The production of alien chromosome addition lines allows the transfer of useful genetic variation into elite wheat varieties from related wild species. However, some wild relatives of wheat, particularly those within the Sitopsis section of the genus Aegilops, possess chromosomes that are transmitted preferentially to the when addition lines are generated. Species within the Sitopsis group possess the S genome, and among these species, Aegilops sharonensis (2n = 14, Ssh Ssh ) carries the Ssh genome which is closely related to the D genome of hexaploid wheat. Some S genome chromosomes carry gametocidal loci, which induce severe chromosome breakage in gametes lacking the gametocidal chromosome, and hence, result in gamete abortion. The preferential transmission of gametocidal loci could be exploited in wheat breeding, because linking gametocidal loci with important agronomic traits in elite wheat varieties would ensure retention of these traits through successive generations. In this study, we have mapped the breaker element of the gametocidal locus derived from Ae. sharonensis to the region immediately proximal to a block of sub-telomeric heterochromatin on the long arm of chromosome 4Ssh .