Resistance to tungro virus and leaf hopper in rice is developed by

Options

A. Genetic engineering
B. Tissue culture
C. Changing in chromosome number
D. Cross breeding

Answer

To solve the question regarding the development of resistance to the tungro virus and leaf hopper in rice, we will analyze the provided techniques step by step.

### Step-by-Step Solution:

1. **Understanding Tungro Virus and Leaf Hopper**:
- The tungro virus is a viral disease affecting rice, transmitted by leaf hoppers. Symptoms include leaf discoloration and stunted growth. Understanding the disease is crucial to determining how to combat it.

2. **Evaluating the Techniques**:
- **Genetic Engineering**: This technique involves altering the genetic makeup of an organism using recombinant DNA technology. It allows for the introduction of specific traits, such as disease resistance, into the rice plant.
- **Tissue Culture**: This is a method of growing plant cells or tissues in a controlled environment. While useful for propagation, it does not directly confer resistance to diseases.
- **Change in Chromosome Number**: This refers to aneuploidy (loss or gain of chromosomes) or polyploidy (more than two complete sets of chromosomes). While it can lead to variations in traits, it is not a targeted method for developing specific disease resistance.
- **Crossbreeding**: This involves mating two pure breeds of different varieties or species to produce offspring. It can lead to the introduction of desirable traits, but it is less precise than genetic engineering.

3. **Conclusion**:
- Among the given techniques, **genetic engineering** is the most effective and precise method for developing resistance to the tungro virus and leaf hopper in rice. It allows for the direct modification of the rice genome to enhance resistance traits.

### Final Answer:
Resistance to tungro virus and leaf hopper in rice is developed by **genetic engineering**.