The early organelle migration response of Arabidopsis to Hyaloperonospora arabidopsidis is independent of RAR1, SGT1b, PAD4 and NPR1

An early cellular reaction necessary for resistance expression of plant cells to pathogen attack is the migration of organelles towards the site of attempted pathogen ingress. We crossed lines expressing either Golgi bodies- or peroxisomal-targeted GFP with rar1-20, sgt1b, pad4-1 and npr1-2 mutants to test whether mutations in these signalling components impaired this cellular reaction. Defence-signalling-mutant-GFP lines and wild-type-GFP lines inoculated with Hyaloperonospora arabidopsidis isolates showed no observable differences. Thus, relocation of intracellular organelles is part of an innate, basal immune response that operates independently of RAR1, SGT1b, PAD4 and NPR1. The evolutionary implications of our results are discussed. (C) 2008 Elsevier Ltd. All rights reserved.