How Earlham Institute scientists are piecing together the wheat genome
- Credit: James Bass
Norwich-based scientists have pieced together the most comprehensive wheat genome to date – helping breeders across the world to identify DNA which could improve crop varieties for farmers.
Wheat is one of the world's most important staple cereals, but also the most complex. Three sub-genomes together contain around five times more DNA than the human genome, and almost 80pc of this genetic material is repetitive, making it even harder to sequence and analyse.
By harnessing advanced sequencing technology and vast computing power, scientists from the Earlham Institute (EI), along with colleagues at the John Innes Centre, have published the world's most complete picture of the wheat genome.
It includes the location and detailed annotation of more than 100,000 wheat genes. More than a fifth of these were completely absent from earlier assemblies, or found only as fragments.
Matthew Clark, head of technology development at the EI, said this work would allow scientists and seed breeders to more accurately identify genes with useful traits relating to yield or disease resistance.
'Wheat has been seen as one of the most challenging genomes to sequence and assemble for some time,' he said. 'One of the reasons for that is there are actually three genomes involved. If you imagine how difficult it is to sequence the human genome, then imagine someone added a gorilla and a chimp's DNA into it – that is what wheat is.
'What we have managed to do is make a much more complete picture. We now have 78pc of the genome, including uncovering previously hidden genes.
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'We developed a combination of laboratory skills to make better data, and we have much better computational methods. Because we are at the EI, it means we have got some of the biggest computers with multiple terabytes of memory, which allow us to upload a massive genome like wheat and run our algorithms.'
Ksenia Krasileva, a co-author of the new study published in Genome Research, likened the creation of a genome assembly to navigating using GPS.
'Breeders might know there is something really useful in wheat, for example for protecting crops against disease or for improving gluten for bread-making, but without a good quality genome assembly it's like driving through thick fog,' she said. 'Full genome assembly and annotating genes provides a 'sat nav' view of wheat genes to signpost the way to useful genes in all varieties of the species.'
SEED BREEDER'S VIEW
The expanded genome sequence developed at the Norwich Research Park will help seed breeders to improve wheat varieties – but they said it will be some time before farmers can benefit.
Chris Burt, a molecular breeder with RAGT Seeds, based in Cambridgeshire, said: ''This is undoubtedly an improvement, but there is a lot of molecular and field breeding to do to utilise what the EI has found.
'I will be using this information to help develop better wheat varieties for the farmer, but it is still 10 years away because it is a very long process of wheat breeding, testing and trialling to make sure the varieties are an improvement on where we were before.
'You never escape from that lag time, but this enables us to be a lot more accurate and smarter in the way we can identify genes, and combine the beneficial traits that farmers and consumers are looking for. We can be more precise in what we are doing, so farmers can get the bread-making characteristics, combined with high yields and disease resistance, so they can produce more reliable crops.'