Editing Salicylic acid (section)

==Plant hormone==
Salicylic acid  is a [[natural phenol|phenolic]] [[phytohormone]], and is found in plants with roles in plant growth and development, [[photosynthesis]], [[transpiration]], and [[ion]] uptake and transport.<ref name="Vlot-et-al-2009">{{cite journal | vauthors = Vlot AC, Dempsey DA, Klessig DF | title = Salicylic Acid, a multifaceted hormone to combat disease | journal = Annual Review of Phytopathology | volume = 47 | pages = 177–206 | year = 2009 | pmid = 19400653 | doi = 10.1146/annurev.phyto.050908.135202 | doi-access =  }}</ref> Salicylic acid is involved in [[endogenous]] signaling, mediating plant defense against [[pathogens]].<ref>{{cite book | title = Salicylic Acid – A Plant Hormone | author1 = Hayat, S. | author2 = Ahmad, A. | isbn = 978-1-4020-5183-8 | year = 2007 | publisher = [[Springer Science+Business Media|Springer]] | url-access = registration | url = https://archive.org/details/salicylicacidpla0000unse }}</ref> It plays a role in the resistance to pathogens (i.e. [[systemic acquired resistance]]) by inducing the production of [[pathogenesis-related protein]]s and other defensive metabolites.<ref>{{cite journal|doi=10.1099/0022-1317-67-10-2135 |title=Induction by Salicylic Acid of Pathogenesis-related Proteins or Resistance to Alfalfa Mosaic Virus Infection in Various Plant Species|year=1986| vauthors = Hooft Van Huijsduijnen RA, Alblas SW, De Rijk RH, Bol JF |journal=[[Journal of General Virology]]|volume=67|issue=10|pages=2135–2143|doi-access=free}}</ref> SA's defense signaling role is most clearly demonstrated by experiments which do away with it: Delaney et al. 1994, Gaffney et al. 1993, Lawton et al. 1995, and Vernooij et al. 1994 each use ''[[Nicotiana tabacum]]'' or ''[[Arabidopsis thaliana|Arabidopsis]]'' expressing ''[[nahG]]'', for [[salicylate hydroxylase]]. Pathogen inoculation did not produce the customarily high SA levels, SAR was not produced, and no [[Pathogenesis-related protein|pathogenesis-related]] (PR) genes were [[gene expression|expressed]] in systemic leaves. Indeed, the subjects were more susceptible to virulent {{endash}} and even normally avirulent {{endash}} pathogens.<ref name="Vlot-et-al-2009" />

[[Exogeny|Exogenously]], salicylic acid can aid plant development via enhanced seed germination, bud flowering, and fruit ripening, though too high of a concentration of salicylic acid can negatively regulate these developmental processes.<ref>{{cite journal | vauthors = Koo YM, Heo AY, Choi HW | title = Salicylic Acid as a Safe Plant Protector and Growth Regulator | journal = The Plant Pathology Journal | volume = 36 | issue = 1 | pages = 1–10 | date = February 2020 | pmid = 32089657 | pmc = 7012573 | doi = 10.5423/PPJ.RW.12.2019.0295 }}</ref>

The volatile methyl ester of salicylic acid, [[methyl salicylate]], can also diffuse through the air, facilitating plant-[[plant communication]].<ref name="Taiz-Zeiger-2002">{{cite book | vauthors = Taiz L, Zeiger E | title=Plant physiology | publisher=Sinauer Associates | publication-place=Sunderland, Mass | year=2002 | isbn=0-87893-823-0 | oclc=50002466 | page=306 | archive-url=https://web.archive.org/web/20140305085915/http://www.scribd.com/doc/87221186/Plant-Physiology-3rd-Edition-Taiz-amp-Zeiger-2002 | archive-date=2014-03-05 | url=http://www.scribd.com/doc/87221186/Plant-Physiology-3rd-Edition-Taiz-amp-Zeiger-2002}}</ref> Methyl salicylate is taken up by the [[stomata]] of the nearby plant, where it can induce an immune response after being converted back to salicylic acid.<ref name="Chamovitz-2012">{{cite book | vauthors = Chamovitz D | title=What A Plant Knows - A Field Guide to the Senses of your Garden - and Beyond | publisher=Oneworld | publication-place=Oxford, England | year=2012 | isbn=978-1-85168-910-1 | oclc=775030365}}</ref>

=== Signal transduction ===
A number of proteins have been identified that interact with SA in plants, especially salicylic acid binding proteins (SABPs) and the NPR genes (nonexpressor of pathogenesis-related genes), which are putative receptors.<ref>Kumar, D. 2014. Salicylic acid signaling in disease resistance. Plant Science 228:127–134.</ref>