Isolation of a novel antimicrobial peptide gene (Sp-AMP) homologue from Pinus sylvestris (Scots pine) following infection with the root rot fungus Heterobasidion annosum

Authors

  • Frederick O Asiegbu,

    Corresponding author
    1. Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, Box 7026, Uppsala, Sweden
    2. Fungal Genomics Laboratory, North Carolina State University, Raleigh, NC, USA
      *Corresponding author. Tel.: +46 (18) 67 15 98; Fax: +46 (18) 67 35 99, E-mail address: fred.asiegbu@mykopat.slu.se
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  • Woobong Choi,

    1. Fungal Genomics Laboratory, North Carolina State University, Raleigh, NC, USA
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  • Guosheng Li,

    1. Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, Box 7026, Uppsala, Sweden
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  • Jarmila Nahalkova,

    1. Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, Box 7026, Uppsala, Sweden
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  • Ralph A Dean

    1. Fungal Genomics Laboratory, North Carolina State University, Raleigh, NC, USA
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*Corresponding author. Tel.: +46 (18) 67 15 98; Fax: +46 (18) 67 35 99, E-mail address: fred.asiegbu@mykopat.slu.se

Abstract

A new family of antimicrobial peptide homologues termed Sp-Amp has been discovered in Pinus sylvestris (Scots pine). This is the first report of such proteins to be characterized in a conifer species. Sp-AMP1 was identified in a substructured cDNA library of root tissue infected with the root rot fungus Heterobasidion annosum and encodes a mature peptide of 79 amino acid residues. Three additional members of the Sp-AMP family (Sp-AMPs 2–4) encode cysteine-rich proteins of 105 amino acids, each containing an N-terminal region with a probable cleavage signal sequence. Northern analysis confirmed that Sp-AMP expression is elevated in Scots pine roots upon infection with H. annosum. These peptides share 64% amino acid identity with a mature protein from Macadamia integrifolia (MiAMP1), which allowed us to build a homology model for preliminary analysis. Southern analyses further confirmed that several copies of the gene are present in the Scots pine genome. The potential significance of Sp-AMP in the H. annosum–conifer pathosystem is discussed.

Ancillary