title: Allantoin, a stress-related purine metabolite, can activate jasmonate signaling in a MYC2-regulated and abscisic acid-dependent manner.
abstract: Allantoin is a metabolic intermediate of purine catabolism that often accumulates in stressed plants. Recently, we used Arabidopsis knockout mutants (aln) of ALLANTOINASE to show that this purine metabolite activates abscisic acid (ABA) production, thereby stimulating stress-related gene expression and enhancing seedling tolerance to abiotic stress. A detailed re-examination of the microarray data of an aln mutant (aln-1) confirmed the increased expression of ABA-related genes and also revealed altered expression of genes involved in jasmonic acid (JA) responses, probably under the control of MYC2, a master switch in the JA signaling pathway. Consistent with the transcriptome profiles, the aln-1 mutant displayed increased JA levels and enhanced responses to mechanical wounding and exogenous JA. Moreover, aln mutants demonstrated modestly increased susceptibility to Pseudomonas syringae and Pectobacterium carotovorum, probably reflecting the antagonistic action of MYC2 on the defense against these bacterial phytopathogens. Exogenously administered allantoin elicited the expression of JA-responsive genes, including MYC2, in wild-type plants, supporting the idea that allantoin might be responsible for the observed JA-related phenotypes of aln mutants. However, mutants deficient in bioactive JA (jar1-1), insensitive to JA (myc2-3), or deficient in ABA (aba2-1 and bglu18) suppressed the effect of exogenous allantoin. The suppression was further confirmed in aln-1 jar1-1 and aln-1 bglu18 double mutants. These results indicate that allantoin can activate the MYC2-regulated JA signaling pathway through ABA production. Overall, this study suggests a possible connection of purine catabolism with stress hormone homeostasis and signaling, and highlights the potential importance of allantoin in these interactions.
authors.affiliation: Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takagi
authors.affiliation: Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ishiga
authors.affiliation: Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Watanabe
authors.affiliation: Faculty of Bioresource Sciences, Akita Prefectural University, Akita 010-0195, Japan.
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Konishi
authors.affiliation: Faculty of Agriculture, Tottori University, Tottori 680-8553, Japan.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Egusa
authors.affiliation: Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Akiyoshi
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan.
authors.forename: Takakazu
authors.initials: T
authors.lastname: Matsuura
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan.
authors.forename: Izumi C
authors.initials: IC
authors.lastname: Mori
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Hirayama
authors.affiliation: Faculty of Agriculture, Tottori University, Tottori 680-8553, Japan.
authors.forename: Hironori
authors.initials: H
authors.lastname: Kaminaka
authors.affiliation: Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shimada
authors.affiliation: Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Sakamoto
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D000481:Allantoin / Q000494:pharmacology*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D003517:Cyclopentanes / Q000378:metabolism* / Q000494:pharmacology; D060467:Disease Resistance / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D007532:Isoleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D055442:Metabolome / Q000187:drug effects*; D009154:Mutation / Q000235:genetics; D054883:Oxylipins / Q000378:metabolism* / Q000494:pharmacology; D044043:Pectobacterium / Q000187:drug effects; D010935:Plant Diseases / Q000382:microbiology; D044224:Pseudomonas syringae / Q000187:drug effects; D011687:Purines / Q000378:metabolism*; D020156:Salicylic Acid / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013312:Stress, Physiological / Q000187:drug effects*
chemical_list: D029681:Arabidopsis Proteins; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D003517:Cyclopentanes; C473611:MYC2 protein, Arabidopsis; D054883:Oxylipins; D011687:Purines; C532883:jasmonoyl-isoleucine; D007532:Isoleucine; D000481:Allantoin; C011006:jasmonic acid; D000040:Abscisic Acid; D020156:Salicylic Acid; C030985:purine
keywords: ABA; Arabidopsis; JA; purine metabolism; small metabolite; stress hormone; stress response; ureide.