Genetic linkage map of Coffea canephora: effect of segregation distortion and analysis of recombination rate in male and female meioses

Two complementary segregating plant populations of Coffea canephora were pr oduced from the same clone. One population (DH) comprised 92 doubled haploi ds derived from female gametes, while the other population (TC) was a test cross consisting of 44 individuals derived from male gametes. Based on the DH population, a genetic linkage map comprising 160 loci was constructed. E leven linkage groups that putatively correspond to the 11 gametic chromosom es of C. canephora were identified. The mapped loci included more than 40 s pecific sequence-tagged site markers, either single-copy RFLP probes or mic rosatellites, that could serve as standard landmarks in coffee-genome analy ses. Furthermore, comparisons for segregation distortion and recombination frequency between the two populations were performed. Although segregation distortions were observed in both populations, the frequency of loci exhibi ting a very pronounced degree of distortion was especially high in the DH p opulation. This observation is consistent with the hypothesis of strong zyg otic selection among the DH population. The recombination frequencies in bo th populations were found to be almost indistinguishable. These results off er evidence in favour of the lack of significant sex differences in recombi nation in C. canephora.