Genetic blueprint of bread wheat genome unveiled

18th Jul 2014

The International Wheat Genome Sequencing Consortium (IWGSC) has published a chromosome-based draft sequence of the bread wheat genome in the international journal Science. This genetic blueprint provides new insights into the structure, organisation, and evolution of the large, complex genome of the world’s most widely grown cereal crop, and is the last step before a full genome sequence is reached.

The sequence is an invaluable resource to plant science researchers and breeders. For the first time, they have at their disposal a set of tools enabling them to rapidly locate specific genes on individual wheat chromosomes throughout the genome.

Professor Robbie Waugh from the James Hutton Institute and the University of Dundee, together with colleagues at the Joint Genome Institute, the universities of Minnesota and Kansas State in the USA and the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) in Germany, contributed a large part of the genetic information which helped bring the majority of the wheat gene sequences into a linear order along each chromosome and reveal their organisation in the wheat genome. Their approach was pioneered previously in barley, a simpler model crop for research in bread wheat.

Professor Waugh said: “These results have the potential to fundamentally change the way wheat research and breeding are conducted. Access to the entire gene complement in its genomic context will allow researchers to unravel the genetic basis of important agronomic traits much faster and more easily. This will in turn allow breeders to select important traits indirectly using molecular diagnostics at an early stage in crop improvement, accelerating breeding cycles and increasing the rate of genetic gain. This is precisely the type of landmark discovery that is required to address the impending challenges of global food security and environmental change”.

The IWGSC draft sequence is a major landmark towards obtaining a complete reference sequence of the complex bread wheat genome, the ultimate aim of the consortium. In the same issue of Science, a separate article presents the first reference sequence for the largest chromosome, 3B. This establishes a proof of concept and a template for sequencing the remaining chromosomes. As of today, researchers in the IWGSC estimate that the full genome sequence will be available within three years.

“With the draft gene sequence for each of the bread wheat chromosome and the first reference sequence of chromosome 3B, we have reached a great milestone in our roadmap,” said Catherine Feuillet, IWGSC co-chair. “We know now the way forward to obtain a reference sequence for the 20 remaining chromosomes and we hopefully will be able to find the resources to achieve this in the next three years.”

With a chromosome-based full sequence in hand, plant breeders will have high quality tools at their disposal to accelerate breeding programmes and allow them to produce a new generation of wheat varieties with higher yields and improved resilience against environmental stress.

Wheat is a major dietary component for many populations across the world. Grown on more land than any other crop, more than 215 million hectares of wheat are harvested annually to generate a world production of almost 700 million tons, making it the third most produced cereal after maize and rice. It is the leading source of vegetable protein in human food, having higher protein content than either maize or rice. The wheat plant is highly versatile due to its ability to grow in a wide range of environments. Wheat grain is easily stored and can be converted readily into flour for making numerous varieties of high quality edible food.

The paper can be read online in a special issue of Science: Slicing the wheat genome. DOI: 10.1126/science.1251788

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