Editing Triticale (section)

==Application of newer techniques==
Abundant information exists concerning [[R-gene]]s (for disease resistance) in wheat, and a continuously updated on-line catalogue, the Catalogue of Gene Symbols, of these genes can be found at [http://wheat.pw.usda.gov/ggpages/wgc/98/] {{Webarchive|url=https://web.archive.org/web/20060923172834/http://wheat.pw.usda.gov/ggpages/wgc/98/ |date=2006-09-23 }}. Another online database of [[cereal]] rust resistance genes is available at [https://web.archive.org/web/20061006193218/http://www.cdl.umn.edu/res_gene/res_gene.html]. Unfortunately, less is known about rye and particularly triticale R-genes. Many R-genes have been transferred to wheat from its wild relatives, and appear in such papers and catalogues, thus making them available for triticale breeding. The two mentioned databases are significant contributors to improving the genetic variability of the triticale [[gene pool]] through gene (or more specifically, allele) provision. Genetic variability is essential for progress in breeding. In addition, genetic variability can also be achieved by producing new primary triticales, which essentially means the reconstitution of triticale, and the development of various hybrids involving triticale, such as triticale-rye hybrids. In this way, some [[chromosomes]] from the R genome have been replaced by some from the D genome. The resulting so-called substitution and translocation triticale facilitates the transfer of R-genes.{{Citation needed|date=June 2021}}

===Introgression===
[[Introgression]] involves the crossing of closely related plant relatives, and results in the [[gene linkage|transfer of 'blocks' of genes]], i.e. larger segments of chromosomes compared to single genes.{{ Dubious | date=May 2023 | reason=This MAY occur during introgression.}} [[R-gene]]s are generally introduced within such blocks, which are usually incorporated/translocated/introgressed into the distal (extreme) regions of [[chromosomes]] of the crop being introgressed. Genes located in the proximal areas of chromosomes may be completely linked (very closely spaced), thus preventing or severely hampering [[genetic recombination|recombination]], which is necessary to incorporate such blocks.{{ Dubious | date=May 2023 | reason=Very strange.}}<ref name="Chelkowski">{{cite journal | url=http://jag.igr.poznan.pl/2004-Volume-45/3/abstracts/210.html | first=Jerzy | last=Chelkowski |author2=Tyrka, Miroslaw | title=Enhancing the resistance of triticale by using genes from wheat and rye | journal=Journal of Applied Genetics| volume=45 | issue=3 | pages=283–295 | date=15 October 2003 | pmid=15306719}}</ref> Molecular markers (small lengths of [[DNA]] of a characterized/known sequence) are used to 'tag' and thus track such translocations.<ref name="Lee">{{cite journal | first=T. G. | last=Lee |author2=Hong, M. J. |author3=Johnson, J. W. |author4=Bland, D. E. |author5=Kim, D. Y. |author6= Seo, Y. W. | title=Development and functional assessment of EST-derived 2RL-specific markers for 2BS.2RL translocations | journal=Theoretical and Applied Genetics| volume=119 | issue=4 | pages=663–673 | year=2009 | doi =10.1007/s00122-009-1077-3|pmid = 19543880| s2cid=22773590}}</ref> A weak [[colchicine]] solution has been employed to increase the probability of recombination in the proximal chromosome regions, and thus the introduction of the translocation to that region. The resultant translocation of smaller blocks that indeed carry the R-gene(s) of interest has decreased the probability of introducing unwanted genes.<ref name="Lukaszewski">{{cite journal | url=http://crop.scijournals.org/cgi/content/abstract/30/5/1151 | first=Adam | last=Lukaszewski | title=Frequency of 1RS.1AL and 1RS.1BL Translocations in United States Wheats | journal=[[Crop Science (journal)|Crop Science]]| volume=30 | issue=5 | pages=1151–1153 | year=1990 | doi=10.2135/cropsci1990.0011183X003000050041x | url-access=subscription }}{{Dead link|date=February 2020 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

The ''{{ Visible anchor |Sr59}}'' [[crop disease resistance gene|resistance gene]] was introgressed into wheat from the [[2R chromosome]] of [[rye]].<ref name="Sc-to-Ta" /> However this was actually done ''through'' triticale.<ref name="Sc-to-Ta" /> Triticale has been the [[amphiploid]] for several such rye{{NBSP}}⇨{{NBSP}}wheat introgressions.<ref name="Sc-to-Ta">
 {{ Cite journal
 | last3=Åhman | first3=Inger
 | last2=Gustavsson | first2=Larisa
 | last1=Herrera | first1=Leonardo
 | year=2017
 | title=A systematic review of rye (''Secale cereale'' L.) as a source of resistance to pathogens and pests in wheat (''Triticum aestivum'' L.)
