The plant–pathogen haustorial interface at a glance

Abstract

Many filamentous pathogens invade plant cells through specialized hyphae called haustoria. These infection structures are enveloped by a newly synthesized plant-derived membrane called the extrahaustorial membrane (EHM). This specialized membrane is the ultimate interface between the plant and pathogen, and is key to the success or failure of infection. Strikingly, the EHM is reminiscent of host-derived membrane interfaces that engulf intracellular metazoan parasites. These perimicrobial interfaces are critical sites where pathogens facilitate nutrient uptake and deploy virulence factors to disarm cellular defenses mounted by their hosts. Although the mechanisms underlying the biogenesis and functions of these host-microbe interfaces are poorly understood, recent studies have provided new insights into the cellular and molecular mechanisms involved. In this Cell Science at a Glance and the accompanying poster, we summarize these recent advances with a specific focus on the haustorial interfaces associated with filamentous plant pathogens. We highlight the progress in the field that fundamentally underpin this research topic. Furthermore, we relate our knowledge of plant-filamentous pathogen interfaces to those generated by other plant-associated organisms. Finally, we compare the similarities between host-pathogen interfaces in plants and animals, and emphasize the key questions in this research area.

Host-interactor screens ofPhytophthora infestansRXLR proteins reveal vesicle trafficking as a major effector-targeted process

“…PexRD12/31 effectors add to a growing list of perihaustorial effectors that are associated with polarized markers at the P. infestans haustorial interface (Bozkurt and Kamoun, 2020). We also discovered that the PexRD12/31 family of RXLR-WY effectors associate with 16 vesicle-trafficking N. benthamiana proteins in a relatively specific manner (Table S3).…”

“…We conclude that PexRD31 specifically localizes to RabC1-positive mobile vesicles and that this localization is specific to PexRD31. We previously reported that several endomembrane compartments are directed towards P. infestans haustoria during infection (Bozkurt et al, 2012;Bozkurt et al, 2015;Dagdas et al, 2018;Bozkurt and Kamoun, 2020). In addition, some effectors display perihaustorial localization accumulating around haustoria in infected plant cells (Bozkurt et al, 2011;Saunders et al, 2012;Dagdas et al, 2018;Wang et al, 2018).…”

“…Processes taking place at this host-pathogen interface are thought to have a major impact on the outcome of the interaction. The mechanisms underlying the biogenesis and functions of host-microbe interfaces remain poorly understood although recent advances have been made (Bozkurt and Kamoun, 2020;Rausche et al, 2020). Well-studied examples of these specialized hyphae are haustoria formed by P. infestans and other filamentous pathogens.…”

“…This study aims at identifying the host plant proteins that are associated with a representative set of P. infestans RXLR effectors to generate a pathogen-host protein interactome and gain an overview of the diversity of effector-targeted processes in this pathosystem. To achieve our aim, we performed an in planta coIP/MS screen in the model plant Nicotiana benthamiana, which has emerged as an optimal experimental system for cell biology and biochemistry studies of P. infestans-host interactions (Bozkurt and Kamoun 2020). In addition, N. benthamiana is particularly appropriate for large-scale coIP/MS screens thanks to rapid transient protein expression using Agrobacterium tumefaciens (agroinfiltration) and the availability of a genome sequence that improves MS proteome predictions (Goodin et al, 2008;Derevnina et al, 2019;Zess et al, 2019).…”

Phytophthora palmivora–Cocoa Interaction

“…Intracellular penetration can occur and germ tubes from encysted zoospores can become swollen and produce a penetration peg [ 57 ]. Then, specialised hyphae invade plant cells to form haustoria ( Figure 2 D–E) [ 26 , 63 , 64 , 65 , 66 , 67 ]. Histological studies in Quercus ilex roots during P. cinnamomi infection found haustoria-like structures in the cortical root and phloem cells [ 63 ].…”