Sequencing the coffee genome (W152)

Commercial coffee production relies mainly on two closely related species: Coffea arabica and C. canephora, which account respectively for 70 and 30% of the coffee production. All coffee species are diploid (2n=2x=22) and generally selfincompatible, except for C. arabica which is the only tetraploid (2n=4x=44) and self-fertile. Molecular analyses (Lashermes et al. 1999) have indicated that C. arabica is a recent allotetraploid (CE genome) formed by hybridisation between two related diploid species: C. canephora (C genome) and C. eugenioides (E genome). In spite of the close relationship between the two constitutive sub-genomes, C. arabica displays diploid-like meiotic behavior with bivalent formation (Krug and Mendes 1940, Lashermes et al. 2000). The genomes of coffee species (Cros et al. 1995; Noirot et al. 2003) appear to be of rather low size (i. e. about 660, 710 and 1300 Mb for C. eugenioides, C. canephora and C. arabica, respectively). Several institutes are combining their scientific resources and expertise to sequence, assemble, and annotate the entire genome of C. canephora. The C. canephora genome consists of 11 chromosomes, is about 710 Mb in size, and is being sequenced de novo with deep coverage using 454 paired-end and single reads, and 50x coverage with Illumina GAIIx data to obtain a reference genome for Coffea. The overall sequencing strategy as well as progress of the project will be described. (Resume d'auteur)