Genome editing technology, particularly CRISPR-Cas9, has brought huge advances in agriculture. However, strict rules on using this technology create problems, especially for countries like India. They need these tools to improve food security and farming.
A new development from India offers a glimmer of hope. Researchers at the Indian Council of Agricultural Research (ICAR) have successfully used a new genome-editing system in rice plants. This system, called RNA-guided transposon associated protein (TpnB), is smaller and easier to use than the current CRISPR technology. It works by changing genes to alter how they function, which can lead to better crops.
Understanding Genome Size and Complexity
Different species have vastly different chromosome numbers and genome sizes. For instance, a deer has just six chromosomes, while humans have 46. Some ferns have as many as 1440 chromosomes! The size of a genome doesn’t always relate to how complex an organism is. The human genome is much larger than yeast’s but smaller than some amphibians. Despite these differences, humans and chimpanzees share about 99% of their DNA, showing that how genes are organised and controlled is more important than the total amount of DNA.
The Role of Transposons
Our genomes are filled with vast amounts of DNA, much of which has been carried over through evolution. Transposons, often called “jumping genes,” are pieces of DNA that can move to different locations in the genome. They make up a significant portion of our DNA, including over 50% of the human and maize genomes. While they can cause harmful mutations by inserting themselves into important genes, they also contribute to evolution by creating new gene functions and helping repair DNA damage.
Origins of Genome Editing Tools
Scientists believe that the widely used CRISPR-Cas9 system may have evolved from transposons. A protein called IscB, found in transposons, shares similarities with Cas9. This suggests that our current gene-editing tools might have their roots in these ancient “jumping genes.”
Introducing TpnB: A New Player
Recent research has shown that TpnB, a protein found in certain transposons, can also be used for genome editing. It’s more compact than Cas proteins, making it easier to deliver into cells. TpnB works with a small RNA molecule to find and cut specific DNA sequences. Like CRISPR-Cas9, it can introduce small changes (insertions and deletions) into the genome. Studies have shown it can edit DNA in bacteria and human cells, with efficiency rates similar to CRISPR-Cas9.
ICAR’s Breakthrough with TpnB
The ICAR team demonstrated that TpnB can be used effectively for genome editing in rice. They were able to achieve a good editing efficiency, even when targeting multiple genes at once. They also tested the system on other plants, like Arabidopsis, with promising results.
One exciting application was creating albino rice plants by editing genes involved in chloroplast development. This shows the potential of TpnB-based editing for developing new crop varieties.
Why This Matters for India
The development of indigenous gene-editing technology like TpnB is crucial for India. It could lead to cheaper and more accessible crop improvement methods. This is vital for ensuring food security and enhancing agricultural productivity in the face of challenges like climate change and growing populations.
This new technology offers a promising alternative to existing genome-editing systems, potentially making advanced crop breeding more attainable for India and other developing nations.