Last July, for the first time, subsistence farmers in Nigeria planted a new variety of genetically modified (GM) cowpea – and it promises to bolster food security for over 200 million Nigerians.
This follows a decision made in December 2019, when Nigeria became the first country in the world to approve the commercialisation of GM cowpea.
The protein-rich cowpea, commonly known as “poor man’s meat”, is the country’s staple legume. This new variety took a team of African and international devotees 40 years to develop: 20 years to improve its traits through traditional breeding and another 20 using genetic engineering to develop resistance to the destructive Maruca pod borer.
Mohammad Ishiyaku, a geneticist and cowpea breeder at Ahmadu Bello University in Northern Nigeria, says the new variety is a game-changer for farmers.
“The demand is outstripping supply,” he says.
Farming families comprise about 70% of the Nigerian population, with most living on half-acre (about 2000 sq m) lots where they grow sorghum, millet, cassava, yams, plantain and – most importantly – cowpea. Most families consume cowpeas daily either boiled and eaten with rice or fermented and cooked in oil to provide a tasty local dish known as akara. The stalks are also nutritious fodder for livestock, and any extra harvest can bring in cash at the local market.
But what farmers grow is what they put on the table and when their crops fail, their families starve. Some 91 million people are considered at risk; most can’t afford fertiliser and chemicals, there’s no irrigation or power, and life has only gotten tougher in recent years due climate change and conflict.
Researchers expect that the GM cowpea will not only increase food security, but also give farming families a leg up out of poverty. Ishiyaku estimates that by lowering their spending on pesticides and raising yields, the crop could enhance farmers’ income by close to 30%.
The new variety should also help the country’s bank balance. While Nigeria is the world’s largest producer of cowpea, it still needs to import 500,000 tonnes per year.
The long road to GM cowpea
Cowpea is a hardy legume, well adapted to the dry conditions and poor soils of the tropical savannah. But while handed down the generations from farmer to farmer, it had been left behind by the breeding programs that dramatically improved the yield of staples like rice, corn or wheat.
Improving cowpea has long been the holy grail for Nigerian plant breeders.
Read more: Gene-edited plants aid food security
Their journey began in 1979 when plant breeder B B Singh joined Nigeria’s International Institute of Tropical Agriculture. Singh was known as ‘Mr Soybean’, for breeding high-yielding soybean varieties in the US and introducing them to India. In Nigeria he was soon to become ‘Mr Cowpea’.
Like a racehorse breeder, Singh appraised the traits of 15,000 varieties of cowpea from around the world, plying his art to mix and match desired traits. When he began farmed varieties of cowpea sprawled along the ground using up precious space and took five months to ripen their pods. Sixteen years later his ‘racehorse’ variety grew upright so more could be packed into the farmer’s field. Their time to ripen was shortened to two months, safeguarding a harvest if seasonal rains failed, an increasingly common occurrence. And to top it off, he bred in resistance to thrip, aphids, bruchids and striga – a pretty pink parasitic weed.
After 16 years Singh’s efforts increased the yield of cowpea grown in the greenhouse from 0.2 tons per hectare to over two tons per hectare.
But out in the fields, those gains could be obliterated by a little brown and white moth: Maruca, whose caterpillars routinely devour between 20% and 80% of the crop.
For the die-hard cowpea breeders, it was a call to arms.
The only weapon was spraying with pesticides up to eight times over the growing period. But besides being prohibitively expensive for farmers living on $1.50 per day, spraying was dangerous for those unfamiliar with pesticide use and lacking protective gear.
Singh knew that the soil bacterium Bacillus thuringiensis offered an organic solution to the Maruca problem. When the bacterium infects caterpillars, it kills them because one of its genes bores a hole into the caterpillar’s stomach. Organic farmers spray the bacterial soup directly onto crops. It’s ecologically friendly because bees and other insects are unaffected. But sprays don’t reach caterpillars inside pea pods. The most effective approach was to supply the plant with an inbuilt version of the bacterium’s gut-boring gene through genetic engineering.
The bacterial gene, commonly referred to as Bt, had been successfully introduced to soybeans, corn and cotton, but success in cowpea had been elusive. Singh’s comrade-in-arms in the Maruca wars, entomologist Larry Murdock at Purdue University, Indiana, had tried for years. But Murdock knew a scientist from Australia’s national research agency, CSIRO, who might succeed. “Higgins was my secret weapon,” he says. Murdock arranged a conference in Senegal in 2001 and invited T J Higgins as keynote speaker.
Higgins was famous for having used genetic engineering to improve legumes for the benefit of sheep. Unaware of the reason for being honoured as keynote speaker, Higgins regaled his audience with his feat of improving livestock fodder. His audience was singularly unimpressed. When they asked him to turn his efforts to improving ‘poor man’s meat’, Higgins, the son of a poor Irish farmer, could not refuse.
He took up the punishing task of introducing the bacterial gene into cowpea. It relied on hijacking the operations of yet another soil bacterium, Agrobacterium tumefaciens, which induces gnarly tumours around the roots of plants. It does this by sneaking its own DNA into plant cells to turn them into factories for producing its preferred nutrients.
