Open AccessActivation of Plant Innate Immunity by Extracellular High Mobility Group Box 3 and Its Inhibition by Salicylic Acid
Author(s) -
Hyong Woo Choi,
Murli Manohar,
Patricia Manosalva,
Mingxing Tian,
Magali Moreau,
Daniel F. Klessig
Publication year - 2016
Publication title -
plos pathogens
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.719
H-Index - 206
eISSN - 1553-7374
pISSN - 1553-7366
DOI - 10.1371/journal.ppat.1005518
Subject(s) - innate immune system , apoplast , biology , extracellular , callose , salicylic acid , microbiology and biotechnology , botrytis cinerea , damp , gene silencing , pattern recognition receptor , kinase , receptor , biochemistry , cell wall , botany , gene , physics , meteorology
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 HMGB s 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.