AFLP analysis of introgression in coffee cultivars ( Coffea arabica L.) derived from a natural interspecific hybrid

Abstract

S.288 an offspring of a putative spontaneous interspecific hybrid between tetraploid Coffea Arabica (2n = 4x = 44) and diploid C. liberica(2n = 2x = 22) and 17 arabica coffee introgression lines (representing F2 and F4) derived from the cross S.288 x Kent arabica were evaluated for introgression of C. liberica genetic material. In all, 36 AFLP primer combinations were used in the analysis. The AFLP profiles of introgressed lines were compared to five accessions each of C. arabica and C. liberica. A total of 137 polymorphic bands were scored among the 29 accessions analysed. The introgressed genotypes exhibited 102 marker bands consisting of 65 additional bands and 37missing bands associated with introgression of C. liberica genetic material. C. liberica accessions of EA group (C. liberica var liberica of Guinean origin) seemed to be the likely progenitor in the origin of natural hybrid. Analysis of genetic relationships in the introgressed lines suggested that introgression was limited to few fragments. Segregation and wide variation in number of marker fragments in the F2 and F4progenies were attributed to chromosome recombinations. The differences in the level of introgression between introgressed parent, F2 and F4 groups was not pronounced. Therefore the alien genetic material appeared to be fixed and there was no elimination or counter-selection over generations, from introgressed parent to F4.In C. arabica accessions, only 35 polymorphic bands were seen confirming the low genetic diversity. On the contrary, although representing a small amount of alien genome introgression, the Liberica-introgressed genotypes provided notable genetic diversity. Considering the fact that the diploid species of Coffea constitute a valuable source of genetic diversity, the potential implications of variability generated by Liberica-introgressed genotypes in C. arabica breeding are discussed.