Editing Vernalization (section)

==History of vernalization research==
In the [[history of agriculture]], farmers observed a traditional distinction between "winter cereals", whose seeds require chilling (to trigger their subsequent emergence and growth), and "spring cereals", whose seeds can be sown in spring, and germinate, and then flower soon thereafter. Scientists in the early 19th century had discussed how some plants needed cold temperatures to flower. In 1857 an American agriculturist [[John Hancock Klippart]], Secretary of the Ohio Board of Agriculture, reported the importance and effect of winter temperature on the germination of wheat. One of the most significant works was by a German plant physiologist [[Gustav Gassner]] who made a detailed discussion in his 1918 paper. Gassner was the first to systematically differentiate the specific requirements of winter plants from those of summer plants, and also that early swollen germinating seeds of winter cereals are sensitive to cold.<ref>{{cite journal |last1=Chouard |first1=P. |date=1960 |title=Vernalization and its Relations to Dormancy |journal=Annual Review of Plant Physiology |volume=11 |issue=1 |pages=191–238 |doi=10.1146/annurev.pp.11.060160.001203}}</ref>

In 1928, the Soviet agronomist [[Trofim Lysenko]] published his works on the effects of cold on cereal seeds, and coined the term "яровизация" (''yarovizatsiya'' : "jarovization") to describe a chilling process he used to make the seeds of winter cereals behave like spring cereals (from яровой : ''yarvoy'', Tatar root ярый : ''[[Yarilo#Etymology|yaryiy]]'' meaning ardent, fiery, associated with the god of spring). Lysenko himself translated the term into "vernalization" (from the Latin ''vernum'' meaning Spring). After Lysenko the term was used to explain the ability of flowering in some plants after a period of chilling due to physiological changes and external factors. The formal definition was given in 1960 by a French botanist P. Chouard, as "the acquisition or acceleration of the ability to flower by a chilling treatment."<ref>{{cite book |last1=Poltronieri |first1=Palmiro |last2=Hong |first2=Yiguo |title=Applied Plant Genomics and Biotechnology |date=2015 |publisher=Woodhead Publishing |location=Cambridge (UK) |isbn=978-0-08-100068-7 |page=121 |url=https://books.google.com/books?id=tMIcBAAAQBAJ}}</ref>

Lysenko's 1928 paper on vernalization and [[plant physiology]] drew wide attention due to its practical consequences for Russian agriculture. Severe cold and lack of winter snow had destroyed many early winter wheat seedlings. By treating wheat seeds with moisture as well as cold, Lysenko induced them to bear a crop when planted in spring.<ref name="lysenkosci">{{cite journal |last1=Roll-Hansen |first1=Nils |year=1985 |title=A new perspective on Lysenko? |journal=[[Annals of Science]] |publisher=Taylor & Francis |volume=42 |issue=3 |pages=261–278 |doi=10.1080/00033798500200201 |pmid=11620694}}</ref> Later however, according to Richard Amasino, Lysenko inaccurately asserted that the vernalized state could be inherited, i.e. the offspring of a vernalized plant would behave as if they themselves had also been vernalized and would not require vernalization in order to flower quickly.<ref name="amasino">{{cite journal |last1=Amasino |first1=R. |date=2004 |title=Vernalization, Competence, and the Epigenetic Memory of Winter |journal=The Plant Cell |volume=16 |issue=10 |pages=2553–2559 |doi=10.1105/tpc.104.161070 |pmc=520954 |pmid=15466409|bibcode=2004PlanC..16.2553A }}</ref> Opposing this view and supporting Lysenko's claim, Xiuju Li and Yongsheng Liu have detailed experimental evidence from the USSR, Hungary, Bulgaria and China that shows the conversion between spring wheat and winter wheat, positing that "it is not unreasonable to postulate [[Epigenetics|epigenetic mechanisms]] that could plausibly result in the conversion of spring to winter wheat or vice versa."<ref>{{Cite journal|last1=Li|first1=Xiuju|last2=Liu|first2=Yongsheng|date=2010-05-06|title=The conversion of spring wheat into winter wheat and vice versa: false claim or Lamarckian inheritance?|url=http://link.springer.com/10.1007/s12038-010-0035-1|journal=Journal of Biosciences|language=en|volume=35|issue=2|pages=321–325|doi=10.1007/s12038-010-0035-1|pmid=20689187|s2cid=10527354|issn=0250-5991|url-access=subscription}}</ref>

Early research on vernalization focused on plant physiology; the increasing availability of molecular biology has made it possible to unravel its underlying mechanisms.<ref name="amasino"/> For example, a lengthening daylight period (longer days), ''as well as'' cold temperatures are required for winter wheat plants to go from the vegetative to the reproductive state; the three interacting genes are called ''VRN1'', ''VRN2'', and ''FT'' (''VRN3'').<ref name="trevaskis">{{cite journal | first1= Ben |last1=Trevaskis |first2=Megan N. |last2=Hemming |first3=Elizabeth S. |last3=Dennis |date=August 2007 | title=The molecular basis of vernalization-induced flowering in cereals | journal=Trends in Plant Science | volume=12 | pmid=17629542 | issue=8 | pages=352–357 | publisher=Elsevier | doi=10.1016/j.tplants.2007.06.010|bibcode=2007TPS....12..352T }}</ref>