Mycological Progress (2018) 17, 1251-1267

Shawn C. Kenaley, Menchus Quan, M. Catherine Aime and Gary C. Bergstrom (2018)
New insight into the species diversity and life cycles of rust fungi (Pucciniales) affecting bioenergy switchgrass (Panicum virgatum) in the Eastern and Central United States
Mycological Progress 17 (11), 1251-1267
Abstract: Research was undertaken to clarify the taxonomic identity of leaf rust (Pucciniales) fungi on bioenergy switchgrass in the Eastern and Central U.S. We integrated internal transcribed spacer 2 (ITS2) and partial 28S ribosomal RNA gene sequence data from collections taken from cultivated switchgrass and herbarium specimens, including purported aecial and telial states of Puccinia graminicola and Puccinia pammelii. Maximum likelihood and Bayesian analyses revealed four monophyletic clades: Puccinia emaculata sensu stricto (s.s.), P. pammelii, P. graminicola, and Puccinia novopanici. Results also indicated that P. emaculata s.s. was not affecting cultivated, bioenergy switchgrass. Aecidium pammelii and P. pammelii were distinct phylogenetically from P. emaculata s.s. and grouped within a well-supported clade, demonstrating aecial-telial host alternation for P. pammelii between Euphorbia corollata and switchgrass. Aecidium stillingiae on queen's delight (Stillingia sylvatica)—a purported aecial state host for P. graminicola—shared identical sequences with the recently described species Puccinia pascua. The latter fungus, however, was recovered within a subclade of P. graminicola. Hence, queen's delight likely is not an aecial host to P. graminicola s.s. Additional molecular studies are warranted to determine species boundaries within the P. graminicola complex. The majority of contemporary collections from cultivated switchgrass were recognized as P. novopanici. Collectively, bioenergy switchgrass is host to at least three phylogenetically distinct species, presenting a significant challenge to the future selection and breeding of switchgrass with improved rust resistance.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
(original language: English)
Link to article at publishers website
Database assignments for author(s): Gary C. Bergstrom, M. Catherine Aime

Research topic(s) for pests/diseases/weeds:
surveys/sampling/distribution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Puccinia emaculata
	Puccinia graminicola	Panicum (crop)
	Puccinia novopanici
	Puccinia pammelii