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Current Genetics

, Volume 39, Issue 5–6, pp 346–354 | Cite as

Patterns of evolution in Discula fungi and the origin of dogwood anthracnose in North America, studied using arbitrarily amplified and ribosomal DNA

  • Gustavo Caetano-Anollés
  • Robert N. Trigiano
  • Mark T. Windham
Original Paper

Abstract.

The anthracnose epidemic caused by exotic filamentous fungi of the genus Discula threatens the future of the prized flowering (Cornus florida L.) and Pacific (C. nuttalli Aud.) dogwoods in North America. A cross-section of fungi that cause anthracnose in broadleaf temperate trees was characterized using DNA amplification fingerprinting, sequence and secondary structure analysis of the internal transcribed spacers (ITS) of nuclear ribosomal DNA (rDNA), and compatibility of hyphal anastomosis. ITS-inferred phylogenies rejected the null hypothesis of only one fungal lineage, by defining four monophyletic and well differentiated groups, corresponding to Discula sp., D. quercina, D. umbrinella and D. destructiva, with the last two species sharing a common and recent ancestor. In turn, they showed that the dogwood pathogen, D. destructiva, did not evolve directly from an indigenous population related to Discula sp. In this study, rDNA spacers that are generally considered important for protein synthesis but are selectively neutral, appeared functionally constrained and subject to selective sequence diversification. Results confirmed the high variability of D. umbrinella and the remarkable homogeneity and exotic nature of D. destructiva at the genetic level, clarified the taxonomy and phylogeny of Discula, and provided clues as to the origin and diversification of dogwood anthracnose-causing fungi.

Discula Dogwood anthracnose ITS sequence Ribosomal DNA 

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  • Gustavo Caetano-Anollés
    • 1
  • Robert N. Trigiano
    • 2
  • Mark T. Windham
    • 3
  1. 1.Division of Molecular Biology, Department of Biology, University of Oslo, P.O. Box 1045, Blindern, 0316 Oslo, Norway
  2. 2.Department of Ornamental Horticulture and Landscape Design, The University of Tennessee, Knoxville, TN 37901-1071, USA
  3. 3.Department of Entomology and Plant Pathology, The University of Tennessee, Knoxville, TN 37901-1071, USA

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