Fusarium torreyae sp. nov., a pathogen causing canker disease of Florida torreya (Torreya taxifolia), a critically endangered conifer restricted to northern Florida and southwestern Georgia

Abstract

During a survey for pathogens of Florida torreya (Torreya taxifolia) in 2009, a novel Fusarium species was isolated from cankers affecting this critically endangered conifer whose current range is restricted to northern Florida and southwestern Georgia. Published multilocus molecular phylogenetic analyses indicated that this pathogen represented a genealogically exclusive, phylogenetically distinct species representing one of the earliest divergences within the Gibberella clade of Fusarium. Furthermore, completion of Koch’s postulates established that this novel species was the causal agent of Florida torreya canker disease. Here we formally describe this pathogen as a new species, Fusarium torreyae. Pure cultures of this species produced long and slender multiseptate sporodochial conidia that showed morphological convergence with two distantly related fusaria, reflecting the homoplasious nature of Fusarium conidial morphology.

• canker disease
• Fusarium torreyae
• gene genealogies
• gopher wood
• molecular phylogenetics
• morphology
• RPB1
• RPB2
• stinking cedar

Acknowledgments

We are pleased to acknowledge the skilled technical assistance of Stacy Sink for generating all of the DNA sequence data reported in this study and Nathane Orwig for collecting the sequence data in the DNA core facility at NCAUR. Thanks are also due the staff and volunteers of the Florida Park Service and Atlanta Botanical Garden who provided invaluable assistance in our field surveys for Florida torreya. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned. The USDA is an equal opportunity provider and employer.