Summary
2C values for angiosperms vary over 2500-fold and a positive correlation exists between C-value and latitude in herbaceous plants. Woody plants differ from herbaceous plants in chromosome size and C-value. In addition, tropical hardwoods have smaller chromosomes than other tropical plants and do not share the correlation of minimum generation time with genome size seen in herbaceous plants. Theobroma cacao is a tropical hardwood cultivated for its beans, which are used to make chocolate and cocoa butter. Its cytology is typical of the pantropical and subtropical family Sterculiaceae. Its small chromosomes, single secondary constriction, and lack of C-banding suggest a small genome. The genome size of T. cacao, measured by reassociation kinetics, is 2.01 x 108, which is small compared to both temperate and tropical plants previously studied. We also provide data on the melting point, base composition, and relative extent of methylation (at sites most commonly methylated in higher plants), of T. cacao DNA.
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Communicated by M. Meyerowitz
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Couch, J.A., Zintel, H.A. & Fritz, P.J. The genome of the tropical tree Theobroma cacao L.. Molec. Gen. Genet. 237, 123–128 (1993). https://doi.org/10.1007/BF00282792
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DOI: https://doi.org/10.1007/BF00282792