Abstract
The chromosome 2Hch of Hordeum chilense. has the potential to improve seed carotenoid content in wheat as it carries a set of endosperm carotenoid-related genes. We have obtained structural changes in chromosome 2Hch in a common wheat (Triticum aestivum L. “Chinese Spring”) background by crossing a wheat double disomic substitution 2Hch(2D) and 7Hch(7D) line with a disomic addition line carrying chromosome 2Cc from Aegilops cylindrica Host.. Seven introgressions of chromosome 2Hch into wheat were characterized by fluorescence in situ hybridization (FISH) and DNA markers. Chromosome-specific simple sequence repeats (SSRs) were used for identifying wheat chromosomes. In addition, we tested 82 conserved orthologous set (COS) markers for homoeologous group 2, of which 65 amplified targets in H. chilense and 26 showed polymorphism between H. chilense and wheat. A total of 24 markers were assigned to chromosome 2Hch with eight allocated to 2HchS and 16 to 2HchL. Among the seven introgressions there was a disomic substitution line 2Hch(2D), a ditelosomic addition line for the 2HchL arm, an isochromosome for the 2HchL arm, a homozygous centromeric 2HchS·2DL translocation, a double monosomic 2HchS·2DL plus 7HchS·D translocation, a homozygous centromeric 7HchS·2HchL translocation and, finally, a 2HchL·7HchL translocation. Wheat—H. chilense macrosyntenic comparisons using COS markers revealed that H. chilense chromosome 2Hch exhibits synteny to wheat homoeologous group 2 chromosomes, and the COS markers assigned to this chromosome will facilitate alien gene introgression into wheat. The genetic stocks developed here include new wheat—H. chilense recombinations which are useful for studying the effect of chromosome 2Hch on grain quality traits.
Highlights
Narrow genetic diversity often limits the improvement of many traits in wheat
The double 2Hch (2D) and 7Hch (7D) disomic substitution line was obtained by pollinating tritordeum with a wheat disomic addition line for gametocidal chromosome 2Cc from Ae. cylindrica Host. following the breeding procedure described in [8]
The pAs1 and H. chilense genomic DNA used as probes in fluorescence in situ hybridization (FISH) analysis allowed the identification of a pair of 2Hch chromosomes and the absence of the wheat 2D chromosome pair in one line with
Summary
The introgression of genes from wild relatives to wheat has become a widely recognized genetic approach for increasing genetic diversity and, the need to explore primary, secondary and tertiary gene pools of wheat has grown [1,2]. Its high crossability with other species of the tribe Triticeae, such as both durum and common wheat, [3,4,5] make it useful in cereal breeding. Addition and substitution lines of alien chromosomes in a common wheat background, are useful for introgressing alien chromosomal segments carrying genes of agronomical interest into wheat. Chromosome addition lines of H. chilense in the Triticum aestivum L. cultivar “Chinese Spring” have been obtained including five for chromosomes 1Hch , 4Hch , 5Hch , 6Hch and 7Hch and the ditelosomic addition line for the short arm of chromosome 2Hch [7].
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