Editing Wheat (section)

== Breeding objectives ==

In traditional agricultural systems, wheat populations consist of [[landrace]]s, informal farmer-maintained populations that often maintain high levels of morphological diversity. Although landraces of wheat are no longer extensively grown in Europe and North America, they continue to be important elsewhere. The origins of [[crop breeding|formal wheat breeding]] lie in the nineteenth century, when single line varieties were created through selection of seed from a single plant noted to have desired properties. Modern wheat breeding developed in the first years of the twentieth century and was closely linked to the development of [[Mendelian genetics]]. The standard method of breeding inbred wheat cultivars is by crossing two lines using hand emasculation, then selfing or inbreeding the progeny. Selections are ''identified'' (shown to have the genes responsible for the varietal differences) ten or more generations before release as a variety or cultivar.<ref name="Bajaj-1990" />

Major breeding objectives include high [[crop yield|grain yield]], good quality, [[crop disease resistance|disease-]] and insect resistance and tolerance to abiotic stresses, including mineral, moisture and heat tolerance.<ref name="MVGS_IAEA"/><ref name="Sarkar-2021">{{cite journal |last1=Sarkar |first1=S. |last2=Islam |first2=A.K.M.Aminul |last3=Barma |first3=N.C.D. |last4=Ahmed |first4=J.U. |title=Tolerance mechanisms for breeding wheat against heat stress: A review |journal=South African Journal of Botany |date=May 2021 |volume=138 |pages=262–277 |doi=10.1016/j.sajb.2021.01.003|doi-access=free }}</ref> Wheat has been the subject of [[mutation breeding]], with the use of [[gamma rays|gamma-]], [[x-rays]], [[ultraviolet light]] (collectively, ''radiation breeding''), and sometimes harsh chemicals. The varieties of wheat created through these methods are in the hundreds (going as far back as 1960), more of them being created in higher populated countries such as China.<ref name="MVGS_IAEA">{{cite web |url=http://mvgs.iaea.org/ |title=Mutant variety database |website=MVGS International Atomic Energy Agency}}</ref> Bread wheat with high grain iron and zinc content has been developed through gamma radiation breeding,<ref>{{Cite journal |last1=Verma |first1=Shailender Kumar |last2=Kumar |first2=Satish |last3=Sheikh |first3=Imran |last4=Malik |first4=Sachin |last5=Mathpal |first5=Priyanka |last6=Chugh |first6=Vishal |last7=Kumar |first7=Sundeep |last8=Prasad |first8=Ramasare |last9=Dhaliwal |first9=Harcharan Singh |display-authors=3 |s2cid=10873152 |date=3 March 2016 |title=Transfer of useful variability of high grain iron and zinc from Aegilops kotschyi into wheat through seed irradiation approach |journal=International Journal of Radiation Biology |volume=92 |issue=3 |pages=132–139 |doi=10.3109/09553002.2016.1135263 |pmid=26883304 }}</ref> and through conventional selection breeding.<ref name="MacNeil-2021">{{cite web |last=MacNeil |first=Marcia |title=CIMMYT scientist Ravi Singh receives prestigious award from the Government of India |website=[[International Maize and Wheat Improvement Center]] |date=20 January 2021 |url=http://www.cimmyt.org/news/cimmyt-scientist-ravi-singh-receives-prestigious-award-from-the-government-of-india/ |access-date=27 January 2021}}</ref> International wheat breeding is led by the International Maize and Wheat Improvement Center in Mexico. [[ICARDA]] is another major public sector international wheat breeder, but it was forced to relocate from Syria to Lebanon in the [[Syrian Civil War]].<ref name="ICARDA">{{cite web |title=Press Release: ICARDA safeguards world heritage of genetic resources during the conflict in Syria |website=[[International Center for Agricultural Research in the Dry Areas]] |url=http://www.icarda.org/media/news/press-release-icarda-safeguards-world-heritage-genetic-resources-during-conflict-syria |access-date=27 January 2021}}</ref>

