The study represents the most detailed examination to date of the DNA that makes up the wheat genome, a crop domesticated thousands of years ago. The wheat genome is five times the size of the human genome, giving it a complexity that makes it difficult to study. The researchers used the whole genome shotgun sequencing approach, which essentially breaks up the genome into smaller, more workable segments for analysis and then pieces them together.
Another international team of scientists is working on a long-term project expected to result in more detailed sequencing results of the wheat genome in the years ahead. But the results published today shed light on wheat's DNA in a way that will help breeders develop hardier varieties by linking genes to key traits, such as disease resistance and drought tolerance.
Wheat evolved from three ancient grasses, and the ARS team, working closely with partners at University of California, Davis, sequenced the genome of one of those three parents, Aegilops tauschii. That sequencing, funded in part by the National Science Foundation, was instrumental in the study. It allowed researchers to identify the origins of many of the genes found in modern-day wheat, a key step in linking genes to traits and developing markers for use in breeding new varieties.
Wheat growers face numerous challenges each year. Acidity in the soil can make wheat difficult to grow in some areas. Stem rust, a fungal disease, can wipe out entire crops, and a particularly aggressive form of stem rust has developed the ability to knock out genetic resistance in many popular wheat varieties and is causing major losses overseas.
USDA scientists have conducted similar genomic studies that have helped to increase the productivity of dairy operations, enhance cattle breeding and improve on varieties of a number of other crops, including tomatoes, corn and soybean. In 2010, another ARS team published a paper in Nature detailing the sequencing of Brachypodium distachyon, a model plant used to study wheat, barley and biofuel crops.
Recent international research collaborations have been critical to meet challenges such as combating wheat rust and increasing wheat productivity, fighting aflatoxin contamination in food, and sequencing genomes of important crops.