拟南芥胚的不同区域对MeV离子辐照的响应

Biological response of Arabidopsis seed to MeV proton irradiation at different region of its embryo

利用不同能量的质子在大气环境中辐照拟南芥的含水种子,能量从1·1MeV到6·5MeV.根据模拟计算结果,相应能量的离子对种子的损伤区域分别为胚的浅层、胚的一半和整个胚.本实验中,具有较高能量的质子可以完全均匀地作用于拟南芥生长、发育及遗传密切相关的胚茎端分生组织,而能量较低的质子则不能直接作用于茎端分生组织.实验所用质子注量范围为4×109ions/cm2—1×1014ions/cm2.实验结果显示,虽然拟南芥种子的发芽率和幼苗存活率随离子注量增加都呈现下降的趋势,但对应于不同的胚损伤区域,即在不同的入射质子能量条件下,注量曲线具有各自的特征.实验结果显示,拟南芥种子中除了胚茎端分生组织作为对离子辐照敏感的辐射主靶外,茎端分生组织之外的胚区域可能作为离子辐射次靶,影响到最终的辐射生物学效应.

The water saturated Arabidopsis seeds were irradiated with protons in air. The ion energy is from 1.1MeV to 6.5MeV. According to TRIM simulation, the damaged region of the seed induced by the incident ions is near the surface region of the embryo, half of the embryo and the whole embryo, respectively. The protons with high energy can damage the shoot apical meristem（SAM） in the embryo while the protons with low energy cannot. The ion fluence used in this experiment was in the range of 4 ×10^9 to 1 ×10^14 ions/cm^2 . The experimental results showed that both the germination and survival rates decrease while increasing ion fluence, and the fluence-respense curve for different damaged region of the embryo has different characters. Besides SAM, which is generally considered as the main radiobiological target, the existence of a secondary target besides SAM is proposed in this paper