Karyomorphology in two species of the genus Phlogacanthus Nees of Assam: some new karyological insights

ABSTRACT

The genus Phlogacanthus Nees belongs to the family Acanthaceae and is represented by herbs or shrubs species. The present work shows detailed karyomorphological studies in two species, Phlogacanthus quadrangularis (Hook.) Heine and Phlogacanthus guttatus Nees. Both the species grow as undergrowth vegetation. The conservation status of both the species are yet to be determined. The somatic chromosome counts of both the mentioned species are available for the first time, 2n = 40 for P. quadrangularis and 2n = 34 for P. guttatus. The karyomorphological observations showed that both plant species show dominance of sub-telocentric chromosomes with a few metacentric chromosomes. P. quadrangularis have telocentric chromosomes which is absent in the other species. The range of length of chromosomes in P. quadrangularis is from 0.340 lm to 1.32 lm and that of P. guttatus is from 0.560 lm to 1.878 lm. The karyotype type of the two species are classified as 3B type. But the dispersion index (DI) value of both the species are different. P. guttatus shows higher value of DI than P. quadrangularis. Higher the DI value more specialized is the karyotype. By comparing the chromosome length, size, DI value and idiogram of both the species, it is concluded that the karyotype of P. guttatus is more asymmetric and advanced than karyotype of P. quadrangularis. The karyomorphological findings of the present study will aid in determining the importance and utility, ex-situ conservation, protection, preservation and regeneration of germplasm