title: SAR increases fitness of Arabidopsis thaliana in the presence of natural bacterial pathogens.
abstract: Given the substantial costs of plant defenses against pathogens, there should be corresponding benefits that prevent resistance from being lost in natural plant populations. Here, we present evidence that systemic acquired resistance (SAR) benefits plants attacked by pathogenic bacteria in nature. In a large field experiment, we found that Arabidopsis thaliana treated with salicylic acid exhibited reduced titers of bacteria in their leaves and elevated fitness relative to controls. Most common members of the culturable bacterial community suffered this decrease, consistent with the role of SAR as a broad spectrum defense. We found no evidence of negative interactions between SAR and jasmonate-dependent resistance. Plants treated with jasmonic acid received significantly lower insect damage to their siliques, but exhibited no differences in bacterial growth or fitness relative to controls. Collectively, these data suggest a likely role of pathogenic bacteria in the maintenance of SAR, but not jasmonate-dependent resistance, in nature.
authors.affiliation: Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA. mbtraw@pitt.edu
authors.forename: M Brian
authors.initials: MB
authors.lastname: Traw
authors.forename: Joel M
authors.initials: JM
authors.lastname: Kniskern
authors.forename: Joy
authors.initials: J
authors.lastname: Bergelson
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects* / Q000382:microbiology*; D001419:Bacteria / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification*; D003517:Cyclopentanes / Q000494:pharmacology; D054883:Oxylipins / Q000494:pharmacology; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000378:metabolism / Q000382:microbiology; D020156:Salicylic Acid / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D003517:Cyclopentanes; D054883:Oxylipins; C011006:jasmonic acid; D020156:Salicylic Acid