The genetic divergence among 14 ecotypes of Nyctanthes arbortristis (L.) were assessed using karyotype, meiotic studies and RAPD analysis. Mitotic and meiotic analysis confirmed 2n = 44 chromosomes. Somatic chromosome analysis revealed symmetric karyotype with prevalence of median and sub-median chromosomes with TF% ranging from 39.8 to 44.08. Meiotic analysis of 14 ecotypes also showed 22 bivalents in majority of PMCs, but in some PMCs bivalents (19.4±1.03 to 21.2±0.24), univalents (2.1±1.06 to 3.9±1.48) and quadrivalents (0.36±0.14 to 1.6±0.24) were also appeared in combination. The PMCs revealed high proportion of ring bivalents over rod bivalents with terminalised chiasmata, and terminalization coefficient ranged from 0.895 to 0.919. Although PMCs showed normal 22:22 segregation of chromosomes to two poles during Anaphase-I, univalents in the form of laggards were often observed. Pollen fertility and percentage of seed germination were low in all ecotypes which was indicative of partial genetic heterozygosity. RAPD marker profile generated by 10 RAPD primers showed moderate polymorphism among the ecotypes with Jaccards similarity indices ranging from 0.648 to 0.962 among the ecotypes of N. arbortristis. The clustering of ecotypes based on RAPD data also agreed with chromosome behaviour, pollen viability and germination of seeds. Moreover, these findings have many implications for future in vitro studies aimed at development of genotypes with higher content of metabolites (rengyolone, urosolic acid, arbortristosides and nyctanthic acid) of pharmaceutical importance.
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