February 1, 2023

How Bread Wheat Got Its Gluten: DNA Detective Work Uncovered an Obscure Ancestor of Modern Bread Wheat

Population genome analysis led by Dr. Kumar Gaurav from the John Innes Centre exposed the presence of an unique lineage of Aegilops tauschii restricted to present-day Georgia, in the Caucuses region– some 500 kilometers from the Fertile Crescent where wheat was first cultivated– a location extending throughout modern-day Iraq, Syria, Lebanon, Palestine, Israel, Jordan, and Egypt.
First author of the study in Nature Biotechnology, Dr. Kumar Gaurav stated, “The discovery of this previously unknown contribution to the bread wheat genome is similar to discovering the introgression of Neanderthal DNA into the out of Africa human genome.
Scientists on a wild wheat family members foraging journey in the central Zagros mountains in western Iran. Credit: Ali Mehrabi
” It is probably to have actually occurred through a hybridization outside the Fertile Crescent. This group of Georgian accessions form an unique family tree that contributed to the wheat genome by leaving a footprint in the DNA.”
The discovery comes via a major worldwide partnership to enhance crops by exploring helpful genetic diversity in Aegilops tauschii, a wild relative of bread wheat. The Open Wild Wheat Consortium brought together 38 research groups and scientists from 17 nations.
More research study by Dr. Jesse Polands group at Kansas State University was published in a buddy paper in Communications Biology and shows that the ancestral Aegilops tauschii DNA found in modern-day bread wheat consists of the gene that offers exceptional strength and elasticity to dough.
Dr. Poland stated, “We were astonished to find that this family tree has actually supplied the best-known gene for superior dough quality.”
The researchers speculate that the recently discovered lineage might have been more geographically extensive in the past, which it might have become separated as a refugium population during the last ice-age.
Reviewing all that has actually come together to make this work possible, Dr Brande Wulff, corresponding author of the study, remarked, “Fifty or sixty years earlier at a time when we hardly understood DNA, my clinical forefathers were traversing the Zagros mountains in the center east and Syria and Iraq. They were gathering seeds, maybe having a hint that one day these might be utilized for improving wheat. Now we are so near to opening that potential, and for me that is extraordinarily interesting.”
Figuring out Wheats Complex Genome
Modern “hexaploid” wheat, is an intricate hereditary mix of various lawns with a substantial genetic code, split into A, B and D sub-genomes. Hexaploid wheat accounts for 95 percent of all cultivated wheat. Hexaploid means that the DNA contains six sets of chromosomes– three pairs of each.
Through a combination of natural hybridizations and human growing, Aegilops tauschii offered the D-genome to modern wheat. The D-genome included the properties for making dough, and made it possible for bread wheat to thrive in various climates and soils.
The origin of modern hexaploid bread wheat has actually long been the topic of intense scrutiny with archeological and hereditary evidence suggesting that the first wheat was cultivated 10,000 years ago in the Fertile Crescent.
Domestication, while increasing yield and increasing agronomic efficiency, came at the expense of a noticable genetic bottleneck eroding hereditary variety for protective traits to be found in Aegilops tauschii such as disease resistance and heat tolerance.
Analysis carried out by Dr. Gaurav and the research group exposed that simply 25% of the hereditary variety present in Aegilops tauschii made it into hexaploid wheat. To explore this variety in the wild gene pool, they used a technique called association mapping to find brand-new prospect genes for illness and bug resistance, yield and environmental durability.
Dr. Sanu Arora, who had earlier led a study to clone illness resistance genes from Aegilops tauschii said, “Previously we were limited to checking out an extremely little subset of the genome for illness resistance, however in the existing study, we have created data and methods to undertake an objective exploration of the types diversity”.
Further experiments demonstrated the transfer of prospect genes for a subset of these characteristics into wheat utilizing hereditary change and conventional crossing– helped with by a library of synthetic wheats– specifically bred material which integrates Aegilops tauschii genomes.
This openly offered library of artificial wheats captures 70 percent of the variety present throughout all three understood Aegilops tauschii family trees, enabling researchers to assess qualities rapidly in a background of hexaploid wheats.
” Our study provides an end-to-end pipeline for rapid and systematic exploration of the Aegilops tauschii gene pool for enhancing modern-day bread wheat,” says Dr. Wulff.
” High molecular weight glutenin gene diversity in Aegilops tauschii demonstrates distinct origin of remarkable wheat quality,” appears in Communications Biology.
Reference: “Population genomic analysis of Aegilops tauschii determines targets for bread wheat improvement” 1 November 2021, Nature Biotechnology.DOI: 10.1038/ s41587-021-01058-4.

Showing on all that has actually come together to make this work possible, Dr Brande Wulff, matching author of the research study, said, “Fifty or sixty years ago at a time when we barely comprehended DNA, my scientific forefathers were traversing the Zagros mountains in the middle east and Syria and Iraq. They were gathering seeds, perhaps having an inkling that one day these could be used for improving wheat. Modern “hexaploid” wheat, is a complex genetic combination of various lawns with a big hereditary code, split into A, B and D sub-genomes. Hexaploid wheat accounts for 95 percent of all cultivated wheat. Hexaploid means that the DNA includes 6 sets of chromosomes– three sets of each.

Tracing the Impact of a Long-Lost Relative on Modern Bread Wheat
Genetic detective work has actually revealed an odd forefather of modern bread wheat, in a finding comparable to uncovering a famous long-lost relative through DNA analysis in people.
In a research study which appears in Nature Biotechnology researchers sequenced the DNA from 242 special accessions of Aegilops tauschii collected over decades from throughout its native variety– from Turkey to Central Asia.

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