Protoplast fusion-derived Ogura male sterile cauliflower with cold tolerance.

Cauliflower (Brassica oleracea L. ssp. botrytis) protoplasts with Ogura male sterile and fertile B. oleracea cytoplasms were fused, producing plants with an array of organellar types. Plants with Ogura mitochondria were male sterile; those with B. oleracea chloroplasts were cold tolerant. In some fusions, unfused parental protoplasts were eliminated by double inactivation with iodoacetate and gamma-irradiation; in others, fused protoplasts were physically isolated by micromanipulation or by cell sorting. Double inactivation fusions produced the most plants, including many which were male sterile, female fertile, cold tolerant and diploid.