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Effector diversification within compartments of the Leptosphaeria maculans genome affected by Repeat-Induced Point mutations.

ABSTRACT: Fungi are of primary ecological, biotechnological and economic importance. Many fundamental biological processes that are shared by animals and fungi are studied in fungi due to their experimental tractability. Many fungi are pathogens or mutualists and are model systems to analyse effector genes and their mechanisms of diversification. In this study, we report the genome sequence of the phytopathogenic ascomycete Leptosphaeria maculans and characterize its repertoire of protein effectors. The L. maculans genome has an unusual bipartite structure with alternating distinct guanine and cytosine-equilibrated and adenine and thymine (AT)-rich blocks of homogenous nucleotide composition. The AT-rich blocks comprise one-third of the genome and contain effector genes and families of transposable elements, both of which are affected by repeat-induced point mutation, a fungal-specific genome defence mechanism. This genomic environment for effectors promotes rapid sequence diversification and underpins the evolutionary potential of the fungus to adapt rapidly to novel host-derived constraints.

SUBMITTER: Rouxel T

PROVIDER: S-EPMC3105345 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature

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Effector diversification within compartments of the Leptosphaeria maculans genome affected by Repeat-Induced Point mutations.

Rouxel Thierry T Grandaubert Jonathan J Hane James K JK Hoede Claire C van de Wouw Angela P AP Couloux Arnaud A Dominguez Victoria V Anthouard Véronique V Bally Pascal P Bourras Salim S Cozijnsen Anton J AJ Ciuffetti Lynda M LM Degrave Alexandre A Dilmaghani Azita A Duret Laurent L Fudal Isabelle I Goodwin Stephen B SB Gout Lilian L Glaser Nicolas N Linglin Juliette J Kema Gert H J GH Lapalu Nicolas N Lawrence Christopher B CB May Kim K Meyer Michel M Ollivier Bénédicte B Poulain Julie J Schoch Conrad L CL Simon Adeline A Spatafora Joseph W JW Stachowiak Anna A Turgeon B Gillian BG Tyler Brett M BM Vincent Delphine D Weissenbach Jean J Amselem Joëlle J Quesneville Hadi H Oliver Richard P RP Wincker Patrick P Balesdent Marie-Hélène MH Howlett Barbara J BJ

Nature communications 20110215

Fungi are of primary ecological, biotechnological and economic importance. Many fundamental biological processes that are shared by animals and fungi are studied in fungi due to their experimental tractability. Many fungi are pathogens or mutualists and are model systems to analyse effector genes and their mechanisms of diversification. In this study, we report the genome sequence of the phytopathogenic ascomycete Leptosphaeria maculans and characterize its repertoire of protein effectors. The L ...[more]

PMID: 21326234

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Project description: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. The genome of the Ascomycete Leptosphaeria maculans comprises alternating gene-rich GC-isochores and gene-poor AT-isochores. The AT-isochores harbor mosaics of transposable elements, encompassing one-third of the genome, and are enriched in putative effector genes that present similar expression patterns, namely no expression or low-level expression during axenic cultures compared to strong induction of expression during primary infection of oilseed rape (Brassica napus). Here, we investigated the involvement of one specific histone modification, histone H3 lysine 9 methylation (H3K9me3), in epigenetic regulation of concerted effector gene expression in L. maculans. For this purpose, we silenced the expression of two key players in heterochromatin assembly and maintenance, HP1 and DIM-5 by RNAi. By using HP1-GFP as a heterochromatin marker, we observed that almost no chromatin condensation is visible in strains in which LmDIM5 was silenced by RNAi. By whole genome oligoarrays we observed overexpression of 369 or 390 genes, respectively, in the silenced-LmHP1 and -LmDIM5 transformants during growth in axenic culture, clearly favouring expression of SSP-encoding genes within AT-isochores. The ectopic integration of four effector genes in GC-isochores led to their overexpression during growth in axenic culture. These data strongly suggest that epigenetic control, mediated by HP1 and DIM-5, represses the expression of at least part of the effector genes located in AT-isochores during growth in axenic culture. Our hypothesis is that changes of lifestyle and a switch toward pathogenesis lift chromatin-mediated repression, allowing a rapid response to new environmental conditions.

Dataset Information

Effector diversification within compartments of the Leptosphaeria maculans genome affected by Repeat-Induced Point mutations.

Publications

Effector diversification within compartments of the Leptosphaeria maculans genome affected by Repeat-Induced Point mutations.

Similar Datasets

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