Communications in Plant Sciences, vol 4, issues 1-2, p.19-22, 2014
Full title: Genotoxic effect of ethephon on the root meristems of Allium cepa L.
Authors: Joyce Sudandara Priya, Preethi Purushothaman, Cordilea Hannah, Sarah Matthew and Sowmya Thomas
Abstract: Genotoxic effect of ethephon [(2-chloroethyl) phosphonic acid], a PGR that has replaced calcium carbide as an agent for fruit ripening, was studied by using a root chromosome assay. Onion root meristems were cultured and analyzed after exposure with ethephon at concentrations of 200 ppm and 500 ppm for 2, 24, and 48 h. There was a time dependent decrease and an immediate toxic effect on dividing cells in mitotic index when compared to control (the mitotic indices of root meristems treated with 200 ppm ethephon for 2, 24, and 48 h were 11.1%, 10.7%, and 8.9%, respectively; and with 500 ppm ethephon for 2, 24, and 48 h the mitotic indices were 10.8%, 10.2%, and 9.0% respectively). The total chromosomal aberrations increased with prolonged exposures indicating duration dependent effect compared to control (the chromosomal aberrations of root meristems treated with 200 ppm ethephon for 2, 24, and 48 h were 14.5%, 15.6%, and 34.0% respectively; and with 500 ppm ethephon for 2, 24, and 48 h the chromosomal aberrations were 20.6%, 26.1%, and 39.8%, respectively). Chromosomal anomalies such as clumps and breaks were of frequent occurrence. This study proves the genotoxic effect of ethephon and emphasizes the judicial use of this compound as a PGR on edible plants and plant parts.
Keywords: Cytotoxicity, Chromosomal anomalies, Onion root meristems.