Selection and enrichment of differentially labeled plant protoplasts.

A fast and efficient method for the selection of plasmamembrane-marked protoplasts via magnetic-associated cell separation (MACS) was developed. Isolated mesophyll protoplasts from sunflower (Helianthus annuus L.) were covalently labeled at their plasma membrane with fluoresceine isothiocyanate (FITC) with an efficiency of greater than 95%. They were subsequently coupled to specific monoclonal antibodies against FITC, which were conjugated to magnetic beads, and mixed with unlabeled hypocotyl protoplasts. About 95% of the marked mesophyll protoplasts were separated by the MACS system with a purity of greater than 80%. Protoplasts embedded in agarose showed normal dividing activities.