Jasmonate Controls Leaf Growth by Repressing Cell Proliferation and the Onset of Endoreduplication while Maintaining a Potential Stand-By Mode

• Published in: Plant physiology (Bethesda) Vol. 161; no. 4; pp. 1930 - 1951
• Main Authors: Noir, Sandra, Bömer, Moritz, Takahashi, Naoki, Ishida, Takashi, Tsui, Tjir-Li, Balbi, Virginia, Shanahan, Hugh, Sugimoto, Keiko, Devoto, Alessandra
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01-04-2013; Oxford University Press ; American Society of Plant Biologists
• Subjects: Acetates - pharmacology; Arabidopsis - cytology; Arabidopsis - drug effects; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Biochemistry, Molecular Biology; Biological and medical sciences; Cell Count; Cell cycle; Cell growth; Cell Nucleus - drug effects; Cell Nucleus - metabolism; Cell Nucleus Size - drug effects; Cell Proliferation - drug effects; Cell Size - drug effects; Cellular Biology; Cluster Analysis; Cotyledon - drug effects; Cotyledon - growth & development; Cyclopentanes - pharmacology; Developmental biology; DNA Replication - drug effects; DNA, Plant - metabolism; Down-Regulation - drug effects; Endoreduplication - drug effects; Endoreduplication - genetics; Epidermal cells; Fundamental and applied biological sciences. Psychology; Gene Expression Profiling; Gene expression regulation; Gene Expression Regulation, Plant - drug effects; Genes; GENES, DEVELOPMENT, AND EVOLUTION; Life Sciences; Meristem - cytology; Meristem - drug effects; Mitosis - drug effects; Mitosis - genetics; Models, Biological; Molecular biology; Oxylipins - pharmacology; Phenotype; Plant cells; Plant growth regulators; Plant Leaves - cytology; Plant Leaves - drug effects; Plant Leaves - growth & development; Plant physiology and development; Plants; Ribosomal Proteins - genetics; Ribosomal Proteins - metabolism; Seedlings; Cell proliferation; Endomitosis; Polyploidy; Plant leaf; Plant physiology; Growth
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.113.214908

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 coil-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.