Question

Which of the following molecular approaches can be used to generate complete knock-out of a target gene in plants?

• A. Homologous recombination
• B. CRISPR-Cas9
• C. Antisense RNA technique
• D. Activation tagging

Hint:

For complete gene knock-outs in plants, CRISPR-Cas9 and homologous recombination are the most widely used methods, while other techniques like antisense RNA and activation tagging are useful for gene regulation rather than complete knock-out.

Answer 1

The Correct Option is A, B

To generate a complete knock-out of a target gene in plants, two powerful molecular approaches are commonly used: homologous recombination and CRISPR-Cas9. Let’s discuss each option in detail.
- (A) Homologous recombination: This technique allows the replacement or disruption of a target gene through recombination with a construct containing a mutated version of the gene or a non-functional allele. It is a well-established method for generating gene knockouts in plants, making statement (A) correct.
- (B) CRISPR-Cas9: CRISPR-Cas9 is a revolutionary gene-editing technique that can be used to create gene knockouts by introducing double-strand breaks at specific locations in the target gene. The repair process often leads to frameshift mutations that disrupt the gene, making statement (B) correct.
- (C) Antisense RNA technique: This technique involves introducing RNA molecules that are complementary to the target gene's mRNA, reducing its expression. While effective in down-regulating gene expression, it does not completely "knock out" the gene as CRISPR-Cas9 or homologous recombination does. Hence, statement (C) is incorrect.
- (D) Activation tagging: This technique involves the insertion of strong enhancer sequences near a target gene, leading to its overexpression rather than its knockout. Therefore, statement (D) is incorrect.
Thus, the correct answers are (A) and (B).