Pathogens and wheat are in a constant process of [[coevolution]].<ref name="Fabre-2022" /> [[Fungal spore|Spore]]-producing wheat rusts are substantially [[evolutionary adaptation|adapted]] towards successful spore propagation, which is essentially to say its [[basic reproduction number|R{{Sub|0}}]].<ref name="Fabre-2022"/> These pathogens tend towards high-R{{ Sub |0}} [[evolutionary attractor]]s.<ref name="Fabre-2022">{{ cite journal |year=2022 |publisher=John Wiley & Sons |issue=1 |volume=15 |pages=95–110 |first6=Ramses |first5=Quentin |first4=Sebastien |first3=Arnaud |first2=Jean-Baptiste |first1=Frederic |last6=Demasse |last5=Richard |last4=Lion |last3=Ducrot |last2=Burie |last1=Fabre |journal=Evolutionary Applications |title=An epi-evolutionary model for predicting the adaptation of spore-producing pathogens to quantitative resistance in heterogeneous environments |doi=10.1111/eva.13328 |pmid=35126650 |pmc=8792485|bibcode=2022EvApp..15...95F }}</ref>

=== For higher yields ===

[[File:Long-term wheat yields in Europe, OWID.svg|thumb|Breeding has increased yields over time|upright=1.5]]

The presence of certain versions of wheat genes has been important for crop yields. Genes for the 'dwarfing' trait, first used by Japanese wheat breeders to produce [[Norin 10 wheat|Norin 10]] short-stalked wheat, have had a huge effect on wheat yields worldwide, and were major factors in the success of the [[Green Revolution]] in Mexico and Asia, an initiative led by [[Norman Borlaug]].<ref>{{Cite journal |last1=Würschum |first1=Tobias |last2=Langer |first2=Simon M. |last3=Longin |first3=C. Friedrich H. |last4=Tucker |first4=Matthew R. |last5=Leiser |first5=Willmar L. |date=2017-09-26 |title=A modern Green Revolution gene for reduced height in wheat |journal=[[The Plant Journal]] |volume=92 |issue=5 |pages=892–903 |doi=10.1111/tpj.13726 |pmid=28949040|s2cid=30146700 |doi-access=free }}</ref> Dwarfing genes enable the carbon that is fixed in the plant during photosynthesis to be diverted towards seed production, and they also help prevent the problem of lodging.<ref>{{Cite journal |last1=Kulshrestha |first1=V. P. |last2=Tsunoda |first2=S. |date=1981-03-01 |title=The role of 'Norin 10' dwarfing genes in photosynthetic and respiratory activity of wheat leaves |url=https://doi.org/10.1007/BF00282421 |journal=[[Theoretical and Applied Genetics]] |volume=60 |issue=2 |pages=81–84 |doi=10.1007/BF00282421 |pmid=24276628 |s2cid=22243940}}</ref> "Lodging" occurs when an ear stalk falls over in the wind and rots on the ground, and heavy nitrogenous fertilization of wheat makes the grass grow taller and become more susceptible to this problem.<ref>{{ Cite book |last1=Milach |first1=S. C. K. |title=Dwarfing genes in plant improvement |date=2001-01-01 |volume=73 |pages=35–63 |publisher=[[Academic Press]] |last2=Federizzi |first2=L. C.|series= Advances in Agronomy |doi=10.1016/S0065-2113(01)73004-0 |isbn=9780120007738}}</ref> By 1997, 81% of the developing world's wheat area was planted to semi-dwarf wheats, giving both increased yields and better response to nitrogenous fertilizer.<ref>{{Cite journal |last1=Lupton |first1=F. G. H.|last2=Oliver |first2=R. H. |last3=Ruckenbauer |first3=P. |date=2009-03-27 |title=An analysis of the factors determining yields in crosses between semi-dwarf and taller wheat varieties|journal=[[The Journal of Agricultural Science]]  |volume=82 |issue=3 |pages=483–496 |doi=10.1017/S0021859600051388 |s2cid=85738377}}</ref>

