中文摘要：

目的：研究γ射线对水稻基因组的诱变效应,明确其诱发突变的类型、分布和频率。创新点：首次针对种子繁殖植物在全基因组范围及单核苷酸水平上揭示了γ射线诱发可遗传变异的频率与特征。方法：利用Illumina Hiseq2000对三种γ射线剂量辐照培育的6株水稻（日本晴）M2植株进行基因组重测序,生物信息学分析确定单碱基替换（SBS）和插入缺失（Indel）突变,以及结构变异和拷贝数等变异的频率和基因组分布。利用Sanger测序、目标片段扩增或定量多聚酶链反应（qP CR）对各类突变进行验证。综合重测序和验证结果估算诱发突变频率。结论：结果表明,γ射线既可以诱发单碱基替换,也可以诱发插入缺失突变和结构变异;水稻M2代植株中的平均突变频率达到7.5×10^-6～9.8×10^-6;Indel突变频率约为SBS变异的1/4,而结构变异频率更低;SBS和Indel突变随机分布在12条染色体上,无明显的突变热点。

英文摘要：

Mutation breeding is based on the induction of genetic variations; hence knowledge of the frequency and type of induced mutations is of paramount importance for the design and implementation of a mutation breeding program. Although γ ray irradiation has been widely used since the 1960 s in the breeding of about 200 economically important plant species, molecular elucidation of its genetic effects has so far been achieved largely by analysis of target genes or genomic regions. In the present study, the whole genomes of six γ-irradiated M2 rice plants were sequenced; a total of 144–188 million high-quality（Q〉20） reads were generated for each M2 plant, resulting in genome coverage of 45 times for each plant. Single base substitution（SBS） and short insertion/deletion（Indel） mutations were detected at the average frequency of 7.5×10^-6～9.8×10^-6 in the six M2 rice plants（SBS being about 4 times more frequent than Indels）. Structural and copy number variations, though less frequent than SBS and Indel, were also identified and validated. The mutations were scattered in all genomic regions across 12 rice chromosomes without apparent hotspots. The present study is the first genome-wide single-nucleotide resolution study on the feature and frequency of γ irradiation-induced mutations in a seed propagated crop; the findings are of practical importance for mutation breeding of rice and other crop species.