Plant pathogenic bacteria are mostly:

Options

A. Gram + Non spore forming
B. Gram – Non spore forming
C. Gram + spore forming
D. Gram (–) spore forming

Answer

To determine the correct answer to the question "Plant pathogenic bacteria are mostly:", we will analyze the options provided and the characteristics of plant pathogenic bacteria.

### Step-by-Step Solution:

1. **Understanding Bacterial Classification**:
- Bacteria can be classified based on their cell wall characteristics into Gram-positive and Gram-negative.
- Gram-positive bacteria have a thick peptidoglycan layer, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.

2. **Identifying Spore Formation**:
- Some bacteria can form spores, specifically endospores, which are a survival mechanism during unfavorable conditions.
- Endospores are primarily formed by Gram-positive bacteria.

3. **Analyzing the Options**:
- **Option A**: Gram positive non-spore forming – This is unlikely as Gram-positive bacteria are known for forming spores.
- **Option B**: Gram negative non-spore forming – This is a strong candidate since many plant pathogenic bacteria are Gram-negative and do not form spores.
- **Option C**: Gram positive spore forming – This is also unlikely as it does not fit the characteristics of plant pathogens.
- **Option D**: Gram negative spore forming – This is incorrect because Gram-negative bacteria generally do not form endospores.

4. **Examples of Plant Pathogenic Bacteria**:
- Common examples of Gram-negative, non-spore forming plant pathogenic bacteria include:
- **Xanthomonas**: Known for causing various plant diseases.
- **Pseudomonas**: Another genus that includes plant pathogens.
- **Agrobacterium**: Known for causing crown gall disease in plants.

5. **Conclusion**:
- Based on the analysis, the correct answer is **Option B: Gram negative non-spore forming**.

### Final Answer:
**Plant pathogenic bacteria are mostly: Gram negative non-spore forming (Option B).**