title: Arabidopsis AZI1 family proteins mediate signal mobilization for systemic defence priming.
abstract: Priming is a major mechanism behind the immunological 'memory' observed during two key plant systemic defences: systemic acquired resistance (SAR) and induced systemic resistance (ISR). Lipid-derived azelaic acid (AZA) is a mobile priming signal. Here, we show that the lipid transfer protein (LTP)-like AZI1 and its closest paralog EARLI1 are necessary for SAR, ISR and the systemic movement and uptake of AZA in Arabidopsis. Imaging and fractionation studies indicate that AZI1 and EARLI1 localize to expected places for lipid exchange/movement to occur. These are the ER/plasmodesmata, chloroplast outer envelopes and membrane contact sites between them. Furthermore, these LTP-like proteins form complexes and act at the site of SAR establishment. The plastid targeting of AZI1 and AZI1 paralogs occurs through a mechanism that may enable/facilitate their roles in signal mobilization.
authors.affiliation: Department of Molecular Genetics and Cell Biology, The University of Chicago, 929 East 57th Street, GCIS Room W519P, Chicago, Illinois 60637, USA.
authors.forename: Nicolás M
authors.initials: NM
authors.lastname: Cecchini
authors.affiliation: Department of Molecular Genetics and Cell Biology, The University of Chicago, 929 East 57th Street, GCIS Room W519P, Chicago, Illinois 60637, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Steffes
authors.affiliation: Department of Biological Sciences, Marquette University, PO Box 1881, Milwaukee, Wisconsin 53233, USA.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Schläppi
authors.affiliation: Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Gifford
authors.affiliation: Department of Molecular Genetics and Cell Biology, The University of Chicago, 929 East 57th Street, GCIS Room W519P, Chicago, Illinois 60637, USA.
authors.forename: Jean T
authors.initials: JT
authors.lastname: Greenberg
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000276:immunology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism*; D008969:Molecular Sequence Data; D055232:Proline-Rich Protein Domains
chemical_list: C539888:AZI1 protein, Arabidopsis; D029681:Arabidopsis Proteins; C419264:EARLI1 protein, Arabidopsis