In Search of the Perfect Loaf: A Home Baker's Odyssey (22 page)

Aside from corn leaf blight
, severe disease epidemics struck wheat in India.

In Russia, a widely planted wheat variety also failed, forcing Moscow to secretly import wheat from the United States for the first time in the 1980s. To prevent this kind of repeated food crisis, which distantly echoed famines of the past, resistant plants needed to be developed—and hopefully faster than threats evolved. But if the
pool of genetic resources
upon which breeders depended for their work narrowed, they would have fewer resources at their disposal: these “resistant” plants would have a built-in vulnerability.

Ironically, this “genetic bottleneck,” as it’s known, was an unintended effect of the Green Revolution—a massively successful wheat breeding effort which took off in the 1960s and created high-yielding varieties to feed a growing world population. At the core of the program were
semidwarf wheat varieties
, so called because of their fat seed ears and short stalks, which were first bred in Japan in the 1920s. Researchers seeking higher productivity crossed a Japanese dwarf wheat variety, thought to have originated in Korea, with another wheat from the Mediterranean. Then this variety was bred with Turkey Red wheat to create the grandmother of modern wheats, Norin 10. (When I learned that modern wheat descended from a Eurasian cross, and one with Japanese and Ukrainian roots no less, I began to feel some weird natural kinship to these plants, for essentially they mirror my own Japanese–Ukrainian Jewish heritage.) These short-stature plants were less prone to falling over in the field and could also devote more of their energy to producing grain instead of fibrous stalk, making the plant more efficient. Discovered by U.S. wheat researchers during the postwar occupation of Japan, these semidwarf wheats were refined at Washington State University and then became the foundation for modern wheat bred by Norman Borlaug, the father of the Green Revolution. In the 1950s, even before the arrival of these new varieties, Borlaug’s work in Mexico produced a dramatic increase in wheat yields—the amount of wheat grown per acre—of nearly 6 percent per year. Then he shifted to the semidwarf varieties that came via Washington State, and after several years and many failures, the gains kicked in again. Yields of these semidwarf varieties rose nearly 5 percent per year in the 1960s and ’70s.

These compact varieties thrived with a regime of synthetic fertilizers, irrigation, and pesticides, eventually becoming so productive that Mexico became self-sufficient in wheat. Mostly spring wheats, they quickly spread to other areas of the world, such as South Asia, Latin America, the Kansas fields of the United States, and Australia. They were
less suited to dry land areas
, where cereal grasses first evolved, though by the 1990s breeders had adapted the semidwarf varieties to these regions as well. During the Green Revolution, global wheat yields increased by about 1 percent a year, which meant that countries like India and Pakistan could feed a growing population.

Borlaug eventually won the Nobel Peace Prize for the work and was credited with saving perhaps one billion people from starvation. But after the mid-1970s, yields began to stagnate. And something else was happening as well—what wheat geneticists called “
a narrowing of genetic diversity
coming out of the breeding pipeline relative to that going in.”

By the 1990s, the vast majority of spring wheat grown in developing countries originated at the International Maize and Wheat Improvement Center, the research center that housed Borlaug’s work, known by its Spanish acronym CIMMYT (pronounced
Sim-mit
). If the seeds did not come directly from CIMMYT, they came from national agricultural programs relying on CIMMYT’s germplasm, its seed bank. In this way, CIMMYT was at the forefront of breeding high-yielding varieties that, as one scientific paper put it, “
replaced the landraces
in great swaths across the world.” The adoption of modern spring wheat was particularly significant, because it accounts for about two thirds of all wheat grown in developing countries—mostly by small-scale farmers for local consumption. By 1997,
97 percent of all spring wheat
landraces had been replaced by modern varieties.

