Biotechnological applications for the improvement of coffee (Coffea arabica L.)

The important advances in coffee biotechnological techniques which have been made particularly during the last 10 yr could benefit the coffee breeder in practice and open new perspectives for the development of new varieties. The molecular phylogeny of Coffea species has been established using DNA sequence data. The molecular markers have revealed an extremely reduced genetic diversity in Coffea arabica L. in comparison to C. canephora. However, wild accessions collected in the Ethiopian highlands appeared to constitute a valuable gene reservoir. A complete genetic linkage map of C. canephora was reported and additional ones are being constructed, particularly on C. arabica. The integration of Molecular Assisted Selection in coffee breeding promises to drastically increase the efficiency of breeding programs. Economically important genes of the caffeine biosynthetic pathway or genes encoding for seed storage proteins have been isolated. The high performance already achieved in the in vitro propagation process by somatic embryogenesis offers the possibility to mass propagate superior hybrids in different countries of both C. arabica (selected F, hybrids) and C. canephora (rootstock variety). Pilot productions by somatic embryogenesis currently permit preparation for commercial application. Somaclonal variation was observed. The percentage of the off-types can vary between 3 and 10% depending on the genotype. Seed cryopreservation enables a routine use for long-term conservation of coffee genetic resources. Transgenic plants have been obtained for the C. arabica and C. canephora cultivated species through Agrobacterium-mediated transformation which constitutes the technique now currently used to transfer directly genes in coffee plants.