Chemical Mutagenesis of Coffea arabica L. var. Venecia Cell Suspensions Using EMS

Abstract Arabica coffee is widely grown in Latin America where it is under threat of leaf rust, a fungal disease caused by Hemileia vastatrix . As a perennial crop, conventional breeding of Arabica coffee is challenged by its long juvenile period and narrow genetic base. Plant mutants are important resources for crop breeding and functional genomics studies. The ethylating agent ethyl methanesulfonate (EMS) is widely used for inducing random point mutations. In a wide range of species, treatment with EMS causes GC-to-AT transitions with great efficiency. These properties, combined with ease of use, make EMS a mutagen of choice for induced mutagenesis. In vitro cell and tissue culture integrated with mutation induction provide an attractive approach for broadening the genetic base and breeding purposes, especially for perennial crops such as Arabica coffee. Embryogenic cell cultures are suitable targets for mutation induction and can accelerate the development of chimera-free mutant plantlets. Here we describe a robust protocol for EMS mutagenesis of embryogenic cell suspensions of Coffea arabica var. Venecia. Dose-response curves were established within 3–4 weeks and showed LD 30 and LD 50 values in the range of 0.5% and 0.6% EMS respectively. Methods and media used for development of the treated cell suspensions and conversion to in vitro plantlets are also described.