Did You Know Wheat Has A More Complex Genome Than Humans?
Image Credit: Wheat | Image Credit: Unsplash.com

Did you know humble wheat proved to be a rather difficult problem to solve for geneticists? A problem that was not solved until 2016, in fact. Most staple food crops had their genomes sequenced long before that! Common strains of corn, soya and rice have 2.3bn, 1.1bn and 420m DNA base pairs respectively. Quick biology lesson reminder: What is a base pair? Remember how Adenine pairs with Thymine and Guanine pairs with Cytosine? This is called a base pair. How many do you think human cells have? A whopping 3 billion. Now take a guess as to how many bread wheat has. 17 billion! That’s how many. No wonder it took as long as it did to crack the wheat genome.  

Humans are diploid, meaning we have two sets of chromosomes, while wheat comes in sets of six! It’s not as though the ancient wheat, from which the newer bread wheat has evolved, was any less complex. Even ancient wheats, such as wild emmer, contain more DNA base pairs than human genomes do. The problem is that wheat not only contains a huge amount of genetic information, but that a lot of it is repeated. So the lack of unique pieces makes this jigsaw puzzle a little more difficult to put together. 

But why is decoding a genome useful or even necessary? Well, for the same reasons that understanding the intricate details of how the human body works is necessary—A, for the pure joy of science and decoding the mysteries of the world around us, and B, to help make something better. It makes it easier for scientists to manipulate wheat to be more disease-resistant and higher-yielding without as much trial and error. Additionally, as the Economist notes, "it allows them to insert attractive traits from ancient wheats into modern ones, rather than introducing genes from other organisms altogether (a process known as transgenics)." As some researchers have suggested, this could be useful because ancient wheats may have better resistance to pests or better tolerance of drought.  

This has become particularly important in recent times. Why? Climate change. For example, last summer, a widespread drought across the United States lowered crop yields by as much as one-third. Corn, wheat, barley, and other plants suffered from too much heat and too little water. This is a scenario that is bound to repeat as the world becomes a hotter and drier place. Scientists are also studying hardy plants such as orchids and agaves to help teach these old food crops a few lessons in hacking photosynthesis. Many orchids, for example, live in the nooks and crannies of trees where their only water comes from infrequent bouts of rain; agaves thrive in the rocky soils of desert grasslands. As the Smithsonian magazine reported, "If scientists could engineer crop plants like rice and wheat to be more like these heat-tolerant species, crops could be grown in lands that can’t be farmed right now. Under the right conditions, researchers say, some crop yields could increase by 50 percent or more." 

Food scarcity is something we will have to take into account as we move forward in these times riven by climate change. Besides, wheat is gaining prominence in areas of the world where it was not the primary cereal consumed. Take Asia. Traditionally, rice has been the dominant food crop in Asia. Around 90% of the world’s rice is consumed in Asia, with 60% of it in just China, India, and Indonesia. In every large country except Pakistan, Asians eat more rice than the global average. But that trend is slowly beginning to change. In some of the more well-off Asian nations, rice is going out of fashion. It is beginning to be replaced by wheat. Rice consumption per head has fallen since 2000 in China, Indonesia, and South Korea, and has crashed in Singapore. Wheat consumption has been steadily rising despite increasing prices in countries like Thailand and Vietnam. As The Economist noted, "South-East Asian countries consumed 23.4m tons of wheat in 2016–17, estimates the USDA – up from 16.5m tons in 2012–13. Almost all of it was imported. In South Asia, consumption is estimated to have grown from 121m to 139m tons over the same period." Where there is demand, there must also be supply. Rice requires a lot more water to grow. In these times of drought and uncertain rainfall, wheat may just be seen as a better and easier crop to grow by farmers, especially given the slowly changing preferences of the people.  

In light of this, it becomes that much more important to study wheat in all its complexity. Hardier, higher-yielding wheat may just be the answer to not only the growing food availability chasm in the present world but also in a future world that is only going to get hotter, drier, and less fertile.