Publishing type：Research paper (scientific journal)  

Summary

Plants activate immunity upon recognition of pathogen‐associated molecular patterns. Although phytopathogens have evolved a set of effector proteins to counteract plant immunity, some effectors are perceived by hosts and induce immune responses.

Here, we show that two secreted ribonuclease effectors, SRN1 and SRN2, encoded in a phytopathogenic fungus, Colletotrichum orbiculare, induce cell death in a signal peptide‐ and catalytic residue‐dependent manner, when transiently expressed in Nicotiana benthamiana. The pervasive presence of SRN genes across Colletotrichum species suggested the conserved roles.

Using a transient gene expression system in cucumber (Cucumis sativus), an original host of C. orbiculare, we show that SRN1 and SRN2 potentiate host pattern‐triggered immunity responses. Consistent with this, C. orbiculare SRN1 and SRN2 deletion mutants exhibited increased virulence on the host. In vitro analysis revealed that SRN1 specifically cleaves single‐stranded RNAs at guanosine, leaving a 3′‐end phosphate. Importantly, the potentiation of C. sativus responses by SRN1 and SRN2, present in the apoplast, depends on ribonuclease catalytic residues.

We propose that the pathogen‐derived apoplastic guanosine‐specific single‐stranded endoribonucleases lead to immunity potentiation in plants.

DOI： 10.1111/nph.19582

Other URL： https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/nph.19582

Publishing type：Research paper (scientific journal)  

Abstract

Anthracnose caused by Colletotrichum spp. is an economically important disease of many plants, including grain, vegetable, and fruit crops. Next-generation sequencing technologies have led to a dramatic growth in the size and availability of genomic data in public repositories. Beginning with genome sequencing projects of C. higginsianum and C. graminicola, many Colletotrichum spp. genomes have been sequenced due to their scientific and agricultural importance. Today, we can access more than a hundred genome assemblies of Colletotrichum spp. Utilizing those abundant genomic datasets would enable a better understanding of adaptation mechanisms of Colletotrichum spp. at the genomic level, which could help to control this important group of pathogens. In this review, we outline the development and application of genomic resources of Colletotrichum spp. with a focus on the benefits of genomic data-driven studies, including reverse-genetics, a range of comparative genomic analyses, species identification, taxonomy, and diagnosis, while describing the potential pitfalls of genome analysis. Further, we discuss future research directions that could allow a more comprehensive understanding of genomic diversity within the genus Colletotrichum.

DOI： 10.1007/s10327-022-01097-y

Other URL： https://link.springer.com/article/10.1007/s10327-022-01097-y/fulltext.html

Publishing type：Research paper (scientific journal)  

DOI： 10.1111/ppa.13532

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

<jats:p>Plant pathogens secrete proteins, known as effectors, that promote infection by manipulating host cells. Members of the phytopathogenic fungal genus <jats:italic>Colletotrichum</jats:italic> collectively have a broad host range and generally adopt a hemibiotrophic lifestyle that includes an initial biotrophic phase and a later necrotrophic phase. We hypothesized that <jats:italic>Colletotrichum</jats:italic> fungi use a set of conserved effectors during infection to support the two phases of their hemibiotrophic lifestyle. This study aimed to examine this hypothesis by identifying and characterizing conserved effectors among <jats:italic>Colletotrichum</jats:italic> fungi. Comparative genomic analyses using genomes of ascomycete fungi with different lifestyles identified seven effector candidates that are conserved across the genus <jats:italic>Colletotrichum</jats:italic>. Transient expression assays showed that one of these putative conserved effectors, CEC3, induces nuclear expansion and cell death in <jats:italic>Nicotiana benthamiana</jats:italic>, suggesting that CEC3 is involved in promoting host cell death during infection. Nuclear expansion and cell death induction were commonly observed in CEC3 homologs from four different <jats:italic>Colletotrichum</jats:italic> species that vary in host specificity. Thus, CEC3 proteins could represent a novel class of core effectors with functional conservation in the genus C<jats:italic>olletotrichum</jats:italic>.</jats:p>

DOI： 10.3389/fmicb.2021.682155

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

<jats:title>Abstract</jats:title><jats:p>Many plant pathogenic fungi contain conditionally dispensable (CD) chromosomes that are associated with virulence, but not growth in vitro. Virulence-associated CD chromosomes carry genes encoding effectors and/or host-specific toxin biosynthesis enzymes that may contribute to determining host specificity. <jats:italic>Fusarium oxysporum</jats:italic> causes devastating diseases of more than 100 plant species. Among a large number of host-specific forms, <jats:italic>F. oxysporum</jats:italic> f. sp. <jats:italic>conglutinans</jats:italic> (<jats:italic>Focn</jats:italic>) can infect Brassicaceae plants including Arabidopsis (<jats:italic>Arabidopsis thaliana</jats:italic>) and cabbage. Here we show that <jats:italic>Focn</jats:italic> has multiple CD chromosomes. We identified specific CD chromosomes that are required for virulence on Arabidopsis, cabbage, or both, and describe a pair of effectors encoded on one of the CD chromosomes that is required for suppression of Arabidopsis-specific phytoalexin-based immunity. The effector pair is highly conserved in <jats:italic>F. oxysporum</jats:italic> isolates capable of infecting Arabidopsis, but not of other plants. This study provides insight into how host specificity of <jats:italic>F. oxysporum</jats:italic> may be determined by a pair of effector genes on a transmissible CD chromosome.</jats:p>

DOI： 10.1038/s42003-021-02245-4

PubMed

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)