Constitutive camalexin production and environmental stress response variation in Arabidopsis populations from the Iberian Peninsula

• Published in: Plant science (Limerick) Vol. 225; pp. 77 - 85
• Main Authors: Zhang, Nana, Lariviere, Andy, Tonsor, Stephen J., Traw, M. Brian
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 01.08.2014
• Subjects: ACD6; Ankyrins - genetics; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis - microbiology; Arabidopsis Proteins - genetics; Base Sequence; Disease Resistance - genetics; Durable resistance; Genetic Variation; Genotype; Indoles - metabolism; Molecular Sequence Data; Optimal defense theory; Phytoalexins; Plant Diseases - genetics; Plant Diseases - microbiology; Polymorphism, Genetic; Pseudomonas syringae; Stress, Physiological - genetics; Temperature; Thiazoles - metabolism; Tradeoffs; Durable resistance; Phytoalexins; ACD6; Tradeoffs; Optimal defense theory
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2014.05.020

•We find that wild Arabidopsis genotypes hyperaccumulate camalexin, a major defense chemical against bacterial infection.•Lines with hyperaccumulation of camalexin were more resistant to bacterial infection.•Camalexin production was dramatically upregulated in all plants following infection.•We report the first evidence of a significant tradeoff between high inducibility and high constitutive production of camalexin, as predicted by optimal defense theory. 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.