Form and function of fungal and oomycete effectors

Sharpee, William; Dean, Ralph A.

doi:10.1016/j.fbr.2016.04.001

Cited by 45 publications

(34 citation statements)

References 120 publications

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“…This shows that the expression of SP genes is important for larch infection and central to biotrophy on both hosts. Many effectors of fungal pathogens are secreted proteins, including avirulence effectors identified in the flax rust fungus Melampsora lini (Tyler and Rouxel, 2011;Sharpee andDean, 2016, Duplessis et al, 2012). Rust fungi exhibit large secretomes composed of expanded gene families and SSP genes specifically expressed in planta represent priority candidate effectors (Aime et al, 2017;Petre et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

The rust fungus Melampsora larici-populina expresses a conserved genetic program and distinct sets of secreted protein genes during infection of its two host plants, larch and poplar

Lorrain

Marchal

Hacquard

et al. 2017

Preprint

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SummaryMechanims required for broad spectrum or specific host colonization of plant parasites are poorly understood. As a perfect illustration, heteroecious rust fungi require two alternate host plants to complete their life cycle. Melampsora larici-populina infects two taxonomically unrelated plants, larch on which sexual reproduction is achieved and poplar on which clonal multiplication occurs leading to severe epidemics in plantations. High-depth RNA sequencing was applied to three key developmental stages of M. larici-populina infection on larch: basidia, pycnia and aecia. Comparative transcriptomics of infection on poplar and larch hosts was performed using available expression data. Secreted protein was the only significantly over-represented category among differentially expressed M. laricipopulina genes in basidia, pycnia and aecia compared together, highlighting their probable involvement in the infection process. Comparison of fungal transcriptomes in larch and poplar revealed a majority of rust genes commonly expressed on the two hosts and a fraction exhibiting a host-specific expression. More particularly, gene families encoding small secreted proteins presented striking expression profiles that highlight probable candidate effectors specialized on each host. Our results bring valuable new information about the biological cycle of rust fungi and identify genes that may contribute to host specificity.

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Section: Discussionmentioning

confidence: 99%

The rust fungus Melampsora larici-populina expresses a conserved genetic program and distinct sets of secreted protein genes during infection of its two host plants, larch and poplar

Lorrain

Marchal

Hacquard

et al. 2017

Preprint

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“…Typically, 6-10% of the fungal proteome is secreted with several hundred representing SSP effector candidates in hemibiotrophic or biotrophic phytopathogens (Lo Presti et al, 2015;Dong et al, 2016). Fungal effectors are often considered as dispensable due to functional or quantitative redundancy (Sharpee & Dean, 2016).…”

Section: Introductionmentioning

confidence: 99%

Life, death and rebirth of avirulence effectors in a fungal pathogen of Brassica crops, Leptosphaeria maculans

2017

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Contents 526I.526II.527III.527IV.529V.529VI.530VII.530531References531 Summary In agricultural systems, major (R) genes for resistance in plants exert strong selection pressure on cognate/corresponding avirulence effector genes of phytopathogens. However, a complex interplay often exists between trade‐offs linked to effector function and the need to escape R gene recognition. Here, using the Leptosphaeria maculans–oilseed rape pathosystem we review evolution of effectors submitted to multiple resistance gene selection. Characteristics of this pathosystem include a crop in which resistance genes have been deployed intensively resulting in ‘boom and bust’ cycles; a fungal pathogen with a high adaptive potential in which seven avirulence genes are cloned and for which population surveys have been coupled with molecular analysis of events responsible for virulence. The mode of evolution of avirulence genes, all located in dispensable parts of the ‘two‐speed’ genome, is a highly dynamic gene‐specific process. In some instances, avirulence genes are readily deleted under selection. However, others, even when located in the most plastic genome regions, undergo only limited point mutations or their avirulence phenotype is ‘camouflaged’ by another avirulence gene. Thus, while hundreds of effector genes are present, some effectors are likely to have an important and nonredundant function, suggesting functional redundancy and dispensability of effectors might not be the rule.

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“…RXLR effectors, which exist by the hundreds in each oomycete genome, are amongst the best‐characterized oomycete effectors (Baxter et al ., ; Haas et al ., ; Jiang et al ., ; Tyler et al ., ). In recent years, a large number of studies have been carried out to elucidate the biological functions of RXLR effectors from Phytophthora infestans , P. sojae and Hyaloperonospora arabidopsidis (Anderson et al ., ; Sharpee and Dean, ; Wang Q et al ., ; Whisson et al ., ; Zheng et al ., ). However, little is known about RXLR effectors from P. parasitica , except PSE1, which has been reported to alter the auxin content and to promote infection (Evangelisti et al ., ).…”

Section: Introductionmentioning

confidence: 99%

An RXLR effector secreted by Phytophthora parasitica is a virulence factor and triggers cell death in various plants

Huang

Liu

et al. 2018

Molecular Plant Pathology

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Summary RXLR effectors encoded by Phytophthora species play a central role in pathogen–plant interactions. An understanding of the biological functions of RXLR effectors is conducive to the illumination of the pathogenic mechanisms and the development of disease control strategies. However, the virulence function of Phytophthora parasitica RXLR effectors is poorly understood. Here, we describe the identification of a P. parasitica RXLR effector gene, PPTG00121 ( PpE4 ), which is highly transcribed during the early stages of infection. Live cell imaging of P. parasitica transformants expressing a full‐length PpE4 (E4FL)‐mCherry protein indicated that PpE4 is secreted and accumulates around haustoria during plant infection. Silencing of PpE4 in P. parasitica resulted in significantly reduced virulence on Nicotiana benthamiana . Transient expression of PpE4 in N. benthamiana in turn restored the pathogenicity of the PpE4 ‐silenced lines. Furthermore, the expression of PpE4 in both N. benthamiana and Arabidopsis thaliana consistently enhanced plant susceptibility to P. parasitica . These results indicate that PpE4 contributes to pathogen infection. Finally, heterologous expression experiments showed that PpE4 triggers non‐specific cell death in a variety of plants, including tobacco, tomato, potato and A. thaliana . Virus‐induced gene silencing assays revealed that PpE4 ‐induced cell death is dependent on HSP90 , NPK and SGT1 , suggesting that PpE4 is recognized by the plant immune system. In conclusion, PpE4 is an important virulence RXLR effector of P. parasitica and recognized by a wide range of host plants.

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Form and function of fungal and oomycete effectors

Cited by 45 publications

References 120 publications

The rust fungus Melampsora larici-populina expresses a conserved genetic program and distinct sets of secreted protein genes during infection of its two host plants, larch and poplar

The rust fungus Melampsora larici-populina expresses a conserved genetic program and distinct sets of secreted protein genes during infection of its two host plants, larch and poplar

Life, death and rebirth of avirulence effectors in a fungal pathogen of Brassica crops, Leptosphaeria maculans

An RXLR effector secreted by Phytophthora parasitica is a virulence factor and triggers cell death in various plants

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