[[Triticum turgidum subsp. polonicum|''T. turgidum'' subsp. ''polonicum'']], known for its longer [[glume]]s and grains, has been bred into main wheat lines for its grain size effect, and likely has contributed these traits to ''Triticum petropavlovskyi'' and the Portuguese [[landrace]] group ''Arrancada''.<ref name="Adamski-2021">{{cite journal |publisher=Oxford University Press |last1=Adamski |first1=Nikolai M. |last2=Simmonds |first2=James |last3=Brinton |first3=Jemima F. |last4=Backhaus |first4=Anna E. |last5=Chen |first5=Yi |last6=Smedley |first6=Mark |last7=Hayta |first7=Sadiye |last8=Florio |first8=Tobin |last9=Crane |first9=Pamela |last10=Scott |first10=Peter |last11=Pieri |first11=Alice |last12=Hall |first12=Olyvia |last13=Barclay |first13=J Elaine |last14=Clayton |first14=Myles |last15=Doonan |first15=John H. |last16=Nibau |first16=Candida |last17=Uauy |first17=Cristobal |display-authors=3 |title=Ectopic expression of ''Triticum polonicum'' VRT-A2 underlies elongated glumes and grains in hexaploid wheat in a dosage-dependent manner |journal=The Plant Cell |date=2021-05-01 |volume=33 |issue=7 |doi=10.1093/plcell/koab119 |pages=2296–2319 |pmid=34009390 |pmc=8364232 |doi-access=free }}</ref> As with many plants, [[MADS-box]] influences flower development, and more specifically, as with other agricultural Poaceae, influences yield. Despite that importance, {{as of|2021|lc=yes}} little research has been done into MADS-box and other such spikelet and flower genetics in wheat specifically.<ref name="Adamski-2021" />

The world record wheat yield is about {{convert|17|t/ha|lb/acre|abbr=off|lk=in}}, reached in New Zealand in 2017.<ref>{{cite web |url=http://www.guinnessworldrecords.com/world-records/highest-wheat-yield |title=Guinness World Records – Highest Wheat Yield |date=10 August 2022}}</ref> A project in the UK, led by [[Rothamsted Research]] has aimed to raise wheat yields in the country to {{convert|20|t/ha|lb/acre|abbr=unit}} by 2020, but in 2018 the UK record stood at {{convert|16|t/ha|lb/acre|abbr=unit}}, and the average yield was just {{convert|8|t/ha|lb/acre|abbr=unit}}.<ref>{{cite web |url=https://www.fwi.co.uk/arable/crop-management/lincs-grower-scoops-top-wheat-and-rapeseed-yield-awards|author=[[Farmers Weekly]] |title=Lincs grower scoops top wheat and rapeseed yield awards |date=23 November 2018}}</ref><ref>{{cite web |url=https://cereals.ahdb.org.uk/markets/market-news/2018/september/28/gb-harvest-progress-2018-report-6.aspx |title=Agricultural and Horticultural Development Board – 2018 GB Harvest Progress Results}}</ref>

