Question

The genetically-modified (GM) brinjal on India, has been developed for
A. Drought resistance
B. Insect-resistance
C. Enhancing shelf life
D. Enhancing mineral content

Answer 1

Transgenic, or GM, plants are those that have been genetically modified using recombinant DNA technology to confer a particular trait or characteristic to that plant.

Complete Answer:
- The genetically modified brinjal, also known as eggplant or aubergine, is created by inserting a crystal protein gene (Cry1Ac) from the soil bacterium Bacillus thuringiensis into the genome of various brinjal cultivars.
- Bacillus thuringiensis (Bt) is a Gram-positive bacterium that produces crystals during sporulation. These crystals consist of ~130 kDa proteins called crystal proteins that are potent and highly specific insecticides.
- When the host ingests it, the crystals dissolve in the alkaline conditions (pH> 9.5) of the gut and the proteins are activated. The active toxins then bind to receptors on midgut epithelial cells and become inserted into the plasma membrane where they form pores in the membrane leading to cell death through osmotic lysis. The Bt brinjal has been developed to provide resistance against the lepidopteran insects.
- The insertion of the gene, along with other genetic elements like promoters, terminators, and an antibiotic resistance marker gene in the brinjal plant is done using Agrobacterium-mediated genetic transformation. In this technique, Agrobacterium tumefaciens are used which can infect the plant with its DNA. The plant tissue is incubated with Agrobacterium cells that carry a recombinant plasmid which has both a selectable marker and the desired transgene.
- When the Agrobacterium recognizes the plant cell, it passes the transfer DNA (T-DNA) that carries the transgene into the cell. Plants that take up the T-DNA and express the selectable marker survive and proliferate to form the callus. The required growth regulators and nutrients are supplied into the culture for the plant to grow properly.

Hence, the correct option is B, ‘Insect-resistance’.

Note: Mahyco, an Indian seed company based in Jalna, Maharashtra, has developed the Bt brinjal. Plants are modified to get a better product than the original one. Genetically modified crops are resistant to many diseases and pests, high productivity can be yielded in less time, they have increased tolerance to the changing environment, can be stored for a long time due to its increased resistance to spoilage, etc.