Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel.
Int J Mol Sci. 2021 Nov 9;22(22):12096. doi: 10.3390/ijms222212096.
Homologous recombination (HR) typically occurs during meiosis between homologs, at a few unplanned locations along the chromosomes. In this study, we tested whether targeted recombination between homologous chromosomes can be achieved via Clustered Regulatory Interspaced Short Palindromic Repeat associated protein Cas9 (CRISPR-Cas9)-induced DNA double-strand break (DSB) repair in . Our experimental system includes targets for DSB induction in euchromatic and heterochromatic genomic regions of hybrid F1 plants, in one or both parental chromosomes, using phenotypic and molecular markers to measure Non-Homologous End Joining and HR repair. We present a series of evidence showing that targeted DSBs can be repaired via HR using a homologous chromosome as the template in various chromatin contexts including in pericentric regions. Targeted crossover was rare, but gene conversion events were the most frequent outcome of HR and were found in both "hot and cold" regions. The length of the conversion tracts was variable, ranging from 5 to 7505 bp. In addition, a typical feature of these tracks was that they often were interrupted. Our findings pave the way for the use of targeted gene-conversion for precise breeding.
同源重组 (HR) 通常发生在减数分裂过程中同源染色体之间，在染色体上的少数几个非计划位置。在这项研究中，我们测试了靶向同源染色体之间的重组是否可以通过 Clustered Regulatory Interspaced Short Palindromic Repeat associated protein Cas9 (CRISPR-Cas9) 诱导的 DNA 双链断裂 (DSB) 修复在. 我们的实验系统包括在杂种 F1 植物的常染色质和异染色质基因组区域的一个或两个亲本染色体中的 DSB 诱导的靶点，使用表型和分子标记来测量非同源末端连接和 HR 修复。我们提出了一系列证据表明，在各种染色质环境中，包括着丝粒区域，可以使用同源染色体作为模板通过 HR 修复靶向 DSB。靶向交叉很少见，但基因转换事件是 HR 的最常见结果，在“热点”和“冷点”区域都有发现。转换片段的长度是可变的，范围从 5 到 7505 bp。此外，这些轨迹的一个典型特征是它们经常被打断。我们的发现为靶向基因转换的精确育种铺平了道路。
