PLANT-REGENERATION FROM CULTURED PROTOPLASTS OF THE COOKING BANANA CVBLUGGOE (MUSA SPP, ABB-GROUP)

Suspensions of embryogenic cells of a triploid banana (Musa spp., cv. Bluggoe) were initiated from the uppermost part of meristematic buds, and used as protoplast source. After 20 weeks in culture, the suspensi on contained a mixture of globular structures or globules and embryoge nic cell clusters, as well as single cells. Two types of protoplasts w ere obtained from embryogenic suspension culture: small (20-30 mum) an d larger (30-50 mum) protoplasts with a dense cytoplasm and large star ch grains respectively. The small protoplasts probably originated from embryogenic cell clusters, and also from pseudocambial cells of globu les, while larger protoplasts were probably released from oval starchy cells and those of the globule peripheral area. In co-culture with a suitable feeder, consisting of suspensions of diploid banana cells, th e protoplasts of triploid banana reformed the cell wall within 24 h an d underwent sustained divisions leading to the formation of small clus ters of 2-3 cells within 7 days. The latter developed directly into em bryos without passing through an apparent callus phase. 10% of such em bryos gave rise to plantlets when subcultured in 2.2 muM 6-benzylamino purine and 2 muM 4 amino-3,5,6-trichloropicolinic acid for 1 week, bef ore transfer to MS medium containing 10 muM 6-benzylaminopurine. The r est of the embryos underwent intensive direct secondary embryogenesis which could lead to the formation of plantlets with a frequency of up to 50% upon further transfer to hormone-free medium.