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Evolution of nucleotide sequences and expression patterns of hydrophobin genes in the ectomycorrhizal fungus Paxillus involutus

Author:
  • Balaji Rajashekar
  • Peter Samson
  • Tomas Johansson
  • Anders Tunlid
Publishing year: 2007
Language: English
Pages: 399-411
Publication/Series: New Phytologist
Volume: 174
Issue: 2
Document type: Journal article
Publisher: Wiley-Blackwell

Abstract english

Hydrophobins are small, secreted proteins that play important roles in the development of pathogenic and symbiotic fungi. Evolutionary mechanisms generating sequence and expression divergence among members in hydrophobin gene families are largely unknown.

Seven hydrophobin (hyd) genes and one hyd pseudogene were isolated from strains of the ectomycorrhizal fungus Paxillus involutus. Sequences were analysed using phylogenetic methods. Expression profiles were inferred from microarray experiments.



The hyd genes included both young (recently diverged) and old duplicates. Some young hyd genes exhibited an initial phase of enhanced sequence evolution owing to relaxed or positive selection. There was no significant association between sequence divergence and variation in expression levels. However, three hyd genes displayed a shift in the expression levels or an altered tissue specificity following duplication.



The Paxillus hyd genes evolve according to the so-called birth-and-death model in which some duplicates are maintained for a long time, whereas others are inactivated through mutations. The role of subfunctionalization and/or neofunctionalization for preserving the hyd duplicates in the genome is discussed.

Keywords

  • Biological Sciences
  • ectomycorrhiza
  • expression patterns
  • gene duplication
  • neofunctionalization
  • hydrophobin
  • subfunctionalization
  • Paxillus involutus

Other

Published
  • Microbial Ecology
  • ISSN: 1469-8137
Tomas Johansson
E-mail: tomas [dot] johansson [at] biol [dot] lu [dot] se

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