Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Record number 434259
Title Dothistromin genes at multiple separate loci are regulated by AflR
Author(s) Chettri, P.; Ehrlich, K.C.; Cary, J.W.; Collemare, J.; Cox, M.P.; Griffiths, S.A.; Olson, M.A.; Wit, P.J.G.M. de; Bradshaw, R.E.
Source Fungal Genetics and Biology 51 (2013). - ISSN 1087-1845 - p. 12 - 20.
Department(s) Laboratory of Phytopathology
Publication type Refereed Article in a scientific journal
Publication year 2013
Keyword(s) aspergillus-parasiticus - aflatoxin biosynthesis - forest pathogen - filamentous fungi - secondary metabolism - cluster protein - pathway genes - needle blight - pini - expression
Abstract In fungi, genes involved in the production of secondary metabolites are generally clustered at one location. There are some exceptions, such as genes required for synthesis of dothistromin, a toxin that is a chemical analog of the aflatoxin precursor versicolorin A and made by the pine needle pathogen Dothistroma septosporum. The availability of the D. septosporum genome sequence enabled identification of putative dothistromin genes, including an ortholog of the aflatoxin regulatory gene AflR, and revealed that most of the genes are spread over six separate regions (loci) on chromosome 12 (1.3 Mb). Here we show that levels of expression of the widely dispersed genes in D. septosporum are not correlated with gene location with respect to their distance from a telomere, but that AflR regulates them. The production of dothistromin by D. septosporum in which the AflR gene was knocked out (¿DsAflR) was drastically reduced, but still detectable. This is in contrast to orthologous ¿AflR mutants in Aspergillus species that lack any aflatoxin production. Expression patterns in ¿DsAflR mutants helped to predict the complete set of genes involved in dothistromin production. This included a short-chain aryl alcohol dehydrogenase (NorB), which is located on chromosome 11 rather than chromosome 12, but was 24-fold down regulated in ¿DsAflR. An orthologous set of dothistromin genes, organized in a similar fragmented cluster arrangement to that seen in D. septosporum, was found in the closely related tomato pathogen Cladosporium fulvum even though this species does not produce dothistromin. In C. fulvum, pseudogenization of key biosynthetic genes explains the lack of dothistromin production. The fragmented arrangement of dothistromin genes provides an example of coordinated control of a dispersed set of secondary metabolite genes; it also provides an example where loss of dothistromin production might have allowed adaptation to a new pathogenic lifestyle.
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