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ARS Home » Northeast Area » Frederick, Maryland » Foreign Disease-Weed Science Research » Research » Publications at this Location » Publication #351069

Research Project: Identification, Biology, Epidemiology, and Control of Foreign and Emerging Fungal Plant Pathogens

Location: Foreign Disease-Weed Science Research

Title: Invasions of gladiolus rust in North America are caused by a widely-distributed clone of Uromyces transversalis

item DELONG, JEFFERY - University Of Georgia
item STEWART, JANE - Colorado State University
item VALENCIA-BOTIN, ALBERTO - University Of Guadalajara
item Pedley, Kerry
item BUCK, JAMES - University Of Georgia
item BREWER, MARIN - University Of Georgia

Submitted to: PeerJ
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/4/2019
Publication Date: 11/28/2019
Citation: Delong, J.A., Stewart, J.E., Valencia-Botin, A., Pedley, K.F., Buck, J.W., Brewer, M.T. 2019. Invasions of gladiolus rust in North America are caused by a widely-distributed clone of Uromyces transversalis. PeerJ. 7:e7986.

Interpretive Summary: Gladiolus rust is a destructive disease caused by the fungus Uromyces transversalis. The pathogen mainly infects Gladiolus species, but is known to infect other ornamental plants of the Iridaceae family. The pathogen is an invasive species in the United States, having been first reported in California in 2006 and Florida in 2007. In an effort determine the origin of the pathogen in the U.S. and to understand the diversity of U. transversalis world-wide, we developed a set molecular markers identified through whole-genome sequencing. Analysis of 108 isolates of the pathogen collected from a wide geographic area with 24 molecular markers revealed no genetic diversity among individual isolates. This novel finding revealed that all U. transversalis populations studied are strictly clonal. Although we were unable to detect genetic diversity among isolates of U. transversalis across a wide geographic range, the genome sequences will serve as a resource for further studies on this destructive fungal pathogen and future studies will help determine the usefulness of the developed markers in diagnosis and detection.

Technical Abstract: Uromyces transversalis, the causal agent of Gladiolus rust, is an invasive plant pathogen in the United States and is regulated as a quarantine pathogen in Europe. The aim of this research was to develop molecular markers to: (i) determine the origin of introductions of U. transversalis to the United States, (ii) track the movement of genotypes, and (iii) understand the worldwide genetic diversity of the species. Whole genome sequencing was performed on three isolates collected in the United States. Genomes were assembled de novo and searched for microsatellite regions. Primers were developed and tested on ten isolates from the United States resulting in the identification of 24 robust polymorphic markers. Among 108 isolates collected, markers revealed polymorphisms within each isolate with no diversity among isolates. The microsatellite loci and flanking regions showed high diversity and two divergent genomes within dikaryotic individuals, yet no diversity among individuals, suggesting that the U. transversalis populations from a widely studied geographic area are strictly clonal.