John Innes Centre scientists explore the huge nutritional potential of peas
PUBLISHED: 13:44 09 May 2016 | UPDATED: 13:44 09 May 2016
Archant Norfolk 2016
During International Year of Pulses 2016, an astonishing diversity of plants is being examined at the Norwich Research Park to unlock the nutritional and yield potential of peas.
While many consumers simply think of them in frozen bags at the supermarket, there is huge untapped potential in the tiny, humble pea.
Which is why, in a year designated by the United Nations as the International Year of Pulses, a concerted scientific effort is under way to unlock the crop’s ability to improve health, nutrition, and farming efficiency.
It is being led by the John Innes Centre (JIC) in Colney, where a germplasm collection of more than 3,000 pea types from all over the world is being studied, in the hope of finding the magic gene which could bring a valuable trait into a commercial variety.
In the centre’s greenhouses, countless rows of plants are being nurtured which could contain the genetic secret to better yields, disease resistance, more digestible proteins, gluten-free nutrition, or more consistent colour.
Dr Claire Domoney is the leader of the Pulse Crop Genetic Improvement Network (PCGIN), a partnership of government, industry and research bodies aiming to deliver scientific resources to help breeders, producers and end users to achieve added value for pulse crops.
“The JIC germplasm collection has 3,000 accessions from all over the world,” she said. “Any one of them could contain the magic gene for anything.
“It is like a supermarket of variation, and we just need the ability to pull out the genes we are interested in.
“Most of what we have got relates to protein quality. There is a huge interest in having home-grown protein and less dependency on imported soya, which is where a lot of our protein comes from for animal feed. That is quite a big driver.
“To do that, we need to increase the amount of protein in a pea. We can do that in a number of ways, but there are some proteins that are less desirable because their nutritional value is low. So if you can remove those then perhaps the plant could make more of the beneficial proteins.”
In another glasshouse, there are mapping populations assessing yield.
“That is what farmers will be looking for, first and foremost,” said Dr Domoney. “Markets care about quality and protein, but farmers want yield.
“This one is a mutation where leaves have been mutated into tendrils. In the field, the plants start knitting together and that’s great in the field because you end up with a robust crop.
“This whole population of 200 all have these tendrils, but among these are lines which have very much higher yields than others. The tendrils improve yield, but there are other determinants other than the ability to stand up straight. That is something that is genetically-determined and consistent.
“We have lines at the moment which have given us 5.5 tonnes per hectare. There are varieties out there which will hit 5t/ha, but the national average is 3.5t/ha. So if we can go from a national average of 3.5t/ha to 5t/ha that would be amazing.”
A Turkish delight
The value of the vast diversity in the JIC’s germplasm collection was proven recently when one individual seed was found to contain a unique property which could boost the digestible protein in peas.
Peas contain several types of proteins which limit the utilisation of plant nutrients in human and farm animal diets. These inhibitors slow down the rate at which humans, poultry or livestock digest proteins by incapacitating the enzymes which break them down.
Dr Domoney’s group identified a wild pea relative from Turkey called Pisum elatius, which lacked this inhibitor protein, and so removed this barrier protein digestion.
She said: “It was in one of these wild relatives from Turkey we found that this inhibitor was not there, so we have crossed that into a cultivated pea so we have got seeds which lack that inhibitor. We have had several requests from breeders already. The animal feed industry phoned up straight away and asked if they could get hold of these seeds to do animal digestion trials.”
Marking out potential
The crosses developed in the JIC glasshouses have all been achieved through traditional breeding techniques.
There are hundreds of wild pea relatives growing which have little commercial use because the plants only stand up with the help of a cane – but they contain two sources of resistance to downy mildew.
In another row, there are plants which have been found to contain a new source of the gene which stabilises the green colour in cotyledons, which is important to export markets, and the processing industry.
Once useful genes have been identified, “markers” are attached to help breeders quickly identify if the valuable traits are emerging in their trial crops.
Some of these markers are molecular, but many are visual, and can be as simple as seed shape, flower colour, the length between stem nodes, pod shape, or the appearance of tendrils.
Dr Domoney said: “If our new green cotyledon trait was close to the gene which gives you purple flowers, then every time you see purple flowers in your crop it could indicate the other trait was present.
“In other places, we did find a variant once which had a trait which reduces ‘off flavours’, which are the negative flavours you can get if you make a flour out of peas. We found an enzyme which gave rise to these off flavours, and when we looked at how that was inherited it was closely linked with the gene which controlled inter-node length. It can be as simple as that.”
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