Editing Triticale (section)

===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"/>