Abstract
Key message The ‘breaker’ element ( GcB ) of the gametocidal locus derived from Aegilops sharonensis has been mapped to a region proximal to a block of sub-telomeric heterochromatin on chromosome 4S sh L. 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 offspring when addition lines are generated. Species within the Sitopsis group possess the S genome, and among these species, Aegilops sharonensis (2n = 14, SshSsh) 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.Electronic supplementary materialThe online version of this article (doi:10.1007/s00122-015-2489-x) contains supplementary material, which is available to authorized users.
Highlights
The Sitopsis section of the genus Aegilops comprises five diploid species that carry the S genome, which is closely related to either the B or D genome of hexaploid wheat (Triticum aestivum) depending on its lineage (Marcussen et al 2014)
As a consequence of these aberrations, the only gametes to survive are those carrying chromosomes with a gametocidal locus (Gc chromosomes), which is roughly 50 % of the pollen cells, ensuring the preferential transmission of these chromosomes to subsequent generations. This genetic phenomenon is of particular interest to breeders, because linking Gc loci with valuable traits in elite varieties would ensure maintenance of these traits in subsequent generations without the need for selection. This could be achieved by a GM approach; whereby the Gc locus would be present in a vector with the gene for the trait of interest, which would be inserted by transformation in the genome of the elite wheat variety
Thirty-three markers were designed to be polymorphic between hexaploid wheat and the 4SshL Ae. sharonensis segment to map the gametocidal breaker element (GcB) within this introgression
Summary
The Sitopsis section of the genus Aegilops comprises five diploid species that carry the S genome, which is closely related to either the B or D genome of hexaploid wheat (Triticum aestivum) depending on its lineage (Marcussen et al 2014). As a consequence of these aberrations, the only gametes to survive are those carrying chromosomes with a gametocidal locus (Gc chromosomes), which is roughly 50 % of the pollen cells, ensuring the preferential transmission of these chromosomes to subsequent generations This genetic phenomenon is of particular interest to breeders, because linking Gc loci with valuable traits in elite varieties would ensure maintenance of these traits in subsequent generations without the need for selection. This could be achieved by a GM approach; whereby the Gc locus would be present in a vector with the gene for the trait of interest (for example a disease resistance gene), which would be inserted by transformation in the genome of the elite wheat variety.
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