India’s First Genome-Edited Rice Varieties
Context
India became the first country in the world to develop genome-edited rice varieties without a foreign DNA.
- The ICAR developed the first genome-edited rice varieties: DRR Dhan 100 (Kamala) and Pusa DST Rice 1, using CRISPR-Cas genome editing
Relevance:
GS-03 (Science and technology)
About the New Varieties
- DRR Dhan 100 (Kamala)
- Developed by: ICAR – Indian Institute of Rice Research (IIRR), Hyderabad
- Base variety: Improved version of Samba Mahsuri
- Target gene: CKX2 (Cytokinin Oxidase 2) – controls cytokinin, a hormone regulating plant growth and cell division.
- Pusa DST Rice 1
- Developed by: ICAR – Indian Agricultural Research Institute (IARI), New Delhi
- Base variety: Improved MTU1010 (Cottondora Sannalu)
- Enhanced drought and stress tolerance traits.
What is Genome Editing?
- Genome editing, also known as gene editing, consists of technologies that enable scientists to modify an organism’s DNA. These technologies allow for the addition, removal, or alteration of genetic material at specific locations within the genome.
- CRISPR Technology: One of the most advanced tools is the CRISPR-Cas9 system, which allows for precise genome editing. This technology has revolutionized plant breeding, enabling agricultural scientists to insert specific traits into the gene sequence.
Types of Genome Editing:
Genome editing is categorized into three types based on the nature of the edits:
- SDN 1: Introduces small insertions or deletions in the DNA without adding foreign genetic material.
- SDN 2: Uses a small DNA template to create specific changes, still without foreign genetic material.
- SDN 3: Involves adding larger DNA elements or full genes from foreign sources, similar to the development of genetically modified organisms (GMOs).
What is CRISPR and Its Applications?
- CRISPR is a gene-editing tool allowing scientists to make precise changes in a plant’s genome.
- It stands for Clustered Regularly Interspaced Short Palindromic Repeats.
- CRISPR-Cas9 edits the parts of the genome by either removing, adding or altering sections of the DNA sequence.
- It has two key molecules –
- Cas9 – This enzyme acts as a ‘molecular scissors’ that can cut the two strands of DNA at a specific location in the genome.
- Guide RNA (gRNA) – The gRNA work is to find and bind to the specific sequence in the DNA.
- It has two key molecules –
- The guide RNA guides the Cas9 to the same location in the DNA sequence and allows Cas9 to make a cut across both strands of the DNA.
- At this stage, the cell recognises that the DNA is damaged and tries to repair it.
- The DNA repair machinery is used to introduce changes to one or more genes in the genome of a cell of interest.
- The technology replicates a natural defence mechanism in some bacteria that uses a similar method to protect itself from virus attacks.
- Applications in GM Crops:
- Reduces development costs by making targeted genetic modifications.
- Creates GM crops without introducing foreign genes, improving public acceptance.
- Equips crops with stacked resistance genes to combat pest and weed resistance effectively.
Prelims Practice Question
DRR Dhan 100, India’s first genome-edited rice variety, was developed using which technique?
A) RNA Interference
B) CRISPR-Cas
C) Recombinant DNA Technology
D) Polymerase Chain Reaction
Answer: B) CRISPR-Cas
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