Genome editing of maize

2021 ◽  
pp. 341-376
Author(s):  
Jacob D. Zobrist ◽  
◽  
Morgan McCaw ◽  
Minjeong Kang ◽  
Alan L. Eggenberger ◽  
...  
Keyword(s):  
Genome Editing ◽  
Genome Engineering ◽  
Target Genes ◽  
Zinc Finger Nucleases ◽  
Maize Genome ◽  
Delivery Methods ◽  
Agricultural Improvement ◽  
Modern Maize ◽  
Associated Proteins ◽  
Short Palindromic Repeat

Developed over thousands of years largely through human intervention, the modern maize genome can now be precisely modified for agricultural improvement and scientific research. This chapter focuses on progress made in recent decades utilizing site-specific nuclease (SSN) technologies in maize genome engineering. Many SSNs, such as meganucleases, zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated proteins (Cas) have been used in maize for both functional analysis and trait improvement. The chapter summarizes the recent innovations related to maize genome editing using SSN technologies, the type of approaches, target genes and traits, and reagent delivery methods. It also discusses the current challenges as well as potential improvements for maize genome engineering protocols.

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 Update of Regulatory Options of New Breeding Techniques and Biosafety Approaches among Selected Countries: A Review

2020 ◽  
pp. 18-35
Author(s):  
Silas Obukosia ◽  
Olalekan Akinbo ◽  
Woldeyesus Sinebo ◽  
Moussa Savadogo ◽  
Samuel Timpo ◽  
...  
Keyword(s):  
Genome Editing ◽  
Genetically Modified Organisms ◽  
Zinc Finger Nucleases ◽  
Intermediate Step ◽  
Homing Endonucleases ◽  
Transcription Activator ◽  
Associated Proteins ◽  
Genomic Editing ◽  
New Breeding Techniques ◽  
Breeding Techniques

A new set of breeding techniques, referred to as New Breeding Techniques developed in the last two decades have potential for enhancing improved productivity in crop and animal breeding globally. These include site directed nucleases based genomic editing procedures-CRISPR and Cas associated proteins, Zinc Finger Nucleases, Meganucleases/Homing Endonucleases and Transcription- Activator Like-Effector Nucleases for genome editing and other technologies including- Oligonucleotide-Directed Mutagenesis, Cisgenesis and intragenesis, RNA-Dependent DNA methylation; Transgrafting, Agroinfiltration, Reverse breeding. There are ongoing global debates on whether the processes of and products emerging from these technologies should be regulated as genetically modified organisms or approved as conventional products. Decisions on whether to regulate as GMOs are based both on understanding of the molecular basis of their development and if the GMO intermediate step was used. For example- cisgenesis, can be developed using Agrobacterium tumefaciens methods of transformation, a process used by GMO but if the selection is properly conducted the intermediate GMO elements will be eliminated and the final product will be identical to the conventionally developed crops. Others like Site Directed Nuclease 3 are regulated as GMOs in countries such as United State of America, Canada, European Union, Argentina, Australia. Progress in genome editing research, testing of genome edited bacterial blight resistant rice, development of Guidelines for regulating new breeding techniques or genome editing in Africa is also covered with special reference to South Africa, Kenya and Nigeria. Science- and evidence-based approach to regulation of new breeding techniques among regulators and policy makers should be strongly supported.

scholarly journals Network-Based Prediction of Novel CRISPR-Associated Genes in Metagenomes

mSystems ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Jake L. Weissman ◽  
Philip L. F. Johnson
Keyword(s):  
Genome Editing ◽  
Viral Infections ◽  
Adaptive Immune System ◽  
Gene Families ◽  
Great Success ◽  
Theory Approach ◽  
Viral Pathogens ◽  
Microbial Life ◽  
Associated Proteins ◽  
Short Palindromic Repeat

ABSTRACT A diversity of clustered regularly interspaced short palindromic repeat (CRISPR)-Cas systems provide adaptive immunity to bacteria and archaea through recording “memories” of past viral infections. Recently, many novel CRISPR-associated proteins have been discovered via computational studies, but those studies relied on biased and incomplete databases of assembled genomes. We avoided these biases and applied a network theory approach to search for novel CRISPR-associated genes by leveraging subtle ecological cooccurrence patterns identified from environmental metagenomes. We validated our method using existing annotations and discovered 32 novel CRISPR-associated gene families. These genes span a range of putative functions, with many potentially regulating the response to infection. IMPORTANCE Every branch on the tree of life, including microbial life, faces the threat of viral pathogens. Over the course of billions of years of coevolution, prokaryotes have evolved a great diversity of strategies to defend against viral infections. One of these is the CRISPR adaptive immune system, which allows microbes to “remember” past infections in order to better fight them in the future. There has been much interest among molecular biologists in CRISPR immunity because this system can be repurposed as a tool for precise genome editing. Recently, a number of comparative genomics approaches have been used to detect novel CRISPR-associated genes in databases of genomes with great success, potentially leading to the development of new genome-editing tools. Here, we developed novel methods to search for these distinct classes of genes directly in environmental samples (“metagenomes”), thus capturing a more complete picture of the natural diversity of CRISPR-associated genes.

