ANALYSIS OF GENETIC AND EPIGENETIC EFFECTS OF SUNFLOWER (Helianthus annuus L.) SEEDLINGS IN RESPONSE TO COPPER STRESS

Abstract

Heavy metals, which are natural components of the Earth's crust, are naturally occurring chemical elements that have a relatively high density. These metals are toxic or poisonous at low concentrations. Many industrial activities, fossil fuels, mining, using pesticide, metal-enriched some materials, automotive emissions and domestic wastes and many other factors have led to their wide distribution in the environment. Heavy metals are dangerous for every living thing, from plants to humans, because they tend to bioaccumulate. The aim of this study is to determine the toxic effects of copper heavy metal in sunflower plants in genetic and epigenetic parameters. In this study genotoxic effects of heavy metal of copper on sunflower plants genome were revealed by using changes in genomic template stability (GTS) and methylation pattern. Sunflower seeds were grown with different concentrations of copper heavy metal solution (0, 20, 40, 80, 160, 320, 640, 1280 mg/L) for 3 weeks. DNA band variations were revealed by RAPD-PCR analysis. Then, levels of methylcytosine in the genome were detected with the technique of coupled restriction enzyme digestion-random amplification (CRED-RA). Results of the RAPD analysis, the highest GTS rate was obtained 87.83% at 20 mg/L copper concentration and the lowest rate 81.75% at 320 mg/L. According to CRED-RA analysis, four different methylation models were determined. The the highest total methylation rate was obtained 96.90% at 20 mg/L copper concentration and the lowest rate 93.70% at 80 mg/L. Similarly, the maximum percentage of non-methylation was detected 6.30% at 80 mg/L copper stress. These results have shown that changes in methylation patterns as epigenetic parameter play an important role in the mechanism of protection against to Cu toxicity. Additionally, results have indicated that sunflower has physiological traits associated with accumulation of copper.