Detect, deploy, defend: Chloroplasts at the forefront of the host pathogen interface

ALEXIA TOUFEXI; CIAN DUGGAN; POOJA PANDEY; ZACHARY SAVAGE; MARÍA EUGENIA SEGRETIN; LOK HIM YUEN; DAVID GABORIAU; ALEXANDRE Y LEARY; VIRENDRASINH S KHANDARE; ANDREW WARD; STANLEY BOTCHWAY; INDRANIL PAN; MARTIN SCHATTAT; IMOGEN SPARKES; TOLGA BOZKURT

Glasgow

Congreso; XVIII International Congress on Molecular Plant-Microbe Interactions - IS-MPMI 2019; 2019

IS-MPMI

Chloroplasts are light harvesting organelles that arose from ancient endosymbiotic cyanobacteria. Upon immune activation, chloroplasts switchoff photosynthesis, produce anti-microbial compounds, and develop tubular extensions called stromules, some of which are observed to extendtoward the nucleus. The Irish potato famine pathogen Phytophthora infestans produces intracellular infection structures known as haustoria.These provide the key interface between host and pathogen where nutrients are taken from the host and exchanged for effectors which sabotageplant immune responses. We report that chloroplasts navigate to the pathogen interface to counter infection by the Irish potato famine pathogenPhytophthora infestans, physically associating with the specialised membrane that engulfs pathogen haustoria. Outer envelope protein,chloroplast unusual positioning1 (CHUP1), anchors chloroplasts to the host-pathogen interface. Stromules are induced during infection in aCHUP1-dependent manner, embracing haustoria and reaching between chloroplasts, to form dynamic organelle clusters. Infection-triggeredreprogramming of chloroplasts relies on surface immune signaling, whereas pathogen effectors subvert these immune pulses. Chloroplast aredeployed focally, and coordinate to restrict pathogen entry into plant cells, a process actively countered by parasite effectors.