How Norwich scientists' wheat DNA breakthrough could help feed the world
PUBLISHED: 06:32 17 August 2018 | UPDATED: 06:32 17 August 2018
Archant Norfolk 2018
It may seem a simple plant – but its DNA is five times more complex than ours, and billions of us rely on it for our food.
So cracking the genetic code of wheat has been a scientific holy grail for decades.
And now a team of Norwich researchers have played a pivotal role in a major global breakthrough which they say could unlock the potential of the most widely-cultivated crop on Earth.
A complete sequence of the wheat genome has been published in a paper authored by more than 200 scientists from 73 research institutions in 20 countries – including the John Innes Centre (JIC) on the Norwich Research Park.
It maps out the plant’s complete set of genes, detailing the sequence of 21 chromosomes, the precise location of 107,891 genes and more than four million molecular markers.
And scientists say this enormous dataset could now help accelerate the breeding of crops that are higher-yielding, more nutritious, or more resistant to drought, floods and diseases – all of which could be vital in feeding a growing population in a changing climate.
Prof Cristobal Uauy, project leader in crop genetics at the JIC, said: “Tackling the colossal wheat genome has been a Herculean challenge, but completing this work means we can identify genes controlling traits of interest more rapidly.
“Where previously we had a broad view and could spot areas of interest, we can now zoom into the detail on the map.
“It is anticipated that the world will need 60% more wheat by 2050 to meet global demand. We are in a better position than ever to increase yield, breed plants with higher nutritional quality and create varieties that are adapted to climate changes thanks to the research we and the international community are publishing.”
Dr Philippa Borrill, research fellow at the centre, added: “This is a completely sequenced version of the wheat genome. So now we know where all the different pieces of the genome fit in a specific order, whereas before we had a fragmented assembly.
“One of the main benefits will be for wheat breeders, so they will be able to know which part of the genome they want to select for, and which parts they maybe don’t want if they have some bad effects such as susceptibility to a particular disease – and knowing where these different traits are in relation to each other in the genome.
“It could be very important as it will inform most of the breeding approaches in wheat, because without the genome you are, in a way, lost – you don’t have a road map. Now we have that road map we can start to know where we want to go and how we can get there.”
WHEAT: A COMPLEX CROP
Wheat is the most widely-cultivated crop on Earth, contributing about a fifth of the calories consumed by humans.
It also has a large and complex genome with 16 billion base pairs – the building blocks of DNA – which is more than five times larger than the human genome.
The plant which provides bread wheat is the rare result of two hybridisations with wild grasses thousands of years ago, which created multiple copies of chromosomes and gave the plant its complex genetic structure.
Sequencing the genome has been a huge challenge for scientists. As well as its enormity, it has three sub-genomes and a large part of it is composed of repetitive elements which has made it difficult, until now, to distinguish each sub-genome and to put the genome together in its correct order.
Dr Philippa Borrill, research fellow at the John Innes Centre, described the process of extracting and sequencing the wheat’s DNA.
“You would harvest a leaf and grind it up with a mortar and pestle like you would at home with spices,” she said. “Then you extract DNA using a solution that can pull out the DNA from the rest of the tissue and, using that DNA, we will be able to sequence it using large genome sequencing machines.
“The genome is very repetitive, so it is like a jigsaw puzzle to match everything together in the right order. We could not have done this without the computing power we now have to make these assemblies, and also new techniques have been developed.”