=== For disease resistance ===

[[File:Stem rust on differential lines wheat.jpg|thumb|Different strains have been infected with the [[stem rust|stem rust fungus]]. The strains bred to be resistant have their leaves unaffected or relatively unaffected by the fungus.]]

Wild grasses in the genus ''Triticum'' and related genera, and grasses such as [[rye]] have been a source of many disease-resistance traits for cultivated wheat [[Transgenic plant|breeding]] since the 1930s.<ref>{{cite journal |last1=Hoisington |first1=D. |last2=Khairallah |first2=M. |last3=Reeves |first3=T. |last4=Ribaut |first4=J.M. |last5=Skovmand |first5=B. |last6=Taba |first6=S. |last7=Warburton |first7=M. |display-authors=3 |year=1999 |title=Plant genetic resources: What can they contribute toward increased crop productivity? |journal=[[Proceedings of the National Academy of Sciences]]|volume=96 |issue=11 |pages=5937–43 |pmid=10339521 |doi=10.1073/pnas.96.11.5937  |pmc=34209|bibcode=1999PNAS...96.5937H |doi-access=free }}</ref> Some [[plant disease resistance|resistance gene]]s have been identified against ''[[Pyrenophora tritici-repentis]]'', especially races 1 and 5, those most problematic in [[Kazakhstan]].<ref name="Dahm-2021">{{cite web |first1=Madeline |last1=Dahm |title=Genome-wide association study puts tan spot-resistant genes in the spotlight |website=[[WHEAT (CGIAR)|WHEAT]] |date=27 July 2021 |url=http://wheat.org/genome-wide-association-study-puts-tan-spot-resistant-genes-in-the-spotlight/ |access-date=28 July 2021 |archive-date=22 September 2021 |archive-url=https://web.archive.org/web/20210922142934/https://wheat.org/genome-wide-association-study-puts-tan-spot-resistant-genes-in-the-spotlight/ |url-status=dead }}</ref> [[crop wild relative|Wild relative]], ''[[Aegilops tauschii]]'' is the source of several genes effective against [[TTKSK]]/Ug99 - ''[[Sr33 (gene)|Sr33]]'', ''Sr45'', ''Sr46'', and ''SrTA1662'' - of which ''Sr33'' and ''SrTA1662'' are the work of Olson ''et al.'', 2013, and ''Sr45'' and ''Sr46'' are also briefly reviewed therein.<ref name="Bohra-2021">{{cite journal |last1=Bohra |first1=Abhishek |last2=Kilian |first2=Benjamin |last3=Sivasankar |first3=Shoba |last4=Caccamo |first4=Mario |last5=Mba |first5=Chikelu |last6=McCouch |first6=Susan R. |last7=Varshney |first7=Rajeev K. |title=Reap the crop wild relatives for breeding future crops |journal=[[Trends in Biotechnology]] |publisher=[[Cell Press]] |year=2021 |volume=40 |issue=4 |doi=10.1016/j.tibtech.2021.08.009 |pages=412–431|pmid=34629170 |s2cid=238580339 |doi-access=free }}</ref>

