Abstract
The genome of perennial forest trees, throughout their lives, is subjected to genotoxic stresses by exogenous and endogenous factors, such as chemicals, reactive oxygen species, ultraviolet and ionizing radiation. DNA damage signaling pathways and DNA repair mechanisms are thus essential for the genome stability. To investigate the effect of ionizing radiation on the expression of DNA repair genes in tress, poplar (Populus nigra var. italica) plantlets were exposed to gamma rays with a dose ranging from 50 to 300 Gy for 20 h, then the gene expression in leaves was examined by RT-PCR/Southern blot analysis. The poplar Rad51, DNA ligase IV, Ku70 and XRCC4 genes were induced in a dose-dependent manner after the irradiation. Although elevated transcription levels of these genes reduced as time passed, high doses resulted in a prolonged persistence of the levels. In contrast, the expression of OGG1 transiently reduced after the irradiation then increased.
