Chen Hao, Neubauer Matthew, Wang Jack P
Department of Plant and Microbial Biology, Program in Genetics, North Carolina State University, Raleigh, NC, United States.
College of Forestry, Shandong Agricultural University, Tai'an, China.
Front Plant Sci. 2022 May 3;13:883421. doi: 10.3389/fpls.2022.883421. eCollection 2022.
Gene-editing tools, such as Zinc-fingers, TALENs, and CRISPR-Cas, have fostered a new frontier in the genetic improvement of plants across the tree of life. In eukaryotes, genome editing occurs primarily through two DNA repair pathways: non-homologous end joining (NHEJ) and homologous recombination (HR). NHEJ is the primary mechanism in higher plants, but it is unpredictable and often results in undesired mutations, frameshift insertions, and deletions. Homology-directed repair (HDR), which proceeds through HR, is typically the preferred editing method by genetic engineers. HR-mediated gene editing can enable error-free editing by incorporating a sequence provided by a donor template. However, the low frequency of native HR in plants is a barrier to attaining efficient plant genome engineering. This review summarizes various strategies implemented to increase the frequency of HDR in plant cells. Such strategies include methods for targeting double-strand DNA breaks, optimizing donor sequences, altering plant DNA repair machinery, and environmental factors shown to influence HR frequency in plants. Through the use and further refinement of these methods, HR-based gene editing may one day be commonplace in plants, as it is in other systems.
基因编辑工具，如锌指核酸酶、转录激活样效应因子核酸酶（TALENs）和规律成簇间隔短回文重复序列及其相关蛋白（CRISPR-Cas），为整个生命之树的植物基因改良开辟了新领域。在真核生物中，基因组编辑主要通过两种DNA修复途径进行：非同源末端连接（NHEJ）和同源重组（HR）。NHEJ是高等植物中的主要机制，但它不可预测，常常导致不期望的突变、移码插入和缺失。通过HR进行的同源定向修复（HDR）通常是基因工程师首选的编辑方法。HR介导的基因编辑可以通过整合供体模板提供的序列实现无错误编辑。然而，植物中天然HR的低频率是实现高效植物基因组工程的一个障碍。本综述总结了为提高植物细胞中HDR频率而实施的各种策略。这些策略包括靶向双链DNA断裂的方法、优化供体序列、改变植物DNA修复机制以及显示出影响植物中HR频率的环境因素。通过使用和进一步完善这些方法，基于HR的基因编辑也许有一天在植物中会像在其他系统中一样普遍。
