Resistance to tongro 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 how resistance to Tongro virus and leafhopper in rice is developed, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Problem**:
- The question asks how rice can develop resistance to the Tongro virus and leafhoppers, which are known to cause significant damage to the plant.

2. **Identifying the Agents of Damage**:
- The Tongro virus is a combination of two viruses, and it is transmitted to rice plants by leafhoppers. These pests not only spread the virus but also cause physical damage to the plants.

3. **Effects of the Virus**:
- The infection leads to symptoms such as discoloration of leaves and stunted growth, which ultimately reduces the nutritional value of the rice plants.

4. **Exploring Solutions**:
- To combat these issues, various methods can be employed, including tissue culture, genetic engineering, and cross-breeding.

5. **Tissue Culture Method**:
- Tissue culture involves growing plant cells in a controlled environment. In this method, healthy genes that confer resistance to the Tongro virus can be introduced into the rice plant. This process enhances the plant's ability to resist the virus.

6. **Genetic Engineering**:
- While genetic engineering can modify plant species, it does not necessarily add disease resistance genes directly. It may lead to mutations and changes in chromosome numbers, which can complicate resistance.

7. **Cross-Breeding**:
- Cross-breeding involves mating different plant varieties. However, this method may inadvertently spread the virus to other plants rather than providing resistance.

8. **Conclusion**:
- Based on the analysis, the most effective method for developing resistance to the Tongro virus and leafhopper in rice is through tissue culture, as it allows for the direct introduction of resistance genes.

### Final Answer:
Resistance to Tongro virus and leafhopper in rice is developed by **tissue culture**.

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