In fungal sexual reproduction, the process by which two hyphae fuse their cytoplasm is called:

• A. Plasmogamy
• B. Karyogamy
• C. Meiosis
• D. Sporulation

Answer: (A)

Cytoplasmic fusion between two compatible fungal hyphae initiates sexual reproduction, and this step is called plasmogamy. By merging the cytoplasm while the nuclei remain separate, a cell with two different haploid nuclei is formed—the dikaryotic (or heterokaryotic) stage. This stage lasts for a while before the nuclei fuse in a later step called karyogamy, producing a diploid nucleus that can then undergo meiosis to generate haploid spores. Sporulation is simply the production of those spores, which comes after meiosis in many fungi. So the process described—two hyphae fusing their cytoplasm—is plasmogamy.