Oxidative stress and DNA damage induced by gamma irradiation in Korean lawngrass (Zoysia japonica Steud.)

摘要

Korean lawngrass is a widely-used turfgrass species. In this study, we determined the effects of gamma irradiation on growth characteristics and cellular damages in this species. Seeds were irradiated with 100, 200, 400, 600, 800, and 1,000 Gy of gamma rays, respectively. To evaluate growth characteristics, germination rate and morphological traits (shoot length and width, root length, fresh weight, leaf blade length and width, sheath length, plant width, and number of tillers) were measured. We also examined the activities of the antioxidant enzymes including ascorbate peroxidase, catalase, superoxide dismutase, and peroxidase and the content of malondialdehyde. The germination rate decreased with an increase of gamma-ray dose, and seeds irradiated with doses higher than 600 Gy did not germinate at all. The 50% lethal dose (LD50) for gamma irradiation was 280-300 Gy. We also conducted a comet assay to observe nuclear DNA damage in the germinated plants. Significant differences were identified between the control and 400 Gy treatments. Increasing gamma ray doses from 0 to 400 Gy, the percentage of head DNA decreased significantly from 93.9% to 67.0%. In addition, the antioxidant enzyme activities and the content of MDA increased with the gamma-ray doses. These results showed that higher doses of gamma irradiation caused the greater oxidative stress and DNA damage in Korean lawngrass.