Dose-response characterization of Allium cepa meristematic cells exposed to 6 MV X-rays

This study investigates the cytogenetic response of Allium cepa meristematic cells to 6 MV X-ray irradiation across a wide dose range. The model is recognized as a sensitive and reproducible experimental system for detecting radiation-induced damage. Genotoxic and proliferative effects were evaluated using the micronucleus assay and mitotic index. A strong linear relationship between dose and micronucleated cell frequency was observed in the 0-4 Gy range (r = 0.99). Beyond this region, a decline in micronucleated cell frequency and mitotic activity was detected, consistent with radiation-induced loss of mitotically competent cells. The overall dose-response is well described by a linear-quadratic model incorporating a cell-killing component. These findings identify a transition between damage accumulation and proliferative inhibition, supporting the potential of Allium cepa as a candidate system for biodosimetric applications involving low-LET photon radiation.