 | volume=154
 | issue=1
 | pages=1–9
 | publisher=[[BioMed Central]]
 | issn=1601-5223
 | journal=[[Hereditas]]
 | doi=10.1186/s41065-017-0033-5
 | pmid=28559761
 | pmc=5445327
| doi-access=free
 }}</ref>

A 2014 study found that ''{{Vanchor|Ddw1}}'' [[dwarfing]] gene from the [[rye 5R chromosome]] also provides [[Fusarium head blight]] (FHB) resistance in this host.<ref name="Height">{{cite book|year=2019|publisher=[[Springer Nature]]|first3=Dennis|pages=363+420|first2=Shri|first1=Jameel|last1=Al-Khayri|last2=Jain|last3=Johnson|isbn=978-3-030-23108-8|title=Advances in Plant Breeding Strategies: Cereals}}</ref><ref>{{cite journal|issue=7|year=2014|first4=Thomas|first3=Bernd|first2=Hans|first1=Rasha|last4=Miedaner|last3=Hackauf|last2=Maurer|last1=Kalih|pages=1527–1536|volume=127|journal=Theoretical and Applied Genetics |issn=0040-5752|s2cid=14913718|pmid=24852306|doi=10.1007/s00122-014-2316-9|title=Effect of a rye dwarfing gene on plant height, heading stage, and Fusarium head blight in triticale (×''Triticosecale'' Wittmack)}}</ref>

===Production of doubled haploids===

[[Doubled haploidy |Doubled haploid]] (DH) plants have the potential to save much time in the development of [[inbred]] lines. This is achieved in a single generation, as opposed to many, which would otherwise occupy much physical space/facilities. DHs also express deleterious recessive [[alleles]] otherwise masked by dominance effects in a genome containing more than one copy of each chromosome (and thus more than one copy of each gene). Various techniques exist to create DHs. The ''in vitro'' culture of [[anthers]] and [[microspore]]s is most often used in [[cereals]], including triticale.<ref name="Bernard">{{cite journal |year=2009 |issue=6 |first4=Kadambot |first3=Ian |first2=Heather |first1=Maya |last4=Siddique |last3=Small |last2=Clarke |last1=Kumari |pages=393–409 |volume=28 |s2cid=85298264 |doi=10.1080/07352680903133252 |journal=Critical Reviews in Plant Sciences |title=Albinism in Plants: A Major Bottleneck in Wide Hybridization, Androgenesis and Doubled Haploid Culture |bibcode=2009CRvPS..28..393K}}</ref><ref>{{cite journal |year=1984 |first1=S. |last1=Bernard |last2=Charmet |first2=G. |title=Diallel analysis of androgenetic plant production in hexaploid Triticale (''X. triticosecale'', Wittmack) |journal=Theoretical and Applied Genetics |volume=69 |issue=1 |pages=55–61 |doi=10.1007/BF00262539 |pmid=24253624 |s2cid=37533199 |doi-access=free}}</ref><ref name="González">{{cite journal |url=http://www.fao.org/agris/search/display.do?f=./2000/v2609/HU2000000254.xml;HU2000000254 |first1=J. M. |last1=González |last2=Jouve |first2=N. |title=Improvement of Anther Culture Media for Haploid Production in Triticale |journal=Cereal Research Communications |volume=28 |issue=1–2 |pages=65–72 |year=2000 |doi=10.1007/BF03543575 |url-access=subscription }}{{Dead link |date=December 2021 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name="González1997">{{cite journal |first1=J. M. |last1=González |last2=Jouve |first2=N. |last3=Hernádez |first3=I. |title=Analysis of anther culture response in hexaploid triticale |journal=Plant Breeding |volume=116 |issue=3 |pages=301–304 |date=January 18, 1997 |doi=10.1111/j.1439-0523.1997.tb01003.x |doi-access=free }}</ref> These two techniques are referred to as androgenesis, which refers to the development of [[pollen]]. Many plant species and [[cultivars]] within species, including triticale, are recalcitrant in that the success rate of achieving whole newly generated (diploid) plants is very low. Genotype by culture medium interaction is responsible for varying success rates, as is a high degree of microspore abortion during culturing.