Submitted to: Persoonia: Molecular Phylogeny and Evolution of Fungi
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/22/2014
Publication Date: 10/6/2014
Citation: Savchenko, K., Carris, L., Castlebury, L.A., Heluta, V., Wasser, S., Nevo, E. 2014. Stripe smuts of grasses: one lineage or high levels of polyphyly? Persoonia: Molecular Phylogeny and Evolution of Fungi. 33(1):169-181. Interpretive Summary: Fungi cause serious diseases of agricultural and forest crops. One group of fungi known as smut fungi cause diseases in grasses, such as corn, wheat and rice by killing leaf, stem or seed tissue. Diseased plant tissue is then filled with dark powdery spores. Because many species of these fungi appear to be very similar, they are difficult to identify. Distinguishing these fungi is essential for controlling smut diseases in grasses. In this paper the smut fungi from different species of grasses were studied using microscopic structures and molecular sequences. They were determined to be distinct species and should have different names that reflect their differences so that they can be accurately identified. This research will be used by pathologists to distinguish these species of fungi on grasses in order to control the diseases that they cause.
Technical Abstract: Stripe smut of grasses, Ustilago striiformis s.l., is caused by a complex of smut fungi widely distributed over temperate and subtropical regions. The disease results in the shredding and death of leaf tissue following the rupture of elongated sori. Nearly 100 different grass species in more than 30 genera are parasitized and during the last two centuries more than 30 smut taxa have been described for members of this complex. The present study is a first attempt to clarify the taxonomy and phylogeny of the stripe smuts of grasses by analyzing both morphological and molecular data. More than 200 specimens from different continents and host plants were examined and analyzed. DNA extracted from teliospores of 23 specimens from different hosts collected in Europe, Asia, and North America was used to amplify ITS and LSU regions used in phylogenetic analyses. The results of Maximum Parsimony and Bayesian analyses demonstrated that there are several lineages of stripe smut fungi. Analyses of morphological characters assessed with light and scanning electron microscopy showed high support for the differentiation of two clades as distinct from U. striiformis s.l., i.e., U. nunavutii sp. nov. and U. bromina. Two additional clades, U. striiformis s.str.on Holcus and a clade containing specimens from Elymus, were identified with molecular data although morphological differences were not apparent. Descriptions are given for each species.