Callus formation from cotyledon protoplasts of Pinus oocarpa and Pinus patula

Protoplasts were isolated from cotyledons of 11-day-old seedlings of Pinus oocarpa and P. patula ssp. tecunumanii . The best enzyme combination was Cellulase R10 + Pectolyase Y-23, associated with bovine serum albumin. When cultured at a low density 1.25 × 10³ to 5 × 10³ protoplast (ml)^?1] in a liquid medium, the cells divided. The medium contained glutamine and casein hydrolysate as nitrogen sources, and glucose as osmoticum. Rate of division was increased by supplementing the medium with l -ornithine, putrescine and spermidine. However, the rate remained low, with an absolute division frequency of ca 1%. Dilution allowed colony proliferation and fragmentation, leading to the formation of numerous microcalli that could be transferred to various solid media for further growth.