GENOME SIZE AND DNA POLYMORPHISM IN THEOBROMA-CACAO

The size of the haploid genome of Theobroma cacao L. (cacao), estimated using laser flow cytometry, was 0.43 pg. An improved DNA extraction procedure was developed based on isolation of a crude nuclei preparation from leaf tissue that effectively eliminated contamination of the DNA by polysaccharides and produced DNA that was, on average, longer than 50kb. DNA yields ranged from 2 to 10-mu-g.g-1 fresh weight of leaf tissue. DNA blot hybridization experiments with a flax (Linum usitatissimum L.) ribosomal DNA probe revealed restriction fragment length polymorphisms between three cacao genotypes. Differences between the DNA of these genotypes were also detected by polymerase chain reaction amplification of polymorphic DNA fragments, using random oligonucleotide primers.