Phenyl mercury acetate induced alterations in the karyotype of Phlox drummondii hook

The adverse effect of phenyl mercury acetate (PMA) solutions, 10⁻⁷ M, 10⁻⁶ M, 10⁻⁵ M, 10⁻⁴ M and 10⁻³ M, on the somatic karyotype of the Ml seedlings (directly treated) and M₂ seedlings (untreated seedlings raised from seeds harvested from M₁ plants) of Phlox drummondii Hook was analysed. A concentration as low as 10⁻⁷M of PMA could induce karyotypic changes confiiming its genotoxic potentiality. Moreover, all the solutions produced alterations in the somatic karyotype of the M₁ seedlings most of which were also visible in M₂ seedlings. Although, M₁ treated sets were having both numerical as well as structural chromosome mosaicism, M₂ ‘treated sets’ were showing only structural chromosome mosaicism. A major effect of PMA was change in the volume of chromosome and total length and volume of chromosome complements of the cells.