关键词: 
低能离子辐照 /
体细胞同源重组 /
基因组不稳定

摘要: 体细胞同源重组产生的DNA重排、 缺失和复制等是基因组不稳定的重要指标， 以拟南芥菜GUS基因重组报告系R2L100和R3L66为实验材料， 以体细胞同源重组频率（每个植株上的GUS斑点数目）作为评估标准， 研究低能Ar+离子和α粒子辐射对植物基因组稳定性的影响。 结果表明： 30 keV的Ar⁺离子辐照拟南芥干种子， 在500×1013—3 000×1013 ions/cm2剂量范围内， 同源重组频率与对照相比明显升高， 最大值是对照的2.4倍; 3.3 MeV的α粒子辐照萌发4 d后的幼苗， 同源重组频率随着剂量的增加呈先增后降的变化趋势， 最大值是对照的1.9倍， 对应的辐照剂量是10 Gy。 以上实验结果表明, 低穿透能力的辐射能有效增加植物基因组的不稳定性。 α粒子辐照拟南芥菜幼苗的根， 未受到辐照的地上部分的同源重组频率较对照增加2.5倍， 表明低能离子诱导的基因组不稳定信号在植物个体水平是可以长程输运的。 以上结果从另一个侧面解释了低能离子的诱变机制。 The somatic homologous recombination was frequently used to evaluate genome stability because it can result in DNA changes， such as rearrangement， deletion and duplication. In this paper， we used Arabidopsis thaliana transgenic for GUS recombination substrate (R2L100 and R3L66) to study the genomic instability induced by low energy ion and α particle characteristic of shortpenetrating properties. The dry seeds of R3L66 line were irradiated by 30 keV Argon ion， the Homologous Recombination Frequency (HRF) had a significant increase at dose range of 500×1013—3 000×1013 ions/cm2. The highest level of HRF was 2.42fold over the control. The 3.3 MeV α particles were used to radiate 4dayold seedlings of R2L100 line. The HRFs had a dosedependent increase at dose of 1—10 Gy， and a dosedependent decrease at 10—100 Gy. The highest level of HRF induced by α particle was 1.9fold over control at the dose of 10 Gy. These results indicate that shortpenetrating irradiation can effectively trigger the plant genomic instability at the level of plant. The local irradiation on the roots of R2L100 by α particle resulted in a 2.5fold increase of HRF in nonirradiated aerial plant，which indicates that a signal of genomic instability generated by α particle radiation can systemically travel in whole plant. It is possible that the genome instability induced by lowenergy ion is a major part of its mutagenic mechanism.