TY - JOUR

T1 - Assignment of a dubious gene cluster to melanin biosynthesis in the tomato fungal pathogen Cladosporium fulvum

AU - Griffiths, Scott A.

AU - Cox, Russell J.

AU - Overdijk, Elysa J.R.

AU - Mesarich, Carl H.

AU - Saccomanno, Benedetta

AU - Lazarus, Colin M.

AU - de Wit, Pierre J.G.M.

AU - Collemare, Jérôme

N1 - Funding information: SAG, JC, CHM, and PJGMdW were financially supported by a grant from the Royal Netherlands Academy of Sciences. RJC thanks DFG for LCMS equipment (INST 187/621-1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. SAG, JC, CHM, and PJGMdW were financially supported by a grant from the Royal Netherlands Academy of Sciences. RJC thanks DFG for LCMS equipment (INST 187/621-1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

PY - 2018/12/31

Y1 - 2018/12/31

N2 - Pigments and phytotoxins are crucial for the survival and spread of plant pathogenic fungi. The genome of the tomato biotrophic fungal pathogen Cladosporium fulvum contains a predicted gene cluster (CfPKS1, CfPRF1, CfRDT1 and CfTSF1) that is syntenic with the characterized elsinochrome toxin gene cluster in the citrus pathogen Elsinoë fawcettii. However, a previous phylogenetic analysis suggested that CfPks1 might instead be involved in pigment production. Here, we report the characterization of the CfPKS1 gene cluster to resolve this ambiguity. Activation of the regulator CfTSF1 specifically induced the expression of CfPKS1 and CfRDT1, but not of CfPRF1. These co-regulated genes that define the CfPKS1 gene cluster are orthologous to genes involved in 1,3-dihydroxynaphthalene (DHN) melanin biosynthesis in other fungi. Heterologous expression of CfPKS1 in Aspergillus oryzae yielded 1,3,6,8-tetrahydroxynaphthalene, a typical precursor of DHN melanin. Δcfpks1 deletion mutants showed similar altered pigmentation to wild type treated with DHN melanin inhibitors. These mutants remained virulent on tomato, showing this gene cluster is not involved in pathogenicity. Altogether, our results showed that the CfPKS1 gene cluster is involved in the production of DHN melanin and suggests that elsinochrome production in E. fawcettii likely involves another gene cluster.

AB - Pigments and phytotoxins are crucial for the survival and spread of plant pathogenic fungi. The genome of the tomato biotrophic fungal pathogen Cladosporium fulvum contains a predicted gene cluster (CfPKS1, CfPRF1, CfRDT1 and CfTSF1) that is syntenic with the characterized elsinochrome toxin gene cluster in the citrus pathogen Elsinoë fawcettii. However, a previous phylogenetic analysis suggested that CfPks1 might instead be involved in pigment production. Here, we report the characterization of the CfPKS1 gene cluster to resolve this ambiguity. Activation of the regulator CfTSF1 specifically induced the expression of CfPKS1 and CfRDT1, but not of CfPRF1. These co-regulated genes that define the CfPKS1 gene cluster are orthologous to genes involved in 1,3-dihydroxynaphthalene (DHN) melanin biosynthesis in other fungi. Heterologous expression of CfPKS1 in Aspergillus oryzae yielded 1,3,6,8-tetrahydroxynaphthalene, a typical precursor of DHN melanin. Δcfpks1 deletion mutants showed similar altered pigmentation to wild type treated with DHN melanin inhibitors. These mutants remained virulent on tomato, showing this gene cluster is not involved in pathogenicity. Altogether, our results showed that the CfPKS1 gene cluster is involved in the production of DHN melanin and suggests that elsinochrome production in E. fawcettii likely involves another gene cluster.

KW - Cladosporium/physiology

KW - Gene Expression Regulation, Fungal

KW - Gene Order

KW - Genes, Fungal

KW - Host-Pathogen Interactions/genetics

KW - Lycopersicon esculentum/microbiology

KW - Melanins/biosynthesis

KW - Multigene Family

KW - Phenotype

KW - Phylogeny

KW - Pigmentation

UR - http://www.scopus.com/inward/record.url?scp=85059261055&partnerID=8YFLogxK

U2 - 10.1371/journal.pone.0209600

DO - 10.1371/journal.pone.0209600

M3 - Article

C2 - 30596695

AN - SCOPUS:85059261055

VL - 13

JO - PLOS ONE

JF - PLOS ONE

SN - 1932-6203

IS - 12

M1 - e0209600

ER -