To be or not to be a nonhost species: A case study of the Leptosphaeria maculans and Brassica carinata interaction.

Leptosphaeria maculans is one of the major fungal pathogens on oilseed rape (Brassica napus), causing stem canker disease. The closely related Brassica species B. nigra, B.

Regulatory insight for a Zn2Cys6 transcription factor controlling effector-mediated virulence in a fungal pathogen of wheat.

The regulation of virulence in plant-pathogenic fungi has emerged as a key area of importance underlying host infections. Recent work has highlighted individual transcription factors (TFs) that serve important roles. A prominent example is PnPf2, a member of the Zn2Cys6 family of fungal TFs, which controls the expression of effectors and other virulence-associated genes in Parastagonospora nodorum during infection of wheat.

Breeding and management of major resistance genes to stem canker/blackleg in Brassica crops.

Blackleg (also known as Phoma or stem canker) is a major, worldwide disease of Brassica crop species, notably B. napus (rapeseed, canola), caused by the ascomycete fungus Leptosphaeria maculans. The outbreak and severity of this disease depend on environmental conditions and management practices, as well as a complex interaction between the pathogen and its hosts.

Regulation of effector gene expression as concerted waves in Leptosphaeria maculans: a two-player game.

Effector genes, encoding molecules involved in disease establishment, are concertedly expressed throughout the lifecycle of plant-pathogenic fungi. However, little is known about how effector gene expression is regulated. Since many effector genes are located in repeat-rich regions, the role of chromatin remodeling in their regulation was recently investigated, notably establishing that the repressive histone modification H3K9me3, deposited by KMT1, was involved in several fungal species including Leptosphaeria maculans.

Genome-wide mapping of histone modifications during axenic growth in two species of Leptosphaeria maculans showing contrasting genomic organization.

Leptosphaeria maculans 'brassicae' (Lmb) and Leptosphaeria maculans 'lepidii' (Lml) are closely related phytopathogenic species that exhibit a large macrosynteny but contrasting genome structure. Lmb has more than 30% of repeats clustered in large repeat-rich regions, while the Lml genome has only a small amount of evenly distributed repeats. Repeat-rich regions of Lmb are enriched in effector genes, expressed during plant infection.

Large-scale transcriptomics to dissect 2 years of the life of a fungal phytopathogen interacting with its host plant.

Background: The fungus Leptosphaeria maculans has an exceptionally long and complex relationship with its host plant, Brassica napus, during which it switches between different lifestyles, including asymptomatic, biotrophic, necrotrophic, and saprotrophic stages. The fungus is also exemplary of "two-speed" genome organisms in the genome of which gene-rich and repeat-rich regions alternate. Except for a few stages of plant infection under controlled conditions, nothing is known about the genes mobilized by the fungus throughout its life cycle, which may last several years in the field.

Building bridges to move recombination complexes.

A central feature of meiosis is pairing of homologous chromosomes, which occurs in two stages: coalignment of axes followed by installation of the synaptonemal complex (SC). Concomitantly, recombination complexes reposition from on-axis association to the SC central region. We show here that, in the fungus , this critical transition is mediated by robust interaxis bridges that contain an axis component (Spo76/Pds5), DNA, plus colocalizing Mer3/Msh4 recombination proteins and the Zip2-Zip4 mediator complex.

Destabilization of chromosome structure by histone H3 lysine 27 methylation.

Chromosome and genome stability are important for normal cell function as instability often correlates with disease and dysfunction of DNA repair mechanisms. Many organisms maintain supernumerary or accessory chromosomes that deviate from standard chromosomes. The pathogenic fungus Zymoseptoria tritici has as many as eight accessory chromosomes, which are highly unstable during meiosis and mitosis, transcriptionally repressed, show enrichment of repetitive elements, and enrichment with heterochromatic histone methylation marks, e.

The Genome Biology of Effector Gene Evolution in Filamentous Plant Pathogens.

Filamentous pathogens, including fungi and oomycetes, pose major threats to global food security. Crop pathogens cause damage by secreting effectors that manipulate the host to the pathogen's advantage. Genes encoding such effectors are among the most rapidly evolving genes in pathogen genomes.

Histone modifications rather than the novel regional centromeres of Zymoseptoria tritici distinguish core and accessory chromosomes.

Background: Supernumerary chromosomes have been found in many organisms. In fungi, these "accessory" or "dispensable" chromosomes are present at different frequencies in populations and are usually characterized by higher repetitive DNA content and lower gene density when compared to the core chromosomes. In the reference strain of the wheat pathogen, Zymoseptoria tritici, eight discrete accessory chromosomes have been found.

Chromatin-based control of effector gene expression in plant-associated fungi.

Plant-associated fungi often present in their genome areas enriched in repeat sequences and effector genes, the latter being specifically induced in planta. The location of effector genes in regions enriched in repeats has been shown to have an impact on adaptability of fungi but could also provide for tight control of effector gene expression through chromatin-based regulation. The distribution of two repressive histone marks was shown to be an important regulatory layer in two fungal species with different lifestyles.

Chromatin analyses of Zymoseptoria tritici: Methods for chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq).

The presence or absence of specific transcription factors, chromatin remodeling machineries, chromatin modification enzymes, post-translational histone modifications and histone variants all play crucial roles in the regulation of pathogenicity genes. Chromatin immunoprecipitation (ChIP) followed by high-throughput sequencing (ChIP-seq) provides an important tool to study genome-wide protein-DNA interactions to help understand gene regulation in the context of native chromatin. ChIP-seq is a convenient in vivo technique to identify, map and characterize occupancy of specific DNA fragments with proteins against which specific antibodies exist or which can be epitope-tagged in vivo.

The APSES transcription factor LmStuA is required for sporulation, pathogenic development and effector gene expression in Leptosphaeria maculans.

Leptosphaeria maculans causes stem canker of oilseed rape (Brassica napus). The APSES transcription factor StuA is a key developmental regulator of fungi, involved in morphogenesis, conidia production and also more recently described as required for secondary metabolite production and for effector gene expression in phytopathogenic fungi. We investigated the involvement of the orthologue of StuA in L.

Epigenetic control of effector gene expression in the plant pathogenic fungus Leptosphaeria maculans.

Plant pathogens secrete an arsenal of small secreted proteins (SSPs) acting as effectors that modulate host immunity to facilitate infection. SSP-encoding genes are often located in particular genomic environments and show waves of concerted expression at diverse stages of plant infection. To date, little is known about the regulation of their expression.