Question

Which of the following is true regarding CRISPR-Cas9 gene editing in crops ?

• A. It involves the insertion of foreign genes into the crop's genome.
• B. It can only be used to delete genes, not modify them.
• C. It allows for precise and targeted modifications to a crop's DNA.
• D. It is a new technology but not for use in crop improvement.

Hint:

CRISPR-Cas9 is classified as a gene editing technology rather than genetic engineering (transgenics) because it can modify endogenous genes directly without leaving any foreign DNA behind in the final improved plant variety.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
CRISPR-Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated protein 9) is a revolutionary genome editing technology.
Derived from a bacterial immune defense system, it uses a guide RNA (gRNA) to direct the Cas9 endonuclease enzyme to a specific target sequence in the genome, where it introduces a precise double-stranded break.

Step 2: Detailed Explanation:
Let us evaluate each statement regarding CRISPR-Cas9 application in crops:
Option (A):
Unlike traditional genetic modification (GM) technologies that randomly insert foreign DNA (transgenes) into the host genome, CRISPR-Cas9 primarily modifies the existing plant genes.
It can achieve gene knockouts or edits without incorporating foreign DNA, making it a non-transgenic approach.
Thus, Option (A) is incorrect.
Option (B):
While CRISPR is highly effective for gene knockouts (deletions), it can also be used for gene insertion, base editing, and precise gene correction (knock-ins) when provided with a donor repair template.
Thus, Option (B) is incorrect.
Option (C):
The primary advantage of CRISPR-Cas9 is its high precision and specificity.
By changing the 20-nucleotide targeting sequence of the guide RNA, researchers can direct the Cas9 enzyme to make precise, targeted modifications at any specific locus in the plant's genomic DNA.
Thus, Option (C) is correct.
Option (D):
CRISPR-Cas9 is widely used in modern crop improvement to enhance disease resistance, drought tolerance, shelf-life, and nutritional quality in various commercial crops.
Thus, Option (D) is incorrect.

Step 3: Final Answer:
CRISPR-Cas9 allows for precise and targeted modifications to a crop's DNA.
This corresponds to Option (C).