Hyaloperonospora arabidopsidis: A Model Pathogen of Arabidopsis

McDowell, John M.

doi:10.1007/978-3-662-44056-8_10

Cited by 10 publications

(9 citation statements)

References 122 publications

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“…To explore how broadly OMV-mediated immune activation was able to protect against pathogens, we tested their effect on oomycete pathogenesis. Hyaloperonospora arabidopsidis is a well-studied biotrophic pathogen, requiring a living host to grow and reproduce (Xin and He, 2013, Coates and Beynon, 2010, McDowell, 2014, Kamoun et al, 2015. In A. thaliana, pre-treatment with Pst OMVs led to a reduction in oomycete growth upon subsequent challenge ( Figure 3A).…”

Section: Pst and Pf Omvs Protect Against Oomycete Challenge In Multipmentioning

confidence: 99%

Protective Plant Immune Responses are Elicited by Bacterial Outer Membrane Vesicles

McMillan

Zebell

Ristaino

et al. 2020

Preprint

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SummaryBacterial outer membrane vesicles (OMVs) perform a variety of functions in bacterial survival and virulence. In mammalian systems, OMVs activate immune responses and have been exploited as vaccines. However, little work has focused on the role that OMVs play during interactions with plant hosts. Here we report that OMVs from the pathogenic Pseudomonas syringae and the beneficial Pseudomonas fluorescens activate plant immune responses that protect against bacterial and oomycete pathogens. OMVs from these two species display different sensitivity to biochemical stressors, which could indicate differences in OMV cargo packaging. Furthermore, our study shows that OMV-induced protective immune responses are T3SS- and protein-independent, while OMV-mediated seedling growth inhibition largely depends on protein cargo. Importantly, OMV-mediated plant responses are distinct from those triggered by PAMP/MAMPs or effector molecules alone. OMVs provide a unique opportunity to study virulence factors in combination and add a new layer of interaction and complexity to host-microbe interactions.

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Section: Pst and Pf Omvs Protect Against Oomycete Challenge In Multipmentioning

confidence: 99%

Protective Plant Immune Responses are Elicited by Bacterial Outer Membrane Vesicles

McMillan

Zebell

Ristaino

et al. 2020

Preprint

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“…The Hpa – Arabidopsis interaction is a valuable reference pathosystem, and its utility has been enhanced by recent sequencing of the Hpa genome, the identification of effector gene candidates and screens for effector targets (Baxter et al ., ; Cabral et al ., ; Caillaud et al ., ; Fabro et al ., ; Mukhtar et al ., ; McDowell, ). These and other advances have created a critical need for new assays that accurately measure small differences in Hpa growth in planta .…”

Section: Discussionmentioning

confidence: 99%

“…Hpa is one of a few eukaryotic microbes that are specifically adapted to Arabidopsis (Holub, ; Koch and Slusarenko, ). The Arabidopsis – Hpa interaction occurs frequently in nature, exhibiting a high level of polymorphism for resistance/susceptibility, lending itself as a useful pathosystem to exploit Arabidopsis for a better understanding of the molecular basis of plant–pathogen interactions and the evolution of obligate biotrophy (Baxter et al ., ; McDowell, ).…”

Section: Introductionmentioning

confidence: 99%

A PCR assay for the quantification of growth of the oomycete pathogen Hyaloperonospora arabidopsidis in Arabidopsis thaliana

Anderson

McDowell

2015

Molecular Plant Pathology

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The accurate quantification of disease severity is important for the assessment of host-pathogen interactions in laboratory or field settings. The interaction between Arabidopsis thaliana and its naturally occurring downy mildew pathogen, Hyaloperonospora arabidopsidis (Hpa), is a widely used reference pathosystem for plant-oomycete interactions. Current methods for the assessment of disease severity in the Arabidopsis-Hpa interaction rely on measurements at the terminal stage of pathogen development; namely, visual counts of spore-producing structures or the quantification of spore production with a haemocytometer. These assays are useful, but do not offer sensitivity for the robust quantification of small changes in virulence or the accurate quantification of pathogen growth prior to the reproductive stage. Here, we describe a quantitative real-time polymerase chain reaction (qPCR) assay for the monitoring of Hpa growth in planta. The protocol is rapid, inexpensive and can robustly distinguish small changes in virulence. We used this assay to investigate the dynamics of early Hpa mycelial growth and to demonstrate the proof of concept that this assay could be used in screens for novel oomycete growth inhibitors.

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“…This pathogen is frequently found in natural Arabidopsis populations (Holub & Beynon, 1996). Because Hpa is one of only two naturally occurring oomycete pathogens of Arabidopsis, it has been adopted as a reference organism for plant-oomycete interactions (McDowell, 2014). Hpa is also a reference organism for the obligate biotrophic lifestyle, in which pathogens extract nutrients exclusively from living host cells and cannot survive apart from their hosts (Coates & Beynon, 2010).…”

Section: Introductionmentioning

confidence: 99%

An oomycete RXLR effector triggers antagonistic plant hormone crosstalk to suppress host immunity

Anderson

Deb

Withers

et al. 2019

Preprint

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Understanding the mechanisms through which pathogens alter plant cell networks is essential for understanding plant-pathogen interactions and will inform efforts to reduce crop diseases. Oomycetes secrete diverse effector proteins into plant cells. The mechanisms through which these effectors promote virulence are largely unknown. We show that the HaRxL10 effector protein from the Arabidopsis thaliana pathogen Hyaloperonospora arabidopsidis (Hpa) targets a transcriptional repressor (JAZ3) involved in jasmonic acid (JA) signalling. This manipulation activates a regulatory cascade that inhibits salicylic acid (SA) signalling, which normally restricts Hpa infection. This virulence mechanism is functionally equivalent to but mechanistically distinct from activation of the antagonistic JA-SA hormone crosstalk by the bacterial JA-mimicking toxin coronatine and by bacterial Type III effectors. These results reveal a key role for JAZ3 in plant immunity and emphasize that JA-SA crosstalk is an Achilles’ heel in the plant immune system, vulnerable to manipulation by diverse microbes.

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Hyaloperonospora arabidopsidis: A Model Pathogen of Arabidopsis

Cited by 10 publications

References 122 publications

Protective Plant Immune Responses are Elicited by Bacterial Outer Membrane Vesicles

Protective Plant Immune Responses are Elicited by Bacterial Outer Membrane Vesicles

A PCR assay for the quantification of growth of the oomycete pathogen Hyaloperonospora arabidopsidis in Arabidopsis thaliana

An oomycete RXLR effector triggers antagonistic plant hormone crosstalk to suppress host immunity

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