Karyotype characterization of three important aromatic Cinnamomum L. species with special emphasis on reversible chromosome banding

Abstract

Conventional stain (orcein) and DNA base-specific fluorochromes (CMA and DAPI) were used to characterize three medicinally and economically important aromatic Cinnamomum L. species namely, C. camphora, C. tamala and C. zeylanicum. Despite having identical somatic chromosome numbers 2n = 24, the studied Cinnamomum L. species had distinct centromeric formulae, such as 24m in C. camphora, 18m + 6sm in C. tamala, and 8m + 16sm in C. zeylanicum. When karyotype assessment criteria were taken into account, these three studied species also displayed distinctiveness, and C. zeylanicum represented a more heterogeneous karyotype than the other two species. The karyotypic diversification was reflected in the symmetry classes of Stebbins’ classification, with C. camphora and C. tamala having 1B karyotype while C. zeylanicum was found to have a 2A karyotype. CMA- and DAPI-banding patterns of these species were different and species-specific regarding the number, location and percentages of GC- and AT-rich repetitive sequences in the genome. Reversible fluorescent banding patterns revealed the stain-specific nature of satellite in C. camphora L. By comparing karyotypic traits and reversible fluorescent banding patterns, characterization was thereby encountered for three Cinnamomum L. species from Bangladesh.