scholarly journals Transgene-Free Genome Editing in Tomato and Potato Plants Using Agrobacterium-Mediated Delivery of a CRISPR/Cas9 Cytidine Base Editor

2019 ◽  
Vol 20 (2) ◽  
pp. 402 ◽  
Author(s):  
Florian Veillet ◽  
Laura Perrot ◽  
Laura Chauvin ◽  
Marie-Paule Kermarrec ◽  
Anouchka Guyon-Debast ◽  
...  
Keyword(s):  
Genome Editing ◽  
First Generation ◽  
Genome Engineering ◽  
Crop Improvement ◽  
Point Mutations ◽  
Acetolactate Synthase ◽  
Agrobacterium Mediated Transformation ◽  
Dicotyledonous Plants ◽  
Function Discovery ◽  
Vegetatively Propagated Plants

Genome editing tools have rapidly been adopted by plant scientists for gene function discovery and crop improvement. The current technical challenge is to efficiently induce precise and predictable targeted point mutations valuable for crop breeding purposes. Cytidine base editors (CBEs) are CRISPR/Cas9 derived tools recently developed to direct a C-to-T base conversion. Stable genomic integration of CRISPR/Cas9 components through Agrobacterium-mediated transformation is the most widely used approach in dicotyledonous plants. However, elimination of foreign DNA may be difficult to achieve, especially in vegetatively propagated plants. In this study, we targeted the acetolactate synthase (ALS) gene in tomato and potato by a CBE using Agrobacterium-mediated transformation. We successfully and efficiently edited the targeted cytidine bases, leading to chlorsulfuron-resistant plants with precise base edition efficiency up to 71% in tomato. More importantly, we produced 12.9% and 10% edited but transgene-free plants in the first generation in tomato and potato, respectively. Such an approach is expected to decrease deleterious effects due to the random integration of transgene(s) into the host genome. Our successful approach opens up new perspectives for genome engineering by the co-edition of the ALS with other gene(s), leading to transgene-free plants harboring new traits of interest.

Recent advances in DNA-free editing and precise base editing in plants

2017 ◽  
Vol 1 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Yi Zhang ◽  
Caixia Gao
Keyword(s):  
Genome Editing ◽  
Genome Engineering ◽  
Point Mutations ◽  
Plant Genome ◽  
The Novel ◽  
Future Perspectives ◽  
Delivery Methods ◽  
Base Editing ◽  
Short Palindromic Repeat ◽  
Target Effects

Genome-editing technologies based on the CRISPR (clustered regularly interspaced short palindromic repeat) system have been widely used in plants to investigate gene function and improve crop traits. The recently developed DNA-free delivery methods and precise base-editing systems provide new opportunities for plant genome engineering. In this review, we describe the novel DNA-free genome-editing methods in plants. These methods reduce off-target effects and may alleviate regulatory concern about genetically modified plants. We also review applications of base-editing systems, which are highly effective in generating point mutations and are of great value for introducing agronomically valuable traits. Future perspectives for DNA-free editing and base editing are also discussed.

scholarly journals Base editors: modular tools for the introduction of point mutations in living cells

2019 ◽  
Vol 3 (5) ◽  
pp. 483-491 ◽  
Author(s):  
Mallory Evanoff ◽  
Alexis C. Komor
Keyword(s):  
Synthetic Biology ◽  
Genome Editing ◽  
Genome Engineering ◽  
Point Mutations ◽  
Living Cells ◽  
Single Base ◽  
New Family ◽  
Alternative Techniques ◽  
Cas Proteins ◽  
Modular Nature

Base editors are a new family of programmable genome editing tools that fuse ssDNA (single-stranded DNA) modifying enzymes to catalytically inactive CRISPR-associated (Cas) endonucleases to induce highly efficient single base changes. With dozens of base editors now reported, it is apparent that these tools are highly modular; many combinations of ssDNA modifying enzymes and Cas proteins have resulted in a variety of base editors, each with its own unique properties and potential uses. In this perspective, we describe currently available base editors, highlighting their modular nature and describing the various options available for each component. Furthermore, we briefly discuss applications in synthetic biology and genome engineering where base editors have presented unique advantages over alternative techniques.

scholarly journals Modern Trends in Plant Genome Editing: An Inclusive Review of the CRISPR/Cas9 Toolbox

2019 ◽  
Vol 20 (16) ◽  
pp. 4045 ◽  
Author(s):  
Ali Razzaq ◽  
Fozia Saleem ◽  
Mehak Kanwal ◽  
Ghulam Mustafa ◽  
Sumaira Yousaf ◽  
...  
Keyword(s):  
Genome Editing ◽  
Genome Engineering ◽  
Crop Improvement ◽  
Crop Plants ◽  
Targeted Mutagenesis ◽  
Plant Genome ◽  
Zinc Finger Nucleases ◽  
Base Substitution ◽  
Transcription Activator ◽  
Abiotic Stressors

