Polyploid species had to develop mechanisms of precise chromosome pairing and segregation to ensure genomic stability. This diploid-like behaviour of chromosomes in polyploids is mainly regulated genetically. Pairing of homologous chromosomes in allohexaploid bread wheat (Triticum aestivum) is controlled by „pairing homoeologous“ Ph1 and Ph2 genes. In ph1 mutant plants, pairing among homoeologous chromosomes was observed. In ph2 mutant plants, wheat chromosomes pair regularly. However, pairing among chromosomes of wheat and closely related species occurs in those plants, which could be used as a tool for gene transfer into wheat. The objective of the project is to physically map Ph2 gene (located on chromosome arm 3DS) in bread wheat using deletion lines produced through gametocidal system. Terminal deletions on 3DS chromosome arm will be characterised using a set of molecular markers and stabilized by self-pollination. Pairing behaviour of chromosomes in wheat-rye hybrids will be determined afterwards to identify lines lacking Ph2 gene.