Direct Somatic Embryogenesis of Selected Commercial Coffea Arabica L. Varieties in Kenya

Abstract

Breeding programs in Kenya have produced disease tolerant Coffea arabica varieties such as Ruiru 11 and Batian. Subsequently demand has surpassed supply. Existing propagation methods do not provide enough planting materials, hence the need to develop alternative methods of coffee propagation. The objective of this study was to develop an efficient In vitro regeneration protocol for coffee varieties Batian, Ruiru 11 and SL28 commercially grown in Kenya. Sterilization was carried out using different concentrations of Jik® (3.85 v/v sodium hypochlorite) for varied exposure times. A single step sterilization procedure was established using 28% for 25minutes and is recommended for further work. The effects of various auxins and cytokinins on the different In vitro regeneration stages of coffee were evaluated. The results showed significant differences among the different cytokinin and auxin levels for regeneration of the evaluated varieties. The best cytokinin level for induction of somatic embryogenesis was found to be 13.3µM Benzyl amino purine giving the highest mean number of somatic embryos across all selected varieties. Germination of somatic embryos was achieved on hormone free (control) Murashige and Skoog media and there were no significant differences amongst the evaluated levels of Benzyl amino purine. 2.5 µM NAA was best in induction of a well-developed root system for all the evaluated varieties with a mean length of 1.71±0.09mm for SL28 variety. The findings of this research work open an otherwise inadequately explored area for maximizing In vitro plantlet production in coffee that needs to be fully exploited.