Cytological and molecular characterization of wheat-Hordeum chilense chromosome 7Hch introgression lines

Abstract

Chromosome 7Hch of Hordeum chilense carries the Phytoene synthase 1 (Psy1) gene encoding the first step in the carotenoid biosynthetic pathway. As such it can be used in the improvement of seed carotenoid content in wheat. Four introgressions of chromosome 7Hch into wheat have been characterized by in situ hybridization of labeled DNA probes and by several sets of DNA markers. Chromosome-specific SSR were used for the identification of wheat chromosomes. Besides 113 conserved orthologous set (COS) markers were tested for homoeologous group 7, of which 97 amplified in H. chilense and 32 were polymorphic between H. chilense and wheat, and 28 expressed sequence tag (EST) barley markers previously allocated to chromosome 7. A total of 60 markers (32 COS and 28 EST) were allocated to chromosome 7Hch with 28 assigned to 7HchS and 22 to 7HchL. A combination of in situ probing and marker genotyping have shown that among the four introgressions there was a substitution line 7Hch (7D), a ditelosomic addition line for the long arm of 7Hch and two homozygous centric translocations 7HchS·2DS and 7HchS·5AL. The Psy1 gene was localized on the short arm of 7Hch. The positions of markers from the international barley consortium map (IBSC2012) were determined and the comparative arm location between H. chilense and H. vulgare is discussed. The genetic stocks characterized here include new wheat-H. chilense recombinations useful for genetic studies and with a potential for breeding.