Cell-based plant biotechnology: which technique combines two cells that lack cell walls, often from different species, to form a somatic hybrid?

Introduction / Context:
Protoplast technologies enable somatic hybridization and novel trait combinations by fusing cells with removed walls (protoplasts). This bypasses sexual incompatibility barriers and allows combining nuclear and cytoplasmic genomes.

Given Data / Assumptions:

• Cell walls are enzymatically removed (cellulase/pectinase) to obtain protoplasts.
• Fusion can be induced by PEG or electric fields (electrofusion).
• Goal may be to combine traits or organelles from different species or genera.

Concept / Approach:
Protoplast fusion merges plasma membranes and cytoplasms, allowing nuclear fusion and reassortment of organelles. The resulting somatic hybrids can be regenerated into plants, providing access to traits otherwise unattainable via conventional crosses.

Step-by-Step Solution:

Verification / Alternative check:
Well-known cases include somatic hybrids in Solanaceae and Brassicaceae to transfer disease resistance or cytoplasmic traits.

Why Other Options Are Wrong:

• A: Micropropagation multiplies existing genotypes; no fusion.
• B: Cybrids transfer cytoplasm/organelles primarily, not full nuclear fusion.
• D: Mutant selection screens variants; no cell fusion.
• E: Callus induction is a preliminary culture step, not a fusion method.

Common Pitfalls:
Confusing cybrids with somatic hybrids; cybrids combine cytoplasm from one parent and nucleus from another, whereas protoplast fusion can combine both nuclei.

Final Answer:
Protoplast fusion (somatic hybridization)