Protoplast isolation and plant regeneration of different doubled haploid lines of cauliflower (Brassica oleracea var. botrytis)

Protoplasts were isolated from hypocotyls of 5-day-old seedlings of five doubled-haploid (DH) lines of cauliflower after enzymatic digestion in 0.1% macerozyme R-10 and 1.0% cellulose R-10. Shoot regeneration was achieved in four of the five DH lines. Protoplast yield and frequency of cell division and shoot regeneration varied among experiments and DH lines. Sequence-related amplified polymorphism (SRAP) analysis on all the regenerated plants of each DH line indicated that their genetic compositions were homologous with their mother plants, but few regenerated plants of DH lines no. 3 and 5 were detected with changes in ploidy levels.