Mon, Jan 09, 2023 page7

• Wheat gene discovery could feed overheated world

  ‘HOLY GRAIL’: A heat-resistant variety of gene-edited wheat could replace harvests that are disappearing due to global warming, with trial crops to be grown soon in Spain

  • The Guardian
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  It is the plant that changed humanity. Thanks to the cultivation of wheat, humanity became able to feed itself in ever-increasing numbers, transforming groups of hunter-gatherers struggling to survive in a hostile world into rulers of the planet.

  In the process, a species of wild grass that was once confined to a small part of the Middle East now covers vast stretches of the planet.

  “In the great plains of North America, where not a single wheat stalk grew 10,000 years ago, you can today walk for hundreds upon hundreds of kilometers without encountering any other plant,” the historian Yuval Noah Harari wrote in Sapiens: A Brief History of Humankind.

  

  Wheat grows limply, a result of the climate phenomenon La Nina, at a farm in Navarro, Argentina, on Dec. 5 last year.

  Photo: Reuters

  Wheat now provides 20 percent of the calories consumed by humans every day, but its production is under threat. Thanks to human-induced climate change, our planet faces a future of increasingly severe heat waves, droughts and wildfires that could devastate harvests, triggering widespread famine in their wake.

  The crisis could be averted thanks to remarkable research now being undertaken at the John Innes Centre in Norwich. Teams are working on a project to make wheat more resistant to heat and drought. Such efforts have proved to be extremely tricky, but are set to be the subject of a new set of trials as part of a project in which varieties of wheat — created, in part, by gene-editing technology — are soon to be planted in Spain.

  The ability of these varieties to withstand the heat of Iberia should determine how well crop scientists might protect future arable farms from the worst vicissitudes of climate change, and bolster food production for the planet, John Innes researchers said.

  Wheat was not the only botanical agent to fuel the agricultural revolution. Other staples such as rice and potatoes played a part, but wheat is generally accorded the lead role in triggering the agricultural revolution that created our modern world of “population explosions and pampered elites,” as Harari wrote.

  Two main forms of wheat are grown in farms: pasta wheat and bread wheat. Together they play a crucial role in the diets of about 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, around 2.5 billion in 89 countries are dependent on wheat for their daily food, so you can see how vitally important the crop is to the world,” he said.

  The problem that has faced crop scientists, who have been seeking to improve the resilience and productivity of wheat varieties, has been the complexity of wheat genetics, Moore said.

  “Human beings have a single genome that contains our DNA instructions, but pasta wheat has two different ancestral genomes while bread wheat has three,” he added.

  This complexity has had important consequences. To control their differing genes and chromosomes, wheat has acquired a stabilizing gene that segregates the different chromosomes in its various genomes. This has ensured that these forms of wheat have high yields.

  However, the gene also suppresses any exchange of chromosomes with wild relatives of wheat, frustrating the efforts of geneticists trying to make new varieties with beneficial properties.

  “Wild relatives have really useful characteristics — disease resistance, salt tolerance, protection against heat — attributes that you want to add to make wheat more robust and easy to grow in harsh conditions.” Moore said. “You couldn’t do that because this gene stopped these attributes from being assimilated.”

  This gene was known as the “holy grail” of wheat geneticists, he added.

  “Wheat — despite its critical importance to feeding the world — has proved to be the most difficult of all the major crops to study because of the complexity and size of its genome. Hence, the importance of the search to find the gene that was the cause of this problem,” Moore said.

  It has taken several decades, but scientists at the John Innes Centre have succeeded in their hunt for their holy grail. They identified the key gene, labeled it Zip4.5B and have created a mutant version that allows the gene to carry out its main function — to allow wheat chromosomes to pair correctly and maintain yields — but which does not block the creation of new variants with attributes from wild grasses.

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

  John Innes scientists have since discovered that there are at least 50 different versions of Zip4.5B.

  “We are now going to test these in different varieties of wheat that we have created,” Moore said. “These will then be grown in Spain, on land near Cordoba, to see how well they do. The aim will be to identify which varieties will do best at surviving the higher temperatures that our farmers are to experience in coming decades.”

  “Wheat has played a remarkable role in human history. Hopefully, this work will help it to maintain its importance as a foodstuff for the future,” he said.
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