This lack of diversity in wheat wasn’t limited to CIMMYT seed lines. European wheat varieties, which showed a great deal of diversity from the 1840s through the 1960s, narrowed considerably as hybrid varieties replaced landraces.
By 1993, the National Academy
pointed out, landraces were all but being ignored because they had little apparent value, and yet it warned that those landraces might hold the key to future environmental stresses—a particularly prescient point as global temperatures rise. As it turned out, the Green Revolution wheats CIMMYT developed in Mexico suffered in years when temperatures rose above average. This is now a growing concern as global warming progresses.
In developing countries such as India
, models project that rising temperatures could stunt the wheat crop and threaten the food resources of hundreds of millions of people. In North America, forecasts project that wheat farming will shift to the north, with amber fields of wheat extending into Alaska by 2050 as temperatures continue to rise. Letting diverse landraces languish, or even vanish, was like playing Russian roulette with the food supply—twice—first from the standpoint of disease vulnerability and second from climate change.

CIMMYT heeded these warnings in the 1990s, and began looking anew for genetic material in wild grasses. Recall that wheat descended from the initial selections made by Neolithic farmers around ten thousand years ago. Bread wheat itself arose from the happenstance interbreeding of these farmers’ emmer wheat with wild goat grass weeds. To bring more genetic diversity into modern wheat, researchers looked anew at the wild goat grass cultivars. They crossed them with lines of durum wheat—the pasta wheat that emmer evolved into over many centuries—trying to re-create versions of the original bread wheats, but with new genetic material. To increase diversity and develop certain traits, wheat breeders were adding genes from wild grasses that were closely related but never interbred into the wheat genome. These were not genetically engineered plants; the breeders used
conventional breeding techniques
to create these hybrids. But these novel creations are known as “synthetic wheat,” because they represent an unprecedented genetic stew. They then crossed these creations with elite breeding lines of wheat, and further mated them with local cultivars in China and other countries. With this work, CIMMYT researchers have boasted that wheat now has
more diversity than before the Green Revolution
, making the wheat crop even more productive, especially in conditions of extreme heat and drought.

But how does this lab-induced biodiversity compare with landraces that evolved in farmers’ fields, over millennia? Nearly all the seeds on which breeders depend are now held in “doomsday” seed vaults designed to protect the world’s store of genetic material, or more accurately, the food supply. The most infamous site, the Svalbard Global Seed Vault, sits below four hundred feet of solid rock on a frozen Norwegian island above the Arctic Circle. CIMMYT alone holds one tenth of the world’s crops and has
more than 168,000 different
varieties of wheat, barley, rye, and wild grasses, which are the foundation material—the germplasm—from which to breed new plants.

Even scientists worry this invaluable seed stock isn’t quite the same as maintaining biodiversity in nature, because biodiversity can’t simply be reduced to a library collection. The very word
biodiversity
means not only genetic variation but variation in the landscape and among species. So if you breed a new wheat plant and then seed it in a monoculture, across an entire nation, you’re essentially undermining the kind of biodiversity you’re trying to recreate. And this is occurring globally, as the latest and most popular wheat varieties are released and then planted across wide swaths of land.
The practice by farmers
of selecting seeds for microclimates—as Earl Clark did with Blackhull wheat, or as farmers did with their landraces—falls dormant. The natural selections and happenstance adaptations that occur in the field go by the wayside.

Meanwhile, wild grasses—another source of biodiversity—are vanishing. “
More and more land
is used for farming in order to grow commercial crops to feed the increasing human population. Extensive herding has led to overgrazing and erosion. The last primary habitats of wild stands will soon be destroyed. We are close to losing a valuable source of genetic diversity that could help plant breeders to provide food for future generations,” a team of archeologists wrote in 2010. This worry isn’t just theoretical.
In 2013, wheat researchers
identified a gene in ancient Turkish einkorn wheat that conferred resistance to a devastating fungal rust disease, known scientifically as Ug99, that has wiped out wheat in East Africa and Iran and threatened to spread globally. Another resistant gene was found in wild goat grass. Once identified, those genes could be bred into new wheat varieties, creating resistance to this new scourge.

This is just the latest example of how relic and wild wheat species provide the genetic keys to preserving wheat. In other words, the future of one fifth of the world’s food supply may reside precisely in the genes of wild grasses or the least productive landrace wheat varieties, with the worst bread-making qualities, which is why
these grasses have been ignored
, even trampled upon, for a century or more, at humanity’s peril.

