PLANT-REGENERATION FROM ADVENTITIOUS ROOTS OF SPINACH (SPINACIA-OLERACEA L) GROWN FROM PROTOPLASTS

An efficient system for plant regeneration from adventitious roots of spinach (Spinacia oleracea L.) was established. The adventitious roots differentiated from calli that had grown from protoplasts. Protoplast s were obtained from the cotyledon of seedlings by partial digestion o f cell walls, followed by mechanical maceration with forceps. The prot oplasts formed colonies at a frequency of 1.6% in a Murashige and Skoo g's (MS) medium containing 1 mu M 2,4-dichlorophenoxyacetic acid (2,4- D) or 10 mu M 1-naphthalene acetic acid (NAA) combined with 10 mu M 6- (4-hydroxy-3-methyl-but-trans-2-enylamino) purine (zeatin). Calli deri ved from the colonies produced adventitious roots on MS medium contain ing 10 mu M NAA and 0.1 mu M gibberellic acid (GA(3)). Root segments e xcised from these adventitious roots differentiated into many embryos when subcultured on MS medium supplemented with 30 mM fructose instead of sucrose. The embryos developed into flowering mature plants on a g rowth regulator-free medium.