SSC, 18,669 bp) region. The composition of the four bases in the circular chloroplast genome is 31.20% A, 32.00% T, 18.02% G, and 18.78% C, and the GC content of the entire C. cainito chloroplast genome is 36.8%. A total of 129 genes were annotated in the C. cainito chloroplast genome, of which 84 were protein-coding genes, 37 were transfer RNA (tRNA) genes, and eight were ribosomal RNA (rRNA) genes. The phylogenetic analysis indicated that C. cainito was most closely related to Pouteria campechiana. This study provides a foundation for further investigation of chloroplast genome evolution and genetic variation within semi-domesticated species.

Domestication of the neotropical tree Chrysophyllum cainito from a geographically limited yet genetically diverse gene pool in Panama

Species in the early stages of domestication, in which wild and cultivated forms co-occur, provide important opportunities to develop and test hypotheses about the origins of crop species. Chrysophyllum cainito (Sapotaceae), the star apple or caimito, is a semidomesticated tree widely cultivated for its edible fruits; it is known to be native to the neotropics, but its precise geographic origins have not been firmly established. Here, we report results of microsatellite marker analyses supporting the hypothesis that the center of domestication for caimito was the Isthmus of Panama, a region in which few crop species are believed to have originated, despite its importance as a crossroads for the dispersal of domesticated plants between North and South America. Our data suggest that caimito was domesticated in a geographically restricted area while incorporating a diverse gene pool. These results refute the generally accepted Antillean origin of caimito, as well as alternative hypotheses that the species was domesticated independently in the two areas or over a broad geographic range including both. Human-mediated dispersal from Panama to the north and east was accompanied by strong reductions in both genotypic and phenotypic diversity. Within Panama, cultivated and wild trees show little neutral genetic divergence, in contrast to striking phenotypic differentiation in fruit and seed traits. In addition to providing a rare example of data that support the hypothesis of a narrow geographic origin on the Isthmus of Panama for a now widespread cultivated plant species, this study is one of the first investigations of the origins of an edible species of the large pantropical family Sapotaceae.