Groundbreaking research by Guo et al. (2023) provides new insights into the molecular and cellular mechanisms underpinning host plant resistance (HPR) against herbivorous insects. This phenomenon has been under investigation for over half a century. This study represents a significant advance in understanding how plants interact with insects, providing crucial knowledge that could shape the future of agricultural crop production.
Plants utilize receptor-like kinases and nucleotide-binding leucine-rich repeat receptors to defend against herbivores. However, comprehending the full scope of these defenses has been challenging, primarily due to the elusive identity and sensing mechanisms of insect avirulence effectors. The researchers’ work has now filled this knowledge gap.
The team identified a particular protein in the saliva of the brown planthopper, an insect that poses a substantial threat to rice crops. This protein, the BPH14-interacting salivary protein (BISP), is secreted into the rice plant during feeding. BISP interacts with a specific rice protein in susceptible rice plants to suppress the plant’s basal defenses. However, in resistant plants, the plant immune receptor BPH14 directly binds BISP to activate HPR.
This finding is particularly significant because continual activation of BPH14-mediated immunity can harm plant growth and productivity. Thus, a delicate balance must be struck. The researchers found that this balance is achieved through autophagy, a cellular process that breaks down and recycles unnecessary or dysfunctional components.
In the presence of BISP, both BISP, and BPH14 bind to the autophagy cargo receptor in rice, leading to the degradation of BISP. When feeding by the brown planthoppers stops, autophagy restores cellular homeostasis by downregulating HPR. This autophagy-controlled regulation mechanism allows the plants to manage their defense response based on the threat level adaptively.
This study’s findings unravel the interaction between insect saliva proteins and plant immune receptors and highlight a novel three-way interaction system that controls plant immunity. This discovery opens new avenues for developing high-yield crops that are also more resistant to insect pests, promising significant benefits for agriculture worldwide.
Photo by Andhika Y. Wiguna on Unsplash
