Genetic diversity of coffee germplasm in Sierra Leone:implications for conservation and breeding programs

Global coffee production is dominated by Coffea arabica(Arabica coffee)and C.canephora(Robusta coffee)due to their relatively high-yielding and quality attributes as opposed to other coffee species.Despite these advantages,production of Arabica and Robusta coffee is facing mounting challenges though not limited to increasing prevalence and severity of biotic and abiotic stresses.These challenges bring forth an indication that the global coffee crop portfolio requires diversification to ensure resilience to the key challenges for sustainable production.Sierra Leone is in the center of genetic diversity of genus Coffea,and the country hosts rich coffee genetic resources.The C.stenophylla,C.affinis and possibly other wild relative species are indigenous to Sierra Leone and these species offer great potential for a new coffee market and income generation.However,more efforts of conservation and genetic improvement on these species,are needed to realize these opportunities.The objective of this paper is to review the coffee genetic resources in Sierra Leone with an emphasis on the wild coffee species including their conservation status,and the phenotypic and molecular characterization.We also present perspectives for future genetic improvement of C.stenophylla,and discuss breeding methods,combining ability,and molecular marker-assisted prediction of hybrid vigor.Moreover,with the availability of recently developed single nucleotide polymorphisms(SNP)markers on C.stenophylla,we suggest that new technologies of molecular breeding,such as genomic selection can significantly accelerate the breeding progress and deliver improved varieties with high yield,good adaptability,and disease resistance.