Abstract
The spikelet is the basal unit of inflorescence in grasses, and its formation is crucial for reproductive success and cereal yield. Here, we report a previously unknown role of the plant hormone jasmonic acid (JA) in determining rice (Oryza sativa) spikelet morphogenesis. The extra glume 1 (eg1) and eg2 mutants exhibit altered spikelet morphology with changed floral organ identity and number, as well as defective floral meristem determinacy. We show that EG1 is a plastid-targeted lipase that participates in JA biosynthesis, and EG2/OsJAZ1 is a JA signalling repressor that interacts with a putative JA receptor, OsCOI1b, to trigger OsJAZ1's degradation during spikelet development. OsJAZ1 also interacts with OsMYC2, a transcription factor in the JA signalling pathway, and represses OsMYC2's role in activating OsMADS1, an E-class gene crucial to the spikelet development. This work discovers a key regulatory mechanism of grass spikelet development and suggests that the role of JA in reproduction has diversified during the flowering plant evolution.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Base Sequence
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Cyclopentanes / metabolism
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Cyclopentanes / pharmacology*
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Gene Expression Regulation, Developmental / drug effects
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Gene Expression Regulation, Plant / drug effects
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Green Fluorescent Proteins / genetics
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Green Fluorescent Proteins / metabolism
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Immunoblotting
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In Situ Hybridization
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Inflorescence / drug effects*
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Inflorescence / genetics
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Inflorescence / growth & development
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Microscopy, Confocal
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Microscopy, Electron, Scanning
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Molecular Sequence Data
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Mutation
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Oryza / drug effects*
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Oryza / genetics
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Oryza / growth & development
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Oxylipins / metabolism
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Oxylipins / pharmacology*
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Plant Development / drug effects
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Plant Development / genetics
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Plant Growth Regulators / metabolism
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Plant Growth Regulators / pharmacology
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Plant Proteins / genetics
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Plant Proteins / metabolism
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Plants, Genetically Modified
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Protein Binding
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Reverse Transcriptase Polymerase Chain Reaction
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Two-Hybrid System Techniques
Substances
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Cyclopentanes
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Oxylipins
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Plant Growth Regulators
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Plant Proteins
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Green Fluorescent Proteins
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jasmonic acid