PCR analysis of genes involved in base excision repair pathway in rice seedlings under Cr(III) exposure

The base excision repair (BER) pathway is an essential defense mechanism against oxidative damage of DNA in plants. Previous studies have reported that chromium (Cr) exposure causes oxidative stress and DNA damage due to accumulation of ROS. In this study, hydroponic experiments were carried out to investigate mRNA expression of 21 candidate genes involved in the BER pathway in rice seedlings exposed to Cr(III) using qRT-PCR. Changes of H2O2 and O2-• content in rice tissues and the relative growth rate (%) of rice seedlings were also determined. The results indicated that Cr(III) induced dose-dependent inhibition on the relative growth rate of rice seedlings. H2O2 content in roots were significantly increased. Changes of the content of H2O2 and O2-• in shoots was consistent. PCR analysis revealed that responses of selected 21 candidate genes to Cr(III) exposure were tissue specific. The BER pathway in roots was repressed by Cr(III) treatment but activated in shoots in response to Cr(III) exposure, suggesting that the BER pathway would play different roles in regulating and repairing DNA damage caused by Cr(III) exposure in rice.