Cephalosporium maydis is a distinct species in the Gaeumannomyces-Harpophora species complex

Abstract

Cephalosporium maydis is an important plant pathogen whose phylogenetic position relative to other fungi has not been established clearly. We compared strains of C. maydis, strains from several other plant-pathogenic Cephalosporium spp. and several possible relatives within the Gaeumannomyces-Harpophora species complex, to which C. maydis has been suggested to belong based on previous preliminary DNA sequence analyses. DNA sequences of the nuclear genes encoding the rDNA ITS region, β-tubulin, histone H3, and MAT-2 support the hypothesis that C. maydis is a distinct taxon within the Gaeumannomyces-Harpophora species complex. Based on amplified fragment length polymorphism (AFLP) profiles, C. maydis also is distinct from the other tested species of Cephalosporium, Phialophora sensu lato and members of Gaeumannomyces-Harpophora species complex, which supports its classification as Harpophora maydis. Oligonucleotide primers for H. maydis were developed that can be used in a PCR diagnostic protocol to rapidly and reliably detect and identify this pathogen. These diagnostic PCR primers will aid the detection of H. maydis in diseased maize because this fungus can be difficult to detect and isolate, and the movement of authentic cultures may be limited by quarantine restrictions.

• AFLP
• β-tubulin
• Corn
• Harpophora maydis
• Histone H3
• Phialophora sensu lato
• maize
• mating type
• rDNA ITS

This work was financially supported in part by the Kansas Agricultural Experimentation Station, and ATUT collaborative research grant No. 58-314-7-057 through the U.S. Agency for International Development (Cairo, Egypt). Mr. Saleh was supported by a fellowship from the Institute of International Education. We thank Bill Bockus for providing us with cultures of Cephalosporium gramineum and Gaeumannomyces graminis var. tritici; Ned Tisserat for providing us with cultures of Acremonium diospyri, Gaeumannomyces cylindrosporus, Gaeumannomyces graminis var. avenae, Gaeumannomyces graminis var. graminis and Gaeumannomyces graminis var. tritici; Amy Beyer and Brook van Scoyoc for technical assistance; and Walter Gams and Kurt Zeller for critically reading the manuscript. Contribution 04-179-J from the Kansas Agricultural Experimentation Station, Manhattan.