The circular RNA circP5CS1 coordinates plant immunity by sequestering miR167 to modulate ARF6/8 signaling and repressing P5CS1-mediated proline biosynthesis in Arabidopsis.
Wang L, Song X, Wei R, Shi X, Xu L
Plant Signaling
Every tomato plant that rots from bacterial speck, every basil that wilts from blight, loses to the same microbial warfare this research is beginning to decode — and understanding the molecular switch that plants use to juggle two defense systems at once is the kind of discovery that eventually reaches breeders who want crops that fight back without costly trade-offs.
Plants have special circular pieces of genetic material that act like molecular sponges, soaking up tiny regulators before those regulators can silence defense genes. Scientists found one such sponge in thale cress — a small weedy plant related to cabbage — that controls two immune pathways at the same time: one using plant hormones to signal danger, and another using an amino acid called proline that helps plants tough out stress. When they blocked this sponge, plants made more proline and fought off bacterial infection much better; when it was overactive, plants became more susceptible, revealing a single molecule that can tip the scales of plant immunity.
Key Findings
circP5CS1 acts as a sponge for the microRNA miR167, preventing it from silencing ARF6 and ARF8 — key factors that fine-tune salicylic acid and jasmonic acid immune hormone signaling during bacterial infection by Pseudomonas syringae DC3000.
circP5CS1 suppresses its own parent gene P5CS1 through splicing competition and post-transcriptional regulation, reducing proline biosynthesis; plants with reduced circP5CS1 had elevated proline and enhanced pathogen resistance, while overexpression plants showed decreased proline and compromised resistance.
Silencing circP5CS1 (RNAi lines) or overexpressing P5CS1 or miR167 all increased resistance to both Pst DC3000 and the effector AvrRpt2, whereas overexpressing circP5CS1 or knocking out P5CS1 had the opposite effect — establishing a causal link between this single circular RNA and two distinct immunity branches.
chevron_right Technical Summary
Researchers discovered a circular RNA molecule in thale cress (Arabidopsis) that simultaneously hijacks a plant immune regulator and suppresses its own parent gene to reduce proline production — acting as a molecular switch that coordinates two separate disease-resistance pathways at once.
Abstract Preview
Circular RNAs (circRNAs) are noncoding RNAs formed by back-splicing, characterized by covalently closed-loop structures with enhanced stability. Although growing evidence highlights their regulator...
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Arabidopsis thaliana, the thale cress, mouse-ear cress or arabidopsis, is a small plant from the mustard family (Brassicaceae), native to Eurasia and Africa. Commonly found along the shoulders of roads and in disturbed land, it is generally considered a weed.