Comparative Cytogenetics and Fluorescent Chromosome Banding in Five Indian Species of Dipcadi Medik

The genus Dipcadi Medik. (Subfamily: Scilloideae) has a narrow distribution in India and several overlapping morphological traits make the genus taxonomically challenging at the species level. Cytogenetic characterization can provide additional taxonomic data and can be used to evaluate genetic diversity at the species level. We have accomplished comparative karyotype analysis and fluorescence banding patterns using 4'-6-Diamidino-2-phenylindole (DAPI) and Chromomycin A₃ (CMA) in five Indian species for the first time. The karyotypes of D. concanense and D. goaense exhibited similar fluorochrome banding profiles. However, D. montanum, D. ursulae and D. erythraeum differ distinctly in their karyotypes. In all taxa, CMA^+ve/DAPI^-ve or DAPI⁰ (GC-rich) constitutive heterochromatin was located at the constriction region or terminal satellite of the nucleolar chromosome. DAPI^+ve/CMA^-ve or CMA⁰ (AT-rich) heterochromatin dominates in D. montanum, D. ursulae and D. erythraeum. However, D. erythraeum shows a distinct variation in fluorochrome banding pattern from all other species. The distribution of CMA and DAPI bands is a reflection of heterochromatin composition and variations acquired by different species. This characterization can be used to assess phylogenetic relationships in the understudied genus Dipcadi and may serve as a basis for other genomic analyses and evolutionary studies.