title: Infection structure-specific reductive iron assimilation is required for cell wall integrity and full virulence of the maize pathogen Colletotrichum graminicola.
abstract: Ferroxidases are essential components of the high-affinity reductive iron assimilation pathway in fungi. Two ferroxidase genes, FET3-1 and FET3-2, have been identified in the genome of the maize anthracnose fungus Colletotrichum graminicola. Complementation of growth defects of the ferroxidase-deficient Saccharomyces cerevisiae strain Δfet3fet4 showed that both Fet3-1 and Fet3-2 of C. graminicola represent functional ferroxidases. Expression of enhanced green fluorescent protein fusions in yeast and C. graminicola indicated that both ferroxidase proteins localize to the plasma membrane. Transcript abundance of FET3-1 increased dramatically under iron-limiting conditions but those of FET3-2 were hardly detectable. Δfet3-1 and Δfet3-2 single as well as Δfet3-1/2 double-deletion strains were generated. Under iron-sufficient or deficient conditions, vegetative growth rates of these strains did not significantly differ from that of the wild type but Δfet3-1 and Δfet3-1/2 strains showed increased sensitivity to reactive oxygen species. Furthermore, under iron-limiting conditions, appressoria of Δfet3-1 and Δfet3-1/2 strains showed significantly reduced transcript abundance of a class V chitin synthase and exhibited severe cell wall defects. Infection assays on intact and wounded maize leaves, quantitative data of infection structure differentiation, and infection stage-specific expression of FET3-1 showed that reductive iron assimilation is required for appressorial penetration, biotrophic development, and full virulence.
authors: Martin-Luther-Universitat Halle-Wittenberg, Halle, Germany.
authors: Emad
authors: E
authors: Albarouki
authors: Holger B
authors: HB
authors: Deising
mesh_terms: D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000201:enzymology; D002473:Cell Wall / Q000378:metabolism*; D002570:Ceruloplasmin / Q000235:genetics* / Q000378:metabolism; D002687:Chitin Synthase / Q000378:metabolism; D020231:Colletotrichum / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005816:Genetic Complementation Test; D025301:Hyphae; D007501:Iron / Q000378:metabolism*; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D017382:Reactive Oxygen Species / Q000494:pharmacology; D011993:Recombinant Fusion Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017384:Sequence Deletion; D014774:Virulence; D003313:Zea mays / Q000382:microbiology*
chemical_list: D005656:Fungal Proteins; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins; D007501:Iron; D002570:Ceruloplasmin; D002687:Chitin Synthase