In the eternal game between humans and pathogenic bacteria, the plant world has long evolved a sophisticated defense system.
On February 28, 2025, the team of Jian-Min Zhou of the Chinese Academy of Sciences and the team of Xiaoguang Lei of Peking University published a research paper entitled "A widespread plant defense compound disarms bacterial type III injectisome assembly" in Science, revealing the mysterious mechanism of plant resistance to pathogenic bacteria invasion. A natural plant metabolite called erucamide can accurately dismantle the "biochemical weapons" of pathogens, providing new possibilities for green agriculture.
Erucamide has a strong protective effect on a variety of crop bacterial diseases such as rice white leaf blight and tomato bacterial wilt, suggesting its potential application value in the prevention and control of crop bacterial diseases.
Plant bacterial diseases are a major threat to plant growth and have a great impact on agriculture and ecosystems. Pathogenic bacteria cause leaf spots, wilt, rot and other diseases by infecting plant tissues, which can lead to crop yield reduction or even crop failure in severe cases. When pathogenic bacteria quietly invade, the chemical defense system of plants is staging a molecular war that is invisible to the naked eye.
Traditionally, plant disease-resistant metabolites mostly use "poisoning" tactics, but the latest research has found that erucamide takes a different approach: it is like a shrewd bomb disposal expert, specializing in dismantling the "biochemical weapon" of pathogens - the Type III secretion system (T3SS).
The T3SS is a device used by various plant and animal pathogens to secrete toxic proteins into host cells, which is indispensable for disease. Erucamide destroys the assembly of the T3SS of pathogenic bacteria, rendering the pathogen harmless.
In 2010, James R Alfano's team observed that immune-activated plants have the ability to inhibit the T3SS of pathogenic bacteria, but the nature of this "talisman" has always been shrouded in mystery.
Jian-Min Zhou and Xiaoguang Lei's team keenly captured this clue and proposed a hypothesis: this may be a natural plant metabolite produced by immune induction. With this conjecture, the two teams embarked on a 15-year "treasure hunt" journey - guided by biochemical activity, through separation and purification, they finally locked the key target in the maze of plant metabolites, namely erucamide. Unlike the "carpet bombing" of traditional plant resistance metabolites, erucamide performs a precise "surgical operation" on pathogenic bacteria, making them lose their pathogenicity without affecting their survival.
Erucamide is widely present in many plants including rice and soybeans. It will accumulate in large quantities after immune activation and has a broad spectrum of activity against a variety of pathogenic bacteria.
Genetic experiments have shown that the accumulation of erucamide is the key to plant immunity to pathogenic bacteria. Through the synthesis and activity analysis of various erucamide derivatives, the joint team revealed the key chemical structure that affects their activity.
Using a combination of proteomics, biochemical experiments, protein structure prediction, molecular docking and molecular dynamics simulation, the research team captured the wonderful picture of this microscopic war: erucamide specifically binds to HrcC, an important component of the T3SS, resulting in the failure of the pathogen's "biochemical weapon" assembly, causing the bacteria to "fail".
Figure 1. Working model of erucamide-mediated defense. (Miao, et al., 2025)
This work reveals a new mechanism of plant chemical defense, laying the foundation for the development of environmentally friendly biopesticides and the breeding of crop disease resistance molecules.
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