title: Different temporal and spatial expression of two hydrophobin-encoding genes of the edible mushroom Agaricus bisporus.
abstract: In a search for genes that are only expressed in fruit bodies of the basidiomycete Agaricus bisporus, two cDNAs, hypA and hypB that encode hydrophobins have been isolated previously. In this study, the structure of hypB is resolved and it is shown that the two genes are differentially expressed, indicating that the encoded hydrophobins serve different functions in A. bisporus mushrooms. hypB encodes a polypeptide (HYPB) of 119 aa that shows little sequence identity with HYPA apart from the characteristic arrangement of eight cysteines found exclusively in hydrophobins. The temporal and spatial expression of the two hydrophobin-encoding genes during fruit body development was compared using Northern analysis and in situ hybridization. Accumulation of hypA mRNA was found in tissue fractions consisting of undifferentiated white hyphae. In situ hybridization showed that the highest hypA mRNA levels are not found in the outermost cell layers of the pileipellis but in the cell layers adjacent to that. The highest level of expression of hypB occurs early in development when the primordium differentiates into densely packed, randomly oriented cap hyphae and loosely packed, vertically oriented stipe hyphae. In mature mushrooms, a strong accumulation of hypB transcripts was found only in the transitional zone between cap and stipe tissue, demonstrating that transcription regulation of hypB is clearly distinct from hypA.
authors.affiliation: Section Molecular Genetics of Industrial Micro-organisms, Wageningen Agricultural University, Dreijenlaan 2, NL-6703 HA, Wageningen, The Netherlands.
authors.forename: Piet W J
authors.initials: PWJ
authors.lastname: De Groot
authors.affiliation: Mushroom Experimental Station, PO Box 6042, NL-5960 AA, Horst, The Netherlands.
authors.forename: Robert T P
authors.initials: RTP
authors.lastname: Roeven
authors.affiliation: Mushroom Experimental Station, PO Box 6042, NL-5960 AA, Horst, The Netherlands.
authors.forename: Leo J L D
authors.initials: LJLD
authors.lastname: Van Griensven
authors.affiliation: Section Molecular Genetics of Industrial Micro-organisms, Wageningen Agricultural University, Dreijenlaan 2, NL-6703 HA, Wageningen, The Netherlands.
authors.forename: Jaap
authors.initials: J
authors.lastname: Visser
authors.affiliation: Section Molecular Genetics of Industrial Micro-organisms, Wageningen Agricultural University, Dreijenlaan 2, NL-6703 HA, Wageningen, The Netherlands.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Schaap
mesh_terms: D000364:Agaricus / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D000595:Amino Acid Sequence; D015152:Blotting, Northern; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D014158:Transcription, Genetic
chemical_list: D005656:Fungal Proteins