scholarly journals Strategies to Increase On-Target and Reduce Off-Target Effects of the CRISPR/Cas9 System in Plants

2019 ◽  
Vol 20 (15) ◽  
pp. 3719 ◽  
Author(s):  
Zahra Hajiahmadi ◽  
Ali Movahedi ◽  
Hui Wei ◽  
Dawei Li ◽  
Yasin Orooji ◽  
...  
Keyword(s):  
Genome Editing ◽  
High Efficiency ◽  
Zinc Finger Nucleases ◽  
Transcription Activator ◽  
Guide Rna ◽  
Short Palindromic Repeat ◽  
External Forces ◽  
Time And Energy ◽  
Reduced Time ◽  
Target Effects

The CRISPR/Cas9 system (clustered regularly interspaced short palindromic repeat-associated protein 9) is a powerful genome-editing tool in animals, plants, and humans. This system has some advantages, such as a high on-target mutation rate (targeting efficiency), less cost, simplicity, and high-efficiency multiplex loci editing, over conventional genome editing tools, including meganucleases, transcription activator-like effector nucleases (TALENs), and zinc finger nucleases (ZFNs). One of the crucial shortcomings of this system is unwanted mutations at off-target sites. We summarize and discuss different approaches, such as dCas9 and Cas9 paired nickase, to decrease the off-target effects in plants. According to studies, the most effective method to reduce unintended mutations is the use of ligand-dependent ribozymes called aptazymes. The single guide RNA (sgRNA)/ligand-dependent aptazyme strategy has helped researchers avoid unwanted mutations in human cells and can be used in plants as an alternative method to dramatically decrease the frequency of off-target mutations. We hope our concept provides a new, simple, and fast gene transformation and genome-editing approach, with advantages including reduced time and energy consumption, the avoidance of unwanted mutations, increased frequency of on-target changes, and no need for external forces or expensive equipment.

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 TALENs—an indispensable tool in the era of CRISPR: a mini review

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Anuradha Bhardwaj ◽  
Vikrant Nain
Keyword(s):  
Genome Editing ◽  
Genome Engineering ◽  
High Specificity ◽  
Zinc Finger Nucleases ◽  
Main Body ◽  
Transcription Activator ◽  
Scientific World ◽  
Dna Modifications ◽  
Pros And Cons ◽  
Indispensable Tool

Abstract Background Genome of an organism has always fascinated life scientists. With the discovery of restriction endonucleases, scientists were able to make targeted manipulations (knockouts) in any gene sequence of any organism, by the technique popularly known as genome engineering. Though there is a range of genome editing tools, but this era of genome editing is dominated by the CRISPR/Cas9 tool due to its ease of design and handling. But, when it comes to clinical applications, CRISPR is not usually preferred. In this review, we will elaborate on the structural and functional role of designer nucleases with emphasis on TALENs and CRISPR/Cas9 genome editing system. We will also present the unique features of TALENs and limitations of CRISPRs which makes TALENs a better genome editing tool than CRISPRs. Main body Genome editing is a robust technology used to make target specific DNA modifications in the genome of any organism. With the discovery of robust programmable endonucleases-based designer gene manipulating tools such as meganucleases (MN), zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats associated protein (CRISPR/Cas9), the research in this field has experienced a tremendous acceleration giving rise to a modern era of genome editing with better precision and specificity. Though, CRISPR-Cas9 platform has successfully gained more attention in the scientific world, TALENs and ZFNs are unique in their own ways. Apart from high-specificity, TALENs are proven to target the mitochondrial DNA (mito-TALEN), where gRNA of CRISPR is difficult to import. This review talks about genome editing goals fulfilled by TALENs and drawbacks of CRISPRs. Conclusions This review provides significant insights into the pros and cons of the two most popular genome editing tools TALENs and CRISPRs. This mini review suggests that, TALENs provides novel opportunities in the field of therapeutics being highly specific and sensitive toward DNA modifications. In this article, we will briefly explore the special features of TALENs that makes this tool indispensable in the field of synthetic biology. This mini review provides great perspective in providing true guidance to the researchers working in the field of trait improvement via genome editing.

scholarly journals CRISPR: a journey of gene-editing based medicine

2020 ◽  
Vol 42 (12) ◽  
pp. 1369-1380
Author(s):  
Zhabiz Golkar
Keyword(s):  
Genome Editing ◽  
Gene Editing ◽  
Genome Engineering ◽  
High Strength ◽  
Evidence Based ◽  
Modern Biology ◽  
Scientific Communities ◽  
Short Palindromic Repeat ◽  
Practical Tool ◽  
Based Medicine

