Somatic cell hybridization terminology — In cytoplast-based hybrid production, which fusion combination defines a cytoplast fusion event?

Introduction / Context:
Somatic cell hybridization allows genome and cytoplasm mixing beyond sexual compatibility barriers. Terminology distinguishes “protoplast” (with nucleus) from “cytoplast” (enucleated cell). Cytoplast fusion is used to create cybrids, combining nuclear DNA from one parent with cytoplasmic organelles from another.

Given Data / Assumptions:

• Protoplast = wall-less cell retaining nucleus and organelles.
• Cytoplast = enucleated protoplast created by irradiation, centrifugation, or micromanipulation.
• PEG or electrofusion promotes membrane fusion.

Concept / Approach:
Cytoplast fusion specifically refers to the union of one nucleated protoplast with an enucleated partner, yielding a cybrid where the nuclear genome comes predominantly from the nucleated donor, while cytoplasmic genomes (mitochondria, plastids) can derive from either/both parents.

Step-by-Step Solution:

Verification / Alternative check:
Cybrid selection markers (chloroplast traits, antibiotic resistance) confirm cytoplasmic contribution from the cytoplast donor.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing somatic hybrids with cybrids; nuclear vs cytoplasmic inheritance goals dictate fusion pairing.

Final Answer:
Fusion of a normal (nucleated) protoplast with an enucleated protoplast (cytoplast).