Physiological Effects And Mechanism Of α-particle Irradiation On Arabidopsis Embryos

The Arabidopsis thaliana columbia seeds are dipped in sterile water at 4℃for three days and the Arabidopsis embryos are dissected easily with a slim forceps under the sterile condition.Arabidopsis thaliana is a small dicotyledonous plant that is widely used as a model organism in plant biology. Arabidopsis embryo represents a simple cellular pattern comprised of a few basic tissues and prototypes of leaf-and root-like organs. These tissues are generated in a series of highly reproducible stages that imply tight control of orientation and frequency of cell division as well as cell morphology and differentiantion. For the short penetrate distance of -particle (30μm), our pre-experiment showed that no difference was found between 150Gy -particle treated Arabidopsis seeds and control group. The irradiation doses adopted in this study were 0Gy, 1Gy, 10Gy and 100Gy. This study about -particle on the multicellular organism has an important role to evaluate the potential risk of alpha radiation to non-human biota.The effects of -particle radiation on Arabidopsis embryos was studied in the present research. The results indicated that the germination percentage of embryos was not affected with irradiation at all doses. As the germination speed, it increased with 1Gy -particle treatment (82.5%), 11.4% higher than that of control. However, with the increase of the dosage, the germination speed decreased accordingly, showing that at 100Gy -particle treatment, the germination speed is about 29.3%. Interestingly, the effects of radiation on root length were consistent with that of germination speed. Moreover, the root gravitropism of 100Gy treatment showed more"S"type curves compared with non-irradiated controls. The mechanism study showed that the root gravitropism recovered while cultured in the MS medium containing 0.2mM Vc, which indicated that H2O2 might joined the process of gravitropism. Furthermore, during the shooting period of Arabidopsis, we detected the content of MDA and the activity of SOD and CAT. It showed that CAT activity and MDA content increased with the increase of doses, while SOD activity of 100Gy treatment decreased 12.6% compared with that of control. All these studies indicated that the induced increase of H2O2 signal molecules after -particle radiation may be the mechanism of radiation physiological effects.