chromosomal study of yellow sweet-clover (Melilotus officinalis (L.) Lam.) under heavy metals pollution of lead and zinc mine of Zeh Abad, Qazvin

Melilotus officinalis (L.) Lam. belonging to Fabaceae growing in the vicinity of zinc and lead mine around Zeh abad village, Qazvin province, Iran. The aim of this study is determination of amount of zinc and lead pollution in sampled soil and water and find out how M. officinalis is affected by a long-term exposure to pollutants focusing on the meiotic behavior of pollen mother cells (PMCs) and pollen fertility. The chemical analysis of soil and water samples from the studied area by the ICP-MS indicates presence of lead and zinc in a concentration much higher than the standard. The results revealed that polluted soil and water with heavy metals had a significant impeding effect on the division of PMCs in M. officinalis as noticed by the increase in meiosis abnormality percentage, decrease in meiotic index (MI) and pollen fertility compared to the control and can lead to genotoxicity in under study plant. The present data indicate that this species is not meiotically stable. In general, the pollen mother cells of specimen grown in polluted soil exhibited an increased incidence of chromosome stickiness, B-chromosomes, chromosome bridges, laggard chromosomes, micronuclei, cytomixis and formation of tripolar cells.