|Goodwin, Stephen - Steve|
Submitted to: Mycological Symposium Asian Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 9/17/2001
Publication Date: N/A
Technical Abstract: The habit of heteroecism is very common among grass rusts. Aecial hosts are unknown in 35% of the rust species attacking grasses. However, the heteroecious rusts may have many species or genera of aecial hosts, and one host may be infected by the aecial stages of different rust species. On the basis of this host plasticity plus the lack of sufficient morphological characters, making connections between specific telial and aecial stages of graminicolous rusts can be very difficult. We sequenced the internal transcribed spacer region (ITS1, 5.8S gene, ITS2) of selected herbarium specimens of aecial stages of rust fungi. It was not possible to identify these anamorphic uredinales using morphological criteria. We also sequenced the telial stages of selected graminicolous rust species as genetic references. Comparing ITS sequences of unknown aecial stages with our own database and GenBank allowed us to identify some of these unknown Aecidium spp. The aecial stages on Clematis orientalis, Berberis sp. and Cerinthe minor were identical to P. wolgensis, P. brachypodii seusu lato, and P. recondita sensu stricto, respectively. This is the first record of the aecial stage of P. wolgensis on any host, and the first record of the aecial stage of P. recondita s.s. on C. minor. Two unknown aecial stages on Thalictrum spp. were related to P. persistens s.l., and an aecial stage on Zygophyllum sp. was distantly related to P. sorghi. The ITS sequences used in this study were appropriate for the identification of rust species during the aecial stage of the life cycle when identification was otherwise impossible.