*''{{visible anchor|Lr67}}'' is an [[R gene]], a [[dominant negative]] for [[partial adult plant resistance|partial adult resistance]] discovered and molecularly characterized by Moore ''et al.'', 2015. {{As of|2018}} ''Lr67'' is effective against all races of [[wheat leaf rust|leaf]], [[wheat stripe rust|stripe]], and [[wheat stem rust|stem]] rusts, and [[wheat powdery mildew|powdery mildew]] (''Blumeria graminis''). This is produced by a [[mutation]] of two [[amino acid]]s in what is [[gene prediction|predicted to be]] a [[hexose transporter]]. The product then [[heterodimerization|heterodimerizes]] with the [[plant susceptibility allele|susceptible's]] product, with the downstream result of reducing [[glucose]] uptake.<ref name="Kourelis-2018">{{cite journal |last1=Kourelis |first1=Jiorgos |last2=van der Hoorn |first2=Renier A.L. |title=Defended to the Nines: 25 Years of Resistance Gene Cloning Identifies Nine Mechanisms for R Protein Function |journal=[[The Plant Cell]] |publisher=[[American Society of Plant Biologists]] ([[Oxford University Press|OUP]]) |volume=30 |issue=2 |date=2018-01-30 |doi=10.1105/tpc.17.00579 |pages=285–299|pmid=29382771 |pmc=5868693 |bibcode=2018PlanC..30..285K }}</ref>
*''{{visible anchor|Lr34}}'' is widely deployed in cultivars due to its abnormally broad effectiveness, conferring resistance against [[wheat leaf rust|leaf-]] and [[wheat stripe rust|stripe-]]rusts, and [[wheat powdery mildew|powdery mildew]].<ref name="Dodds-2010">{{cite journal |last1=Dodds |first1=Peter N. |last2=Rathjen |first2=John P. |title=Plant immunity: towards an integrated view of plant–pathogen interactions |journal=[[Nature Reviews Genetics]] |publisher=[[Nature Portfolio]] |volume=11 |issue=8 |date=2010-06-29 |doi=10.1038/nrg2812 |pages=539–548|pmid=20585331 |hdl=1885/29324 |s2cid=8989912 |hdl-access=free }}</ref> An important quantitative resistance gene, Lr34, has been isolated and used intensively in wheat cultivation worldwide; it provides a novel resistance mechanism.<ref name="Krattinger-2009">{{cite journal |last1=Krattinger |first1=Simon G. |last2=Lagudah |first2=Evans S. |last3=Spielmeyer |first3=Wolfgang |last4=Singh |first4=Ravi P. |last5=Huerta-Espino |first5=Julio |last6=McFadden |first6=Helen |last7=Bossolini |first7=Eligio |last8=Selter |first8=Liselotte L. |last9=Keller |first9=Beat |display-authors=6 |title=A Putative ABC Transporter Confers Durable Resistance to Multiple Fungal Pathogens in Wheat |journal=Science |volume=323 |issue=5919 |date=2009-03-06 |issn=0036-8075 |doi=10.1126/science.1166453 |pages=1360–1363|pmid=19229000 |bibcode=2009Sci...323.1360K }}</ref><ref name="Krattinger-2019">{{cite journal |last1=Krattinger |first1=Simon G. |last2=Kang |first2=Joohyun |last3=Bräunlich |first3=Stephanie |last4=Boni |first4=Rainer |last5=Chauhan |first5=Harsh |last6=Selter |first6=Liselotte L. |last7=Robinson |first7=Mark D. |last8=Schmid |first8=Marc W. |last9=Wiederhold |first9=Elena |last10=Hensel |first10=Goetz |last11=Kumlehn |first11=Jochen |last12=Sucher |first12=Justine |last13=Martinoia |first13=Enrico |last14=Keller |first14=Beat |display-authors=6 |title=Abscisic acid is a substrate of the ABC transporter encoded by the durable wheat disease resistance gene Lr34 |journal=New Phytologist |volume=223 |issue=2 |date=2019 |issn=0028-646X |pmid=30913300 |pmc=6618152 |doi=10.1111/nph.15815 |pages=853–866|bibcode=2019NewPh.223..853K }}</ref> Krattinger et al. 2009 find ''Lr34'' to be an [[ATP-binding cassette transporter|ABC transporter]], and conclude that this is the probable reason for its effectiveness<ref name="Dodds-2010" /><ref name="Furbank-2011">{{cite journal |last1=Furbank |first1=Robert T. |last2=Tester |first2=Mark |title=Phenomics – technologies to relieve the phenotyping bottleneck |journal=[[Trends in Plant Science]] |publisher=[[Cell Press]] |volume=16 |issue=12 |year=2011 |doi=10.1016/j.tplants.2011.09.005 |pages=635–644|pmid=22074787 |bibcode=2011TPS....16..635F }}</ref> and the reason that it produces a 'slow rusting'/[[adult plant resistance|adult resistance]] phenotype.<ref name="Furbank-2011" />
* ''{{ Visible anchor |Pm8 }}'' is a widely used [[wheat powdery mildew|powdery mildew]] resistance [[introgressed]] from [[rye]] (''[[Secale cereale]]'').<ref name="Herrera-2017" /> It comes from the rye [[1R (chromosome)|1R chromosome]], a source of many resistances since the 1960s.<ref name="Herrera-2017">{{cite journal |pages=1–9 |year=2017 |issue=1 |volume=154 |publisher=[[BioMed Central]] |journal=[[Hereditas]] |first3=Inger |first2=Larisa |first1=Leonardo |last3=Åhman |last2=Gustavsson |last1=Herrera |doi=10.1186/s41065-017-0033-5 |title=A systematic review of rye (''Secale cereale'' L.) as a source of resistance to pathogens and pests in wheat (''Triticum aestivum'' L.)|pmid=28559761 |pmc=5445327 |doi-access=free }}</ref>

