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Poster

Session: Session 2 Presenting Authors at Posters (Evens)

P-102 - A Phytophthora effector targets the host chloroplast movement mechanism

Thursday, July 17, 2025
13:30 - 15:15  
Location: Confex Hall 3
Effector Interference Mechanisms
Pathogens secrete a variety of effector proteins to act as virulence factors in the host apoplast and cytoplasm. Effectors promote pathogen infection by various mechanisms including suppression of host immune response, alteration of organelle function and promotion of nutrient acquisition from the host. Chloroplasts, besides being a central hub in plant metabolism, play a key role in plant immunity by synthesizing defense hormone precursors and generating reactive oxygen species, and hence tend to be a prime target of effectors. Recent evidence indicates that chloroplasts alter morphology and accumulate at the plant/pathogen interface called haustorium during infection. We identified an RXLR effector from Phytophthora palmivora that promotes the pathogen infection when transiently expressed in Nicotiana benthamiana leaves. It is conserved in various Phytophthora species and appears to have a unique structural fold. The effector targets a specific kinesin involved in regulating chloroplast-actin filaments and cytosolic actin filament density is reduced in plant cells expressing the effector. Additionally, we observe an impact on nuclear movement. Ongoing experiments clarify whether the altered nuclear dynamics are an indirect effect due to altered chloroplast-nucleus linkages. Our work points towards Phytophthora species using effectors to target host chloroplast movement towards the haustorium to possibly mitigate host immunity.