Analysis of alien introgression in coffee tree (Coffea arabica L.)

The transfer of desired traits from related wild diploid Coffea species into the cultivated allotetraploid C. arabica is essential in coffee breeding to develop pest/disease-resistant cultivars. The present work is an attempt to gain insights into alien introgression in C. arabica. An F2 population derived from a cross between T5296 and Et6 was analysed with simple sequence repeat (SSR; microsatellite) and amplified fragment length polymorphism (AFLP) molecular markers. The T5296 is a derivative of an interspecific hybrid introgressed by the diploid C. canephora species and Et6 is a wild Ethiopian accession of C. arabica. The origin of the revealed polymorphism was determined by comparisons using representative accessions from C. arabica and its two diploid parental species, C. eugenioides and C. canephora. The number and mode of inheritance of canephora-introgressed segments were investigated, as well as their sub-genome localisation and rate of recombination. The results suggested that the transfer of desirable genes into C. arabica from C. canephora is not limited by the ploidy level differences or the suppression of recombination between the different genomes.