An adult whitefly (Bemisia tabaci) on an eggplant's leaf. Image credit: John Smith (CC BY-SA 4.0)” or “Image credit: CC BY-SA 4.0
Plants cannot escape from insects, so they rely on their own defense systems. One key strategy involves proteins on the cell surface that act as sensors. These sensors detect insect attacks and trigger protective responses within the plant.
Scientists have long known that microbes can disable these sensors, thereby weakening plant defences. However, it has been unclear whether plant-eating insects use similar tactics. Many insects feed by inserting needle-like mouthparts (stylets) into plants and releasing saliva, which contains proteins capable of altering plant responses.
To investigate this, Wang et al. studied two major crop pests: the whitefly Bemisia tabaci and the brown planthopper Nilaparvata lugens. They focused on a plant sensor called RLP4, a surface protein that helps plants recognize insect attack and activate defenses. The researchers found that both insects produce salivary proteins that bind to RLP4 and trigger its breakdown inside plant cells. This weakens the plant’s defenses and makes feeding easier for the insects.
Experiments in tobacco and rice plants showed that increasing RLP4 levels improved resistance to these pests. In contrast, reducing RLP4 levels or introducing the insect salivary proteins made plants more susceptible. Although the two insect proteins are unrelated, they perform the same function, suggesting that different insects have independently evolved similar strategies to overcome plant defenses.
These findings reveal a shared mechanism used by plant-eating insects and provide new insight into plant–insect interactions. In the future, this knowledge could help guide the development of crops with improved resistance to insect pests. However, further research is needed to determine how widespread this mechanism is and how it can be effectively applied in agriculture.