{{visible anchor|Fusarium head blight resistance|text=[[Fusarium head blight resistance|Resistance to Fusarium head blight]]}} (FHB, Fusarium ear blight) is also an important breeding target. [[Marker-assisted breeding]] panels involving [[kompetitive allele specific PCR]] can be used. Singh et al. 2019 identify a KASP [[genetic marker]] for a [[pore-forming toxin]]-like gene providing FHB resistance.<ref name="Kaur-2020">{{cite journal |last1=Kaur |first1=Bhavjot |last2=Mavi |first2=G. S. |last3=Gill |first3=Manpartik S. |last4=Saini |first4=Dinesh Kumar |title=Utilization of KASP technology for wheat improvement |journal=Cereal Research Communications |publisher=Springer Science+Business Media |volume=48 |issue=4 |date=2020-07-02 |doi=10.1007/s42976-020-00057-6 |pages=409–421 |s2cid=225570977}}</ref>

In 2003 the first resistance genes against fungal diseases in wheat were isolated.<ref name="Feuillet-2003">{{cite journal |last1=Feuillet |first1=Catherine |last2=Travella |first2=Silvia |last3=Stein |first3=Nils |last4=Albar |first4=Laurence |last5=Nublat |first5=Aurélie |last6=Keller |first6=Beat |title=Map-based isolation of the leaf rust disease resistance gene Lr10 from the hexaploid wheat ( Triticum aestivum L.) genome |journal=Proceedings of the National Academy of Sciences |volume=100 |issue=25 |date=2003-12-09 |issn=0027-8424 |pmid=14645721 |pmc=299976 |doi=10.1073/pnas.2435133100 |pages=15253–15258|doi-access=free |bibcode=2003PNAS..10015253F }}</ref><ref name="Yahiaoui-2004">{{cite journal |last1=Yahiaoui |first1=Nabila |last2=Srichumpa |first2=Payorm |last3=Dudler |first3=Robert |last4=Keller |first4=Beat |title=Genome analysis at different ploidy levels allows cloning of the powdery mildew resistance gene Pm3b from hexaploid wheat |journal=The Plant Journal |volume=37 |issue=4 |date=2004 |issn=0960-7412 |doi=10.1046/j.1365-313X.2003.01977.x |pages=528–538|pmid=14756761 }}</ref> In 2021, novel resistance genes were identified in wheat against [[powdery mildew]] and [[wheat leaf rust]].<ref name="Sánchez-Martín-2021">{{cite journal |last1=Sánchez-Martín |first1=Javier |last2=Widrig |first2=Victoria |last3=Herren |first3=Gerhard |last4=Wicker |first4=Thomas |last5=Zbinden |first5=Helen |last6=Gronnier |first6=Julien |last7=Spörri |first7=Laurin |last8=Praz |first8=Coraline R. |last9=Heuberger |first9=Matthias |last10=Kolodziej |first10=Markus C. |last11=Isaksson |first11=Jonatan |last12=Steuernagel |first12=Burkhard |last13=Karafiátová |first13=Miroslava |last14=Doležel |first14=Jaroslav |last15=Zipfel |first15=Cyril |last16=Keller |first16=Beat |display-authors=6 |title=Wheat Pm4 resistance to powdery mildew is controlled by alternative splice variants encoding chimeric proteins |journal=Nature Plants |volume=7 |issue=3 |date=2021-03-11 |issn=2055-0278 |pmid=33707738 |pmc=7610370 |doi=10.1038/s41477-021-00869-2 |pages=327–341|bibcode=2021NatPl...7..327S }}</ref><ref name="Kolodziej-2021">{{cite journal |last1=Kolodziej |first1=Markus C. |last2=Singla |first2=Jyoti |last3=Sánchez-Martín |first3=Javier |last4=Zbinden |first4=Helen |last5=Šimková |first5=Hana |last6=Karafiátová |first6=Miroslava |last7=Doležel |first7=Jaroslav |last8=Gronnier |first8=Julien |last9=Poretti |first9=Manuel |last10=Glauser |first10=Gaétan |last11=Zhu |first11=Wangsheng |last12=Köster |first12=Philipp |last13=Zipfel |first13=Cyril |last14=Wicker |first14=Thomas |last15=Krattinger |first15=Simon G. |last16=Keller |first16=Beat |display-authors=6 |title=A membrane-bound ankyrin repeat protein confers race-specific leaf rust disease resistance in wheat |journal=Nature Communications |volume=12 |issue=1 |date=2021-02-11 |page=956 |issn=2041-1723 |pmid=33574268 |pmc=7878491 |doi=10.1038/s41467-020-20777-x|bibcode=2021NatCo..12..956K }}</ref>
Modified resistance genes have been tested in transgenic wheat and barley plants.<ref name="Koller-2023">{{Cite journal |last1=Koller |first1=Teresa |last2=Camenzind |first2=Marcela |last3=Jung |first3=Esther |last4=Brunner |first4=Susanne |last5=Herren |first5=Gerhard |last6=Armbruster |first6=Cygni |last7=Keller |first7=Beat |display-authors=6 |date=2023-12-10 |title=Pyramiding of transgenic immune receptors from primary and tertiary wheat gene pools improves powdery mildew resistance in the field |journal=Journal of Experimental Botany |volume=75 |issue=7 |pages=1872–1886 |doi=10.1093/jxb/erad493 |issn=0022-0957 |doi-access=free|pmid=38071644 |pmc=10967238 }}</ref>
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=== To create hybrid vigor ===