Increasing agricultural productivity via modern breeding strategies is of prime interest to attain global food security. An array of biotic and abiotic stressors affect productivity as well as the quality of crop plants, and it is a primary need to develop crops with improved adaptability, high productivity, and resilience against these biotic/abiotic stressors. Conventional approaches to genetic engineering involve tedious procedures. State-of-the-art OMICS approaches reinforced with next-generation sequencing and the latest developments in genome editing tools have paved the way for targeted mutagenesis, opening new horizons for precise genome engineering. Various genome editing tools such as transcription activator-like effector nucleases (TALENs), zinc-finger nucleases (ZFNs), and meganucleases (MNs) have enabled plant scientists to manipulate desired genes in crop plants. However, these approaches are expensive and laborious involving complex procedures for successful editing. Conversely, CRISPR/Cas9 is an entrancing, easy-to-design, cost-effective, and versatile tool for precise and efficient plant genome editing. In recent years, the CRISPR/Cas9 system has emerged as a powerful tool for targeted mutagenesis, including single base substitution, multiplex gene editing, gene knockouts, and regulation of gene transcription in plants. Thus, CRISPR/Cas9-based genome editing has demonstrated great potential for crop improvement but regulation of genome-edited crops is still in its infancy. Here, we extensively reviewed the availability of CRISPR/Cas9 genome editing tools for plant biotechnologists to target desired genes and its vast applications in crop breeding research.

scholarly journals Genome editing in plants using CRISPR type I-D nuclease

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Keishi Osakabe ◽  
Naoki Wada ◽  
Tomoko Miyaji ◽  
Emi Murakami ◽  
Kazuya Marui ◽  
...  
Keyword(s):  
Genome Editing ◽  
First Generation ◽  
Genome Engineering ◽  
Targeted Mutagenesis ◽  
Plant Genome ◽  
Type I ◽  
Crispr System ◽  
Target Dna ◽  
Short Indels

Abstract Genome editing in plants has advanced greatly by applying the clustered regularly interspaced short palindromic repeats (CRISPRs)-Cas system, especially CRISPR-Cas9. However, CRISPR type I—the most abundant CRISPR system in bacteria—has not been exploited for plant genome modification. In type I CRISPR-Cas systems, e.g., type I-E, Cas3 nucleases degrade the target DNA in mammals. Here, we present a type I-D (TiD) CRISPR-Cas genome editing system in plants. TiD lacks the Cas3 nuclease domain; instead, Cas10d is the functional nuclease in vivo. TiD was active in targeted mutagenesis of tomato genomic DNA. The mutations generated by TiD differed from those of CRISPR/Cas9; both bi-directional long-range deletions and short indels mutations were detected in tomato cells. Furthermore, TiD can be used to efficiently generate bi-allelic mutant plants in the first generation. These findings indicate that TiD is a unique CRISPR system that can be used for genome engineering in plants.

scholarly journals Base editing and prime editing in laboratory animals

2021 ◽  
pp. 002367722199389
Author(s):  
Federico Caso ◽  
Benjamin Davies
Keyword(s):  
Genome Editing ◽  
Laboratory Animal ◽  
Genome Engineering ◽  
Point Mutations ◽  
Animal Research ◽  
Ease Of Use ◽  
Laboratory Animals ◽  
Genomic Change ◽  
Base Editing ◽  
Adenine Base

Genome editing by programmable RNA-dependent Cas endonucleases has revolutionised the field of genome engineering, achieving targeted genomic change at unprecedented efficiencies with considerable application in laboratory animal research. Despite its ease of use and wide application, there remain concerns about the precision of this technology and a number of unpredictable consequences have been reported, mostly resulting from the DNA double-strand break (DSB) that conventional CRISPR editing induces. In order to improve editing precision, several iterations of the technology been developed over the years. Base editing is one of most successful developments, allowing for single base conversions but without the need for a DSB. Cytosine and adenine base editing are now established as reliable methods to achieve precise genome editing in animal research studies. Both cytosine and adenine base editors have been applied successfully to the editing of zygotes, resulting in the generation of animal models. Similarly, both base editors have achieved precise editing of point mutations in somatic cells, facilitating the development of gene therapy approaches. Despite rapid progress in optimising these tools, base editing can address only a subset of possible base conversions within a relatively narrow window and larger genomic manipulations are not possible. The recent development of prime editing, originally defined as a simple ‘search and replace’ editing tool, may help address these limitations and could widen the range of genome manipulations possible. Preliminary reports of prime editing in animals are being published, and this new technology may allow significant advancements for laboratory animal research.

scholarly journals Multiplex nucleotide editing by high-fidelity Cas9 variants with improved efficiency in rice

