Dr Colin Cavanagh investigates the wheat genome.
Wheat genetic markers shed light on selective breeding
Our researchers have developed a test for 9,000 genetic markers in wheat and they’re using it to find out what parts of the wheat genome have been targeted by selective breeding to make better crops.
An assay for SNPs in wheat
Humans have been growing wheat since around 8,000 BC, and generating varieties with characteristics that suit our farming requirements by selective breeding.
Modern breeders often use genetic markers to test new varieties of wheat for genes that give the plant useful characteristics.
Using these markers makes wheat breeding faster and more reliable.
Scientists from our Food Futures Flagship have developed an assay (which is a type of test), that can be used on a gene chip or microarray to measure multiple genetic markers simultaneously.
It can detect 9,000 markers known as Single Nucleotide Polymorphisms (SNPs) located in wheat genes.
This gives scientists a quick way to scan the wheat genome for regions that vary between different varieties of wheat.
A special feature of the assay is that all of the DNA markers are for genes that are used by the wheat plant, while other types of DNA aren't included.
This makes it more useful for finding regions of the wheat genome that are relevant to plant breeders.
Dr Colin Cavanagh from the team that developed the assay said, "We're very pleased that the genetic markers we've identified are commercially available to other researchers, because we want other scientists to be able to use this knowledge too."
Selective breeding and the wheat genome
Dr Cavanagh and his team used the assay to find out which regions of the genome generations of breeders have been targeting as they've bred modern varieties of wheat.
They scanned thousands of varieties of wheat and grouped them according to:
- geographic origin
- whether they were modern varieties or much older landraces
- whether they were winter or spring wheats (which have different cold requirements to trigger flowering).
The researchers compared the genetic markers between these groups to find out which regions of the wheat genome have been targeted by selective breeding over time, in different locations and between winter and spring wheat.
"Some of the genetic regions we found that had been targeted by selective breeding weren't surprising, such as regions containing genes for flowering time or resistance to common diseases," Dr Cavanagh said.
"We're more excited about the regions whose functions we don’t know, because they could contain genes that influence characteristics that are normally hard to breed into wheat."
Dr Colin Cavanagh, plant scientist.
"We're more excited about the regions whose functions we don't know, because they could contain genes that influence characteristics that are normally hard to breed into wheat – such as adaptation to particular climate conditions."
The research team will now work on identifying some of the new genes and finding out how they influence the characteristics of wheat plants.
Information about useful genes can be passed on to breeders to utilise when they generate new wheat varieties.
Markers for genes that influence particular characteristics help breeders select plants more quickly because they allow them to test seedlings and keep only the ones that were carrying the gene for the characteristic they want.
This is more efficient than growing large numbers of plants to maturity under particular conditions to see if they've inherited a desirable trait.
Farmers need wheat that grows well in their local climate, produces a good yield of grain, is resistant to common diseases and has high quality grain.
The new assay we've developed to test for 9000 different genetic markers will help scientists find out more about genes that make good wheat, and allow breeders work more quickly to bring new varieties to farmers.
Read more about our work in Future grains, grain based foods and feed.
Cavanagh C, et al. 2013. Genome-wide comparative diversity uncovers multiple targets of selection for improvement in hexaploid wheat landraces and cultivars. PNAS 110 (20): 8057–8062. Available online.