Evidence supporting the separation of the Vulpia- and Bromus-infecting isolates in the Tilletia fusca (T. bromi) complex

Abstract

The teliospore morphology of Vulpia- and Bromus-infecting collections of the Tilletia fusca (T. bromi) complex differs in the reticulate ornamentation and thickness of the areolae wall. Cytological studies showed that 1–12% of the primary sporidia in the Vulpia-infecting isolates were binucleate, whereas only 0.1% of the sporidia in the Bromus-infecting isolates were binucleate. These differences are used in conjunction with previous studies on host specificity and molecular characterization to support the separation of the Vulpia- and brome-infecting taxa. Tilletia fusca is proposed as a binomial restricted to the bunt fungus on V. microstachys and V. octoflora in North America. Tilletia bromi is retained for the bunt infecting species of Bromus, Festuca, Nardurus, Ventenata and other species of Vulpia on a worldwide basis.

Key Words:

• annual fescues
• bunt
• grass smuts
• Ustilaginales