Magnaporthiopsis, a new genus in Magnaporthaceae (Ascomycota)

Abstract

The phylogenetic relationships among taxa in the Magnaporthaceae are investigated based on DNA sequences of multiple genes including SSU, ITS, LSU, MCM7, RPB1 and TEF1. The genera Magnaporthe and Gaeumannomyces are shown to be polyphyletic and their members are divided into four major groups based on the phylogenetic analyses. Considering morphological, biological and molecular data, we establish a new genus, Magnaporthiopsis. It is characterized by black and globose perithecia with a cylindrical neck, two-layered perithecial wall, clavate asci with a refractive apical ring, fusiform to fusoid and septate ascospores, simple hyphopodia, and Phialophora-like anamorph. Species in this genus are necrotrophic parasites infecting roots of grasses. Three new combinations, Magnaporthiopsis poae, M. rhizophila and M. incrustans, are proposed accordingly. Pyricularia is suggested as the generic name for the rice blast fungus over Magnaporthe, following Article 59.1 of the International Code of Nomenclature for algae, fungi and plants. A new combination, Nakataea oryzae, is proposed for the rice stem rot fungus.

• Gaeumannomyces
• Magnaporthe
• phylogeny
• Pyricularia
• rice blast
• summer patch
• systematics
• taxonomy

Acknowledgments

We thank Drs B.B. Clarke, Y-L Jia, Z-F Yu and K-Q Zhang for providing fungal cultures. We also thank Drs T. Aoki, I. Chuma, J. Crouch, P. Crous, S. Klaubauf, L. Kohn, M. LeBrun A. Minnis, L. Norvell, S. Redhead, A. Rossman, D. Tharreau, B. Valent, J. Xu and W-Y Zhuang for discussion. The research is financially supported by the Rutgers Center for Turfgrass Science, US Golf Association and National Science Foundation (grant number DEB 1145174 to N. Zhang).