Less water, more rice: Why gene editing of rice may be a game changer

Two varieties of rice - 'DRR Dhan 100 (Kamala)' and 'Pusa DST Rice 1', developed by ICAR and its institutes - are the world's first genome-edited varieties, and promise to be a game-changer in sustainable agriculture .

Scientists say these two varieties, when cultivated on 5 million hectares, can produce 4.5 million tonnes of additional paddy and save a total of 7,500 million cubic metres of irrigation water. And, apart from a yield advantage of 20%-30%, these climate-resilient varieties could reduce methane emissions by 20%, the scientists claim.

This could go a long way towards solving one of the biggest problems in cultivating rice, a staple for about 800 million Indians: its resource-heaviness. Each kilo of traditional rice requires, on average, 2,500 litres of water, and its cultivation consumes more than 50% of the irrigation water available to the country's agriculture sector.

Genome editing enables scientists to make targeted changes in the native genes of living organisms, creating new and desirable traits without introducing foreign DNA. It involves adding, removing or modifying DNA sequences at specific locations in the genome. This technology has applications in various fields, including medicine, agriculture and basic research.

Because rice is such a resource-guzzler, ICAR's National Rice Research Institute (NRRI), which scientifically calculated the amount of water needed to produce 1kg of rice, noted that a major impact of climate change would be visible in the form of water stress, and that rice cultivation was likely to be most affected.

"In the next two decades, there's a need to produce around 25% more from 10%-15% reduced share of water," said ICAR-NRRI in a research paper on managing water for rice-production systems.

Genome editing allows the development of drought-tolerant rice varieties that have a low water requirement.

ICAR (Indian Council of Agricultural Research) had launched a genome-editing research project in rice in 2018 and selected two widely cultivated mega rice varieties - 'Samba Mahsuri (BPT5204)' and 'MTU1010 (Cottondora Sannalu)' - to enhance their qualities through tech interventions.

Scientists enhanced these rice varieties with better stress tolerance, improved yield and climate adaptability without compromising on their existing strengths as they developed the two new genome-edited varieties.

Genome-edited varieties are, however, suitable for only those states/UTs for which the parent varieties are recommended: Tamil Nadu, Karnaktaka, Puducherry, Chhattisgarh, Andhra Pradesh, Telangana, Odisha, Maharashtra, Kerala, Madhya Pradesh, Bengal, Bihar, Jharkhand and (eastern) UP.

ICAR is now accessing intellectual property rights before the newly developed genome-edited varieties are made available to farmers. Seeds for commercial cultivation are expected to reach farmers within two years.

The Coalition for a GM-Free India - a network of organisations and individuals advocating for a GM-free India - has demanded that govt immediately withdraw the two genome-edited rice varieties and bring them under the purview of rigorous regulation. They claim the two varieties have the potential to harm humans and cause irreversible damage to the environment, apart from threatening the country's seed sovereignty.

Since the genome-edited line contains no foreign DNA, it makes it comparable to conventionally bred varieties.

Two key approaches - Site Directed Nuclease 1 (SDN1) and Site Directed Nuclease 2 (SDN2) - produce genetically edited organisms that are considered "indistinguishable from naturally occurring or conventionally bred mutants". As such, they are exempt from stringent bio-safety regulations under Rules 7-11 of the Environment (Protection) Act, 1986.

The Institutional Bio-safety Committee (IBC) of ICAR institutes approved the lines, and the Review Committee on Genetic Manipulation (RCGM) granted clearance on May 31, 2023, for classification under India's relaxed regulatory framework for SDN1 and SDN2 genome edits.

Viswanathan Chinnusamy, lead developer of the genome-edited rice and joint director (research), IARI, said plants with genome-edited seed varieties do not contain 'exogenous' (foreign) DNA, unlike genetically modified crops.

He also dispelled health fears with gene-edited rice varieties, saying the genome-edited variety is equivalent to a mutant variety developed by a conventional approach.

"Hence, it has no health or environmental concerns," he said.