Cytomorphological analysis and in situ 4C nuclear DNA estimation in species and varieties of Tabernaemontana (fam. Apocynaceae)

Abstract

Tabernaemontana coronaria, a common garden plant in tropical countries, has been used as a traditional medicine. The beneficial properties of T. coronaria are antioxidant and anti-inflammatory. The active biocompounds including the alkaloids in the leaf extract enhance the cholinergic activity in both central and peripheral nervous system. A detailed analysis of morphological and cytological characters was carried out on three varieties and populations of T. coronaria and one population of T. dichotoma. Morphological characters like inter-node length, petiole length, leaf area and leaf index differed in species and varieties which may serve as identifying characters. Somatic chromosome analysis revealed 2n = 22 chromosomes in T. dichotoma, T. coronaria var. variegata, T. coronaria var. Dwarf, T. coronaria and 2n = 3X = 33 chromosomes in T. coronaria var. Flore-pleno with 2n = 3X = 33 being triploid. The species and varieties of Tabernaemontana have distinct total chromosome length, volume and nuclear DNA contents. Karyotype analysis showed differences in chromosome types and number of chromosome in each type. A conspicuous variation in chromosome characteristics was observed at intra specific and intra varietal level.