A constitutivePR-1::luciferaseexpression screen identifies Arabidopsis mutants with differential disease resistance to both biotrophic and necrotrophic pathogens.

A complex signal transduction network involving salicylic acid, jasmonic acid and ethylene underlies disease resistance inArabidopsis. To understand this defence signalling network further, we identified mutants that expressed the marker genePR-1::luciferasein the absence of pathogen infection. Thesecirmutants all display constitutive expression of a suite of defence-related genes but exhibit different disease resistance profiles to two biotrophic pathogens,Pseudomonas syringaepv.tomatoandPeronospora parasiticaNOCO2, and the necrotrophic pathogenBotrytis cinerea. We further characterizedcir3, which displays enhanced resistance only to the necrotrophic pathogen.Cir3-mediated resistance toB. cinereais dependent on accumulated salicylic acid and a functional EIN2 protein. [ABSTRACT FROM AUTHOR]