Karyological diversity among six medicinally important species of Acanthaceae in Bangladesh

Six medicinally important species of Acanthaceae family namely, Asystasia gangetica (L.) T. Anderson, Barleria cristata L., Braleria prionitis L., Ruellia simplex C. Wright, Thunbergia erecta (Benth.) T. Anderson and Thunbergia mysorensis (Wright) T. Anderson were cytogenetically investigated to evaluate the karyotype diversity and chromosomal relationship. The somatic chromosome numbers and the centromeric formulas of these species were 2n = 2x = 24 (22m + 2sm) for A. gangetica, 2n = 4x = 40 (38m + 2sm) for B. cristata, 2n = 4x = 40 (36m + 4sm) for B. prionitis, 2n = 2x = 36 (34m + 2sm) for R. simplex, 2n = 4x+6 = 62 (56m + 6sm) for T. erecta and 2n = 2x = 34 (34m) for T. mysorensis. Considering the karyotype assessment parameters, T. erecta, R. simplex, B. cristata and B. prionitis were shown to be cytogenetially more advanced than A. gangetica and T. mysorensis. Three categories of karyotypes were observed such as 1B type in B. cristata, B. prionitis, R. simplex and T. mysorensis, whereas the most primitive one 1A in A. gangetica and the most advanced karyotype 2B in T. erecta. Three new reports of somatic chromosome count yielded in case of A. gangetica, R. simplex and T. mysorensis which might have been resulted from aneuploidy or allopolyploidy. The cytological data presented for six species of the Acanthaceae family demonstrated significant variation and distinctiveness from one another, assisting in the evaluation of the karyological diversity that aided in the understanding of evolutionary changes.