The Effect Of Heavy-ion Radiation Induced Oxidative Stress On Rice

Preliminary studies show that low-dose heavy-ion radiation of rice seeds could induce growth stimulation at three-leaf stage, increasing both the height of plant and the numbers of mitochondria of the leaves. Since mitochondrial is an important organelle involved in the antioxidative systems, its dysfunction could result in the increase of reactive oxygen species and lipid peroxidation. It also could change the activity of antioxidase system and the expression of key proteins in mitochondria. It suggests that there might be a direct relation of mitochondria dysfunction and the generation of secondary ROS induced by low-dose heavy ion radiation. The mechanism of the changes of mitochondria dysfunction at different development stages is not well studied on rice. To investigate the effects of low-dose radiation induced oxidative stress on rice at different development stages, rice seeds(Oryza saliva L. Japonica. cv. Nipponbare) were exposed to carbon-ion beam (LET=30KeV/um) with the energy of1.98GeV, the doses were0,0.1,0.2,1and2Gy respectively. The weight of the plant, the activity changes of antioxidase system and the expression of key encoding genes in mitochondria at different development stages were studied. The connection between mitochondria dysfunction and biological effects induced by low-dose radiation at different stages were also analyzed on rice which seeds was exposed to heavy-ion radiation. The results showed that the changes of the weight were not same at different development stages. Growth stimulation induced by low-dose radiation mainly occurred at three-leaf stage along with the increasing activity of antioxidase system and damage of lipid peroxidation. We also found that the relative expression of genes sdhb and AOXla which encode the key proteins in mitochondria changed differently after exposed to different doses of radiation, and the lower dose of the radiation could cause longer effect. This study is important to analysis the mitochondria dysfunction and biological effects induced by low-dose radiation.