<ref name= "Development-Androgenesis" >{{ Cite book |year=2009 |edition=1st |volume=3 |location=New York |publisher=Springer-Verlag |pages=|first=Marcelo |last=Carena |editor-first1=Marcelo J. |editor-last1=Carena |doi=10.1007/978-0-387-72297-9 |isbn=978-0-387-72294-8 |title=Cereals |series=Handbook of Plant Breeding |oclc=405546128 }}</ref><ref>{{ Cite journal |last1=González |first1=J. M. |last2=Jouve |first2=N. |year=2005 |title=Microspore development during in vitro androgenesis in triticale |volume=49 |issue=1 |pages=23–28 |journal=Biologia Plantarum |s2cid=35661525 |doi=10.1007/s10535-005-3028-4 |doi-access=free }}</ref><ref name="Stresses-Re-Programming">{{cite journal |last1=Shariatpanahi |first1=Mehran E. |last2=Bal |first2=Ugur |last3=Heberle-Bors |first3=Erwin |last4=Touraev |first4=Alisher |title=Stresses applied for the re-programming of plant microspores towards in vitro embryogenesis |journal=Physiologia Plantarum |publisher=John Wiley & Sons |volume=127 |issue=4 |year=2006 |doi=10.1111/j.1399-3054.2006.00675.x |pages=519–534 |s2cid=84771294 |doi-access=free}}</ref><ref>{{cite journal |last1=Tuvesson |first1=S. |last2=Ljungberg |first2=A. |last3=Johansson |first3=N. |last4=Karlsson |first4=K.-E. |last5=Suijs |first5=L. W. |last6=Josset |first6=J.-P. |title=Large-scale production of wheat and triticale double haploids through the use of a single-anther culture method |journal=Plant Breeding |publisher=Wiley-VCH GmbH |volume=119 |issue=6 |year=2000 |doi=10.1046/j.1439-0523.2000.00536.x |pages=455–459 |s2cid=84991814}}
</ref> The response of parental triticale lines to [[anther]] culture is known to be correlated to the response of their progeny.<ref name="González1997"/><ref name="Konzak">{{cite journal |url=http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=eng&journal=gen&volume=35&year=1992&issue=6&msno=g92-146 |first1=Calvin |last1=Konzak |last2=Zhou |first2=Huaping |title=Genetic control of green plant regeneration from anther culture of wheat |journal=[[Genome (journal) |Genome]] |volume=35 |issue=6 |pages=957–961 |date=1 December 1992 |doi=10.1139/g92-146 |url-access=subscription }}{{Dead link |date=February 2020 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name="Anderson">{{cite journal |first1=S. B. |last1=Andersen |last2=Tuvesson |first2=I. K. D. |last3=Pedersen |first3=S. |title=Nuclear genes affecting albinism in wheat (''Triticum aestivum'' L.) anther culture |journal=Theoretical and Applied Genetics |volume=78 |issue=6 / December, 1989 |pages=879–889 |date=9 August 1989 |doi=10.1007/BF00266675 |pmid=24226023 |s2cid=9686842 }}</ref> Chromosome elimination is another method of producing DHs, and involves [[Hybrid (biology) |hybridisation]] of wheat with [[maize]] (''Zea mays'' L.), followed by [[auxin]] treatment and the artificial rescue of the resultant haploid embryos before they naturally abort. This technique is applied rather extensively to wheat.<ref name="Bennett2">{{cite conference |first1=M. D. |last1=Bennett |last2=Laurie |first2=D. A. |last3=O'Donoughue |first3=L. S. |title=Wheat x maize and other wide sexual hybrids: their potential for crop improvement and genetic manipulations |book-title=Gene Manipulation in Plant Improvement II: Proceedings of the 19th Stadler Genetics Symposium |pages=95–126 |publisher=[[Plenum Press]] |date=13–15 March 1989 |location=New York}}</ref> Its success is in large part due to the insensitivity of maize pollen to the crossability inhibitor genes known as Kr1 and Kr2 that are expressed in the floral style of many wheat cultivars.