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Phyllachora species infecting maize and other grass species throughout the Americas represents a complex of closely related species which vary in their host and geographic range
  • +16
  • Kirk Broders,
  • Gloria Iriarte,
  • Gary Bergstrom,
  • Emmanuel Byamukama,
  • Martin Chilvers,
  • Christian Cruz,
  • Felipe Dalla Lana,
  • Zachary Duray,
  • Dean Malvick,
  • Darren Mueller,
  • Pierce Paul,
  • Diana Plewa ,
  • Richard Raid,
  • Alison Robertson,
  • Catalina Salgado,
  • Damon Smith,
  • Darcy Telenko,
  • Katherine VanEtten,
  • Nathan Kleczewski
Kirk Broders

Corresponding Author:[email protected]

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Gloria Iriarte
Colorado State University
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Gary Bergstrom
Cornell University
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Emmanuel Byamukama
South Dakota State University
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Martin Chilvers
Michigan State University
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Christian Cruz
Purdue University
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Felipe Dalla Lana
Pennsylvania State University
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Zachary Duray
University of Illinois at Urbana-Champaign
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Dean Malvick
University of Minnesota Twin Cities
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Darren Mueller
Iowa State University
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Pierce Paul
The Ohio State University
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Diana Plewa
University of Illinois at Urbana-Champaign
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Richard Raid
University of Florida
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Alison Robertson
Iowa State University
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Catalina Salgado
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Damon Smith
University of Wisconsin-Madison
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Darcy Telenko
Purdue University
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Katherine VanEtten
University of Illinois at Urbana-Champaign
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Nathan Kleczewski
University of Illinois at Urbana-Champaign
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The genus Phyllachora contains numerous obligate fungal parasites that produce raised, melanized structures called stromata on their plant hosts referred to as tar spot. Members of this genus are known to infect many grass species but generally do not cause significant damage or defoliation, with the exception of P. maydis which has emerged as an important pathogen of maize throughout the Americas, but the origin of this pathogen remains unknown. To date, species designations for Phyllachora have been based on host associations and morphology, and most species are assumed to be host specific. We assessed the sequence diversity of 186 single stroma isolates collected from 16 hosts representing 15 countries. Samples included both herbarium and contemporary strains that covered a temporal range from 1905-2019. These 186 isolates were grouped into 5 distinct species with strong bootstrap support. We found three closely related, but genetically distinct groups of Phyllachora are capable of infecting maize in the United States, we refer to these as the P. maydis species complex. Based on herbarium species, we hypothesize that these three groups in the P. maydis species complex originated from Central America, Mexico and the Caribbean. Although two of these groups were only found on maize, the third and largest group contained contemporary strains found on maize and other grass hosts, as well as herbarium specimens from maize and other grasses that include 10 species of Phyllachora. The herbarium specimens were identified based on morphology and host association, but our sequence data indicates some Phyllachora species are capable of infecting a broad range of host species and there may be significant synonymy in the Phyllachora genus and additional work on species delineation and host specificity should be considered.
14 Dec 2021Submitted to Ecology and Evolution
15 Dec 2021Submission Checks Completed
15 Dec 2021Assigned to Editor
18 Dec 2021Reviewer(s) Assigned
04 Jan 2022Review(s) Completed, Editorial Evaluation Pending
10 Jan 2022Editorial Decision: Revise Minor
07 Feb 20221st Revision Received
08 Feb 2022Submission Checks Completed
08 Feb 2022Assigned to Editor
08 Feb 2022Review(s) Completed, Editorial Evaluation Pending
08 Feb 2022Reviewer(s) Assigned
31 Mar 2022Editorial Decision: Accept