Somatic Embryogenesis and Temporary Immersion for Mass Propagation of Chimera-Free Mutant Arabica Coffee Plantlets

Abstract Coffee is one of the most valuable cash crops providing employment for millions of people worldwide. Arabica coffee is widely grown in Latin America where it is under threat of leaf rust. Conventional breeding of Arabica coffee is challenged by its narrow genetic base and long reproductive cycle, and it can take up to 30 years for variety development and release. In vitro somatic embryogenesis is a propagation technique whereby a single plant somatic cell can give rise to a somatic embryo under appropriate culture conditions. For tree crops such as Arabica coffee, single-cell mutagenesis using embryogenic cell cultures provides a powerful approach to produce chimera-free mutant lines directly from cells. Here we describe protocols to induce friable embryogenic callus, establish embryogenic cell suspensions, and convert somatic embryos into plantlets using a RITA ® bioreactor for Coffea arabica var. Venecia. In addition, methods for gamma-ray mutagenesis of regenerable cell suspensions are described.