title: Analysis of salicylic acid-dependent pathways in Arabidopsis thaliana following infection with Plasmodiophora brassicae and the influence of salicylic acid on disease.
abstract: Salicylic acid (SA) biosynthesis, the expression of SA-related genes and the effect of SA on the Arabidopsis-Plasmodiophora brassicae interaction were examined. Biochemical analyses revealed that, in P. brassicae-infected Arabidopsis, the majority of SA is synthesized from chorismate. Real-time monitored expression of a gene for isochorismate synthase was induced on infection. SA can be modified after accumulation, either by methylation, improving its mobility, or by glycosylation, as one possible reaction for inactivation. Quantitative reverse transcription-polymerase chain reaction (qPCR) confirmed the induction of an SA methyltransferase gene, whereas SA glucosyltransferase expression was not changed after infection. Col-0 wild-type (wt) did not provide a visible phenotypic resistance response, whereas the Arabidopsis mutant dnd1, which constitutively activates the immune system, showed reduced gall scores. As dnd1 showed control of the pathogen, exogenous SA was applied to Arabidopsis in order to test whether it could suppress clubroot. In wt, sid2 (SA biosynthesis), NahG (SA-deficient) and npr1 (SA signalling-impaired) mutants, SA treatment did not alter the gall score, but positively affected the shoot weight. This suggests that SA alone is not sufficient for Arabidopsis resistance against P. brassicae. Semi-quantitative PCR revealed that wt, cpr1, dnd1 and sid2 showed elevated PR-1 expression on P. brassicae and SA + P. brassicae inoculation at 2 and 3 weeks post-inoculation (wpi), whereas NahG and npr1 showed no expression. This work contributes to the understanding of SA involvement in the Arabidopsis-P. brassicae interaction.
authors.affiliation: Deakin University, Faculty of Science, Engineering and Built Environment, School of Life and Environmental Science, Geelong Campus at Waurn Ponds, Vic. 3217, Australia. david.lovelock@nt.gov.au.
authors.forename: David A
authors.initials: DA
authors.lastname: Lovelock
authors.affiliation: Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, 10000, Zagreb, Croatia. ivana.sola@biol.pmf.hr.
authors.forename: Ivana
authors.initials: I
authors.lastname: Šola
authors.affiliation: Institute of Botany, Technische Universität Dresden, D-01062, Dresden, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Marschollek
authors.affiliation: Department of Primary Industries, Private bag 15, Ferntree Gully DC, Vic., 3156, Australia.
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Donald
authors.affiliation: Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, 10000, Zagreb, Croatia.
authors.forename: Gordana
authors.initials: G
authors.lastname: Rusak
authors.affiliation: Department of Chemistry, Biochemistry, Technische Universität Dresden, D-01062, Dresden, Germany.
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: van Pée
authors.affiliation: Institute of Botany, Technische Universität Dresden, D-01062, Dresden, Germany.
authors.forename: Jutta
authors.initials: J
authors.lastname: Ludwig-Müller
authors.affiliation: Deakin University, Faculty of Science, Engineering and Built Environment, School of Life and Environmental Science, Geelong Campus at Waurn Ponds, Vic. 3217, Australia.
authors.forename: David M
authors.initials: DM
authors.lastname: Cahill
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D018533:Biomass; D053898:Biosynthetic Pathways; D002827:Chorismic Acid / Q000737:chemistry / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D016695:Glycosyltransferases / Q000235:genetics / Q000378:metabolism; D019751:Intramolecular Transferases; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010935:Plant Diseases / Q000382:microbiology*; D018517:Plant Roots / Q000382:microbiology; D018520:Plant Shoots / Q000187:drug effects / Q000382:microbiology; D010941:Plant Tumors / Q000382:microbiology; D056909:Plasmodiophorida / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction; D020156:Salicylic Acid / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C077262:PR-1 protein, Arabidopsis; D008780:Methyltransferases; D016695:Glycosyltransferases; D019751:Intramolecular Transferases; C058486:isochorismate synthase; D002827:Chorismic Acid; D020156:Salicylic Acid
keywords: Arabidopsis thaliana; Plasmodiophora brassicae; defence gene expression; salicylic acid biosynthesis; salicylic acid mutants