title: Jasmonate controls leaf growth by repressing cell proliferation and the onset of endoreduplication while maintaining a potential stand-by mode.
abstract: Phytohormones regulate plant growth from cell division to organ development. Jasmonates (JAs) are signaling molecules that have been implicated in stress-induced responses. However, they have also been shown to inhibit plant growth, but the mechanisms are not well understood. The effects of methyl jasmonate (MeJA) on leaf growth regulation were investigated in Arabidopsis (Arabidopsis thaliana) mutants altered in JA synthesis and perception, allene oxide synthase and coi1-16B (for coronatine insensitive1), respectively. We show that MeJA inhibits leaf growth through the JA receptor COI1 by reducing both cell number and size. Further investigations using flow cytometry analyses allowed us to evaluate ploidy levels and to monitor cell cycle progression in leaves and cotyledons of Arabidopsis and/or Nicotiana benthamiana at different stages of development. Additionally, a novel global transcription profiling analysis involving continuous treatment with MeJA was carried out to identify the molecular players whose expression is regulated during leaf development by this hormone and COI1. The results of these studies revealed that MeJA delays the switch from the mitotic cell cycle to the endoreduplication cycle, which accompanies cell expansion, in a COI1-dependent manner and inhibits the mitotic cycle itself, arresting cells in G1 phase prior to the S-phase transition. Significantly, we show that MeJA activates critical regulators of endoreduplication and affects the expression of key determinants of DNA replication. Our discoveries also suggest that MeJA may contribute to the maintenance of a cellular "stand-by mode" by keeping the expression of ribosomal genes at an elevated level. Finally, we propose a novel model for MeJA-regulated COI1-dependent leaf growth inhibition.
authors: School of Biological Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, United Kingdom.
authors: Sandra
authors: S
authors: Noir
authors: Moritz
authors: M
authors: Bömer
authors: Naoki
authors: N
authors: Takahashi
authors: Takashi
authors: T
authors: Ishida
authors: Tjir-Li
authors: TL
authors: Tsui
authors: Virginia
authors: V
authors: Balbi
authors: Hugh
authors: H
authors: Shanahan
authors: Keiko
authors: K
authors: Sugimoto
authors: Alessandra
authors: A
authors: Devoto
mesh_terms: D000085:Acetates / Q000494:pharmacology*; D017360:Arabidopsis / Q000166:cytology* / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002452:Cell Count; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D053145:Cell Nucleus Size / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D016000:Cluster Analysis; D018548:Cotyledon / Q000187:drug effects / Q000254:growth & development; D003517:Cyclopentanes / Q000494:pharmacology*; D004261:DNA Replication / Q000187:drug effects; D018744:DNA, Plant / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D062951:Endoreduplication / Q000187:drug effects* / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018519:Meristem / Q000166:cytology / Q000187:drug effects; D008938:Mitosis / Q000187:drug effects / Q000235:genetics; D008954:Models, Biological; D054883:Oxylipins / Q000494:pharmacology*; D010641:Phenotype; D018515:Plant Leaves / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development*; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000085:Acetates; D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D018744:DNA, Plant; D054883:Oxylipins; D012269:Ribosomal Proteins; C072239:methyl jasmonate