Periwinkle plant has a built-in brake for its own poison
Zhang Y, Liu Q, Liu P, Ni X, Liu H
Plant Signaling
The same periwinkle you might grow as a garden groundcover is quietly running a chemical factory for cancer-fighting compounds, and this discovery shows how it keeps that factory from poisoning itself.
Madagascar periwinkle makes powerful toxic compounds to fend off pests and disease, but those same chemicals would hurt the plant if production ran unchecked. Researchers found a set of proteins that act like a thermostat: when the plant's stress hormone jasmonate flips on alkaloid production, it also flips on its own brake pedal, so output ramps up and then reins itself back in. It's a tidy self-regulating loop, one signal doing double duty as both accelerator and brake.
Key Findings
CrWRKY4, a jasmonate-induced transcription factor, directly binds and activates multiple genes in the terpenoid indole alkaloid (TIA) biosynthesis pathway
Two co-repressor proteins, CrVQ4 and CrVQ9, block CrWRKY4's DNA-binding ability, while CrJAZ1 interferes with this VQ-WRKY repressive complex to relieve the brake under jasmonate signaling
CrWRKY4 activates its own repressors (CrVQ4, CrVQ9, CrJAZ1), forming a self-limiting negative feedback loop that prevents overproduction of cytotoxic alkaloids
chevron_right Technical Summary
Scientists discovered how the medicinal plant Madagascar periwinkle keeps its toxic chemical defenses from spiraling out of control, using a built-in molecular brake that switches on right alongside the signal that triggers production. The finding reveals a general strategy plants may use to balance defense with self-preservation.
Abstract Preview
Original paper
A JAZ-VQ-WRKY transcriptional feedback loop enforces homeostasis in cytotoxic alkaloid biosynthesis.
Plants face the challenge of balancing the production of defense-related secondary metabolites, requiring inducible "accelerators" and intrinsic "braking" systems to avoid overproduction. While the...
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