Influence of different ethylene inhibitors on somatic embryogenesis and secondary embryogenesis from Coffea canephora P ex Fr.

The effect of cobalt chloride, salicylic acid, and silver nitrate for embryogenesis was studied in in vitro cultures of Coffea canephora. Murashige and Skoog (in Physiol. Plant. 15:473-497, 1962) medium containing 20 and 40 mu M either of cobalt chloride, silver nitrate, or salicylic acid supplemented with 1.1 mu M N-6 benzyladenine and 2.85 mu M indole-3-acetic acid was used for the study. At 20 and 40 mu M silver nitrate treatment, 35-48% explants responded for embryogenesis, and 38 +/- 7 and 153 +/- 27 embryos were produced from each callus mass, respectively, whereas only 5% control explants responded on medium devoid of silver nitrate, cobalt chloride, or salicylic acid. Secondary embryogenesis was observed in 70-90% of the explants, and around 100-150 embryos were produced from each explant cultured on a medium containing silver nitrate, and only a 3% response was noticed in control embryo explants. Yellow friable embryogenic calluses were obtained from the cut edges of most of the tissues grown in a medium supplemented with cobalt chloride. The results clearly demonstrated that, among the tested ethylene inhibitors, silver nitrate is very effective in reprogramming the cellular machinery toward embryogenesis.