Abstract:

Barley possesses a large and highly repetitive genome that is difficult to fully sequence, but scientists at the University of California, Riverside have reached a new milestone on sequencing its work. The researchers have sequenced large portions of the genome that together contain nearly two-thirds of all barley genes.

The new information, published in The Plant Journal, will not only expand geneticists’ knowledge of barley’s DNA but will also help in the understanding, at the genetic level, of wheat and other sources of food. It also has applications in plant breeding by increasing the precision of markers for traits such as malting quality or stem rust.

Prior to this work, a long-held view was that the distribution of genes in the genomes of barley, wheat and their relatives is such that the gene-dense regions are only out near the ends of chromosomes where there is also a high rate of recombination. The work revealed clear exceptions, identifying deviant regions that are gene-rich but low recombination.

Recombination refers to the formation of new combinations of genes naturally during meiosis, which is a stage of the cell cycle where chromosomes pair up and undergo exchange. Close explained that plant breeders rely on meiotic recombination to introduce favorable forms of genes for malting quality, stem rust or any number of traits into cultivated varieties. Crosses are made and progeny plants are screened for desirable new combinations of traits. When a favorable form of a gene lies within a gene-dense, low recombination region it requires much more work to bring that favorable allele into an existing variety without also dragging in neighboring genes that may exist in undesirable forms.

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