How bread wheat got its gluten: Tracing the impact of a long-lost
relative on modern bread wheat

Date:
November 1, 2021
Source:
John Innes Centre
Summary:
Genetic detective work has uncovered an obscure ancestor of modern
bread wheat, in a finding similar to uncovering a famous long-lost
relative through DNA analysis in humans.



FULL STORY ========================================================================== Genetic detective work has uncovered an obscure ancestor of modern bread
wheat, in a finding similar to uncovering a famous long-lost relative
through DNA analysis in humans.


==========================================================================
In a study which appears in Nature Biotechnology researchers sequenced
the DNA from 242 unique accessions of Aegilops tauschiigathered over
decades from across its native range -- from Turkey to Central Asia.

Population genome analysis led by Dr Kumar Gaurav from the John
Innes Centre revealed the existence of a distinct lineage ofAegilops tauschiirestricted to present day Georgia, in the Caucuses region --
some 500 kilometers from the Fertile Crescent where wheat was first
cultivated -- an area stretching across modern-day Iraq, Syria, Lebanon, Palestine, Israel, Jordan, and Egypt.

First author of the study in Nature Biotechnology, Dr Kumar Gaurav said,
"The discovery of this previously unknown contribution to the bread
wheat genome is akin to discovering the introgression of Neanderthal
DNA into the out of Africa human genome," "It is most likely to have
occurred though a hybridization outside the Fertile Crescent. This group
of Georgian accessions form a distinct lineage that contributed to the
wheat genome by leaving a footprint in the DNA." The discovery comes
via a major international collaboration to improve crops by exploring
useful genetic diversity in Aegilops tauschii,awild relative of bread
wheat. The Open Wild Wheat Consortium brought together 38 research groups
and researchers from 17 countries.



========================================================================== Further research by Dr Jesse Poland's group at Kansas State University
was published in a companion paper in Communications Biologyand shows
that the ancestral Aegilops tauschii DNA found in modern bread wheat
includes the gene that gives superior strength and elasticity to dough.

Dr. Poland said, "We were amazed to discover that this lineage
has provided the best-known gene for superior dough quality."
The researchers speculate that the newly discovered lineage may have
been more geographically widespread in the past, and that it may have
become separated as a refugium population during the last ice-age.

Reflecting on all that has come together to make this work possible,
Dr Brande Wulff, corresponding author of the study, remarked, "Fifty or
sixty years ago at a time when we barely understood DNA, my scientific forebears were traversing the Zagros mountains in the middle east and
Syria and Iraq. They were collecting seeds, perhaps having an inkling that
one day these could be used for improving wheat. Now we are so close to unlocking that potential, and for me that is extraordinarily exciting." Deciphering Wheat's Complex Genome Modern "hexaploid" wheat, is a complex genetic combination of different grasses with a huge 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 cultivation,
Aegilops tauschiiprovided the D-genome to modern wheat. The D-genome added
the properties for making dough, and enabled bread wheat to flourish in different climates and soils.

The origin of modern hexaploid bread wheat has long been the subject of
intense scrutiny with archeological and genetic evidence suggesting that
the first wheat was cultivated 10,000 years ago in the Fertile Crescent.

Domestication, while increasing yield and increasing agronomic
performance, came at the cost of a pronounced genetic bottleneck eroding genetic diversity for protective traits to be found in Aegilops tauschii
such as disease resistance and heat tolerance.

Analysis performed by Dr. Gaurav and the research team revealed that
just 25% of the genetic diversity present in Aegilops tauschii made it
into hexaploid wheat. To explore this diversity in the wild gene pool,
they used a technique called association mapping to discover new candidate genes for disease and pest resistance, yield and environmental resilience.

Dr. Sanu Arora, who had earlier led a study to clone disease resistance
genes from Aegilops tauschii said, "Previously we were restricted to
exploring a very small subset of the genome for disease resistance, but
in the current study, we have generated data and techniques to undertake
an unbiased exploration of the species diversity." Further experiments demonstrated the transfer of candidate genes for a subset of these traits
into wheat using genetic transformation and conventional crossing -- facilitated by a library of synthetic wheats -- specially bred material
which incorporates Aegilops tauschii genomes.

