Genetic mapping of sex-linked markers in Salix viminalis L.

A total of 88 selective primer combinations were screened using bulked males and females sampled from four families of Salix viminalis. A total of more than 1000 polymorphic fragments was obtained, of which only four cosegregated with sex. These four sex-linked markers were subsequently scored in individuals that were used for bulked sample preparation in additional individuals of the same families, and in individuals in other families. A pair of primers that amplified the sex-linked fragments was constructed from one of the sex-linked amplified fragment length polymorphism (AFLP) fragments. In hybridization of Southern blot filters with the sex-linked DNA fragments, the band was present in females and absent in males, but the opposite pattern of band segregation ( a band found in males and no band in females) was never observed in either the AFLP or RFLP experiments. Two of the sex-linked markers were placed on a linkage map. They both map at the same location in a linkage group comprising other markers not segregating with sex. Our data suggest that a single locus governs the sex determination and that nonrecombining sex chromosomes are absent in S. viminalis. A close association was found between skewed sex ratio and segregation distortion at this locus.