Because wheat self-pollinates, creating [[hybrid seed]] to provide the possible benefits of [[heterosis]], hybrid vigor (as in the familiar F1 hybrids of maize), is extremely labor-intensive; the high cost of hybrid wheat seed relative to its moderate benefits have kept farmers from adopting them widely<ref>Mike Abram for Farmers' Weekly. 17 May 2011. [http://www.fwi.co.uk/articles/17/05/2011/126829/hybrid-wheat-to-make-a-return.htm Hybrid wheat to make a return]</ref><ref>Bill Spiegel for agriculture.com 11 March 2013 [http://www.agriculture.com/crops/wheat/technology/hybrid-wheats-comeback_147-ar30398 Hybrid wheat's comeback]</ref> despite nearly 90 years of effort.<ref>{{cite web|url=http://www.hybridwheat.net/anglais/growing-hybrid-wheat-in-europe/history-of-hybrid-wheat/history-of-hybrid-wheat-627.aspx|title=The Hybrid wheat website|date=18 December 2013|url-status=dead|archive-url=https://web.archive.org/web/20131218051925/http://www.hybridwheat.net/anglais/growing-hybrid-wheat-in-europe/history-of-hybrid-wheat/history-of-hybrid-wheat-627.aspx|archive-date=18 December 2013}}</ref><ref name="Bajaj-1990">Bajaj, Y.P.S. (1990) ''Wheat''. [[Springer Science+Business Media]]. pp. 161–163. {{ISBN|3-540-51809-6}}.</ref> Commercial hybrid wheat seed has been produced using chemical hybridizing agents, [[Plant hormone|plant growth regulators]] that selectively interfere with pollen development, or naturally occurring [[cytoplasmic male sterility]] systems. Hybrid wheat has been a limited commercial success in Europe (particularly France), the United States and South Africa.<ref>Basra, Amarjit S. (1999) ''Heterosis and Hybrid Seed Production in Agronomic Crops''. Haworth Press. pp. 81–82. {{ISBN|1-56022-876-8}}.</ref>

Synthetic hexaploids made by crossing the wild goatgrass wheat ancestor ''[[Aegilops tauschii]]'',<ref>{{Cite journal |last1=Aberkane |first1=Hafid |last2=Payne |first2=Thomas |last3=Kishi |first3=Masahiro |last4=Smale |first4=Melinda |last5=Amri|first5=Ahmed |last6=Jamora |first6=Nelissa |date=1 October 2020 |title=Transferring diversity of goat grass to farmers' fields through the development of synthetic hexaploid wheat |journal=[[Food Security (journal)|Food Security]] |volume=12|issue=5 |pages=1017–1033 |doi=10.1007/s12571-020-01051-w |s2cid=219730099 |doi-access=free }}</ref> and other ''[[Aegilops]]'',<ref name="Kishii-2019">{{cite journal |last=Kishii |first=Masahiro |title=An Update of Recent Use of ''Aegilops'' Species in Wheat Breeding |journal=[[Frontiers in Plant Science]] |publisher=[[Frontiers Media]] SA |volume=10 |date=9 May 2019 |page=585 |doi=10.3389/fpls.2019.00585 |pmid=31143197 |pmc=6521781 |doi-access=free }}</ref> and various durum wheats are now being deployed, and these increase the genetic diversity of cultivated wheats.<ref>(12 May 2013) [https://www.bbc.co.uk/news/uk-22498274 Cambridge-based scientists develop 'superwheat'] BBC News UK, Retrieved 25 May 2013</ref><ref>[http://www.k-state.edu/wgrc/Germplasm/synthetics.html Synthetic hexaploids] {{webarchive|url=https://web.archive.org/web/20111128114349/http://www.k-state.edu/wgrc/Germplasm/synthetics.html |date=28 November 2011 }}</ref><ref>(2013) [http://www.niab.com/uploads/files/NIAB_Synthetic_Hexaploid_Wheat.pdf Synthetic hexaploid wheat] {{webarchive|url=https://web.archive.org/web/20140416183627/http://www.niab.com/uploads/files/NIAB_Synthetic_Hexaploid_Wheat.pdf |date=16 April 2014 }} UK [[National Institute of Agricultural Botany]], Retrieved 25 May 2013</ref>

