Functional specialization of two jasmonic acid-amido synthetases in rice defense and spikelet development.
Li LL, Xiao Y, Lin Y, Chen Y, Song X
Plant Signaling
Rice paddy fields are quietly locked in an arms race with tiny sap-sucking insects called brown planthoppers, and understanding how rice mounts its own chemical defense could help breeders grow varieties that need far fewer pesticide applications.
Plants make a natural alarm chemical called jasmonic acid that does double duty — it both fights off hungry insects and guides the plant's own flower and seed development. Researchers found that rice has two separate "activator" proteins for this chemical: one switches on specifically when bugs start feeding, and the other quietly works during flowering to make sure grains form correctly. By knocking out each activator separately using gene-editing tools, they proved these two jobs are kept intentionally separate, giving the plant precise control over when and where the alarm fires.
Key Findings
OsJAR1 is specifically responsible for producing the bioactive insect-defense signal (JA-Ile) when brown planthoppers attack, and rice plants lacking it showed measurably reduced resistance under both lab and real field conditions.
OsJAR2 is not involved in pest defense but instead drives jasmonic acid activation during early flower formation, and mutants lacking it developed abnormal spikelets (the structures that become rice grains).
A positive feedback loop exists where the defense enzyme OsJAR1 is directly switched on by stress-responsive transcription factors (MYC2-bHLH6), amplifying the plant's chemical alarm signal during herbivore attack.
chevron_right Technical Summary
Scientists discovered that rice plants use two specialized enzymes to activate the same stress hormone for completely different jobs — one fights off insect pests, the other shapes how flowers and grains develop. This division of labor explains how a single hormone can orchestrate such different plant responses.
Abstract Preview
The phytohormone jasmonic acid (JA) regulates diverse aspects of plant growth, development, and defense, yet how a single hormone coordinates such varied outputs remains poorly understood. Central ...
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