<ref name="Bennett">{{cite journal |first1=M. D. |last1=Bennett |last2=Laurie |first2=D. A. |title=The effect of the crossability loci ''Kr1'' and ''Kr2'' on fertilization frequency in hexaploid wheat x maize crosses |journal=[[Theoretical and Applied Genetics]] |volume=73 |issue=3 / January, 1987
 |pages=403–409 |date=31 August 1986 |doi=10.1007/BF00262508 |pmid=24241002 |s2cid=7530770 }}</ref> The technique is unfortunately less successful in triticale.<ref name="Marcinska">{{cite journal |url=http://www3.interscience.wiley.com/journal/119118108/abstract |archive-url=https://archive.today/20121015184323/http://www3.interscience.wiley.com/journal/119118108/abstract |url-status=dead |archive-date=15 October 2012 |first1=I. |last1=Marcińska |last2=Wodzony |first2=M. |last3=Ponitka |first3=A. |last4=Ślusarkiewicz-Jarzina |first4=A. |last5=Woźna |first5=J. |title=Production of doubled haploids in triticale (×Triticosecale Wittm.) by means of crosses with maize (Zea mays L.) using picloram and dicamba |journal=Plant Breeding |volume=117 |issue=3 |pages=211–215 |date=26 January 1998 |doi=10.1111/j.1439-0523.1998.tb01928.x|url-access=subscription }}</ref> However, ''[[Imperata cylindrica]]'' (a grass) was found to be just as effective as [[maize]] with respect to the production of DHs in both [[wheat]] and triticale.<ref name="Chaudhary">{{cite journal |url=http://www3.interscience.wiley.com/journal/118695340/abstract |archive-url=https://archive.today/20130105072243/http://www3.interscience.wiley.com/journal/118695340/abstract |url-status=dead |archive-date=January 5, 2013 |first1=H. K. |last1=Chaudhary |last2=Pratap |first2=A. |last3=Sethi |first3=G. S. |title=Relative efficiency of different Gramineae genera for haploid induction in triticale and triticale x wheat hybrids through the chromosome elimination technique |journal=Plant Breeding |volume=124 |issue=2 / April, 2005 |pages=147–153 |date=August 16, 2004 |doi=10.1111/j.1439-0523.2004.01059.x|url-access=subscription }}</ref>

===Application of molecular markers===
An important advantage of [[biotechnology]] applied to plant breeding is the speeding up of cultivar release that would otherwise take 8–12 years. It is the process of [[Selection (biology)|selection]] that is actually enhanced, i.e., retaining that which is desirable or promising and ridding that which is not. This carries with it the aim of changing the genetic structure of the plant population. The website [https://web.archive.org/web/20071018151244/http://maswheat.ucdavis.edu/protocols/protocols.htm] is a valuable resource for [[marker assisted selection]] (MAS) protocols relating to R-genes in wheat. MAS is a form of indirect [[Selection (biology)|selection]]. The Catalogue of Gene Symbols mentioned earlier is an additional source of [[molecular]] and morphological markers. Again, triticale has not been well characterised with respect to molecular markers, although an abundance of rye molecular markers makes it possible to track rye chromosomes and segments thereof within a triticale background.{{Citation needed|date=June 2021}}

