ASSESSMENT OF GENOTOXIC EFFECTS PRODUCED BY HYPOXIA AND THERMAL STRESS IN MERISTEMATIC CELLS OF Allium cepa GERM ROOTS

CANGIANO MA, GALLARDO L, JOFRÉ M

San Luis

Congreso; XXXII Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2014

Sociedad de Biología de Cuyo

The Alliun cepa root chromosome aberrations and micronucleus test is a widespread bioassay for genotoxicityassessment. Different protocols of this bioassay employ meristematic tissue obtained from bulbs of A. cepa, whichare placed in treatment solutions, with continuous aeration. Chromosomal aberrations as C - mitosis, fragments andmicronuclei have been observed in meristematic cells obtained from bulbs of A. cepa exposed to tap water, underhypoxic conditions. Given the need to assess the genotoxicity of chemicals and plant extracts available in smallquantities, a test with germinal roots of A. cepa seeds has been developed. The aim of this study was to analyze thegenotoxic effect of hypoxia andlow temperature in germ root meristematic cells of A. cepa. Seeds of A. cepa wereplaced to germinate in distilled water under three conditions: a) in a BIOESNAKY seed germinator, b) in Petri dishunder hypoxia c) in Petri dish with aeration, in all three cases at two temperatures: 19 °C and 25 °C. Roots obtainedfrom each treatment, were fixed, stained, and squashed in order to get mitotic slides. Meristematic cells in alltreatments at 19 °C, showed a decrease in the mitotic index (MI) and karyolysis. Cells obtained from rootsgerminated at 25 °C showed an increase of MI compared with 19 °C and exhibited chromosomal aberrations (AC)as sticky chromosomes, C - mitosis and chromosome loose, among others. From these first experimental resultsweconclude that low temperature stress delays the physiological and biochemical mechanisms involved in the initialstage of germination decreasing the IM and causing karyolysis; also hypoxic conditions cause AC. To performcorrectly his genotoxicity bioassay, from seeds, it is necessary to maintaina temperature of 23 °C to 25 °C andoptimal oxygen availability. Future studies will assess which is the optimal oxygen availability to avoid falsepositives.