Editing Plant hormone (section)

===Auxins===
[[File:Indol-3-ylacetic acid.svg|thumb|right|155px|The auxin, indole-3-acetic acid]]
[[Auxin]]s are compounds that positively influence cell enlargement, bud formation, and root initiation. They also promote the production of other hormones and, in conjunction with [[cytokinin]]s, control the growth of stems, roots, and fruits, and convert stems into flowers.<ref>{{cite book | vauthors = Osborne DJ, McManus MT |author-link=Daphne J. Osborne |title=Hormones, signals and target cells in plant development |url=https://archive.org/details/hormonessignalst00osbo_0 |url-access=registration |year=2005 |publisher=Cambridge University Press |isbn=978-0-521-33076-3 |page=[https://archive.org/details/hormonessignalst00osbo_0/page/158 158] }}
</ref> Auxins were the first class of growth regulators discovered.
A Dutch Biologist [[Frits Warmolt Went]] first described auxins.<ref>{{cite journal | vauthors = Tomic S, Gabdoulline RR, Kojic-Prodic B, Wade RC | title = Classification of auxin related compounds based on similarity of their interaction fields: Extension to a new set of compounds. | journal = Internet Journal of Chemistry | date = 1998 | volume = 1 | issue = 26 | pages = CP1–U21 }}</ref> They affect cell elongation by altering cell wall plasticity. They stimulate [[Cambium (botany)|cambium]], a subtype of [[meristem]] cells, to divide, and in stems cause [[secondary xylem]] to differentiate.

Auxins act to inhibit the growth of buds lower down the stems in a phenomenon known as [[apical dominance]], and also to promote lateral and [[adventitious root]] development and growth. Leaf abscission is initiated by the growing point of a plant ceasing to produce auxins. Auxins in seeds regulate specific protein synthesis,<ref>{{cite journal | vauthors = Walz A, Park S, Slovin JP, Ludwig-Müller J, Momonoki YS, Cohen JD | title = A gene encoding a protein modified by the phytohormone indoleacetic acid | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 99 | issue = 3 | pages = 1718–23 | date = February 2002 | pmid = 11830675 | pmc = 122257 | doi = 10.1073/pnas.032450399 | bibcode = 2002PNAS...99.1718W | doi-access = free }}</ref> as they develop within the flower after [[pollination]], causing the flower to develop a fruit to contain the developing seeds.

In large concentrations, auxins are often toxic to plants; they are most toxic to [[dicot]]s and less so to [[monocot]]s. Because of this property, [[Chemical synthesis|synthetic]] auxin herbicides including [[2,4-dichlorophenoxyacetic acid]] (2,4-D) and [[2,4,5-trichlorophenoxyacetic acid]] (2,4,5-T) have been developed and used for [[weed]] control by defoliation. Auxins, especially [[1-naphthaleneacetic acid]] (NAA) and [[indole-3-butyric acid]] (IBA), are also commonly applied to stimulate root growth when taking [[Cutting (plant)|cuttings]] of plants. The most common auxin found in plants is [[indole-3-acetic acid]] (IAA).