An international team of scientists, including some from USDA’s Agricultural Research Service, has identified the 90,000-plus genes that make up the wheat genome. This was a monumental task, considering that the wheat genome is five times the size of the human genome.
Why does this matter? Wheat is one of the world’s “big three” crops, along with rice and corn, and unlocking its secrets will help researchers develop an overall picture of the plant’s genetic makeup and broaden their understanding of how genetics and environment determine a crop’s health and viability. Why is one variety of wheat susceptible to drought or a particular disease, but not another? Why does one variety grow well in one type of soil, but not another? The genome map will help scientists find those answers by making it easier to link specific genes with important traits and develop genetic markers that can lead to breeding of new wheat varieties that produce higher yields and better tolerate drought, diseases and pests.
Today’s wheat growers and breeders face a number of challenges. A fungal disease called stem rust can wipe out an entire crop. A particularly aggressive form of stem rust called Ug99 can overcome the genetic resistance in many popular wheat varieties, and is causing major losses overseas. Stripe rust can cause wheat yield losses of up to 40 percent in the Pacific Northwest. These diseases are spread by fungi that are constantly evolving new tactics to overcome the mechanisms bred into wheat to prevent infection. Scientists have compared what they do to running on a treadmill because they are always trying to stay a step ahead of nature’s evolving threats.
Acidity in the soil can make wheat difficult to grow in some areas. Prolonged wet weather can delay a harvest, allowing the seed to germinate inside the wheat head. Researchers are always looking for DNA markers associated with genes that regulate pre-harvest sprouting and increase tolerance to acidic soils. Better genetic information will speed up their efforts.
Remember that the next time you bite into a piece of toast.