30 Questions
What is the function of CRISPR sequences in bacterial genomes and sequenced archaeal species?
They are a component of the bacterial immune system and confer endogenous adaptive immunity.
What is stored in the CRISPR array?
A sort of 'immune memory' of phages and plasmids in the form of brief spacer sequences that intercalate between repetitions and specify CRISPR/Cas immune targets.
What is the primary distinction between the two classes of the CRISPR system?
The nature of the effector complexes. The first class (types I, III, and IV) produces multisubunit effector complexes, while the second class (types II, V, and VI) solely includes bacteria and uses one multidomain protein.
What is the CRISPR/Cas9 system targeted against?
It is targeted against invading DNA molecules, particularly in preventing the invasion of plant DNA viruses.
What is the advantage of using the CRISPR/Cas9 system to combat eukaryotic viruses?
Eukaryotic viruses have not yet evolved the ability to withstand CRISPR immune systems.
What is the limitation of the CRISPR/Cas9 system in terms of the types of viruses it can combat?
It can only be used to combat DNA viruses.
What are the two main types of pathogens that significantly harm the production of crops?
Bacterial and fungal pathogens
What are the economic losses from plant viral diseases estimated to be annually?
60–80 billion US dollars
What are the two main methods currently used to defend against insect carriers of viruses?
Physical barriers and chemical pesticides
Why are there no effective or long-lasting ways to fight viral diseases in plants?
Epidemiological changes caused by viral disease outbreaks, the speed with which viruses change, and the fact that viral vectors are always moving
What is the most cost-effective technique for reducing losses caused by viral infections in plants?
Introducing plant varieties that are resistant to viral infections into commercial production
What has opened up new ways to make plants' immune systems work better against viruses?
Modern biotechnologies and in-depth studies of the molecular and biochemical processes that drive interactions between plants and viruses
Explain the impact of geminivirus IRs on the CRISPR/Cas9 system in plants.
Geminivirus IRs can copy and spread throughout the body without being noticed by the CRISPR/Cas9 system.
How did Mao et al. (2018) enhance the efficacy of CRISPR/Cas9 in editing the AP1 and TT4 genes in Arabidopsis plants?
Mao et al. (2018) inhibited RNA interference by co-expressing the TBSV P19 suppressor protein, which enhanced the efficacy of CRISPR/Cas9 in editing the AP1 and TT4 genes in Arabidopsis plants.
What is the function of the FnCas9 protein variation (FnCas9) discovered by Schunder et al. (2013)?
The FnCas9 protein variation (FnCas9) discovered by Schunder et al. (2013) can target RNA sequences.
How did Price et al. (2015) employ CRISPR/FnCas9 in hepatoma cell lines?
Price et al. (2015) employed CRISPR/FnCas9 to target the ssRNA-positive hepatitis C virus genome, resulting in a reduction in viral protein expression.
What is the repair mechanism used to fix the double-strand breaks resulting from the CRISPR/Cas9 system targeting the viral genome?
Error-prone non-homologous end joins are used to fix the double-strand breaks resulting from the CRISPR/Cas9 system targeting the viral genome.
What can limit the utility of the CRISPR/Cas9 system when employed in A. thaliana according to Q. Zhang et al. (2018)?
Sequence-nonspecific effects are well recognized and can considerably limit the editing method’s utility when employing the CRISPR/Cas9 system in A. thaliana according to Q. Zhang et al. (2018).
What is pathogen-derived resistance (PDR) and when was it proposed?
Pathogen-derived resistance (PDR) was proposed in 1985, and the theory suggests that a phytopathogen's genetic components expressed in plant cells offer resistance to viral pathogenesis.
What are the two types of resistance mechanisms involved in the plant's defense against pathogens?
The two types of resistance mechanisms are the first type of resistance, involving the innate immune system and the thickening of the cell wall, and the second type of universal resistance, triggered by local necrosis and recognizing particular structures or proteins linked to microorganisms or pathogens.
How do phytoviruses enter plant cells?
Phytoviruses enter plant cells through manual inoculation or vectors, and they can penetrate the cell wall's physical defenses.
What are the essential substances needed for the molecular mechanisms of viral infection resistance?
Salicylic acid, ROS, and Ca2+ are essential substances needed for the molecular mechanisms of viral infection resistance.
What are dominant resistance genes and what response do they cause?
Dominant resistance genes, most commonly NB-LRR type, cause a hypersensitive response or an extreme response.
What is the role of recessive resistance genes in the spread of the plant potyvirus family?
Recessive resistance genes are often used to halt the spread of the plant potyvirus family as they encode translation initiation factors of the eIF4E/eIF4G family, which interact with the viral transcript cap structure to translate.
What is the role of eIF4E/eIF4G in translation and how does it relate to plant defense mechanisms?
eIF4E/eIF4G interact with cap-like structures for translation and their selection is important in plant defense mechanisms against viruses.
Differentiate between dominant R-genes and recessive S-genes in terms of resistance to infections.
Dominant R-genes are more resistant to infections than recessive S-genes and are utilized in antiviral strategies against various viruses.
Explain the mechanism of recessive resistance and its effectiveness in plant defense against viruses.
Recessive resistance relies on the absence of host factors eIF4E/4G, and it is a passive yet effective defense mechanism against viruses.
What did Gawehns, Cornelissen, and Takken (2013) research regarding eIF4 and their homologs in relation to viruses?
They conducted research on the use of eIF4 and their homologs as defense mechanisms against potyviruses.
How does RNA interference work as an antiviral strategy in plants?
RNA interference uses dsRNA molecules to inhibit viral RNA translation or hydrolysis, involving proteins like RDR, SGS, DCL, and argonautes.
Describe the role of the P19 protein of the Tomato bushy stunt virus (TBSV) in countering plant defense mechanisms.
The P19 protein acts as a suppressor, reducing DICER and RISC activity, sequestering dsRNA/siRNA, and destabilizing AGO proteins.
Study Notes
- The interaction between cap-like structures and eIF4E/eIF4G for translation involves strict selection in the host selection mechanism.
- Dominant R-genes are more resistant to infections than recessive S-genes and are used in antiviral strategies against TYLCV and other viruses.
- Recessive resistance, which relies on the absence of host factors eIF4E/4G, is a passive and effective resistance.
- Gawehns, Cornelissen and Takken (2013) published research on the use of eIF4 and their homologs against potyviruses.
- RNA interference is an antiviral strategy that uses dsRNA molecules to inhibit viral RNA translation or hydrolysis.
- Proteins like RDR, SGS, DCL, and argonautes participate in RNA interference, cleaving and destroying antisense RNA or recruiting DNA modifiers and histones to limit gene transcription.
- RNA interference shields plants from viruses, regulating growth and development, and dsRNA-mediated silencing can suppress foreign gene expression.
- RNA suppression technology has been used to stop over 60 economically important plant viruses, including PRSV, PPV, MDMV, TYLCV, and others.
- RNA interference can be induced by exogenous application of dsRNA in viral pandemics.
- Most plant viruses have developed defenses against RNA interference, and suppressor proteins can be used to counteract these defenses.
- The P19 protein of the Tomato bushy stunt virus (TBSV) is a well-researched suppressor protein that can reduce DICER and RISC activity, sequester dsRNA/siRNA, and destabilize AGO proteins.
- CRISPR/CAS is a new genome editing tool that offers acquired immunity against viruses and other mobile genetic elements, similar to RNAi-mediated plant defense against pathogens.
Test your knowledge on the interaction of cap-like structures with eIF4E/eIF4G for translation and the host selection mechanism. Explore the roles of recessive S-genes and dominant R-genes in combatting infections.
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