Discovery of the ‘Holy Grail’ wheat gene could feed our overheated world

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This is the plant that changed humanity. Thanks to the cultivation of wheat Homo sapiens he was able to feed himself in increasing numbers, transforming bands of hunter-gatherers struggling to survive in a hostile world into the planet’s rulers.

In the process, a species of wild grass that was once confined to a small part of the Middle East now covers vast swaths of the Earth. As historian Yuval Noah Harari observed: “In the great plains of North America, where 10,000 years ago not a single blade of wheat grew, today you can walk hundreds of miles without encountering any other plant.”

Wheat currently provides 20% of the calories people consume daily, but its production is under threat. Thanks to man-made global warming, our planet is facing increasingly severe heatwaves, droughts and wildfires that could destroy crops in the future, causing widespread famine.

But the crisis could have been averted thanks to remarkable research now being undertaken by scientists at the John Innes Center in Norwich. They are working on a project to make wheat more resistant to heat and drought. Such efforts have proven extremely challenging, but in a few weeks they will be the subject of a new set of trials as part of a project that will plant wheat varieties – created in part by gene-editing technology in field trials in Spain.

The ability of these varieties to withstand the heat of the Iberian Peninsula will determine how well crop scientists will be able to protect future crop farms from the worst vicissitudes of climate change and thus boost food production for billions of Earth, the John Innes Center team says.

Wheat was not the only botanical fueling the agricultural revolution. Other staples such as rice and potatoes played a role. But generally, wheat is credited with leading the way in sparking the agricultural revolution that created our modern world of “population explosions and pampered elites,” as Harari puts it in his international bestseller sapiens.

Two main forms of wheat are grown on farms: pasta wheat and bread wheat. Together, they play a key role in the diets of some 4.5 billion people, said Professor Graham Moore, a wheat geneticist and director of the John Innes Centre, one of the world’s leading crop research institutes. “Of these, about 2.5 billion in 89 countries depend on wheat as their daily food, so you can see how vitally important this crop is to the world,” he added.

The problem crop scientists faced as they sought to improve the resistance and productivity of wheat varieties was the complexity of wheat genetics, added Moore. “Human beings have a single genome that contains our DNA instructions. But pasta wheat has two different ancestral genomes, while bread wheat has three.”

This complexity had important consequences. To control different genes and chromosomes, wheat acquired a stabilizing gene that segregates different chromosomes in different genomes. This ensured that these forms of wheat have high yields. However, this gene also inhibits any chromosomal exchange with wheat’s wild relatives, thwarting the efforts of geneticists trying to create new varieties with beneficial properties.

“The wild relatives have some really useful traits – disease resistance, salt tolerance, heat protection – traits you want to add to make the wheat more hardy and easy to grow in harsh conditions. But you couldn’t do that because that gene stopped the assimilation of those traits.”

This gene has been known as the “holy grail” of wheat geneticists, Moore added. “Wheat – despite its crucial importance to feeding the world – has proven to be the most difficult of all major crops to study due to the complexity and size of its genome. Hence the importance of searching to find the gene that was causing this problem.”

It took several decades, but researchers at the John Innes Center have now managed to hunt down the Holy Grail. They identified a key gene, labeled it Zip4.5B, and created a mutant version of it that allows the gene to perform its main function – allowing wheat chromosomes to pair properly and sustain yields – but which lacks the ability to block the creation of new varieties with attributes of wild grasses.

“A key tool in this work was gene editing, which allowed us to make precise changes to the wheat DNA. Without it, we would still be struggling with it. It changed everything.”

Since then, researchers at Jones Innes have discovered that there are at least 50 different versions of Zip4.5B. “We’ll now test them in the different wheat varieties we’ve created,” added Moore.

“They will then be bred in Spain, on land near Córdoba, to see how they fare. The aim will be to determine which varieties will best cope with the higher temperatures our farmers are expected to experience in the coming decades.

“Wheat has played an extraordinary role in human history. We hope this work will help keep it relevant as a foodstuff in the future.”

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