Improving our genetic knowledge of wheat is not a drag
When it comes to breeding better wheat varieties, often, though we seek to introduce desirable genes that increase yield, these can come along with less wanted genes that reduce some other vital plant function.
This is known as linkage drag, and it’s something that’s hard to break: especially in crops that show relatively low rates of recombination.
One way of breaking up these linked regions is recombination, the process of genetic reshuffling that sees segments of paired chromosomes exchanged through crossover events.
Another process that can have a similar effect in breaking linkage is ‘gene conversion’, which essentially sees one version of a gene (allele) being converted to another during double-stranded DNA break repair.
Up until now, relatively little has been known about the genes that control genome-wide gene conversion or the high level of gene conversion in wheat.
This latest study, published in the Genome Biology scientific journal by the Anthony Hall Group at the Earlham Institute (EI) in Norwich, provides a positive step towards being able to overcome a lack of recombination as a limit to breeding efforts.
This gene, a helicase (essential during DNA replication in separating double-stranded helix to single strands, allowing each strand to be copied) as well as other genes identified through this process, might therefore be harnessed to break linkage-drag in future wheat breeding efforts.
The team looked at a number of wheat varieties that had been crossbred, comparing the genotype back against that of the parents. In this way, they were able to find many crossover events that signified gene recombination.
One significant finding was that gene conversion is more prevalent and far larger in size in wheat than in other analysed plant data.
The work heralds a new frontier in wheat research. Over the last few years, huge strides have been made building data-rich resources in wheat.
Professor Anthony Hall, who led the project, said: “The gene and phenotype will have huge implications for wheat breeders, accelerating the breeding pipeline.”