title: Infection of the brown alga Ectocarpus siliculosus by the oomycete Eurychasma dicksonii induces oxidative stress and halogen metabolism.
abstract: Pathogens are increasingly being recognized as key evolutionary and ecological drivers in marine ecosystems. Defence mechanisms of seaweeds, however, have mostly been investigated by mimicking infection using elicitors. We have established an experimental pathosystem between the genome brown model seaweed Ectocarpus siliculosus and the oomycete Eurychasma dicksonii as a powerful new tool to investigate algal responses to infection. Using proteomics, we identified 21 algal proteins differentially accumulated in response to Eu. dicksonii infection. These include classical algal stress response proteins such as a manganese superoxide dismutase, heat shock proteins 70 and a vanadium bromoperoxidase. Transcriptional profiling by qPCR confirmed the induction of the latter during infection. The accumulation of hydrogen peroxide was observed at different infection stages via histochemical staining. Inhibitor studies confirmed that the main source of hydrogen peroxide is superoxide converted by superoxide dismutase. Our data give an unprecedented global overview of brown algal responses to pathogen infection, and highlight the importance of oxidative stress and halogen metabolism in these interactions. This suggests overlapping defence pathways with herbivores and abiotic stresses. We also identify previously unreported actors, in particular a Rad23 and a plastid-lipid-associated protein, providing novel insights into the infection and defence processes in brown algae.
authors.affiliation: The Scottish Association for Marine Science, Scottish Marine Institute, Oban, Argyll, Scotland, PA37 1QA, UK.|Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, AB25 2ZD, UK.
authors.forename: Martina
authors.initials: M
authors.lastname: Strittmatter
authors.affiliation: Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, AB25 2ZD, UK.|Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, 230 53, Sweden.
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Grenville-Briggs
authors.affiliation: Fachbereich Biologie, Universität Konstanz, Konstanz, D-78457, Germany.
authors.forename: Lisa
authors.initials: L
authors.lastname: Breithut
authors.affiliation: Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, AB25 2ZD, UK.
authors.forename: Pieter
authors.initials: P
authors.lastname: Van West
authors.affiliation: The Scottish Association for Marine Science, Scottish Marine Institute, Oban, Argyll, Scotland, PA37 1QA, UK.
authors.forename: Claire M M
authors.initials: CM
authors.lastname: Gachon
authors.affiliation: The Scottish Association for Marine Science, Scottish Marine Institute, Oban, Argyll, Scotland, PA37 1QA, UK.|Oceanlab, University of Aberdeen, Main Street, Newburgh, Scotland, AB41 6AA, UK.
authors.forename: Frithjof C
authors.initials: FC
authors.lastname: Küpper
mesh_terms: D020418:Algal Proteins / Q000302:isolation & purification; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006219:Halogens / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D008954:Models, Biological; D009868:Oomycetes / Q000502:physiology*; D018384:Oxidative Stress / Q000235:genetics; D000459:Phaeophyceae / Q000382:microbiology*; D020543:Proteome / Q000378:metabolism; D040901:Proteomics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D013481:Superoxides / Q000378:metabolism
chemical_list: D020418:Algal Proteins; D006219:Halogens; D020543:Proteome; D012333:RNA, Messenger; D013481:Superoxides; D006861:Hydrogen Peroxide
keywords: model brown alga; reactive oxygen species; vanadium-dependent bromoperoxidase