# DBT JRF 2022 — Question 82

Exam: DBT JRF 2022 · Section: B · Topic: Plant Biotechnology › Pest Resistance - Lectin Genes · Difficulty: Medium

## Question

In plants, the overexpression of lectin genes confers resistance to:

## Options

- **A.** Virus
- **B.** Insects
- **C.** Fungus
- **D.** Bacteria

## Answer

Option B

## Explanation

Lectins as insect resistance genes in plants: Plant lectins are carbohydrate-binding proteins: • When expressed in plant tissues (leaves, seeds), lectins bind to glycoproteins in the insect's midgut epithelium. • Disrupts digestion, nutrient absorption, and midgut cell integrity. • Reduces insect survival, growth, and reproduction → plant resistance to insect herbivory. Examples: • Snowdrop lectin (GNA from Galanthus nivalis): effective against aphids and some Lepidoptera. • Concanavalin A (ConA): binds glucose/mannose residues in insect gut. Application: Transgenic expression of lectin genes in crop plants (rice, wheat) for pest resistance is an active research area. Distinction: Lectins work as INSECT DETERRENTS (binding to gut glycoproteins), not as anti-herbivore TOXINS (like Bt toxin, which forms pores in the insect gut membrane). Answer: Lectins confer insect resistance by binding to glycoproteins in insect digestive systems, disrupting digestion.

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