Introduction
Plant viruses are pathogens that damage plants, including both agricultural and ornamental species. Many distinct types of plant pathogens can trigger a variety of symptoms, such as mosaic patterns on plants’ leaves, retarded growth, distorted fruit, and decreased harvest. Plant viruses can be introduced in various ways, including insect vectors, mechanical contact, and infected seeds or plant material.
TMV, TEV, and PVX are three common plant viruses targeted for control using CRISPR-Cas12 and CRISPR-Cas13 (Marqués et al., 2022). CRISPR-Cas12 is especially effective against TEV because of its single-stranded RNA virus genome, while CRISPR-Cas13 is highly potent against both single-stranded and double-stranded RNA viruses, including TMV and PVX.
Family and Genome
Plant viruses, such as TMV (Tobacco mosaic virus), TEV (Tobacco etch virus), and PVX (Potato virus X), are members of the Virgaviridae family. The primary component of these pathogens is a single-stranded RNA genome surrounded by a protein coat or capsid. The genome has a length of about 6-8 kilobases and is organized into a single-stranded positive-sense RNA. The versions of these viruses are rod-shaped or filamentous, about 300-700 nm long and 18-20 nm wide (Evtushenko et al., 2020). Additionally, the virions consist of a spiral helical protein coat, which is formed of a single type of protein, and the RNA genome is coiled within the spiral.
Host Range, Mode of Transmission, and Pathology
The host range of these viruses is inconsistent and depends on specific plant species and families. The TMV species is designed to infect tobacco and other plants of this family. PVX, on the other hand, infects potatoes and related legumes. However, these viruses are transmitted mainly through mechanical contact, such as contaminated hands, tools, or plant material.
When the virus enters the plant’s galls, it continues to multiply. Moreover, viruses enter the cytoplasm of plants and move through the plant’s vascular system (Evtushenko et al., 2020). This causes the following symptoms: mosaic leaves, stunted germination, and curvature of the fruit. Moreover, these viruses are transmitted mainly through contact with infected plant material or contaminated tools.
CRISPR-Cas12 and CRISPR-Cas13
CRISPR-Cas12 and CRISPR-Cas13 are designed to affect the genome of viruses. These methods edit the genome and fight the damage caused by viruses to plants. These tools mainly fight against viruses by specifically dividing and degrading the virus. In this way, it helps to ensure that infections are continuously combated.
Notably, CRISPR-Cas12 is extensively used against single-stranded RNA viruses such as TEV. CRISPR-Cas13 is already efficiently used for fighting double-stranded RNA viruses, in addition to TMV, the tool also fights PVX (Marqués et al., 2022). Thus, using CRISPR-Cas systems to combat plant viruses is a promising area of research, as it suggests a targeted approach to virus eradication without damaging the host plant or the natural world.
The article “Diagnostics of Infections Produced by the Plant Viruses TMV, TEV, and PVX with CRISPR-Cas12 and CRISPR-Cas13” intends to explore the potential of CRISPR-Cas12 and CRISPR-Cas13 systems for detecting these three viruses in plants. According to the authors, CRISPR-Cas12 and CRISPR-Cas13 are RNA-guided nucleases that target specific DNA or RNA strands (Marqués et al., 2022). Thus, the authors concluded that the systems are used for genome editing, gene regulation, and diagnostic applications. In addition, the researchers used a variety of CRISPR-Cas12 and CRISPR-Cas13-based diagnostic tools to study the three virus types in the article, including lateral flow assays, fluorescence assays, and isothermal amplification.
Conclusion
The authors found that CRISPR-Cas12 and CRISPR-Cas13 systems could detect TMV, TEV, and PVX accurately. Moreover, in the lateral flow and fluorescence assays, it was found that they detected the virus within 30 minutes and had a detection limit of 0.1 ng/μL and one pg/μL, respectively. At the same time, the article states that the detection limit of isothermal amplification was 0.1 pg/mL for TMV and TEV and 0.5 pg/mL for PVX (Marqués et al., 2022). Thus, the authors note that the diagnostic methods based on CRISPR-Cas12 and CRISPR-Cas13 have advantages like speed and sensitivity to viral changes.
Moreover, these methods detect the virus and do not require special pens and equipment to eliminate it. Also, the CRISPR-Cas12 and CRISPR-Cas13-based control systems can be programmed to target different viral sequences, making them suitable for detecting other plant viruses. Thus, this study demonstrates the potential of CRISPR-Cas12 and CRISPR-Cas13 for rapid and accurate detection of plant viruses.
References
Evtushenko, E. A., Ryabchevskaya, E. M., Nikitin, N. A., Atabekov, J. G., & Karpova, O. V. (2020). Plant virus particles with various shapes as potential adjuvants. Scientific Reports, 10(1), 1-10. Web.
International Committee on Taxonomy of Viruses. (n.d.). Family: Virgaviridae. Web.
Katalani, C., Boone, H. A., Hajizade, A., Sijercic, A., & Ahmadian, G. (2020). CRISPR-based diagnosis of infectious and noninfectious diseases. Biological Procedures Online, 22(1), 1-14. Web.