=== For gluten content ===

Modern bread wheat varieties have been [[breeding (plant)|cross-bred]] to contain greater amounts of gluten,<ref>{{Cite journal|last=Belderok|first=B.|s2cid=46259398|date=1 January 2000|title=Developments in bread-making processes |journal=Plant Foods for Human Nutrition |location=Dordrecht, Netherlands|volume=55 |issue=1|pages=1–86 |pmid=10823487 |doi=10.1023/A:1008199314267}}</ref> which affords significant advantages for improving the quality of breads and pastas from a functional point of view.<ref name="Delcour-2012">{{cite journal|pmid=22224557|year=2012 |last1=Delcour |first1=J. A. |title=Wheat gluten functionality as a quality determinant in cereal-based food products|journal=Annual Review of Food Science and Technology |volume=3 |pages=469–492 |last2=Joye |first2=I. J. |last3=Pareyt |first3=B. |last4=Wilderjans |first4=E. |last5=Brijs |first5=K. |last6=Lagrain |first6=B. |doi=10.1146/annurev-food-022811-101303 |url=https://www.researchgate.net/publication/221728752}}{{open access}}</ref> However, a 2020 study that grew and analyzed 60 wheat cultivars from between 1891 and 2010 found no changes in albumin/globulin and gluten contents over time. "Overall, the harvest year had a more significant effect on protein composition than the cultivar. At the protein level, we found no evidence to support an increased [[immunostimulant|immunostimulatory]] potential of modern winter wheat."<ref name="Pronin-2020">{{cite journal |last1=Pronin |first1=Darina |last2=Borner |first2=Andreas |last3=Weber |first3=Hans |last4=Scherf |first4=Ann |title=Wheat (''Triticum aestivum'' L.) Breeding from 1891 to 2010 Contributed to Increasing Yield and Glutenin Contents but Decreasing Protein and Gliadin Contents |journal=[[Journal of Agricultural and Food Chemistry]] |date=10 July 2020 |volume=68 |issue=46 |pages=13247–13256 |doi=10.1021/acs.jafc.0c02815 |pmid=32648759 |bibcode=2020JAFC...6813247P |s2cid=220469138 }}</ref>

=== For water efficiency ===

Stomata (or leaf pores) are involved in both uptake of carbon dioxide gas from the atmosphere and water vapor losses from the leaf due to water [[transpiration]]. Basic physiological investigation of these gas exchange processes has yielded carbon [[isotope]] based method used for breeding wheat varieties with improved water-use efficiency. These varieties can improve crop productivity in rain-fed dry-land wheat farms.<ref>{{cite journal |last1=Condon |first1=AG |year=1990 |title=Genotypic variation in carbon isotope discrimination and transpiration efficiency in wheat. Leaf gas exchange and whole plant studies |journal =[[Australian Journal of Plant Physiology]] |volume=17 |pages=9–22 |doi=10.1071/PP9900009 |last2=Farquhar |first2=GD |last3=Richards |first3=RA |citeseerx=10.1.1.691.4942 }}</ref>

=== For insect resistance ===

The complex genome of wheat has made its improvement difficult. Comparison of hexaploid wheat genomes using a range of chromosome pseudomolecule and molecular scaffold assemblies in 2020 has enabled the resistance potential of its genes to be assessed. Findings include the identification of "a detailed multi-genome-derived nucleotide-binding leucine-rich repeat protein repertoire" which contributes to disease resistance, while the gene ''Sm1'' provides a degree of insect resistance,<ref name="Walkowiak-2020">{{cite journal |last1=Walkowiak |first1=Sean |last2=Gao |first2=Liangliang |last3=Monat |first3=Cecile |last4=Haberer |first4=Georg |last5=Kassa |first5=Mulualem T. |last6=Brinton |first6=Jemima |last7=Ramirez-Gonzalez |first7=Ricardo H. |last8=Kolodziej |first8=Markus C. |last9=Delorean |first9=Emily |last10=Thambugala |first10=Dinushika |last11=Klymiuk |first11=Valentyna |last12=Byrns |first12=Brook |display-authors=5 |title=Multiple wheat genomes reveal global variation in modern breeding |journal=[[Nature (journal)|Nature]] |publisher=[[Nature Research]]/[[Springer Nature]] |volume=588 |issue=7837 |date=25 November 2020 |doi=10.1038/s41586-020-2961-x |pages=277–283 |pmid=33239791 |pmc=7759465 |bibcode=2020Natur.588..277W |doi-access=free }}</ref> for instance against the [[orange wheat blossom midge]].<ref name="Kassa-2016">{{cite journal |last1=Kassa |first1=Mulualem T. |last2=Haas |first2=Sabrina |last3=Schliephake |first3=Edgar |last4=Lewis |first4=Clare |last5=You |first5=Frank M. |last6=Pozniak |first6=Curtis J. |last7=Krämer |first7=Ilona |last8=Perovic |first8=Dragan |last9=Sharpe |first9=Andrew G. |last10=Fobert |first10=Pierre R. |last11=Koch |first11=Michael |last12=Wise |first12=Ian L. |display-authors=5 |title=A saturated SNP linkage map for the orange wheat blossom midge resistance gene Sm1 |journal=[[Theoretical and Applied Genetics]] |publisher=[[Springer Science+Business Media]] |volume=129 |issue=8 |date=9 May 2016 |doi=10.1007/s00122-016-2720-4 |pages=1507–1517 |pmid=27160855 |s2cid=14168477 }}</ref>