 • • • 

T
he lack of diversity doesn’t just have implications for farming or the food supply. It may be related to gluten toxicity as well. While the broad array of “gluten sensitivity” issues has only
recently been defined
by physicians, let alone understood, celiac disease, which affects about 1 percent of the population, has been the focus of sustained research.

For those people with the disease, gluten acts as a trigger, causing the immune system to misfire and attack itself. The targets frequently are the microscopic folds, or villi, of the intestinal wall, which once damaged can no longer absorb nutrients into the body. Classic symptoms include diarrhea, intestinal pain, and signs of malnutrition. Atypical signs, such as tiredness, depression, osteoporosis, migraine headaches, muscle or joint pain, anemia, delayed growth, and even schizophrenia, are also associated with the disease.

Although celiac disease was first described by a Greek physician in the first century, gluten was only identified as the culprit in the mid-twentieth century. More recently scientists have located the most troublesome proteins, which reside in the gliadin segment of gluten. If you put your baker’s hat back on, you’ll recall that gliadin proteins are crucial for dough’s extensibility—that is, its ability to stretch out without snapping back like a rubber band. Gliadin contains a specific segment of proteins—or chain of amino acids—that prompts an immune response in about half of all people with celiac disease. Gliadin’s sister protein, glutenin, which adds strength or elasticity to dough, isn’t an innocent bystander, for it, too, can prompt an immune reaction, but it occurs less frequently.

Because wheat has been the subject of intensive selection and breeding, geneticist Hetty van den Broeck, at the Wageningen University and Research Center in the Netherlands, wondered whether modern wheat differed from older varieties in a way that would prompt more expressions of celiac disease. Did the toxic gliadin protein fragment—known as an “epitope”—appear more frequently in modern wheat than in ancient landraces? A paper by a team of
Norwegian researchers in 2005
had sparked this line of inquiry, as it identified einkorn and durum wheat that lacked this specific disease-triggering epitope. But they hadn’t looked extensively at modern and landrace wheat varieties.

“Before we started the analysis we didn’t have a clue how prevalent the celiac disease epitopes would be in modern and old varieties,” van den Broeck told me. So she tested thirty-six modern European varieties and compared them with fifty landrace and ancient wheats, from regions as distant as the Middle East and Ethiopia—admittedly a small sample considering the tens of thousands of wheat varieties, but still large enough to get a meaningful result. What she found was that the toxic fragment was far more prevalent in the modern varieties. “
This suggests that modern wheat breeding
practices may have led to an increased exposure to celiac disease epitopes,” she and her coauthors wrote in the
Journal of Theoretical and Applied Genetics
in 2010.

While she didn’t locate any wheat varieties that lacked the toxic sequence, there were varieties where the epitope was minimally present, even among a few modern wheat lines. Van den Broeck suggested that if breeders focused on these less toxic varieties, they could eventually produce less toxic flour for people genetically susceptible to celiac disease. “Breeding was always done for baking quality, or yield and pest resistance, but there’s never been breeding done for the presence of CD epitopes,” she told me.

This is admittedly a challenging task, because gliadin proteins are essential to bread making. Think about it: if you’re breeding wheat and stumble on a variety that produces an especially light loaf, then you’re going to make sure other wheat varieties share the same characteristics. So breeders are sure to crossbreed this trait into the hybrid wheat they develop. Given this selection criterion, it isn’t too surprising that modern wheat shares a basket of similar traits. But van den Broeck’s findings suggest that less toxic wheat varieties may one day be available, in part because scientists now know where this prevalent toxic gluten fragment arose from: it came from the
gliadin proteins transferred
thousands of years ago from wild goat grass, when it mated with emmer wheat.

This suggests that wheat species that lack these genes—einkorn wheat, for example—would lack these toxic gliadin fragments, too. But that turns out to be ambiguous.
While some studies have found that einkorn
wheat can be tolerated by patients with celiac disease, other studies have found toxic protein fragments in the grain. “Einkorn does have epitopes, just less of them,” van den Broeck explained. “It’s not as if you can just get rid of one protein and the story is over. That is what makes it complicated to find a wheat variety suitable to all patients.”