title: Activation of Plant Innate Immunity by Extracellular High Mobility Group Box 3 and Its Inhibition by Salicylic Acid.
abstract: Damage-associated molecular pattern molecules (DAMPs) signal the presence of tissue damage to induce immune responses in plants and animals. Here, we report that High Mobility Group Box 3 (HMGB3) is a novel plant DAMP. Extracellular HMGB3, through receptor-like kinases BAK1 and BKK1, induced hallmark innate immune responses, including i) MAPK activation, ii) defense-related gene expression, iii) callose deposition, and iv) enhanced resistance to Botrytis cinerea. Infection by necrotrophic B. cinerea released HMGB3 into the extracellular space (apoplast). Silencing HMGBs enhanced susceptibility to B. cinerea, while HMGB3 injection into apoplast restored resistance. Like its human counterpart, HMGB3 binds salicylic acid (SA), which results in inhibition of its DAMP activity. An SA-binding site mutant of HMGB3 retained its DAMP activity, which was no longer inhibited by SA, consistent with its reduced SA-binding activity. These results provide cross-kingdom evidence that HMGB proteins function as DAMPs and that SA is their conserved inhibitor.
authors.affiliation: Boyce Thompson Institute for Plant Research, Ithaca, New York, United States of America.
authors.forename: Hyong Woo
authors.initials: HW
authors.lastname: Choi
authors.affiliation: Boyce Thompson Institute for Plant Research, Ithaca, New York, United States of America.
authors.forename: Murli
authors.initials: M
authors.lastname: Manohar
authors.affiliation: Boyce Thompson Institute for Plant Research, Ithaca, New York, United States of America.
authors.forename: Patricia
authors.initials: P
authors.lastname: Manosalva
authors.affiliation: Boyce Thompson Institute for Plant Research, Ithaca, New York, United States of America.
authors.forename: Miaoying
authors.initials: M
authors.lastname: Tian
authors.affiliation: Boyce Thompson Institute for Plant Research, Ithaca, New York, United States of America.
authors.forename: Magali
authors.initials: M
authors.lastname: Moreau
authors.affiliation: Boyce Thompson Institute for Plant Research, Ithaca, New York, United States of America.
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Klessig
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D020171:Botrytis / Q000276:immunology* / Q000378:metabolism; D003517:Cyclopentanes / Q000378:metabolism; D060467:Disease Resistance; D005030:Ethylenes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D054883:Oxylipins / Q000378:metabolism*; D010935:Plant Diseases / Q000469:parasitology*; D018515:Plant Leaves / Q000235:genetics; D010944:Plants / Q000276:immunology*; D044224:Pseudomonas syringae / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D005030:Ethylenes; D054883:Oxylipins; D020156:Salicylic Acid