Research Information System
Thesis Type: Postgraduate
Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey
Approval Date: 2016
Student: MERAL ÖZKUL
Co-Supervisor: ÇİĞDEM ALEV ÖZEL, DENİZ YÜZBAŞIOĞLU
Abstract:The most well known synthetic auxins include 2,4-dichlorophenoxy acetic acid (2,4-D) and picloram. While 2,4-D and picloram promote rooting, cell division, cell and fruit development in lower concentrations, they are used as herbicides in higher concentrations. The aim of this study was to examine genotoxic effects of 2,4-D and picloram by using in Allium cepa root tip cells. Allium cepa roots were treated with 0,67; 1,34; 2,01; 2,68; 3,35, and 4,02 mg/L concentrations of 2,4-D and picloram for 24 and 48 hours in tissue cultures. Mitotic indices, mitotic phase frequencies, and total abnormalities were determined for each concentration and treatment period. The mitotic index increased significantly at three lower concentrations (0,67, 1,34, 2,01 mg/L) after treatment with 2,4-D for 24 h and decreased significantly at higher concentrations (2,68; 3,35 and 4,02 mg/L). Notwithstanding, mitotic index increased significantly at all concentrations in the treatment period for 48h, and it only decreased at the highest concentration (4,02 mg/L). Picloram decreased mitotic index at four highest concentrations (2,01; 2,68; 3,35 and 4,02 mg/L) for both 24 and 48 hour treatments. Phase frequencies were not effected by 2,4-D usage. However, Picloram treatment for 24 hours showed significant increas at prophase frequency at the highest concentration (4,02 mg/L) and decreased telophase frequency at 3,35 mg/L concentration. The total percentage of mitotic aberrations did not significantly increased after the treatment with both of plant growth regulators. The most common types of mitotic abnormalities are C-mitosis, lagging chromosomes, stickiness, bridges, fragments, multi-polarity, and polyploidy. 2,4-D and picloram showed no genotoxic effect at low concentrations. On the other hand, comet assay was performed to determine the damage after using 2,4-D treatments for 24 and 48 hours. Comet assay showed only 4,02 mg/L of 2,4-D for 48 hour was toxic. However, the other concentrations did not show significant DNA damage compared to the control