Editing Plant hormone (section)

===Cytokinins===
[[File:Zeatin.png|thumb|150px|[[Zeatin]], a cytokinin]]
[[Cytokinin]]s (CKs) are a group of chemicals that influence cell division and shoot formation. They also help delay [[senescence]] of tissues, are responsible for mediating auxin transport throughout the plant, and affect internodal length and leaf growth. They were called kinins in the past when they were first isolated from [[yeast]] cells. Cytokinins and auxins often work together, and the ratios of these two groups of plant hormones affect most major growth periods during a plant's lifetime. Cytokinins counter the apical dominance induced by auxins; in conjunction with ethylene, they promote abscission of leaves, flower parts, and fruits.<ref>
{{cite journal |vauthors=Sipes DL, Einset JW |title=Cytokinin stimulation of abscission in lemon pistil explants |journal=J Plant Growth Regul |volume=2 |issue=1–3 |pages=73–80 |date=August 1983 |doi=10.1007/BF02042235 |s2cid=43997977 }}</ref>

Among the plant hormones, the three that are known to help with immunological interactions are ethylene (ET), salicylates (SA), and jasmonates (JA), however more research has gone into identifying the role that cytokinins play in this. Evidence suggests that cytokinins delay the interactions with pathogens, showing signs that they could induce resistance toward these pathogenic bacteria. Accordingly, there are higher CK levels in plants that have increased resistance to pathogens compared to those which are more susceptible.<ref>{{cite journal | vauthors = Akhtar SS, Mekureyaw MF, Pandey C, Roitsch T | title = Role of Cytokinins for Interactions of Plants With Microbial Pathogens and Pest Insects | language = English | journal = Frontiers in Plant Science | volume = 10 | pages = 1777 | date = 2020 | pmid = 32140160 | doi = 10.3389/fpls.2019.01777 | pmc = 7042306 | doi-access = free }}</ref> For example, pathogen resistance involving cytokinins was tested using the ''Arabidopsis'' species by treating them with naturally occurring CK (trans-zeatin) to see their response to the bacteria ''Pseudomonas syringa''. Tobacco studies reveal that over expression of CK inducing IPT genes yields increased resistance whereas over expression of CK oxidase yields increased susceptibility to pathogen, namely ''P. syringae''.

While there’s not much of a relationship between this hormone and physical plant behavior, there are behavioral changes that go on inside the plant in response to it.  Cytokinin defense effects can include the establishment and growth of microbes (delay leaf senescence), reconfiguration of secondary metabolism or even induce the production of new organs such as galls or nodules.<ref>{{cite web|title=Cytokinin - an overview {{!}} ScienceDirect Topics|url=https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/cytokinin#:~:text=Cytokinins%20are%20essential%20plant%20hormones,bud%20release%20from%20apical%20dominance|access-date=2021-06-10|website=www.sciencedirect.com}}</ref> These organs and their corresponding processes are all used to protect the plants against biotic/abiotic factors.