Killer Fungus Could Threaten World Food Supply
In John Christopher’s sci-fi tale No Blade of Grass, a virus wipes out all the world’s grasses—the entire family Poaceae, which includes some 10,000 different species, among them wheat, barley, oats, rye, millet, rice, sorghum, and sugarcane.
The result, of course, was disastrous. There was worldwide famine (presumably also obliterating grazing animals and the pandas; bamboo is a grass). Starving people formed bands of marauders. In England—where the story is set—farms savvy enough to have concentrated on such non-grass crops as cabbages and potatoes turned themselves into armed fortresses and shot desperate people who tried to breach their stockades.
‘Let Them Eat Cake’
It’s not all that outlandish a scenario. Wheat, the staple crop that provides 20 percent of the world’s calories, is the major component of the staff of life: bread. For much of history, the bulk of the human diet has consisted of bread—and when people are deprived of it, all hell breaks loose. The French and Russian Revolutions both began with bread riots. The Romans attempted to placate an unhappy populace with “bread and circuses.” And the Bolsheviks won a lot of popular support by promising “peace, land, and bread.” Marie Antoinette’s famously insensitive “Let them eat cake” in the face of France’s crippling bread shortages is generally said to have set the monarchy on the road to the guillotine.
To be fair, she almost certainly never said it—the story has been attributed to any number of rich and reputedly clueless figures, among them a Chinese emperor whom, upon being told his starving subjects lacked rice, supposedly replied “Let them eat meat!” However, no matter who said what, it’s clear that lousy wheat harvests and lack of available bread played no small part in the French crown’s demise.
Cultural Implications of Bread
An indication of the importance of bread is its widespread cultural significance. Almost every region has its characteristic bread—among them New England anadama bread, Irish soda bread, Indian naan and chapatis, Middle Eastern pita bread, French baguettes and croissants, and German pumpernickel. (This last is possibly the world’s best-named bread; the word translates as “devil’s fart.”)
The sharing of bread traditionally signals hospitality (an act performed continually and duplicitously in Game of Thrones). The medieval designations of “lord” and “lady” derive from the Old English for, respectively, “bread eater” and “loaf kneader,” reflecting the central role of bread in the European household. Downton Abbey’s aristocratic Lord and Lady Grantham—nibblers of cucumber sandwiches—have their roots in bread. Special breads play a role in any number of holidays and celebrations, from Passover’s matzo to Good Friday’s hot cross buns.
To supply the demand for bread—and buns, crackers, cookies, cupcakes, muffins, ice cream cones, and dozens of different kinds of pasta—the world produces nearly 700 million tons of wheat a year. In the United States, we’ve got over 60 million acres planted in wheat.
So what if something goes wrong?
SciFi Thriller Could be a Real-Life Nightmare
Wheat’s nemesis is a fungus commonly known as wheat stem rust, the latest permutation of which is known as Ug99, first identified in Uganda and formally named in 1999. If Ug99 turns into a pandemic, we’re in trouble. Just 10 percent of wheat is resistant to it; the other 90 percent of the world crop, a sitting duck, would flop over and rot within weeks of infection. Ug99 has the potential to make the horrific Irish Potato Famine look like a Sunday School picnic.
Nobelist Norman Borlaug, the father of the 20th-century Green Revolution, was able to fend off wheat stem rust beginning in the 1940s by crossing commercial rust-sensitive wheat varieties with rust-resistant strains. The problem with rust resistance, though, is that it’s inevitably short-lived. On average, a single rust-resistant gene lasts only three to four years before rust finds a way to weasel around it.
Rust is a resilient organism with a large and relentlessly evolving genome. Balked of one means of nabbing its victim, rust will cunningly bide its time and come up with another mode of attack. In this sense, it’s much like influenza virus, which killed 50 million people in the pandemic of 1918 and whose constantly shifting genetic makeup forces us to get new flu shots year after year. When it comes to persistence, there’s nothing like a microorganism.
GMOs Could Offer a Fix
More effective rust resistance comes from a technique called “pyramiding” in which multiple resistance genes are loaded onto a single strain of wheat. As was true of the Three Musketeers, there’s strength in numbers: multiply-resistant wheat strains can sometimes fight off rust for decades. Traditional breeding strategies are effective here, but are painfully slow, sometimes taking fifteen years or more to produce a rust-resistant variety. Better and faster is genetic engineering in which an entire string of rust-resistant genes—many plucked from tough wild grasses—is pieced together and inserted as a block into a wheat chromosome. Public opposition to GMOs, however, has slowed or blocked the development of such rust-resistant wheats—and that could come back to bite us. If Ug99 gets off the ground, we’re going to need a lot of help, and fast.
Rust isn’t a problem that’s going to go away—and even the best and brightest of rust-resistant strains won’t remain so forever. As Norman Borlaug presciently said: “Rust never sleeps.” It’s something to think long and hard about.
Especially if we hope to keep on eating our daily bread.
This story is part of National Geographic’s special eight-month Future of Food series.
Grens, Kerry. “Putting Up Resistance.” The Scientist, June 2014, pp 34-39.
See Stem rust of wheat from the American Phytopathological Society.
Oppenneer, Betsy. Celebration Breads: Recipes, Tales, and Traditions. Simon & Schuster, 2010.
