Bread wheat DNA sequenced

Dr Cristobal Uauy in a bread wheat greenhouse (Photo courtesy Ruby O'Grady. All rights reserved)
Dr Cristobal Uauy in a bread wheat greenhouse (Photo courtesy Ruby O’Grady. All rights reserved)

Three articles, two published in the journal “Science” and one in the journal “Science Advances”, describe various aspects of the sequencing of the genome of bread wheat (Triticum aestivum). An international consortium sequenced its huge DNA in an operation illustrated in the first article in “Science”. A map of the so-called transcriptome of this plant is described in the second article in “Science”. 828 genes, which for the most part were unknown, illustrated in the “Science Advances” article, are potentially connected with immune reactions to bread wheat.

Bread wheat is a plant that has a very large and complex DNA, consisting of 107,891 genes divided into three sub-genomes for a total of six sets of chromosomes with a large part composed of repeated elements. This conformation is due to the fact that bread wheat, or common wheat, is the result of some hybridizations: one occurred between 820,000 and 580,000 years ago between the Triticum urartu and Aegilops speltoides species that provided four sets of chromosomes and one that occurred between 230,000 and 430,000 years ago with the Aegilops tauschii species that provided two more sets of chromosomes.

The complexity of the bread wheat’s DNA made the sequencing task even more difficult because of the need to be able to distinguish each sub-genome to put the genome in its correct order. The International Wheat Genome Sequencing Consortium (IWGSC) worked on this project for 13 years involving over 200 scientists from 73 institutions in 20 countries.

The article illustrating the bread wheat transcriptome map was written by a team led by Ricardo Ramirez-Gonzalez from Norwich Research Park. It provides a series of annotations and resources to support the work of researchers but also of breeders who want to develop new varieties of this plant that can better withstand climatic changes and diseases.

This is a crucial result of the sequencing because bread wheat suffers drought and floods and is attacked by diseases such as the one caused by the fungus Puccinia triticina. Cristobal Uauy of the John Innes Center, one of the authors of the research and part of one of the institutions that participated in the project, stressed the fact that knowing the genome of bread wheat will make it easier to select characteristics resistant to those vulnerabilities.

There are various predictions on the amount of bread wheat that will be needed in the coming decades to produce the bread required by the growing population but you don’t need to be a scientist to understand that more and more bread wheat is needed while the problems to produce it due to more extreme rainfalls and drought are increasing.

The article published in “Science Advances” focuses on bread wheat genes that are potentially linked to proteins that cause immune reactions. Of the 828 genes identified, only a few were known. Celiac disease is a well-known problem but there are allergies and other problems that can result from a diet that includes foods produced with bread wheat.

In essence, this is a very important research for a series of reasons related to the future of production and consumption of bread wheat. The enormous effort made to sequence its genome will be useful in various ways improving the resistance of this plant with the hope of creating varieties that cause less health problems for celiacs and other people.

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