In which of the following fungi , the plasmogamy is followed by karyogamy, immediately?

Options

A. Mucor
B. Aspergillus
C. Ustilago
D. Puccinia

Answer

To solve the question regarding which fungi undergo immediate karyogamy following plasmogamy, we can follow these steps:

### Step 1: Understand the Definitions
- **Plasmogamy**: This is the fusion of the protoplasm of two fungal cells. It is the first step in sexual reproduction in fungi.
- **Karyogamy**: This is the fusion of the nuclei of the two cells that have undergone plasmogamy. It follows plasmogamy and results in the formation of a diploid nucleus.

### Step 2: Identify the Fungal Classes
- Fungi can be classified into various groups, including:
- **Phycomycetes**: This group typically undergoes plasmogamy followed immediately by karyogamy.
- **Ascomycetes**: In this group, there is an intermediate dikaryotic stage (N + N) before karyogamy occurs.
- **Basidiomycetes**: Similar to ascomycetes, they also have a dikaryotic stage before karyogamy.

### Step 3: Analyze the Options
1. **Mucor**: This fungus belongs to the class of phycomycetes. In this group, plasmogamy is followed immediately by karyogamy.
2. **Aspergillus**: This fungus belongs to the class of ascomycetes, which has a dikaryotic stage before karyogamy.
3. **Ostiolego**: This fungus belongs to the class of basidiomycetes, which also has a dikaryotic stage before karyogamy.
4. **Paxenia**: Like ostiolego, this fungus is also part of the basidiomycetes class and has a dikaryotic stage.

### Step 4: Conclusion
From the analysis, the only fungus where plasmogamy is followed immediately by karyogamy is **Mucor** (phycomycetes).

### Final Answer
The correct answer is **Mucor**.

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