A protocol for regenerating genetically stable coffee (Coffea arabica L.) plantlets through direct somatic embryogenesis

Abstract

Coffee is an important beverage crop owing to its economic benefits at individual and national levels. The most important part of coffee in vitro micropropagation is the generation of genetically homogenous and uniform plantlets with all desirable characters of the mother plant. Somaclonal variation may lead to generation of off-types planting material with undesirable character(s) due to loss of genetic fidelity. The present experiment investigated genetic stability and somaclonal variation of 54 somatic embryo-regenerated Coffea arabica ‘Ruiru 11’ sibs 93, 100, 121 and 137 and 2 clonal mother plants of each sib. The Sibs were characterized using 13 SSR molecular markers. The molecular data was organized into a matrix and genetic similarity calculated with Jaccard’s distances using XLSTAT statistical software and a profile plot constructed using Unweighted Pair Group Method with Arithmetic average cluster analysis to evaluate the genetic fidelity amongst the regenerated plantlets. All banding profiles from somatic embryogenesis regenerated plantlets were monomorphic and similar to those of the mother plants with a similarity value of 1. The profile plot revealed 100% similarity between the somatic embryo-regenerated plantlets and the clonal mother plants. These results confirmed that the somatic embryo-regenerated progenies were uniform according to the SSR markers. The somatic embryogenesis process had a mechanism for selecting competent cells and the regenerated plantlets were genetically stable. Therefore, the protocol for regenerating somatic embryos is recommended for use in mass propagation of the disease-resistant somaclones for distribution to farmers to use in expansion of the acreage planted with coffee.