Department of Genetics, University of Georgia, Athens, Georgia 30602.
Department of Biology, Hamilton College, Clinton, New York 13323.
Plant Cell. 2019 Feb;31(2):368-383. doi: 10.1105/tpc.18.00613. Epub 2019 Jan 16.
Biolistic transformation delivers nucleic acids into plant cells by bombarding the cells with microprojectiles, which are micron-scale, typically gold particles. Despite the wide use of this technique, little is known about its effect on the cell's genome. We biolistically transformed linear 48-kb phage lambda and two different circular plasmids into rice () and maize () and analyzed the results by whole genome sequencing and optical mapping. Although some transgenic events showed simple insertions, others showed extreme genome damage in the form of chromosome truncations, large deletions, partial trisomy, and evidence of chromothripsis and breakage-fusion bridge cycling. Several transgenic events contained megabase-scale arrays of introduced DNA mixed with genomic fragments assembled by nonhomologous or microhomology-mediated joining. Damaged regions of the genome, assayed by the presence of small fragments displaced elsewhere, were often repaired without a trace, presumably by homology-dependent repair (HDR). The results suggest a model whereby successful biolistic transformation relies on a combination of end joining to insert foreign DNA and HDR to repair collateral damage caused by the microprojectiles. The differing levels of genome damage observed among transgenic events may reflect the stage of the cell cycle and the availability of templates for HDR.
弹道式转化通过将微弹丸（通常是金颗粒）轰击细胞，将核酸递送到植物细胞中。尽管该技术得到了广泛应用，但人们对其对细胞基因组的影响知之甚少。我们将线性 48kb 噬菌体 lambda 和两种不同的环状质粒生物转化到水稻（）和玉米（）中，并通过全基因组测序和光学作图分析结果。尽管一些转基因事件显示简单的插入，但其他事件则显示出极端的基因组损伤形式，包括染色体截断、大片段缺失、部分三体性，以及染色体碎裂和断裂-融合桥循环的证据。一些转基因事件包含混合有通过非同源或微同源介导连接组装的基因组片段的兆碱基规模的导入 DNA 阵列。通过检测其他地方移位的小片段存在情况来检测基因组受损区域，通常会无痕修复，推测是通过同源依赖性修复（HDR）。结果表明，成功的弹道式转化依赖于末端连接插入外源 DNA 和 HDR 修复微弹丸造成的附带损伤的组合。在转基因事件中观察到的不同程度的基因组损伤可能反映了细胞周期的阶段和 HDR 可用模板的情况。
