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Poster

Session: Session 2 Presenting Authors at Posters (Evens)

P-442 - Plant immunity-mediated host cell death during the necrotrophic phase of hemibiotrophic fungal pathogen infection

Thursday, July 17, 2025
13:30 - 15:15  
Location: Confex Hall 3
Spatial & temporal resolution of the interaction interface

Hemibiotrophic pathogens infect living host tissues in the early biotrophic phase and spread within dead host tissues in the later necrotrophic phase. While previous studies suggest that virulence factors produced by hemibiotrophic pathogens kill host cells during the necrotrophic phase, it remains unclear whether the host immune system also plays a role in this process. Here, using Colletotrichum higginsianum, a hemibiotrophic fungal pathogen infecting Arabidopsis thaliana, we demonstrated that plant immune system contributes to the host cell death during the necrotrophic phase. Our cytological analysis revealed that, in wild-type A. thaliana, hypersensitive-response-like cell death, marked by trypan blue staining, occurs in mesophyll cells distant from invaded epidermal cells during the necrotrophic phase. However, this trypan-blue stained mesophyll cell death was absent in a mutant plant lacking a key immune component, while allowing a significant increase in fungal growth. These findings suggest that A. thaliana recognizes C. higginsianum in epidermal cells and activate a signaling pathway that triggers cell death in distant mesophyll cells. To test this hypothesis, we performed single-nucleus RNA-seq and identified candidate genes contributing to mesophyll-specific cell death. Our study provides insights into how the plant immune system mediates host cell death during the necrotrophic phase of hemibiotrophic pathogens and proposes a potential mechanism for this process.