Abstract:Genome editing technology, as an innovative biotechnology, has been widely used for editing the genome from model organisms, animals, plants and microbes. CRISPR/Cas9-based genome editing technology shows its great value and potential in the dissection of functional genomics, improved breeding and genetic disease treatment. In the present special issue, the principle and application of genome editing techniques has been summarized. The advantages and disadvantages of the current genome editing technology and future prospects would also be highlighted.

Abstract:Non-human-primates would be particularly valuable in life sciences and biomedical research area. Gene-modified monkeys with gene overexpression or loss of function have been successfully generated with the rapid advance in gene manipulation technology such as lentivirus infection and programmable nucleases (ZFN, TALEN, CRISPR-Cas9). Here we review the recent development on gene-modified monkey generation by lentivirus and programmable nucleases. Then we discuss three concerns, the long time for sexual maturation, the off target and the mosaicism of founders, which limit the wide application of gene-modified non-human-primates. At last, hotspots and future trend for gene-modified non-human-primates generation are proposed.

Abstract:The increasing number of genetic manipulation approaches and high-resolution live imaging technique applied in zebrafish have propelled the rise of this organism as a mainstream model for developmental biology and human diseases studies. Zebrafish has many advantages for functional genomics analysis, allowing for easy, cheap and fast functional characterization of novel genes in the vertebrate genome. Here we provide an overview of the principles of genetic manipulation in zebrafish, such as Ethylnitrosourea (ENU) mutagenesis, insertional mutagenesis, gene trapping mutagenesis, Morpholino mediated gene knockdown, targeting induced local lesions in genomes (TILLING), genome editing with engineered nucleases ZFN (Zinc finger nuclease), TALEN (Transcription activator-like effector nuclease) and CRISPR/Cas9 system, and transgenic methods used in zebrafish.

Abstract:The development of genome editing techniques based on CRISPR (Clustered regularly interspaced short palindromic repeats)-Cas9 system has revolutionized biomedical researches. It can be utilized to edit genome sequence in almost any organisms including Caenorhabditis elegans, one of the most convenient and classic genetic model animal. The application of CRISPR-Cas9 mediated genome editing in C. elegans promotes the functional analysis of gene and protein under many physiological conditions. In this mini-review, we summarize the development of CRISPR-Cas9-based genome editing in C. elegans.

Abstract:In the past 4 years, CRISPR/Cas9-mediated genome editing becomes the revolutionary tool in life sciences. This tool enables us to edit plant genes with unprecedented throughput, scalability, speed and low cost. In addition to targeted knock-in and knock-out applications, CRISPR/Cas9 also provides an efficient platform for targeted gene activation and suppression. At the same time, accuracy, capacity and efficiency of CRISPR/Cas9 genome editing have been improved for sophisticated genetic manipulation. Furthermore, the genome editing toolbox is expanded by new technologies like CRISPR/Cpf1-mediated genome editing and single base editing. Owing to these recent progresses, CRISPR technology is close to the dream tool for plant sciences and will accelerate the crop genetic improvement through precise genome editing.

Abstract:Targeted genome editing technology is an important tool to study the function of genes and to modify organisms at the genetic level. Recently, CRISPR-Cas (clustered regularly interspaced short palindromic repeats and CRISPR-associated proteins) system has emerged as an efficient tool for specific genome editing in animals and plants. CRISPR-Cas system uses CRISPR-associated endonuclease and a guide RNA to generate double-strand breaks at the target DNA site, subsequently leading to genetic modifications. CRISPR-Cas system has received widespread attention for manipulating the genomes with simple, easy and high specificity. This review summarizes recent advances of diverse applications of the CRISPR-Cas toolkit in plant research and crop breeding, including expanding the range of genome editing, precise editing of a target base, and efficient DNA-free genome editing technology. This review also discusses the potential challenges and application prospect in the future, and provides a useful reference for researchers who are interested in this field.

Abstract:Targeted replacement genome editing refers to DNA modification and engineering technology that could induce and achieve mutations of targeted gene replacement or knockin at a target gene or DNA region. In this review, the principles, implementation methods, factors that influence efficiency and accuracy, and applications of gene replacement editing were summarized and discussed. It provides the reference for gene functional characterization and genetic improvements through gene replacement strategies in higher plant especially crops.

Abstract:Genome editing is a novel targeted genome modification biotechnology, which could successfully mutate specific loci as well as generate gene replacement and insertion in various organisms. So far, genome editing technology has been widely applied in investigating gene function and developing valuable traits in both model plants and major crops. In this review, we briefly survey the historical development of genome editing technology, summarize recent progress using the CRISPR/Cas9 system for plant genome editing and explore the potential of the CRISPR/Cas technology in improving forage legumes.

Abstract:CRISPR-based genome editing has been widely implemented in various cell types. In-silico single guide RNA (sgRNA) design is a key step for successful gene editing using CRISPR system. Continuing efforts are made to refine in-silico sgRNA design with high on-target efficacy and reduced off-target effects. In this paper, we summarize the present sgRNA design tools, and show that efficient in-silico models can be built that integrate current heterogeneous genome-editing data to derive unbiased sgRNA design rules and identify key features for improving sgRNA design. Our review shows that systematic comparisons and evaluation of on-target and off-target effects of sgRNA will allow more precise genome editing and gene therapies using the CRISPR system.

Abstract:Breakthroughs of genome-editing in recent years have paved the way to develop new therapeutic strategies. These genome-editing tools mainly include Zinc-finger nucleases (ZFNs), Transcription activator-like effector nucleases (TALENs), and clustered regulatory interspaced short palindromic repeat (CRISPR)/Cas-based RNA-guided DNA endonucleases. However, off-target effects are still the major issue in genome editing, and limit the application in gene therapy. Here, we summarized the cause and compared different detection methods of off-targets.

Abstract:To gain more insights into the rice base editor (rBE3 and rBE4), we evaluated the mutation efficiency, off-target and inheritance of OsSERK1(D428N) and pi-ta(S918F) genes modified with rBE endonucleases. We predicted and analyzed the putative off-target sites of the sgRNA designed for OsSERK1(D428N) and pi-ta(S918F) by PCR amplification and Sanger sequencing. Then we further characterized the inheritance and stability of targeted base mutations and T-DNA segregation in the progeny of the self-fertilized T0 plants. Analysis of the DNA sequencing data of T0 plants of OsSERK1(D428N) revealed no nucleotide change at any of the four potential off-target sites. For OsSERK1(D428N) and Os08g07774 carry the same sgRNA targeting sites, base substitution at both two loci were detected at a frequency of 41.67%. The targeted base mutations could be transmitted readily to T1 progeny. Furthermore, genetic segregation caused the loss of T-DNA at a frequency between 25.0% and 40.9% in the T1 transgenic plants of OsSERK1(D428N) and pi-ta(S918F). These results demonstrated that the rBE3 and rBE4 systems could mediate specifically targeted base editing in one- or multi-site, and the targeted base editing could be stably inherited to next generation.