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Wen Xu ◽  
Wei Song ◽  
Yongxing Yang ◽  
Ying Wu ◽  
Xinxin Lv ◽  
...  
Keyword(s):  
Genome Editing ◽  
Genome Engineering ◽  
Crop Improvement ◽  
High Fidelity ◽  
Knock Out ◽  
Base Editing ◽  
Guide Rna ◽  
Genome Modification ◽  
Targeted Genome Modification ◽  
Target Effect

Abstract Background Application of the CRISPR/Cas9 system or its derived base editors enables targeted genome modification, thereby providing a programmable tool to exploit gene functions and to improve crop traits. Results We report that PmCDA1 is much more efficient than rAPOBEC1 when fused to CRISPR/Cas9 nickase for the conversion of cytosine (C) to thymine (T) in rice. Three high-fidelity SpCas9 variants, eSpCas9(1.1), SpCas9-HF2 and HypaCas9, were engineered to serve with PmCDA1 (pBEs) as C-to-T base editors. These three high-fidelity editors had distinct multiplex-genome editing efficiencies. To substantially improve their base-editing efficiencies, a tandemly arrayed tRNA-modified single guide RNA (sgRNA) architecture was applied. The efficiency of eSpCas9(1.1)-pBE was enhanced up to 25.5-fold with an acceptable off-target effect. Moreover, two- to five-fold improvement was observed for knock-out mutation frequency by these high-fidelity Cas9s under the direction of the tRNA-modified sgRNA architecture. Conclusions We have engineered a diverse toolkit for efficient and precise genome engineering in rice, thus making genome editing for plant research and crop improvement more flexible.

scholarly journals Knock-in and precise nucleotide substitution using near-PAMless engineered Cas9 variants in Dictyostelium discoideum

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuu Asano ◽  
Kensuke Yamashita ◽  
Aoi Hasegawa ◽  
Takanori Ogasawara ◽  
Hoshie Iriki ◽  
...  
Keyword(s):  
Genome Editing ◽  
Dictyostelium Discoideum ◽  
Streptococcus Pyogenes ◽  
Nucleotide Substitution ◽  
Point Mutations ◽  
Targeted Mutagenesis ◽  
Single Amino Acid ◽  
Specific Gene ◽  
Knock Out ◽  
Protospacer Adjacent Motif

AbstractThe powerful genome editing tool Streptococcus pyogenes Cas9 (SpCas9) requires the trinucleotide NGG as a protospacer adjacent motif (PAM). The PAM requirement is limitation for precise genome editing such as single amino-acid substitutions and knock-ins at specific genomic loci since it occurs in narrow editing window. Recently, SpCas9 variants (i.e., xCas9 3.7, SpCas9-NG, and SpRY) were developed that recognise the NG dinucleotide or almost any other PAM sequences in human cell lines. In this study, we evaluated these variants in Dictyostelium discoideum. In the context of targeted mutagenesis at an NG PAM site, we found that SpCas9-NG and SpRY were more efficient than xCas9 3.7. In the context of NA, NT, NG, and NC PAM sites, the editing efficiency of SpRY was approximately 60% at NR (R = A and G) but less than 22% at NY (Y = T and C). We successfully used SpRY to generate knock-ins at specific gene loci using donor DNA flanked by 60 bp homology arms. In addition, we achieved point mutations with efficiencies as high as 97.7%. This work provides tools that will significantly expand the gene loci that can be targeted for knock-out, knock-in, and precise point mutation in D. discoideum.

scholarly journals Recent advances in CRISPR/Cas9 and applications for wheat functional genomics and breeding

aBIOTECH ◽  
2021 ◽  
Author(s):  
Jun Li ◽  
Yan Li ◽  
Ligeng Ma
Keyword(s):  
Functional Genomics ◽  
Genome Editing ◽  
Functional Annotation ◽  
Genome Engineering ◽  
Agronomic Traits ◽  
Wheat Breeding ◽  
Breeding Programs ◽  
Base Editing ◽  
The World ◽  
World Food Security

AbstractCommon wheat (Triticum aestivum L.) is one of the three major food crops in the world; thus, wheat breeding programs are important for world food security. Characterizing the genes that control important agronomic traits and finding new ways to alter them are necessary to improve wheat breeding. Functional genomics and breeding in polyploid wheat has been greatly accelerated by the advent of several powerful tools, especially CRISPR/Cas9 genome editing technology, which allows multiplex genome engineering. Here, we describe the development of CRISPR/Cas9, which has revolutionized the field of genome editing. In addition, we emphasize technological breakthroughs (e.g., base editing and prime editing) based on CRISPR/Cas9. We also summarize recent applications and advances in the functional annotation and breeding of wheat, and we introduce the production of CRISPR-edited DNA-free wheat. Combined with other achievements, CRISPR and CRISPR-based genome editing will speed progress in wheat biology and promote sustainable agriculture.

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