In terms of colony formation, the agarose method turned out to be the most successful. Protoplasts embedded in 1 % agarose showed an average plating efficiency of 0.11 % after 30 days of culture (defined as the number of recoverable calli per total number of protoplasts plated), while gellan gum and liquid medium had lower efficiencies of 0.016 and 0.0033 %, respectively