Use of molecular characters to identify holomorphs: an example from the rust genus Cronartium

Vogler, D. R., and Bruns, T. D. 1993.

Department of Plant Pathology, University of California, Berkeley 94720.

Pages 237-245 in The fungal holomorph: mitotic, meiotic, and pleomorphic speciation in fungal systematics. D. R. Reynolds and J. W. Taylor, eds. CAB International, Wallingford, UK. (1993)


We discuss molecular techniques that, when used to supplement morphological and other characters, may help resolve anamorph-teleomorph relationships within the pine stem rusts, Cronartium and Peridermium. First, isozyme electrophoresis, which is being used increasingly to address taxonomic and population genetics questions in fungi, may prove useful in constructing phylogenies of closely-related rusts. Second, sequences of the internal transcribed spacer (ITS) in the nuclear ribosomal gene complex, obtained by amplification and direct sequencing with the polymerase chain reaction (PCR), may be ideal for defining inter-specific relationships within Cronartium. As an example of what these techniques can do, we describe our work-in-progress with Peridermium harknessii, cause of western gall rust, and our attempts to identify the macrocyclic, heteroecious ancestor of this autoecious, microcyclic rust. We also discuss the relative advantages and disadvantages of several alternatives for re-naming P. harknessii based on its phylogenetic affinities.

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