Rice-specific miRNA Boosts Rice Blast Resistance

The natural defenses of plants rely on tiny molecules called microRNAs (miRNAs), and scientists are still finding new ones that help plants fight off diseases. In a study published in The Plant Journal, Sichuan Agricultural University researchers discovered a crucial player in the defense of rice plants against a devastating fungus called rice blast (Magnaporthe oryzae). This new helper is a small molecule we named miR24584. When rice plants were naturally resistant to the fungus, they produced a lot of this molecule. However, susceptible plants produced very little. When we genetically modified rice to produce extra miR24584, the plants became highly resistant to different strains of the fungus, confirming its role as a powerful defender.

Furthermore, the researchers elucidated the mechanism of miR24584 in protecting rice. It acts by shutting down a gene called OsJAZ13. This gene is normally a brake on the plant's immune system, specifically on a defense pathway called jasmonate signaling. By suppressing OsJAZ13, miR24584 essentially releases the brakes on the JA defense system. Activating this defense not only boosts the overall immune response but also significantly strengthens the physical barriers of the plant—like the cell walls—making it much harder for the fungus to invade.

This finding reveals a new, important switch (the miR24584-OsJAZ13 module) that rice uses to turn on its defenses and successfully fight off the blast disease.

Read more from The Plant Journal.