Drought-tolerant and nutritious, grass pea plants could be very useful with climate change – and they are being gene-edited to try and remove a toxin that can lead to paralysis if eaten for a sustained period of time. 

Growing in the greenhouse at the John Innes Centre in Norwich, England, grass pea plants present a pretty display of blue, white and pink flowers. But this ancient crop is not just decorative, mostly cultivated in parts of sub-Saharan Africa and Asia, it is hardy and high in protein. 

"It’s a very resilient plant," says Ann Edwards, a plant scientist at the John Innes Centre. "It's very drought-tolerant and it's very nutritious but it does have one problem. It produces a neurotoxin, which is quite safe to eat as part of a balanced diet, but if it’s the sole source of food – in the worst of the famines in Ethiopia, for instance, nothing else to eat but grass pea for months on end – then it can cause this condition called neurolathyrism, which is an irreversible paralysis of the legs. 

"So, we’re looking to understand how the plant makes it, why the plant makes it, and whether we can stop it making it to produce safe crops for the future."

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That involves using the DNA sequence of the plant to genome-edit the enzyme that contributes to producing the toxin, to either eliminate or greatly reduce it. Scientists in England now have greater scope to use gene editing technology since the law changed in March this year. The government says it will allow the development of crops that are healthier and more resistant to stresses that climate change is placing on agriculture. 

"Climate change is the main reason why we're interested in working on this crop, because the conditions under which grass pea survives better than other crops. Drought and flooding and salinity stress, as climate change impacts accelerate and become more severe round the world," said Peter Emmrich, a John Innes Foundation fellow who is also working on the grass pea plant. 

"Now that we’ve identified the enzymes in the plant that are responsible for actually making this toxin, we can use modern genome editing to knock those out and see if that has drastically reduced toxin content."

The change in the law has also given the green light for gene-edited tomatoes enriched with Vitamin D to be grown outdoors and sold commercially, which researchers at the John Innes Centre see as a step forward. "We’re really excited, and happy to see you we now have a clear route, if we want to take these nutritionally enhanced tomatoes, or crops into the market," said plant scientist Jie Li.

At a nearby research farm in the Norfolk countryside, scientists are also investigating how well grass pea plants grow in European soil. With extended roots that seek out moisture in dry conditions, it could become beneficial during hotter, drier summers. 

"It is very possible that a crop like this it’s not grown in the UK at all will become a mainstay of UK agriculture throughout this century, as we become much more dependent on crops that withstand a wide variety of extreme weather events," said Emmrich.

The hope is also to one day establish a method to transfer the climate tolerance of the grass pea to other crops. But breeding the right plants takes time and with climate change accelerating, food production solutions are becoming ever more urgent.

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