Resolving host and species boundaries for perithecia-producing nectriaceous fungi across the central Appalachian Mountains

Cameron M Stauder,Nicole M Utano,Matt T Kasson

doi:10.1016/j.funeco.2020.100980

Abstract

Abstract The Nectriaceae includes numerous canker pathogens. Due to the scarcity of ascomata on many hosts, comprehensive surveys are lacking. Here we characterize the diversity of perithecia-producing nectriaceous fungi across the central Appalachians in eastern North America. Nine species from eleven hosts were recovered including a novel Corinectria sp. from Picea rubens. Neonectria ditissima and Neonectria faginata were most abundant and associated with Fagus grandifolia with beech bark disease (BBD). Neonectria ditissima was also recovered from additional cankered hardwoods, including previously unreported Acer spicatum, Ilex mucronata, and Sorbus americana. Cross-pathogenicity inoculations of N. ditissima confirmed susceptibility of Acer and Betula spp. Neonectria magnoliae was recovered from cankered Liriodendron tulipifera and Magnolia fraseri and pathogenicity on L. tulipifera was confirmed. Fusarium babinda was consistently recovered from beech with BBD, although its role remains unclear. This survey provides a contemporary snapshot of Nectriaceae diversity across the Appalachian Mountains. The following nomenclatural changes are proposed: Neonectria magnoliae comb. nov.

Highlights

Members of the Nectriaceae occupy diverse ecological niches from mycoparasites to phytopathogens, with numerous genera and species implicated in causing annual and perennial cankers on diverse woody plant hosts with varying degrees of host specificity
Over the course of the survey, ten species of Nectriaceae belonging to Bionectria, Corinectria, Cosmospora, Fusarium, Neonectria, Thelonectria, and Thyronectria were recovered from twelve tree hosts spanning 17 sites across six states (Table 1; Fig. 3)
Many former members of the genus Nectria have since been reclassified into different genera (Brayford et al, 2004; Castlebury et al, 2006; Mantiri et al, 2001; Rossman et al, 1999). None of these studies considered Nectria magnoliae, and its taxonomy was never properly resolved with one erroneous exception: Castlebury and colleagues (2006) included one isolate of Nectria magnoliae from tulip poplar from Tennessee in a phylogenetic study of Neonectria

Summary

Introduction

Members of the Nectriaceae occupy diverse ecological niches from mycoparasites to phytopathogens, with numerous genera and species implicated in causing annual and perennial cankers on diverse woody plant hosts with varying degrees of host specificity. One such canker disease, beech bark disease (BBD), is a disease complex occurring across the range of American beech (Fagus grandifolia Ehrh.) in North America and European beech (Fagus sylvatica L.) in Europe. Tul.] Samuels & Rossman) and either N. faginata & Watson) on American beech or N. coccinea ([Pers.] Rossman and Samuels) (Houston, 1994b; Thomsen et al, 1949). Other members of Nectriaceae have occasionally been associated with BBD, including Bionectria ochroleuca ([Schwein.] Schroers & Samuels) and Fusarium spp., but their roles, if any, in BBD are not well understood (Cotter and Blanchard, 1982; Houston et al, 1987; Kasson and Livingston, 2009)

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