This publicly available library of synthetic wheats captures 70
per cent of the diversity present across all three known Aegilops tauschiilineages, enabling researchers to assess traits rapidly in a
background of hexaploid wheats.

"Our study provides an end-to-end pipeline for rapid and systematic
exploration of the Aegilops tauschiigene pool for improving modern bread wheat." says Dr Wulff.

This research is part of a global collaboration to improve crops by
exploring useful genetic diversity in Aegilops tauschii,a wild relative
of bread wheat.

The Open Wild Wheat Consortium brings together 38 research groups and researchers from 17 countries.

========================================================================== Story Source: Materials provided by John_Innes_Centre. Note: Content
may be edited for style and length.


========================================================================== Journal References:
1. Kumar Gaurav, Sanu Arora, Paula Silva, Javier Sa'nchez-Marti'n,
Richard
Horsnell, Liangliang Gao, Gurcharn S. Brar, Victoria Widrig,
W. John Raupp, Narinder Singh, Shuangye Wu, Sandip M. Kale,
Catherine Chinoy, Paul Nicholson, Jesu's Quiroz-Cha'vez, James
Simmonds, Sadiye Hayta, Mark A. Smedley, Wendy Harwood, Suzannah
Pearce, David Gilbert, Ngonidzashe Kangara, Catherine Gardener,
Macarena Forner-Marti'nez, Jiaqian Liu, Guotai Yu, Scott A. Boden,
Attilio Pascucci, Sreya Ghosh, Amber N.

Hafeez, Tom O'Hara, Joshua Waites, Jitender Cheema, Burkhard
Steuernagel, Mehran Patpour, Annemarie Fejer Justesen, Shuyu
Liu, Jackie C. Rudd, Raz Avni, Amir Sharon, Barbara Steiner,
Rizky Pasthika Kirana, Hermann Buerstmayr, Ali A. Mehrabi,
Firuza Y. Nasyrova, Noam Chayut, Oadi Matny, Brian J. Steffenson,
Nitika Sandhu, Parveen Chhuneja, Evans Lagudah, Ahmed F. Elkot,
Simon Tyrrell, Xingdong Bian, Robert P. Davey, Martin Simonsen,
Leif Schauser, Vijay K. Tiwari, H. Randy Kutcher, Pierre Hucl,
Aili Li, Deng-Cai Liu, Long Mao, Steven Xu, Gina Brown-Guedira,
Justin Faris, Jan Dvorak, Ming-Cheng Luo, Ksenia Krasileva,
Thomas Lux, Susanne Artmeier, Klaus F. X. Mayer, Cristobal Uauy,
Martin Mascher, Alison R.

Bentley, Beat Keller, Jesse Poland, Brande B. H. Wulff. Population
genomic analysis of Aegilops tauschii identifies targets for
bread wheat improvement. Nature Biotechnology, 2021; DOI:
10.1038/s41587-021-01058-4
2. Emily Delorean, Liangliang Gao, Jose Fausto Cervantes Lopez,
Ali Mehrabi,
Alison Bentley, Amir Sharon, Beat Keller, Brande Wulff, Brian
Steffenson, Burkhard Steuernagel, Carolina Paola Sansaloni,
Deng-Cai Liu, Evans Lagudah, Firuza Nasyrova, Gina Brown-Guedira,
Hanan Sela, Jan Dvorak, Jesse Poland, Klaus Mayer, Ksenia Krasileva,
Kumar Gaurav, Long Mao, Mario Caccamo, Martin Mascher, Mingcheng
Luo, Parveen Chhuneja, Rob Davey, Justin Faris, Steven Xu, Paul
Nicholson, Noam Chayut, Mike Ambrose, Nidhi Rawat, Vijay K. Tiwari,
Brande B. H. Wulff, Maria Itria Ibba, Jesse Poland. High molecular
weight glutenin gene diversity in Aegilops tauschii demonstrates
unique origin of superior wheat quality.

Communications Biology, 2021; 4 (1) DOI: 10.1038/s42003-021-02563-7 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211101141728.htm

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