CHENGDU -- It is a "molecular spy" that slips into rice cells, hijacks the plant's immune defenders and leaves the crop defenseless. But now, after a decade of detective work, Chinese scientists have not only exposed the invader but also found a way to fight back.

Researchers from Sichuan Agricultural University in Southwest China have identified a previously unknown weapon used by rice blast fungus, one of agriculture's most destructive pathogens. The findings were published on May 20 in the journal Nature.

This discovery offers a new strategy for broad-spectrum crop disease resistance breeding and environmentally friendly disease management, Chen Xuewei from the university's State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, who also led the research, told Xinhua on Tuesday.

Rice blast is a fungal disease that attacks rice plants, causing lesions on leaves, stems and grains. Globally, it reduces harvests by 10 to 30 percent each year.

For China, the world's largest rice producer, the stakes are high, as rice is the staple food for hundreds of millions, especially in southern China, where it is consumed at almost every meal. In 2025, China produced 209.04 million metric tons of rice, according to the National Bureau of Statistics.

The team discovered that the rice blast fungus secretes a long non-coding RNA molecule, which they named "lnc117761."

A long non-coding RNA is a type of genetic molecule that does not code for proteins but can regulate biological processes. Think of it as a covert operative that enters the plant cell and disrupts its defense system from within.

Once inside, lnc117761 latches onto a rice microRNA called miR5827 -- an "immune guard" that normally helps rice fight disease by suppressing a gene that weakens immunity. By neutralizing this guard, the fungal RNA lnc117761 destroys the plant's ability to defend itself.

"It is like an attack-defend battle," Chen explained. "The pathogen sends a 'saboteur' RNA into the rice cell and precisely hijacks the rice defense system."

The team also found that the sequence pairing between lnc117761 and miR5827 is widespread across many pathogens and plants, indicating that this mechanism is ancient and universal.

This insight opens the door to a new class of broad-spectrum "biological weapons." That is, RNA-based biopesticides that target pathogenic RNAs, and immune-boosting agents that supplement a crop's own defenders.

Unlike traditional chemical pesticides, which can harm the environment and human health, this approach is considered green and safe.

The team has already synthesized an artificial RNA agent. Laboratory tests showed it can significantly boost disease resistance in major grain crops, including rice and wheat, reducing fungal infection rates by 30 to 40 percent.

"This is a conceptual breakthrough in the field of plant disease," the researchers said in a statement, noting that the discovery overturns the long-held belief that only proteins or small RNAs could perform such cross-species communication.

A patent about the agent has been filed, and the team hopes to put the technology into practice in the near future, said Chen.

In addition, the team plans to use elite rice varieties with naturally high expression of miR5827 to breed broad-spectrum disease-resistant rice varieties, thereby enhancing crop disease resistance at the source and providing greater variety support for safe grain production, he added.