title: Cytokinin receptors are involved in alkamide regulation of root and shoot development in Arabidopsis.
abstract: Alkamides and N-acilethanolamides are a class of lipid compounds related to animal endocannabinoids of wide distribution in plants. We investigated the structural features required for alkamides to regulate plant development by comparing the root responses of Arabidopsis (Arabidopsis thaliana) seedlings to a range of natural and synthetic compounds. The length of the acyl chain and the amide moiety were found to play a crucial role in their biological activity. From the different compounds tested, N-isobutyl decanamide, a small saturated alkamide, was found to be the most active in regulating primary root growth and lateral root formation. Proliferative-promoting activity of alkamide treatment was evidenced by formation of callus-like structures in primary roots, ectopic blades along petioles of rosette leaves, and disorganized tumorous tissue originating from the leaf lamina. Ectopic organ formation by N-isobutyl decanamide treatment was related to altered expression of the cell division marker CycB1:uidA and an enhanced expression of the cytokinin-inducible marker ARR5:uidA both in roots and in shoots. The involvement of cytokinins in mediating the observed activity of alkamides was tested using Arabidopsis mutants lacking one, two, or three of the putative cytokinin receptors CRE1, AHK2, and AHK3. The triple cytokinin receptor mutant was insensitive to N-isobutyl decanamide treatment, showing absence of callus-like structures in roots, the lack of lateral root proliferation, and absence of ectopic outgrowths in leaves under elevated levels of this alkamide. Taken together our results suggest that alkamides and N-acylethanolamides may belong to a class of endogenous signaling compounds that interact with a cytokinin-signaling pathway to control meristematic activity and differentiation processes during plant development.
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, CP 58030 Morelia, Michoacan, Mexico. jbucio@zeus.umich.mx
authors.forename: José
authors.initials: J
authors.lastname: López-Bucio
authors.forename: Mayra
authors.initials: M
authors.lastname: Millán-Godínez
authors.forename: Alfonso
authors.initials: A
authors.lastname: Méndez-Bravo
authors.forename: Alina
authors.initials: A
authors.lastname: Morquecho-Contreras
authors.forename: Enrique
authors.initials: E
authors.lastname: Ramírez-Chávez
authors.forename: Jorge
authors.initials: J
authors.lastname: Molina-Torres
authors.forename: Anahí
authors.initials: A
authors.lastname: Pérez-Torres
authors.forename: Masayuki
authors.initials: M
authors.lastname: Higuchi
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Kakimoto
authors.forename: Luis
authors.initials: L
authors.lastname: Herrera-Estrella
mesh_terms: D000473:Alkanes / Q000378:metabolism*; D000577:Amides / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D049109:Cell Proliferation; D003583:Cytokinins / Q000378:metabolism*; D015870:Gene Expression; D009154:Mutation; D018517:Plant Roots / Q000254:growth & development* / Q000378:metabolism; D018520:Plant Shoots / Q000254:growth & development* / Q000378:metabolism; D053284:Polyunsaturated Alkamides / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D000473:Alkanes; D000577:Amides; D003583:Cytokinins; C489346:N-isobutyl-decanamide; D053284:Polyunsaturated Alkamides