Yield improvements of up to 20% have been achieved in hybrid triticale cultivars due to [[heterosis]].<!-- Góral 2002; --><ref name="Góral">{{cite journal | url=http://www.ihar.edu.pl/biblioteka/plant_breeding_and_seed_science.php | first=H. | last=Góral | title=Heterosis and Combining Ability in Spring Triticale (x ''Triticosecale'', Wittm.) | journal=Plant Breeding and Seed Science| volume=43 | pages=25–34 | year=1999 | display-authors=etal | access-date=2009-06-22 | archive-date=2009-04-23 | archive-url=https://web.archive.org/web/20090423081215/http://www.ihar.edu.pl/biblioteka/plant_breeding_and_seed_science.php | url-status=dead }}</ref><ref name="Becker">{{cite journal | url=http://www3.interscience.wiley.com/journal/118988062/abstract?CRETRY=1&SRETRY=0 | archive-url=https://archive.today/20130105075608/http://www3.interscience.wiley.com/journal/118988062/abstract?CRETRY=1&SRETRY=0 | url-status=dead | archive-date=January 5, 2013|first1=H. C.|last1=Becker|last2=Oettler|first2=G.|last3=Hoppe|first3=G.|title=Heterosis for yield and other agronomic traits of winter triticale F<sub>1</sub> and F<sub>2</sub> hybrids | journal=Plant Breeding| volume=120 | issue=4 | pages=351–353 | date= March 8, 2001 | doi=10.1046/j.1439-0523.2001.00624.x| url-access=subscription}}</ref><ref name="Burger">{{cite journal | url=http://www3.interscience.wiley.com/journal/118879174/abstract | archive-url=https://archive.today/20121015184111/http://www3.interscience.wiley.com/journal/118879174/abstract | url-status=dead | archive-date=2012-10-15 | first=H. | last=Burger |author2=Oettler, G. |author3=Melchinger, A. E. | title=Heterosis and combining ability for grain yield and other agronomic traits in winter triticale | journal=Plant Breeding| volume=122 | issue=4 | pages=318–321 | date= August 2003 | doi=10.1046/j.1439-0523.2003.00877.x| url-access=subscription }}</ref> This raises the question of what inbred lines should be crossed (to produce hybrids) with each other as parents to maximize yield in their hybrid progeny. This is termed the 'combining ability' of the parental lines. The identification of good combining ability at an early stage in the breeding programme can reduce the costs associated with 'carrying' a large number of plants (literally thousands) through it, and thus forms part of efficient selection. Combining ability is assessed by taking into consideration all available information on [[Common descent|descent]] ([[Genetics|genetic]] relatedness), [[Morphology (biology)|morphology]], qualitative (simply inherited) traits and [[biochemical]] and molecular markers. Exceptionally little information exists on the use of molecular markers to predict heterosis in triticale.<ref name="Góral2005">{{cite journal | url=http://jag.igr.poznan.pl/2005-Volume-46/2/abstracts/259.html | first=Halina | last=Góral |author2=Tyrka, Miroslaw |author3=Spiss, Ludwik | title=Assessing genetic variation to predict the breeding value of winter triticale cultivars and lines | journal=Journal of Applied Genetics | volume=46 | issue=2 |pages=125–131 | date=2 March 2005 | pmid=15876679}}</ref> Molecular markers are generally accepted as better predictors than morphological markers (of [[agronomy|agronomic]] traits) due to their insensitivity to variation in environmental conditions.{{Citation needed|date=June 2021}}

