Two new endophytic Atractiellomycetes, Atractidochium hillariae and Proceropycnis hameedii

ABSTRACT

Sterile fungal isolates are often recovered in leaf and root endophytic studies, although these seldom play a significant role in downstream analyses. The authors sought to identify and characterize two such endophytes—one representing the most commonly recovered fungal isolate in recent studies of needle endophytes of Pinus taeda and the other representing a rarely isolated root endophyte of Populus trichocarpa. Both are shown by DNA sequencing to be undescribed species of Atractiellomycetes (Pucciniomycotina, Basidiomycota), a poorly characterized class of mostly plant-associated and presumably saprobic microfungi. The authors describe the new genus and species Atractidochium hillariae (Phleogenaceae) and the new species Proceropycnis hameedii (Hoehnelomycetaceae), both in the Atractiellales, to accommodate these unusual isolates. Following incubations of 1–2 mo, A. hillariae produces minute white sporodochia, similar to those produced by several other members of Atractiellales, whereas Pr. hameedii forms conidia singly or in chains in a manner similar to its sister species Pr. pinicola. Additionally, we provide a taxonomic revision of Atractiellomycetes based on multilocus analyses and propose the new genera Neogloea (Helicogloeaceae) and Bourdotigloea (Phleogenaceae) to accommodate ex-Helicogloea species that are not congeneric with the type H. lagerheimii. Atractiellomycetes consists of a single order, Atractiellales, and three families, Hoehnelomycetaceae, Phleogenaceae, and Helicogloeaceae. Accumulated evidence suggests that Atractiellomycetes species are common but infrequently isolated members of plant foliar and root endobiomes.

KEYWORDS:

• Atractiella
• Helicogloeaceae
• Hobsonia
• Leucogloea
• orchid mycorrhizae
• Phleogena
• Saccoblastia
• 7 new taxa

ACKNOWLEDGMENTS

We are grateful to Shannon Newerth, John Klimek, Merje Toome-Heller, Alejandro Rojas, Khalid Hameed, and Rytas Vilgalys for useful discussions, assistance in culture maintenance and generation of some of the sequence data used in this study and two anonymous reviewers for their insight and suggested improvements to the manuscript.

Additional information

Funding

This work was supported by the USDA National Institute of Food and Agriculture Hatch project 1010662, and funded in part by NSF DEB 1502887 & NSF DEB 0732968. GB acknowledges Michigan State University AgBioResearch NIFA project MICL02416 and Plant-Microbe Interfaces program (DE-AC05-00OR22725) for support.