Identification and Characterization of Plant Cell Death–Inducing Secreted Proteins From <i>Ustilaginoidea virens</i>

Fang, Anfei; Han, Yanqing; Zhang, Nan; Zhang, Min; Liu, Lijuan; Li, Shuai; Lu, Fei; Sun, Wenxian

doi:10.1094/mpmi-09-15-0200-r

Cited by 74 publications

(98 citation statements)

References 61 publications

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“…2) but also for its cell death–inducing activity (Fig. 3) 15, 33, 34 . We found that cell death was only observable with PstSCR1-FLAG when expressed in the strong pTRBO vector.…”

Section: Resultsmentioning

confidence: 99%

A Puccinia striiformis f. sp. tritici secreted protein activates plant immunity at the cell surface

Dagvadorj

Ozketen

Andac

et al. 2017

Sci Rep

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Pathogens secrete effector proteins to suppress host immunity, mediate nutrient uptake and subsequently enable parasitism. However, on non-adapted hosts, effectors can be detected as non-self by host immune receptors and activate non-host immunity. Nevertheless, the molecular mechanisms of effector triggered non-host resistance remain unknown. Here, we report that a small cysteine-rich protein PstSCR1 from the wheat rust pathogen Puccinia striiformis f. sp. tritici (Pst) activates immunity in the non-host solanaceous model plant Nicotiana benthamiana. PstSCR1 homologs were found to be conserved in Pst, and in its closest relatives, Puccinia graminis f. sp. tritici and Puccinia triticina. When PstSCR1 was expressed in N. benthamiana with its signal peptide, it provoked the plant immune system, whereas no stimulation was observed when it was expressed without its signal peptide. PstSCR1 expression in N. benthamiana significantly reduced infection capacity of the oomycete pathogens. Moreover, apoplast-targeted PstSCR1 triggered plant cell death in a dose dependent manner. However, in Brassinosteroid insensitive 1-Associated Kinase 1 (SERK3/BAK1) silenced N. benthamiana, cell death was remarkably decreased. Finally, purified PstSCR1 protein activated defence related gene expression in N. benthamiana. Our results show that a Pst-secreted protein, PstSCR1 can activate surface mediated immunity in non-adapted hosts and contribute to non-host resistance.

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“…2) but also for its cell death–inducing activity (Fig. 3) 15, 33, 34 . We found that cell death was only observable with PstSCR1-FLAG when expressed in the strong pTRBO vector.…”

Section: Resultsmentioning

confidence: 99%

A Puccinia striiformis f. sp. tritici secreted protein activates plant immunity at the cell surface

Dagvadorj

Ozketen

Andac

et al. 2017

Sci Rep

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“…It was predicted that UV_2799 encodes a putative secreted cysteine‐rich effector (named thereafter SCRE1) in U. virens (Zhang et al ., ) . We first used a yeast secretion system to verify the functionality of the SCRE1 signal peptide (Fang et al , ; Jacobs et al ., ). The predicted signal peptide‐encoding sequence of SCRE1 was fused in frame with a truncated SUC2 gene that encodes invertase but lacks its own signal peptide.…”

Section: Resultsmentioning

confidence: 99%

“…Effectors play essential roles in fungal virulence (Lo Presti et al , ; Oliveira‐Garcia and Valent, ). However, despite genomics‐based predictions, few effectors have been functionally characterized in U. virens (Fang et al , ). In this study, we identified an essential virulence effector, SCRE1, in U. virens and provided evidence that this effector suppresses rice immunity.…”

Section: Discussionmentioning

confidence: 99%

“…These mycotoxins inhibit cell division and impose a health threat to humans and animals (Koiso et al , ). Because false smut is a newly emerging disease, little is known about the virulence mechanisms of U. virens , which makes this fungal disease difficult to predict and manage (Fang et al , ; Han et al , ; Zhang et al ., ).…”

Section: Introductionmentioning

confidence: 99%

“…Comparative transcriptome analyses suggest that a set of U. virens secreted proteins could be putative effectors (Han et al , ; Zhang et al ., ). In a large‐scale screening, eight U. virens putative effectors were identified to induce the immunity‐associated hypersensitive responses when transiently overexpressed in the nonhost plant Nicotiana benthamiana (Fang et al , ). On the other hand, when delivered by the type III secretion system of the bacterium Burkholderia glumae , many putative U. virens effectors were found to suppress B. glumae ‐induced hypersensitive cell death in N. benthamiana (Zhang et al ., ).…”

