Gene-edited mustard: Less pungent, more useful

Source: The post is based on the article “Gene-edited mustard: Less pungent, more useful” published in The Indian Express on 21^st August 2023.

Syllabus: GS 3 – Agriculture

Relevance: About GTR genes-edited mustard

News: Oilseeds provide oil for cooking and protein-rich meals for animals. Rapeseed-mustard is a key Indian oilseed, constituting 42.6% of oil production and 30.3% of meal production.

However, its high glucosinolate levels create pungent taste and odor in its products, making the oil less preferred by consumers and the meal unpalatable for the livestock.

What alternative is being adopted by the scientists for the rapeseed-mustard?

Scientists are trying to breed rapeseed-mustard along the lines of canola quality by lowering glucosinolate levels. This will help in reducing the pungent taste and odor of the oil and meal.

However, these low-glucosinolate mustard lines face issues in large-scale farming due to vulnerability to pests and diseases. Because glucosinolates also shield crops like mustard against pests and pathogens.

While lowering glucosinolates benefits oil and meals, it compromises the plant’s overall defense. Therefore, novel breeding research plays a crucial role in addressing these challenges.

How does novel research breeding help in addressing these challenges?

Novel breeding research involves glucosinolate production in leaves and pod walls, transported to seeds via glucosinolate transporter (GTR) genes. GTR1 and GTR2 classes encompass 12 genes responsible for this process.

For example, CRISPR/Cas9 gene editing was used to modify 10 out of 12 GTR genes in ‘Varuna’ Indian mustard.

Targeted gene editing of the Varuna mustard variety resulted in seed glucosinolate levels below the 30-ppm of the canola-quality limit. Whereas other parts like leaves and pod walls had notably higher glucosinolates.

This low-seed, high-leaf glucosinolate edited lines demonstrated defense responses better than the wild-type mustard, due to the high glucosinolate concentration in leaves and pod walls.

Whereas the low glucosinolate levels in seeds will reduce the pungent taste and odor in the oil and meals, making it useful for both animals and humans.

What are the characteristics of this new GTR genes-edited mustard?

The new GTR genes-edited mustard lines are transgene-free, meaning they are not genetically modified (GM) and lack foreign genes found in Bt cotton or GM hybrid mustard.

The low-seed high-leaf glucosinolate mustard lines are genome edited (GE), different from GM or transgenic plants. The final GE lines also do not possess the Cas9 protein and are devoid of transgenes.

Moreover, in India, strict rules governed by the Genetic Engineering Appraisal Committee (GEAC) under the Ministry of Environment oversee GM crop cultivation.

But in March 2022, a new rule was introduced by the Ministry stating that GM plants without added foreign DNA don’t require GEAC approval for field tests or commercial sale.

This change means that clearance is now only required from an Institutional Biosafety Committee (IBSC).

What is the way ahead?

India imports a substantial amount of edible oils, covering over 60% of consumption.

Therefore, it’s crucial to boost domestic oilseed production through breeding for improved yields, pest resistance, and quality, to curb foreign exchange outflow.