MORPHOGENESIS IN LEAF AND SINGLE-CELL CULTURES OF MATURE JUNIPERUS-OXYCEDRUS

Single cells were mechanically isolated from leaf-derived callus of ma ture Juniperus oxycedrus L. These cells divided and gave rise to callu s when plated on medium containing growth regulators. Best plating eff iciency was obtained on a modified Schenk and Hildebrandt medium suppl emented with 0.6 mu M 2,4-dichlorophenoxyacetic acid and 100 mg l(-1) casein hydrolyzate. Although single-cell-derived callus showed poor mo rphogenic potential, both adventitious shoots and embryogenic tissues differentiated from the callus. We also achieved induction of somatic embryogenesis in leaf explants of mature J. oxycedrus trees cultured i n the presence of 6.0 or 10.0 mu M 2,4-dichlorophenoxyacetic acid or p icloram. Frequency of embryogenic callus ranged from 6 to 18%; however , under the culture conditions tested, isolated embryos failed to deve lop into plants.