Alkamides Activate Jasmonic Acid Biosynthesis and Signaling Pathways and Confer Resistance to Botrytis cinerea in Arabidopsis thaliana Alfonso Me´ ndez-Bravo1,2, Carlos Caldero´ n-Va´ zquez2,5, Enrique Ibarra-Laclette2, Javier Raya-Gonza´ lez1, Enrique Ramı´rez-Cha´ vez3, Jorge Molina-Torres3, Angel A. Guevara-Garcı´a4, Jose´ Lo´ pez-Bucio1*, Luis Herrera-Estrella2* 1 Instituto de Investigaciones Qu´ımico-Biol o´gicas, Universidad Michoacana de San Nicola´s de Hidalgo, Morelia, Michoaca´n, Me´xico, 2 Laboratorio Nacional de Gen o´mica para la Biodiversidad, Cinvestav Irapuato, Irapuato, Guanajuato, Me´xico, 3 Departamento de Biotecnolog´ıa y Bioqu´ımica, Unidad Irapuato, Cinvestav, Irapuato, Guanajuato, Me´xico, 4 Instituto de Biotecnolog´ıa-UNAM, Cuernavaca, Morelos, Me´xico, 5 Centro Interdisciplinario de Investigacio´ n para el Desarrollo Integral Regional-IPN, Guasave, Sinaloa, Me´xico Abstract Alkamides are fatty acid amides of wide distribution in plants, structurally related to N-acyl-L-homoserine lactones (AHLs) from Gram-negative bacteria and to N- acylethanolamines (NAEs) from plants and mammals. Global analysis of gene expression changes in Arabidopsis thaliana in response to N-isobutyl decanamide, the most highly active alkamide identified to date, revealed an overrepresentation of defense-responsive transcriptional networks. In particular, genes encoding enzymes for jasmonic acid (JA) biosynthesis increased their expression, which occurred in parallel with JA, nitric oxide (NO) and H2O2 accumulation. The activity of the alkamide to confer resistance against the necrotizing fungus Botrytis cinerea was tested by inoculating Arabidopsis detached leaves with conidiospores and evaluating disease symptoms and fungal proliferation. N-isobutyl decanamide application significantly reduced necrosis caused by the pathogen and inhibited fungal proliferation. Arabidopsis mutants jar1 and coi1 altered in JA signaling and a MAP kinase mutant (mpk6), unlike salicylic acid- (SA) related mutant eds16/sid2-1, were unable to defend from fungal attack even when N-isobutyl decanamide was supplied, indicating that alkamides could modulate some necrotrophic-associated defense responses through JA- dependent and MPK6-regulated signaling pathways. Our results suggest a role of alkamides in plant immunity induction. Citation: Me´ndez-Bravo A, Caldero´ n-Va´zquez C, Ibarra-Laclette E, Raya-Gonza´lez J, Ram´ırez-Cha´vez E, et al. (2011) Alkamides Activate Jasmonic Acid Biosynthesis and Signaling Pathways and Confer Resistance to Botrytis cinerea in Arabidopsis thaliana. PLoS ONE 6(11): e27251. doi:10.1371/journal.pone.0027251 Editor: Michael Freitag, Oregon State University, United States of America Received April 13, 2011; Accepted October 12, 2011; Published November 4, 2011 Copyright: 2011 Me´ndez-Bravo et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported in part by the Consejo Nacional de Ciencia y Tecnolog´ıa (CONACYT C02-43978/330 and 106725), the Coordinacio´ n de la Investigacio´ n Cient´ıfica-UMSNH (CIC 2.26), the Consejo Estatal de Ciencia y Tecnolog´ıa (COECYT), the DGAPA-UNAM (IN-217698), the Howard Hughes Medical Institute (grant no. Nbr55003677), and the European Commission (grant no. ICA-4-CT2000-30017). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No additional external funding received for this study. Competing Interests: The authors have declared that no competing interests exist. * E-mail: jbucio@umich.mx (JL-B); lherrera@ira.cinvestav.mx (LH-E) Introduction Plants continuously respond to abiotic and biotic stress by adjusting their metabolism and activating diverse intracellular and systemic responses. Biotic stress induced by pathogens triggers complex signaling cascades regulated by hormones once an invader has been detected. Three main phytohormones have been classically recognized as essential components of responses triggered by pathogens, namely salicylic acid (SA), jasmonic acid (JA) and ethylene (ET). Hormonal-dependent pathways result in the expression of defense-related genes such as those encoding pathogenesis-related (PR) proteins, and the production of antimicrobial secondary metabolites [1]. These responses are assisted by reactive molecules, such as nitric oxide (NO) and reactive oxygen species (ROS) that function both, as signaling components of transcriptional and metabolic readjustment and as antimicrobial substances [2]. Lifestyle of pathogens largely determines the effectiveness of a plant-induced response to combat the pathogen challenge. The SA-dependent signaling pathway is often considered to be effective against pathogens that derive nutrients from living hosts cells (biotrophs), and JA/ET pathways against pathogens that derive nutrients from dead cells (necro- trophs), although, the persistence of defense responses and the disease outcome are determined by complex networks of interactions between multiple hormone signaling pathways [3]. Lipids have a key role in maintaining the fluidity and structural integrity of all cell membranes. Additionally, lipids and various fatty acid derivatives have been described to act as signaling molecules in response to diverse environmental cues [4]. Structural features of fatty acids, such as the chain length and their unsaturation degree, determine their function and biological activity by altering membrane lipid composition [5]. Exogenous and endogenous mono- and poly-unsatured fatty acids (PUFAs) alter plant gene expression and metabolism, thus impacting the plant-microbe and plant-herbivore interactions [5,6]. For instance, alterations in enzymatic machinery that regulates production of cellular unsaturated fatty acids alter the SA- and JA-mediated defense signaling. A reduction in the endogenous levels of oleic PLoS ONE | www.plosone.org 1 November 2011 | Volume 6 | Issue 11 | e27251