IMPROVEMENT OF PLANT-REGENERATION FROM LINUM PROTOPLASTS BY THE INDUCTION OF SOMATIC EMBRYOGENESIS

Plant regeneration was obtained through the induction of somatic embryogenesis from protoplast-derived calli of the Linum species L. alpinum, L. amurense, L. hologynum, and L. perenne. Globular embryoids were formed on MS agar medium (Murashige and Skoog, 1962) with 5-mu-M NAA from calli that were previously cultivated for 1 month on MS medium containing 50-mu-M 2,4-D. This concentration was evaluated as optimum with L. perenne, revealing highest speed and highest frequency of embryoid formation. About 20% differentiated embryoids could be germinated into complete plantlets on MS medium containing 0.25-mu-M each of BAP, kinetin and zeatin, and 0.5-mu-M IBA, while 70% developed only shoots and 10% only roots, respectively. Differentiation of shoots from regenerated root tips was also observed. Plantlets transferred to the greenhouse grew vigorously. In the four species, regeneration frequencies were significantly improved by somatic embryogenesis as compared with adventitious shoot formation.