AbstractCRISPR (Clustered Regularly Interspaced Short Palindromic Repeat) is one of the hallmark of biological tools, contemplated as a valid and hopeful alternatives to genome editing. Advancements in CRISPR-based technologies have empowered scientists with an editing kit that allows them to employ their knowledge for deleting, replacing and lately “Gene Surgery”, and provides unique control over genes in broad range of species, and presumably in humans. These fast-growing technologies have high strength and flexibility and are becoming an adaptable tool with implementations that are altering organism’s genome and easily used for chromatin manipulation. In addition to the popularity of CRISPR in genome engineering and modern biology, this major tool authorizes breakthrough discoveries and methodological advancements in science. As scientists are developing new types of experiments, some of the applications are raising questions about what CRISPR can enable. The results of evidence-based research strongly suggest that CRISPR is becoming a practical tool for genome-engineering and to create genetically modified eukaryotes, which is needed to establish guidelines on new regulatory concerns for scientific communities.

scholarly journals Integrating Biomaterials and Genome Editing Approaches to Advance Biomedical Science

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Amr A. Abdeen ◽  
Brian D. Cosgrove ◽  
Charles A. Gersbach ◽  
Krishanu Saha
Keyword(s):  
Genome Editing ◽  
Gene Editing ◽  
Genome Engineering ◽  
Subsequent Development ◽  
Biomedical Science ◽  
Annual Review ◽  
Publication Date ◽  
Nonviral Delivery ◽  
Short Palindromic Repeat

The recent discovery and subsequent development of the clustered regularly interspaced short palindromic repeat (CRISPR)–CRISPR-associated (Cas) platform as a precise genome editing tool have transformed biomedicine. As these CRISPR-based tools have matured, multiple stages of the gene editing process and the bioengineering of human cells and tissues have advanced. Here, we highlight recent intersections in the development of biomaterials and genome editing technologies. These intersections include the delivery of macromolecules, where biomaterial platforms have been harnessed to enable nonviral delivery of genome engineering tools to cells and tissues in vivo. Further, engineering native-like biomaterial platforms for cell culture facilitates complex modeling of human development and disease when combined with genome engineering tools. Deeper integration of biomaterial platforms in these fields could play a significant role in enabling new breakthroughs in the application of gene editing for the treatment of human disease. Expected final online publication date for the Annual Review of Biomedical Engineering, Volume 23 is June 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals From Traditional Breeding to Genome Editing for Boosting Productivity of the Ancient Grain Tef [Eragrostis tef (Zucc.) Trotter]

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 628
Author(s):  
Muhammad Numan ◽  
Abdul Latif Khan ◽  
Sajjad Asaf ◽  
Mohammad Salehin ◽  
Getu Beyene ◽  
...  
Keyword(s):  
Genome Editing ◽  
Target Genes ◽  
Crop Yields ◽  
Agronomic Traits ◽  
Eragrostis Tef ◽  
Forage Production ◽  
Stress Resilience ◽  
Climate Conditions ◽  
Associated Proteins ◽  
Traditional Breeding

Tef (Eragrostis tef (Zucc.) Trotter) is a staple food crop for 70% of the Ethiopian population and is currently cultivated in several countries for grain and forage production. It is one of the most nutritious grains, and is also more resilient to marginal soil and climate conditions than major cereals such as maize, wheat and rice. However, tef is an extremely low-yielding crop, mainly due to lodging, which is when stalks fall on the ground irreversibly, and prolonged drought during the growing season. Climate change is triggering several biotic and abiotic stresses which are expected to cause severe food shortages in the foreseeable future. This has necessitated an alternative and robust approach in order to improve resilience to diverse types of stresses and increase crop yields. Traditional breeding has been extensively implemented to develop crop varieties with traits of interest, although the technique has several limitations. Currently, genome editing technologies are receiving increased interest among plant biologists as a means of improving key agronomic traits. In this review, the potential application of clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated proteins (CRISPR-Cas) technology in improving stress resilience in tef is discussed. Several putative abiotic stress-resilient genes of the related monocot plant species have been discussed and proposed as target genes for editing in tef through the CRISPR-Cas system. This is expected to improve stress resilience and boost productivity, thereby ensuring food and nutrition security in the region where it is needed the most.

scholarly journals Delivery Approaches for Therapeutic Genome Editing and Challenges

Genes ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1113 ◽  
Author(s):  
Ilayda Ates ◽  
Tanner Rathbone ◽  
Callie Stuart ◽  
P. Hudson Bridges ◽  
Renee N. Cottle
Keyword(s):  
Clinical Trials ◽  
Genome Editing ◽  
Zinc Finger ◽  
Gene Editing ◽  
Zinc Finger Nucleases ◽  
Systemic Delivery ◽  
Transcription Activator ◽  
Therapeutic Gene ◽  
Major Barrier ◽  
Associated Proteins

Impressive therapeutic advances have been possible through the advent of zinc-finger nucleases and transcription activator-like effector nucleases. However, discovery of the more efficient and highly tailorable clustered regularly interspaced short palindromic repeats (CRISPR) and associated proteins (Cas9) has provided unprecedented gene-editing capabilities for treatment of various inherited and acquired diseases. Despite recent clinical trials, a major barrier for therapeutic gene editing is the absence of safe and effective methods for local and systemic delivery of gene-editing reagents. In this review, we elaborate on the challenges and provide practical considerations for improving gene editing. Specifically, we highlight issues associated with delivery of gene-editing tools into clinically relevant cells.

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