A useful molecular marker known as a [[Short tandem repeat|simple sequence repeat]] (SSR) is used in breeding with respect to selection. SSRs are segments of a genome composed of [[Variable number tandem repeat|tandem repeats]] of a short sequence of [[nucleotides]], usually two to six [[base pair]]s. They are popular tools in genetics and breeding because of their relative abundance compared to other marker types, a high degree of polymorphism (number of variants), and easy assaying by polymerase chain reaction. However, they are expensive to identify and develop. Comparative genome mapping has revealed a high degree of similarity in terms of sequence colinearity between closely related crop species. This allows the exchange of such markers within a group of related species, such as wheat, rye and triticale. One study established a 58% and 39% transferability rate to triticale from wheat and rye, respectively.<ref name="Baenziger">{{cite journal | first=P. S. | last=Baenziger |author2=Kuleung, C. |author3=Dweikat I. | title=Transferability of SSR markers among wheat, rye, and triticale | journal=Theoretical and Applied Genetics| volume=108 | issue=6 / April, 2004 | pages=1147–1150 | date=5 December 2003 | doi=10.1007/s00122-003-1532-5 | pmid=15067402| s2cid=20537650 }}</ref> Transferability refers to the phenomenon where the sequence of DNA nucleotides flanking the SSR locus (position on the [[chromosome]]) is sufficiently homologous (similar) between genomes of closely related species. Thus, DNA primers (generally, a short sequence of nucleotides used to direct the copying reaction during PCR) designed for one species can be used to detect SSRs in related species. SSR markers are available in wheat and rye, but very few, if any, are available for triticale.<ref name="Baenziger"/>

===Genetic transformation===
The [[genetic transformation]] of crops involves the incorporation of 'foreign' genes or, rather, very small DNA fragments compared to introgression discussed earlier. Amongst other uses, transformation is a useful tool to introduce new traits or characteristics into the transformed crop. Two methods are commonly employed: infectious [[bacteria]]l-mediated (usually ''[[Agrobacterium]]'') transfer and [[biolistics]], with the latter being most commonly applied to [[allopolyploid]] cereals such as triticale. ''Agrobacterium''-mediated transformation, however, holds several advantages, such as a low level of DNA rearrangement in the [[transgenic]] plant, a low number of introduced copies of the transforming DNA, stable integration of an a-priori characterized T-DNA fragment (containing the DNA expressing the trait of interest) and an expected higher level of [[transgene]] expression. Triticale has, until recently, only been transformed via biolistics, with a 3.3% success rate.<ref name="Zimny">{{cite journal | first=J. | last=Zimny |author2=Becker, D. |author3=Brettschneider, R. |author4=Lörz, H. | title=Fertile, transgenic Triticale (''×Triticosecale'' Wittmack) | journal=Molecular Breeding | volume=1 | issue=2 | pages=155–164 | date=10 October 1994 | doi=10.1007/BF01249700| s2cid=27470553 }}</ref> Little has been documented on ''Agrobacterium''-mediated transformation of wheat: while no data existed with respect to triticale until 2005, the success rate in later work was nevertheless low.<ref name="Binka">{{cite journal | first=A. | last=Binka |author2=Nadolska-Orczyk, A. |author3=Przetakiewicz, A. |author4=Kopera, K. |author5=Orczyk, W. | title=Efficient Method of Agrobacterium-mediated Transformation for Triticale (x Triticosecale Wittmack) | journal=Journal of Plant Growth Regulation| volume=24 | issue=1 / March, 2005 | pages=2–10 | date=28 July 2005 | doi=10.1007/s00344-004-0046-y| s2cid=22996555 }}</ref>