Section: Introductionmentioning

confidence: 99%

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The essential effector SCRE1 in Ustilaginoidea virens suppresses rice immunity via a small peptide region

Zhang

Yang

Fang

et al. 2020

Molecular Plant Pathology

Self Cite

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Summary The biotrophic fungal pathogen Ustilaginoidea virens causes rice false smut, a newly emerging plant disease that has become epidemic worldwide in recent years. The U. virens genome encodes many putative effector proteins that, based on the study of other pathosystems, could play an essential role in fungal virulence. However, few studies have been reported on virulence functions of individual U. virens effectors. Here, we report our identification and characterization of the secreted cysteine‐rich protein SCRE1, which is an essential virulence effector in U. virens. When SCRE1 was heterologously expressed in Magnaporthe oryzae, the protein was secreted and translocated into plant cells during infection. SCRE1 suppresses the immunity‐associated hypersensitive response in the nonhost plant Nicotiana benthamiana. Induced expression of SCRE1 in rice also inhibits pattern‐triggered immunity and enhances disease susceptibility to rice bacterial and fungal pathogens. The immunosuppressive activity is localized to a small peptide region that contains an important ‘cysteine‐proline‐alanine‐arginine‐serine’ motif. Furthermore, the scre1 knockout mutant generated using the CRISPR/Cas9 system is attenuated in U. virens virulence to rice, which is greatly complemented by the full‐length SCRE1 gene. Collectively, this study indicates that the effector SCRE1 is able to inhibit host immunity and is required for full virulence of U. virens.

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Simple and efficient heterologous expression of necrosis‐inducing effectors using the model plant Nicotiana benthamiana

Dagvadorj

Solomon

2021

Plant Direct

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Plant fungal pathogens cause devastating diseases on cereal plants and threaten global food security. During infection, these pathogens secrete proteinaceous effectors that promote disease. Some of these effectors from necrotrophic plant pathogens induce a cell death response (necrosis), which facilitates pathogen growth in planta. Characterization of these effectors typically requires heterologous expression, and microbial expression systems such as bacteria and yeast are the predominantly used. However, microbial expression systems often require optimization for any given effector and are, in general, not suitable for effectors involving cysteine bridges and posttranslational modifications for activity. Here, we describe a simple and efficient method for expressing such effectors in the model plant Nicotiana benthamiana.Briefly, an effector protein is transiently expressed and secreted into the apoplast of N. benthamiana by Agrobacterium-mediated infiltration. Two to three days subsequent to agroinfiltration, the apoplast from the infiltrated leaves is extracted and can be directly used for phenotyping on host plants. The efficacy of this approach was demonstrated by expressing the ToxA, Tox3, and Tox1 necrosis-inducing effectors from Parastagonospora nodorum. All three effectors produced in N. benthamiana were capable of inducing necrosis in wheat lines, and two of three showed visible bands on Coomassie-stained gel. These data suggest that N. benthamiana-agroinfiltration system is a feasible tool to obtain fungal effectors, especially those that require disulfide bonds and posttranslational modifications. Furthermore, due to the low number of proteins typically observed in the apoplast (compared with intracellular), this simple and high-throughput approach circumvents the requirement to lyse cells and further purifies the target proteins that are required in other heterologous systems.Because of its simplicity and potential for high-throughput, this method is highly amenable to the phenotyping of candidate protein effectors on host plants.

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Identification and Characterization of Plant Cell Death–Inducing Secreted Proteins From Ustilaginoidea virens

Cited by 74 publications

References 61 publications

A Puccinia striiformis f. sp. tritici secreted protein activates plant immunity at the cell surface

A Puccinia striiformis f. sp. tritici secreted protein activates plant immunity at the cell surface

The essential effector SCRE1 in Ustilaginoidea virens suppresses rice immunity via a small peptide region

Simple and efficient heterologous expression of necrosis‐inducing effectors using the model plant Nicotiana benthamiana

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