Primer sets were developed from 85 Coffea arabica sequences in addition to 25 already published primer sets. They were subsequently used for amplification in six African Coffea species: Coffea canephora (CAN), Coffea eugenioides (EUG), Coffea heterocalyx (HET), Coffea liberica (LIB), Coffea sp. Moloundou (MOL) and Coffea pseudozanguebariae (PSE). The amplification percentages for these 110 primer pairs ranged from 72.7% for LIB to 86.4% for PSE. Good transferability was thus obtained within the Coffea genus. When focusing on the two species CAN and PSE, high genetic diversity, high polymorphic locus rates (above 80%) and a mean allele number per polymorphic locus of more than 3 were noted. The estimated null allele percentage was -11% for PSE and -9% for CAN. Sixty three percent (CAN) and 79.5% (PSE) of the fixation index (Fis) values were positive. The within-species polymorphism information content (PIC) distribution showed two modes for both species. Although the two species shared 30 polymorphic loci, no correlation between CAN and PSE PIC values was obtained. All of these data are discussed in relation to the polymorphism level and the potential use of these SSRs for subsequent analysis of genetic diversity or genetic mapping.

Some conditions related to the transient expression of β-glucuronidase in biolistically-treated Coffea spp. tissues were investigated, and subsequently used in a promoter study. Bombardments were performed on different types of tissue (leaves, somatic embryos and suspension cultures) of genotypes of C. arabica, C. canephora and Arabusta, using 4 different promoter sequences. Tobacco leaves were used as a comparison. In general, similar large variation and mean values of transient expression were observed between coffee and tobacco leaves. With regard to the coffee tissues effect, transient expression was best detectable and most frequently observed with bombarded leaves of microcuttings. Disturbing endogenous light blue staining was found with control treatments of somatic embryos. For the three coffee species tested, the most effective promoter was the EF1α-A1 promoter of Arabidopsis thaliana.