Description: The Arabidopsis mutant cir1 displayed constitutive expression of defence genes and enhanced resistance to the virulent pathogens Pseudomonas syringae pv tomato (Pst) and Peronospora parasitica Noco2 In order to dissect the downstream signalling components constitutively activated in cir1  cir1 plants were crossed to the ethylene-insensitive mutant ein2