title: Jasmonic acid perception by COI1 involves inositol polyphosphates in Arabidopsis thaliana.
abstract: Plant responses to wounding are part of their defense responses against insects, and are tightly regulated. The isoleucin conjugate of jasmonic acid (JA-Ile) is a major regulatory molecule. We have previously shown that inositol polyphosphate signals are required for defense responses in Arabidopsis; however, the way in which inositol polyphosphates contribute to plant responses to wounding has so far remained unclear. Arabidopsis F-box proteins involved in the perception of JA-Ile (COI1) and auxin (TIR1) are structurally similar. Because TIR1 has recently been shown to contain inositol hexakisphosphate (InsP₆) as a co-factor of unknown function, here we explored the possibility that InsP₆ or another inositol polyphosphate is required for COI1 function. In support of this hypothesis, COI1 variants with changes in putative inositol polyphosphate coordinating residues exhibited a reduced interaction with the COI1 target, JAZ9, in yeast two-hybrid tests. The equivalent COI1 variants displayed a reduced capability to rescue jasmonate-mediated root growth inhibition or silique development in Arabidopsis coi1 mutants. Yeast two-hybrid tests using wild-type COI1 in an ipk1Δ yeast strain exhibiting increased levels of inositol pentakisphosphate (InsP₅) and reduced levels of InsP₆ indicate an enhanced COI1/JAZ9 interaction. Consistent with these findings, Arabidopsis ipk1-1 mutants, also with increased InsP₅ and reduced InsP₆ levels, showed increased defensive capabilities via COI1-mediated processes, including wound-induced gene expression, defense against caterpillars or root growth inhibition by jasmonate. The combined data from experiments using mutated COI1 variants, as well as yeast and Arabidopsis backgrounds altered in inositol polyphosphate metabolism, indicate that an inositol polyphosphate, and probably InsP₅, contributes to COI1 function.
authors.affiliation: Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany.
authors.forename: Alina
authors.initials: A
authors.lastname: Mosblech
authors.forename: Corinna
authors.initials: C
authors.lastname: Thurow
authors.forename: Christiane
authors.initials: C
authors.lastname: Gatz
authors.forename: Ivo
authors.initials: I
authors.lastname: Feussner
authors.forename: Ingo
authors.initials: I
authors.lastname: Heilmann
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D003517:Cyclopentanes / Q000378:metabolism*; D018744:DNA, Plant / Q000235:genetics; D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism; D017343:Genes, Plant; D007295:Inositol Phosphates / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D054883:Oxylipins / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism; D010833:Phytic Acid / Q000378:metabolism; D030821:Plants, Genetically Modified; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; C112279:COI1 protein, Arabidopsis; D003517:Cyclopentanes; D018744:DNA, Plant; D044783:F-Box Proteins; D007295:Inositol Phosphates; D054883:Oxylipins; D011956:Receptors, Cell Surface; C501405:TIR1 protein, Arabidopsis; C013571:inositol pentaphosphate; C011006:jasmonic acid; D010833:Phytic Acid; D017853:Phosphotransferases (Alcohol Group Acceptor); C508906:inositol 1,3,4,5,6-pentakisphosphate 2-kinase, Arabidopsis