But while Agrobacterium readily infects roses and fruit trees, it shows little inclination for grains and legumes. To infect them requires tissue culture. That means mincing plant tissue into clumps of cells, incubating them in a cocktail of Agrobacterium, plant hormones and nutrients, selecting out plant cells that had taken up the bacterial genes and then trying to generate a complete plant from those cells.
Every step of the procedure is “hit and miss” and success is often hard to replicate.
Large companies like US agricultural and chemicals company Monsanto (acquired by German company Bayer in 2018) ultimately succeeded for soybeans, cotton, canola and corn – the huge investment justified by the profits.
But Higgins was a public sector scientist – his day job was deputy head of CSIRO Plant Industry – and he was on a modest budget.
At first it was a night-time affair. While CSIRO space and infrastructure was allotted for the African cause, Higgins had to get grants from the Rockefeller Foundation and then USAID in order to fund manpower and material.
By 2006, the team had their first success at coaxing the reluctant cowpea to accept new genes from Agrobacterium tumefaciens. It was a slow quest – only one in a thousand baby plants accepted the new gene.
By 2009, Nigerian scientists were testing GM plants in the field at Ahmadu Bello University. Compared to non-GM plants, they were highly protected against Maruca.
The plants are ready – but the public isn’t
Developing the GM cowpea in Higgin’s lab took a decade. Carrying out the necessary safety studies – along with navigating Nigeria’s biosafety regulatory hoops – took another.
In most African and Asian countries, campaigns led by anti-GM groups have blocked genetically modified crops from being approved. This is despite more than 30 years of testing by the world’s food safety regulators, which has consistently found that the consumption of genetically modified crops such as corn, soybeans, rice or papaya to be as safe as consuming conventional crops.
Arguably, GM crops are safer because of the stringent testing required. GM produce must be tested for potential allergenic or inflammatory effects. But while traditional breeding or organic farming can produce foods with harmful health effects, neither are subject to the same high bar of safety testing.
Testing GM foods is based on a commonsense approach, explains Don MacKenzie, head of the not-for-profit Institute for International Crop Improvement at the Donald Danforth Plant Science Center in St Louis, Missouri, which contributed to the testing of GM cowpea.
MacKenzie illustrates the basic logic of food safety testing with a simple question: “Is there a study that’s looked at the safety of rice?”
“It’s impossible to prove absolute safety,” MacKenzie says. “All you can do is show the GM food is as safe as the food that we have a long history and familiarity with.
“Our mission is to do what we can do to shorten the time it takes to put good safe technology in the hands of smallholder farmers. The number of hungry people in the world is going up.”
Testing focuses on the known differences between the traditional variety and the GM version. These differences are the protein products of the introduced genes. GM plants are tested for their effects on human or animal health, as well as their performance in the field to see if the inserted genes affect the plant’s growth. There are also ecological tests, to assess the risk of whether a GM plant might interbreed with another variety to create a super weed, or take over from wild varieties reducing biodiversity.
The GM cowpea variety produced by the Higgins group passed all these tests. They showed that the insertion of the foreign genes in the cowpea did not result in a toxic or allergenic effect. Neither did the genes alter the growth or nutritional composition of the plant. Hundreds of studies with other crops (including those organically grown) attest to the safety of the Bt protein for human and animal consumption. And finally, tests showed that the GM plant was unlikely to interbreed. As a self-pollinator, cowpea keeps its genes to itself.
Finally, after a decade of testing, in December 2019 Nigeria became the first country to approve the commercialisation of GM cowpea.
Cowpea of the future
Over the last year, the seeds (which go by the trade name SAMPEA 20-T) have been multiplied by three certified local growers and sold to farmers across the country.
“The cost is on par with traditional varieties,” says Ishiyaku.
Farmers are free to re-sew their seeds just as they do with traditional varieties.
At the end of July this year, Ishiyaku says almost all the stock of GM cowpea had gone and farmers were clamouring for more.
“They are excited by what they have seen in planted demonstrations in the north and southwest,” he says.
Plans are being made to increase the supply of the seed for the next season.
Improved seed can make a real difference to subsistence farmers, just as it did in Asia, when high yielding wheat and rice varieties lifted millions out of poverty during the Green Revolution of the 1970s.
According to a recent estimate, Nigeria’s producers and consumers could gain US$350 million (AUD480 million) over 25 years if 15–45% of farmers take up GM cowpea. If adopted at 100% in Nigeria, Niger and Benin, the gain would be at least US$840 million (AUD1.15 billion) per year across the three countries.
For the cowpea scientists, this is their dream. But it is not yet complete.
B B Singh continues his work on improving the traits of the cowpea, splitting his time between Texas A&M University and G B Pant University in northern India.
Meanwhile Higgins is working on an upgrade to fortify the cowpea in its battle against Maruca.
The arms race between plants and pests is never-ending and sooner or later Maruca is likely to develop resistance to the Bt gene in the cowpea.
Jose Barrero, Higgins’ heir apparent for the CSIRO cowpea project, is now leading the effort to equip cowpeas with two different types of Bt resistance genes – a hurdle that will be much harder for Maruca to overcome.
“We’re working like crazy,” says Higgins. He expects it will be ready in another five years.
And then, says the 77-year-old, “I can retire.”
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