Direct somatic embryogenesis from Coffea arabica L. and Coffea canephora P ex Fr. under the influence of ethylene action inhibitor-silver nitrate

For the first time direct somatic embryogenesis from
hypocotyl explants of in vitro regenerated plantlets of C. arabica and C. canephora was achieved on modified MS medium containing 10 - 70 mM silver nitrate supplemented with
1.1 mM N6 benzyl adenine and 2.85 mM indole-3-acetic acid. A
maximum of 144.1±7.3 and 68.7±3.3 embryos per explant
were produced at 40 mM silver nitrate in C. canephora and C.
arabica respectively. Only yellow friable embryogenic callus obtained from the cut edges of most of leaf explants of both C. arabica and C. canephora at all concentrations of silver nitrate were tried in this experiment. Formation of secondary embryos from stage I primary embryos (small yellow, round, globular embryos) was more (28.23±1.3) at 60 mM silver nitrate in C. canephora, while 40 mM silver nitrate supported more of secondary embryo formation in C. arabica (40.5±1.2). When stage II (green globular round matured embryos) and stage III primary embryos (tubular stage embryos) were used, secondary embryo formation was very small and many of these embryos developed into plantlets and some of them even rooted. By using these protocols within 45 - 60 days it is possible to get
secondary embryos from primay embryos and direct somatic
embryos from hypocotyls of in vitro plantlets in both these
Coffea species.