Cytokinin

Not to be confused with Cytokine, a class of small proteins important in cell signaling.
The cytokinin zeatin is named after the genus of corn, Zea.

Cytokinins (CK) are a class of plant hormones that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence.

There are two types of cytokinins: adenine-type cytokinins represented by kinetin, zeatin, and 6-benzylaminopurine, and phenylurea-type cytokinins like diphenylurea and thidiazuron (TDZ).[1] Most adenine-type cytokinins are synthesized in roots.[2] Cambium and other actively dividing tissues also synthesize cytokinins.[3] No phenylurea cytokinins have been found in plants.[4] Cytokinins participate in local and long-distance signalling, with the same transport mechanism as purines and nucleosides.[5] Typically, cytokinins are transported in the xylem.[2]

Cytokinins act in concert with auxin, another plant growth hormone. The two are complementary,[6] [7] having generally opposite effects.[2]

  1. ^ Aina O, Quesenberry K, Gallo M (2012). "Thidiazuron-Induced Tissue Culture Regeneration from Quartered-Seed Explants of Arachis paraguariensis". Crop Science. 52 (3): 555. doi:10.2135/cropsci2011.07.0367. S2CID 82510749.
  2. ^ a b c Campbell NA, Reece JB, Urry LA, Cain ML, Wasserman SA, Minorsky PV, Jackson RB (2008). Biology (8th ed.). San Francisco: Pearson, Benjamin Cummings. pp. 827–30. ISBN 978-0-555-03883-3.
  3. ^ Chen CM, Ertl JR, Leisner SM, Chang CC (July 1985). "Localization of cytokinin biosynthetic sites in pea plants and carrot roots". Plant Physiology. 78 (3): 510–513. doi:10.1104/pp.78.3.510. PMC 1064767. PMID 16664274.
  4. ^ Mok DW, Mok MC (June 2001). "Cytokinin Metabolism and Action". Annual Review of Plant Physiology and Plant Molecular Biology. 52 (1): 89–118. doi:10.1146/annurev.arplant.52.1.89. PMID 11337393.
  5. ^ Sakakibara H (2006). "Cytokinins: activity, biosynthesis, and translocation". Annual Review of Plant Biology. 57 (1): 431–449. doi:10.1146/annurev.arplant.57.032905.105231. PMID 16669769. S2CID 25584314.
  6. ^ Schaller GE, Bishopp A, Kieber JJ (January 2015). "The yin-yang of hormones: cytokinin and auxin interactions in plant development". The Plant Cell. 27 (1): 44–63. doi:10.1105/tpc.114.133595. PMC 4330578. PMID 25604447.
  7. ^ Großkinsky DK, Petrášek J (February 2019). "Auxins and cytokinins - the dynamic duo of growth-regulating phytohormones heading for new shores". The New Phytologist. 221 (3): 1187–1190. doi:10.1111/nph.15556. PMID 30644580.