Control of Plant Viral Diseases by CRISPR/Cas9: Resistance Mechanisms, Strategies and Challenges in Food Crops

Abstract

Protecting food crops from viral pathogens is a significant challenge for agriculture. An integral approach to genome-editing, known as CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats and CRISPR associated protein 9), is used to produce virus-resistant cultivars. The CRISPR/Cas9 tool is an essential part of modern plant breeding due to its attractive features. Advances in plant breeding programs due to the incorporation of Cas9 have enabled the development of cultivars with heritable resistance to plant viruses. The resistance to viral DNA and RNA is generally provided using the Cas9 endonuclease and sgRNAs (single-guide RNAs) complex, targeting particular virus and host plant genomes by interrupting the viral cleavage or altering the plant host genome, thus reducing the replication ability of the virus. In this review, the CRISPR/Cas9 system and its application to staple food crops resistance against several destructive plant viruses are briefly described. We outline the key findings of recent Cas9 applications, including enhanced virus resistance, genetic mechanisms, research strategies, and challenges in economically important and globally cultivated food crop species. The research outcome of this emerging molecular technology can extend the development of agriculture and food security. We also describe the information gaps and address the unanswered concerns relating to plant viral resistance mediated by CRISPR/Cas9.

CRISPR/Cas- and Topical RNAi-Based Technologies for Crop Management and Improvement: Reviewing the Risk Assessment and Challenges Towards a More Sustainable Agriculture

“…During the activity of CRISPR/Cas machinery, the gRNA can direct the Cas protein to other regions and consequently lead to unintentional cleavage of DNA sequence, a process known as off-target effect. Shahriar et al ( Shahriar et al, 2021 ) classified the off-targets into two types: 1) sequences sharing high similarities to the target, and 2) irrelevant genomic off-target sites. These off-target mutations are of great concern mainly in the clinical-therapeutic area ( Zhang et al, 2015 ), which restricts its application due to technical and ethical issues.…”

CRISPR/Cas: The New Frontier in Plant Improvement

“…CRISPR strategies were also employed to increase plant resistance toward viral diseases. , Genes such as eukaryotic translation initiation factor 4 ( ELF4 ) isoforms, involved in natural resistance against virus infection, were selected as the target of gene editing. The disruption of ELF4E in Crocus sativus and of ELF4G in O. sativa by CRISPR knockout strategy produced similar results.…”

Is the best resistance strategy against begomoviruses yet to come? A Comprehensive Review

“…Due to its fascinating features, the Cas9 genome editing system has developed into a versatile method to achieve specific gene targeting, gene replacements, gene insertions/deletions, and single base-pair alterations. As a result, this tool has become a crucial component of contemporary plant breeding (82). Cas9 technique has advanced the plant breeding programs and has made resistant cultivars possible even with transmissible resistance against plant viruses.…”

“…This technique can act in two ways: it can detect and degrade pathogenic genes of viruses, making them less virulent or non-virulent, or it can be used to develop crops with resistance genes against viruses. Therefore, this approach has created a buzz in reforming the research against viruses due to its sequence-specific nuclease proficiency (82,55,47). CRISPR-Cas9 system has been engineered to confer resistance to various human viruses and plant geminiviruses (91).…”