Comparative Study on the Effects of Colchicine on Mitosis in Allium cepa var aggregatum and Allium sativum var sativum Root Meristem Cells

Colchicine acts as a microtubule-destabilizing agent and is a plant metabolite. Allium cepa (onion) and Allium sativum (garlic) are members of the Allium genus and belong to the Liliaceae family. Both Allium cepa var aggregatum and Allium sativum var sativum are excellent model organisms for studying the cytogenetic effects of colchicine treatment due to their large, easily observable chromosomes.  This study investigates the effects of colchicine on mitosis in Allium cepa var aggregatum and Allium sativum var sativum root meristem cells, with a focus on colchicine-induced chromosomal abnormalities and metaphase arrest. Roots of both plants were treated with different concentrations of colchicine (0.5%, 1%, and 1.5%) for varying durations. Mitotic abnormalities such as c-metaphase, chromosomal stickiness, laggard chromosomes, anaphase bridges, and polyploidy were observed in both species. The results showed a higher incidence of c-metaphase in Allium cepa var aggregatum, whereas Allium sativum var sativum exhibited more severe chromosomal fragmentation and dumbbell shaped nucleus was observed for the first time. The frequency and severity of abnormalities increased with colchicine concentration and exposure duration, highlighting differential sensitivities of Allium cepa var aggregatum and Allium sativum var sativum to colchicine-induced mitotic arrest.