Uromyces rebeccae, sp. nov., a newly described rust on the federally endangered plant, California sea-blite (Suaeda californica)

ABSTRACT

Rust disease was observed on populations of Suaeda californica near Morro Bay, California. The pathogen was identified as a species of Uromyces based on teliospore and urediniospore morphology and nuc 28S rDNA sequence analysis. The isolate was compared with previously described species of Uromyces that infect members of Chenopodiaceae, prompting a taxonomic reevaluation of Uromyces species on Suaeda. Herein, Uromyces rebeccae is described. It can be differentiated from the closely related U. chenopodii (syn.: Aecidium chenopodii-fruticosi; U. giganteus) based on host range, teliospore morphology, and 28S sequence data. The new combination, Uromyces chenopodii-fruticosi, is made for Aecidium chenopodii-fruticosi, the oldest name for Eurasian Suaeda rust. Finally, it was determined that U. giganteus likely does not occur in the United States and that the rust of S. taxifolia in the United States likely comprises a third, yet unnamed taxon, different from both U. rebeccae and U. chenopodii-fruticosi. This is the first record of a rust fungus on S. californica. An identification key for Uromyces species reported on Chenopodiaceae is provided.

KEYWORDS:

• Chenopodiaceae
• Pucciniales
• Pucciniaceae
• rusts
• systematics
• 2 new taxa

ACKNOWLEDGMENTS

The authors thank Melissa V. Patten and Katharyn E. Boyer from San Francisco State University for providing Suaeda californica seed; Peter Baye, coastal ecologist, Annapolis, California, for consultations about S. californica; and a reviewer and the executive editor for Mycologia.

Additional information

Funding

Funding for this research was from the United States Department of Agriculture (USDA) Agricultural Research Service appropriated project 8044-22000-043-00D, and National Science Foundation grants DEB-1458290 and DEB-1502887 to M.C.A. This work was also supported by the USDA National Institute of Food and Agriculture Hatch project 1010662 (M.C.A.). Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture. USDA is an equal opportunity provider and employer. The authors declare no conflicts of interest.