GM Crops in Agriculture
வேளாண்மையில் மரபணு மாற்றப் பயிர்கள்
Golden rice is yellow because it makes beta-carotene, the precursor of vitamin A — not because of a yellow pigment gene for colour's sake. NEET has asked about Golden rice and herbicide-tolerant crops repeatedly.
The idea
Plants, bacteria, fungi and animals whose genes have been altered by manipulation are called genetically modified organisms (GMOs). Genetic modification has made crops more tolerant to abiotic stresses (cold, drought, salt, heat), reduced reliance on chemical pesticides (pest-resistant crops such as Bt cotton), helped reduce post-harvest losses, increased efficiency of mineral use by plants, and enhanced the nutritional value of food. Golden rice is a vitamin A-enriched rice: it carries genes that make beta-carotene (provitamin A) in the grain. GM crops have also been engineered to tolerate herbicides such as glyphosate, so the herbicide can kill weeds without harming the crop. In India, the Genetic Engineering Approval Committee (GEAC) decides on the validity of GM research and the safety of releasing GM organisms.
Why it matters
Conventional breeding is slow and limited to genes within related plants; genetic engineering can add one useful gene — from any organism — directly into a crop.
NEET lens
NEET keys: Golden rice = vitamin A enriched (beta-carotene) — not pest resistant or drought tolerant. Glyphosate-tolerant crops = herbicide resistance. Bt crops = insect resistance (cry genes). Know the five NCERT advantages of GM plants and that GEAC is the Indian regulator.
Clinical significance
Vitamin A deficiency causes night blindness and weakens immunity, especially in children who depend on rice; Golden rice was designed to address this. Pest-resistant crops cut farmers' pesticide exposure, while the safety and biodiversity concerns of GM crops are why GEAC approval is required in India.
Introduction
Genetically modified (GM) crops carry one or more genes added by genetic engineering to give them a useful new trait.
Core concept
Uses of GM plants (NCERT): (i) more tolerant to abiotic stresses — cold, drought, salt, heat; (ii) reduced reliance on chemical pesticides — pest-resistant crops; (iii) reduced post-harvest losses; (iv) increased efficiency of mineral usage by plants (prevents early exhaustion of soil fertility); (v) enhanced nutritional value — e.g. Golden rice, vitamin A enriched rice. Also: alternative resources to industries (starches, fuels, pharmaceuticals). Examples: Bt cotton (cry genes from Bacillus thuringiensis, insect resistant); herbicide (glyphosate)-tolerant crops; Golden rice (beta-carotene/provitamin A in the grain). Regulation in India: GEAC.
Go deeper
Pest-resistant crops can also be made by RNA interference (e.g. tobacco resistant to the nematode Meloidogyne incognita). Bt toxin genes (cry) are covered in 'Bt Toxin Mechanism'.
From Class 10
Farmers have always chosen better seeds. Genetic engineering speeds this up by inserting a single useful gene directly into the crop.