The Schizophyllum commune SC3 gene, which encodes a hydrophobin that coats aerial hyphae, is expressed in both monokaryons and dikaryons. The dikaryons were formed by mating two monokaryons with different MATA and MATB genes, leading to activation of the MATA- and MATB-controlled pathways (MATA-on and MATB-on). In contrast to the monokaryons, the dikaryons also expressed other hydrophobin genes (SC1, SC4) as well as a gene (SC7) encoding a hydrophilic wall protein. None of these four genes was expressed in MATA-off MATB-on mycelia, indicating that MATB-on represses SC3 and that both MATA-on and MATB-on are required for activation of SC1, SC4 and SC7. In fruiting dikaryons, immunolabelling revealed that SC3p was produced by aerial hyphae but not by hyphae that constitute the fruit-body tissue. In contrast to aerial hyphae, the latter produced dikaryon-specific transcripts and secreted SC7p into the extracellular matrix of the tissue. This suggests that in the aerial hyphae of the dikaryon the MATB-on pathway was not effective (MATB-off). We observed that in these aerial hyphae the two nuclei were wider apart than in a typical dikaryon. Although other explanations are not ruled out, we tentatively propose that effective interaction of different MATB genes requires proximity of the two nuclei containing these genes, and that disruption of this binucleate state represents a novel mechanism of gene control for spatial cell differentiation in the secondary mycelium.
CasseltonLA.,
KüesU.1994; Mating-type genes in homobasidiomycetes.. In The Mycota, vol. 1: Growth, Differentiation and Development pp. 307–321 Edited by
WesselsJ. G. H.,
MeinhardtF.
Heidelberg: Springer-Verlag;
DonsJ.J.M.,
de VriesO.M.H.,
WesselsJ.G.H.1979; Characterization of the genome of the basidiomycete Schizophyllum commune.. Biochim Biophys Acta 563:100–112
MulderG.H.,
WesselsJ.G.H.1986; Molecular cloning of RNAs differentially expressed in monokaryons and dikaryons of Schiyophyllum commune in relation to fruiting.. Exp Mycol 10:214–227
RaperC.A.1988; Schizophyllum commune, a model for genetic studies of the Basidiomycetes.. In Genetics of Plant Pathogenic Fungi pp. 511–522 Edited by
SidhuG. S.
London: Academic Press;
RossI.K.,
LoftusM.G.,
FosterL.M.1991; Homokaryon-dikaryon phenotypic switching in an arginine requiring mutant of Coprinus congregatus.. Mycol Res 95:776–781
RuitersM.H.J.,
SietsmaJ.H.,
WesselsJ.G.H.1988; Expression of dikaryon-specific mRNAs of Schizophyllum commune in relation to incompatibility genes, light and fruiting.. Exp Mycol 12:60–69
RuitersM.H.J.,
WesselsJ.G.H.1989; In situ localization of specific RNAs in developing fruit bodies of the basidiomycete Schizophyllum commune.. Exp Mycol 13:212–222
SchurenF.H.J.,
WesselsJ.G.H.1990; Two genes specifically expressed in fruiting dikaryons of Schizophyllum commune: homologies with a gene not regulated by mating-type genes.. Gene 90:199–205
SchurenF.H.J.,
ÁsgeirsdóttirS.A.,
KotheE.M.,
ScheerJ.M.J.,
WesselsJ. G. H.1993a; The Sc7/Sc14 gene family of Schizophyllum commune codes for extracellular proteins specifically expressed during fruit-body formation.. J Gen Microbiol 139:2083–2090
SchurenF.H.J.,
HarmsenM.C.,
WesselsJ.G.H.1993b; A homologous gene-reporter system for the basidiomycete Schi^o- phyllum commune based on internally deleted homologous genes.. Mol & Gen Genet 238:91–96
SpechtC.A.,
StankisM.M.,
GiassonL.,
NovotnyC.P.,
UllrichR.C.1992; Functional analysis of the homeodomain-related proteins of the Aα locus of Schizophyllum commune.. Proc Natl Acad Sci USA897174–7178
SpringerJ.,
WesselsJ.G.H.1989; A frequently occurring mutation that blocks the expression of fruiting genes in Schizophyllum commune.. Mol & Gen Genet 219:486–488
StankisM.M.,
SpechtC.A.,
YangH.,
GiassonL.,
UllrichR.C.1992; The Aα mating locus of Schizophyllum commune encodes two dissimilar multiallelic homeodomain proteins.. Proc Natl Acad Sci USA897169–7173
ToddN.K.,
AylmoreR.C.1985; Cytology of hyphal interactions and reactions in Schizophyllum commune.. In Developing Biology of Higher Fungi pp. 231–248 Edited by
MooreD.,
CasseltonL. A.,
WoodD.A.,
FranklandJ. C.
Cambridge: Cambridge University Press;
WendlandJ.,
KotheE.1994; A multiallelic signal transduction system in the mating-type locus Bα of Schizophyllum commune.. Int Union MicrobiolSoc: Abstr 7th Int Congr Mycol Division, Prague p. 380
WesselsJ.G.H.,
MulderG.H.,
SpringerJ.1987; Expression of dikaryon-specific and non-specific mRNAs of Schizophyllum commune in relation to environmental conditions and fruiting.. J Gen Microbiol 133:2557–2561
WesselsJ.G.H.,
de VriesO.M.H.,
ÁsgeirsdóttirS.A.,
SchurenF.H.J.1991a; Hydrophobin genes involved in formation of aerial hyphae and fruit bodies in Schizophyllum.. Plant Cell 3:793–799
WesselsJ.G.H.,
de VriesO.M.H.,
ÁsgeirsdóttirS.A.,
SpringerJ.1991b; The thn mutation of Schizophyllum commune, which suppresses formation of aerial hyphae, affects expression of the Sc3 hydrophobin gene.. J Gen Microbiol 137:2439–2445
WöstenH.A.B.,
de VriesO.M.H.,
WesselsJ.G.H.1993; Interfacial self-assembly of a fungal hydrophobin into a hydrophobic rodlet layer.. Plant Cell 5:1567–1574
WöstenH.A.B.,
ÁsgeirsdóttirS.A.,
KrookJ.H.,
DrenthJ. H. H.,
WesselsJ.G.H.1994a; The fungal hydrophobin Sc3p self- assembles at the surface of aerial hyphae as a protein membrane constituting the hydrophobic rodlet layer.. Eur J Cell Biol 63:122–129
WöstenH.A.B.,
SchurenF.H.J.,
Wesselsi.G.H.1994b; Interfacial self-assembly of a hydrophobin into an amphipathic membrane mediates fungal attachment to hydrophobic surfaces.. EMBO J 13:5848–5854