Whither the grasspea?

Would you knowingly eat something that could harm you? That’s the dilemma facing millions of poor, subsistence farmers and their families from time to time, especially in India, Bangladesh, and Ethiopia, when the alternative is not eating anything at all. Famine.

From the beginnings of agriculture and earlier, 10,000 or more years ago, farmers have cultivated and consumed in times of adversity, the seeds of a plant known scientifically as Lathyrus sativus L.¹ Or, more commonly, the grasspea. It’s also an important fodder crop for livestock.

On the plus side, grasspea has a good protein profile and, as a legume, it supplies nitrogen to the soil through its root nodules. Its particular agricultural value is that it can be grown in times of drought, as well as when the land is flooded. It’s the ultimate insurance crop for poor, subsistence farmers.

Yet, it holds a deadly secret. β-ODAP. Or more precisely, β-L-oxalyl-2,3-diaminopropionic acid to give its full name, an amino acid that is also a neurotoxin responsible for the condition known as lathyrism, a non-reversible paralysis. No wonder, then, that its cultivation is banned in some Indian states. In the past, its consumption has also had severe consequences in Europe.

‘Gracias a la Almorta’ or ‘Thanks to the Grasspea’ by Francisco de Goya (painted between 1811 and 1813), painted during the Spanish War of Independence, when poor people turned to eating grasspea, and suffered paralysis from lathyrism. However, on the British Museum website it suggests grain (millet) rather than ‘grasspea’, and no mention of lathyrism. ‘Almorta’ is a Spanish word for grasspea.

Yet, when needs must, poor farmers turn to the grasspea when there is nothing else to eat because drought or floods have wiped out other crops.

So what’s being done to overcome the grasspea’s downside? Fortunately, an international collaborative research effort (funded by the UK Government’s Global Challenges Research Fund), Unlocking the Potential of Grass pea for Resilient Agriculture in Drought Prone Environments (UPGRADE), aims to breed ‘sweet’ varieties of grasspea with a low content of the neurotoxin.

I learned about this project yesterday evening when I happened to tune into BBC Radio 4’s Inside Science (you can listen from about 11′ 20″ into the program). The John Innes Centre in the UK is one of the project members, and in Prof. Cathie Martin‘s lab, Dr Anne Edwards is screening about 500 different grasspea lines, testing them for β-ODAP content, and also introgressing the lower content trait into different genetic backgrounds, for future testing in the field.

I was fascinated to hear how this international collaboration was making progress towards defeating the scourge of lathyrism, as I’d also worked on grasspea almost 40 years ago. But from a crop evolution and genetic resources point of view.

When I returned to The University of Birmingham in 1981, I decided to start a small research project on grasspea, looking at the diversity and broader genetic resources of this important but somewhat neglected crop, in addition to continuing my research on potatoes.

In 1981, one of the students attending the one-year MSc Course on Conservation and Utilization of Plant Genetic Resources was Abdul bin Ghani Yunus from Malaysia. He worked on his dissertation project under my supervision, to study the diversity of grasspea. I already had assembled a collection of grasspea varieties from different sources around the world including the Vavilov Institute in St Petersburg, so Ghani had quite a stock of varieties to work with.

His dissertation led to one scientific paper, Variation in the grasspea, Lathyrus sativus L. and wild species, published in the journal Euphytica in 1984. There were two principal conclusions:

  • L. sativus is a highly variable species, and there is a clear distinction between the blue-flowered forms from south-west Asia, Ethiopia and the Indian subcontinent, and the white and white and blue flowered forms with white seeds which have a more westerly distribution. Differences in vegetative parts may be due to selection for forage types.
  • L. sativus appears to be closely related to L. cicera and L. gorgoni, and this relationship needs further investigation.

Ghani returned to Malaysia in 1982 to continue his research and teaching at the University of Agriculture, Selangor and I heard little from him, until about 1986. Then, he contacted me again, asking about the possibilities of returning to Birmingham to complete a PhD under my supervision. He wanted to work on a tropical species from Malaysia. But since he did not envision spending time back in Malaysia during his PhD program, I explained that working on this species (I don’t now remember what it was) was not feasible, since we wouldn’t be able to grow it successfully in the glasshouse at Birmingham. After all, it wasn’t the species per se that was the most important aspect for his PhD; it would be the focus, the scientific methods and approaches he would learn and employ that were more important.

I convinced him to continue his work on Lathyrus, but broadening its scope to study the biosystematics or biological relationships of the grasspea with the species considered to be its closest relatives. In that way we anticipated better defining the genetic resources or gene pools of the grasspea (an essential prerequisite if, at some time in the future, a breeding program was set up that needed to exploit more diversity), as well as trying to shed some light on the origin of this neglected food crop.

In 1990, Ghani successfully presented his PhD thesis, Biosystematics of Lathyrus Section Lathyrus with special reference to the grass pea, L. sativus L., leading to two more useful scientific papers that have been widely cited:

  • The genepools of the grasspea, Lathyrus sativus L., in Plant Breeding (1991). This research concerned the cross-breeding relationships of the grasspea and its closest relatives, based on experimental pollinations, pollen tube growth microscopy, and chromosome pairing, confirming one of our earlier hypotheses about L. cicera.
  • Phenotypic polymorphism of six isozymes in the grasspea (Lathyrus sativus L.), in Euphytica (1991). Ghani concluded that there was more genetic variation than perhaps expected in this self-pollinating species, and we discussed the implications of exploiting this diversity in plant breeding.

Today, the International Center for Agricultural Research in the Dry Areas (ICARDA) receives financial support from the Crop Trust to conserve almost 4200 samples of grasspea in its genebank, with 2000 safely stored in the Svalbard Global Seed Vault above the Arctic Circle.

Of course, grasspea is not the only edible plant species that comes with a health risk. In South America, for example, there are so-called ‘bitter’ varieties of cassava, an important source of carbohydrate, producing cyanogenic compounds that must be removed before the roots are safe to eat. Indigenous communities throughout Brazil evolved techniques to express the poisonous juice and make the food safe. In other parts of South America ‘sweet’ varieties were selected over thousands of years, and became the genetic base of commercial cassava varieties grown world-wide. The International Center for Tropical Agriculture (CIAT), based in Cali, Colombia has the world’s largest cassava germplasm that I was privileged to see in 2016 when I was conducting an evaluation of the CGIAR’s genebanks program.

This grasspea story is a good example of how progress can be made when there’s a clear research project objective, funding is available, and researchers around the world agree to pool their expertise towards solving an important problem. With recent reports that the head of DFID (the UK’s government department managing overseas development assistance or ODA) is seriously considering making changes to the 0.7% of national income commitment to the ODA budget, grasspea improvement for marginalized communities goes to show just how important such funding is, and the potential impact it can have on the lives of some of the poorest people around the world. This is the raison d’être of international agricultural research for development, an endeavor in which I participated over four decades.

¹ Grasspea is a relative of the garden sweetpea, Lathyrus odoratus, a plant that is grown for its showy, fragrant blooms.

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