title: Constitutive camalexin production and environmental stress response variation in Arabidopsis populations from the Iberian Peninsula.
abstract: Optimal defense theory predicts that induction of defensive secondary metabolites in plants will be inversely correlated with constitutive expression of those compounds. Here, we asked whether camalexin, an important defense against fungal and bacterial pathogens, support this prediction in structured natural populations of Arabidopsis thaliana from the Iberian Peninsula. In common garden experiments, we found that genotypes from the VIE population constitutively hyper-accumulated camalexin. Camalexin concentrations were not induced significantly when plants were exposed to a temperature of 10°C for 48h. However, they were induced when plants were exposed to 48h of infection by the virulent bacterial pathogen, Pseudomonas syringae pv. tomato DC3000. Genotypes from the VIE population with the hyper-accumulation of camalexin were significantly more resistant to bacterial growth. Induction of camalexin was negatively correlated with constitutive camalexin concentrations following log transformation and two different corrections for autocorrelation, thus supporting the tradeoff predicted by optimal defense theory. Constitutive overexpression of camalexin was not explained by the only known natural genetic polymorphism at the Accelerated Cell Death 6, ACD6, locus. Collectively, the results support an important role of camalexin in defense against P. syringae as well as significant structured variation in defense levels within wild populations.
authors.affiliation: Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, United States.
authors.forename: Nana
authors.initials: N
authors.lastname: Zhang
authors.affiliation: Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, United States.
authors.forename: Andy
authors.initials: A
authors.lastname: Lariviere
authors.affiliation: Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, United States.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Tonsor
authors.affiliation: Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, United States. Electronic address: mbtraw@pitt.edu.
authors.forename: M Brian
authors.initials: MB
authors.lastname: Traw
mesh_terms: D017487:Ankyrins / Q000235:genetics; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics; D001483:Base Sequence; D060467:Disease Resistance / Q000235:genetics*; D014644:Genetic Variation; D005838:Genotype; D007211:Indoles / Q000378:metabolism*; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D011110:Polymorphism, Genetic; D044224:Pseudomonas syringae; D013312:Stress, Physiological / Q000235:genetics*; D013696:Temperature; D013844:Thiazoles / Q000378:metabolism*; D000094162:Phytoalexins
chemical_list: D017487:Ankyrins; D029681:Arabidopsis Proteins; D007211:Indoles; D013844:Thiazoles; C480953:ACD6 protein, Arabidopsis; C102405:camalexin; D000094162:Phytoalexins
keywords: ACD6; Durable resistance; Optimal defense theory; Phytoalexins; Tradeoffs