Phylogeny and taxonomy of the North American clade of the Ceratocystis fimbriata complex

Abstract

Ceratocystis fimbriata is a widely distributed, plant pathogenic fungus that causes wilts and cankers on many woody hosts. Earlier phylogenetic analyses of DNA sequences revealed three geographic clades within the C. fimbriata complex that are centered respectively in North America, Latin America and Asia. This study looked for cryptic species within the North American clade. The internal transcribed spacer regions (ITS) of the rDNA were sequenced, and phylogenetic analysis indicated that most isolates from the North American clade group into four host-associated lineages, referred to as the aspen, hickory, oak and cherry lineages, which were isolated primarily from wounds or diseased trees of Populus, Carya, Quercus and Prunus, respectively. A single isolate collected from P. serotina in Wisconsin had a unique ITS sequence. Allozyme electromorphs also were highly polymorphic within the North American clade, and the inferred phylogenies from these data were congruent with the ITS-rDNA analyses. In pairing experiments isolates from the aspen, hickory, oak and cherry lineages were interfertile only with other isolates from their respective lineages. Inoculation experiments with isolates of the four host-associated groupings showed strong host specialization by isolates from the aspen and hickory lineages on Populus tremuloides and Carya illinoensis, respectively, but isolates from the oak and cherry lineages did not consistently reveal host specialization. Morphological features distinguish isolates in the North American clade from those of the Latin American clade (including C. fimbriata sensu stricto). Based on the phylogenetic evidence, interfertility, host specialization and morphology, the oak and cherry lineages are recognized as the earlier described C. variospora, the poplar lineage as C. populicola sp. nov., and the hickory lineage as C. caryae sp. nov. A new species associated with the bark beetle Scolytus quadrispinosus on Carya is closely related to C. caryae and is described as C. smalleyi.

Real-Time PCR for Ceratocystis platani detection: in-depth validation to assess the diagnostic potential and include additional technical options

“…Of the other members of the Ceratocystidaceae within the geographic distribution of C. platani in Europe and Asia Minor (Tsopelas et al 2017), Endoconiophora coerulescens and E. resinifera were detected occasionally at 5 ng or 500 pg per reaction, but these species are only known in wood of Pinaceae (Harrington & Wingfield 1997). There may be some geographic overlap for C. harringtonii or C. variospora with C. platani in the USA (Johnson et al 2005), but these and the other tested species are not known to colonize Platanus spp., and C. platani is highly specific to this host (Baker et al 2003.…”

Reconsidering species boundaries in theCeratocystis paradoxacomplex, including a new species from oil palm and cacao in Cameroon

“…Under the dual nomenclature system, the asexual states of Ceratocystis species were treated in the genus Chalara (Nag Raj and Kendrick 1975) and were more recently consolidated in Thielaviopsis (Paulin-Mahady et al 2002). Based on DNA sequence analyses, it is now recognized that there are distinct phylogenetic lineages in Ceratocystis, defining complexes in which species have similar morphological and ecological characteristics (Harrington et al 1996, Harrington and Wingfield 1998, Baker et al 2003, Johnson et al 2005, van Wyk et al 2006. Indeed, it has been suggested that some of these lineages represent discrete genera .…”

“…However, in the taxonomic literature of Ceratocystis during the past decade, the endoconidia have been described consistently as of two forms. These have been referred to as cylindrical versus doliform endoconidia (Baker-Engelbrecht andHarrington 2005, Johnson et al 2005) or by other authors as primary versus secondary conidia (van Wyk et al 2006(van Wyk et al , 2007(van Wyk et al , 2009(van Wyk et al , 2011Heath et al 2009). For the purpose of the present study we define the endoconidia produced in phialides as primary conidia when they are aseptate, hyaline and cylindrical.…”

Global analyses of Ceratocystis cacaofunesta mitochondria: from genome to proteome

“…This fungus is a member of the Latin American clade of the Ceratocystis fimbriata complex [1,2], a taxonomic group that includes species with high genetic variability and wide host ranges [3,4]. These species cause canker and wilt diseases in many economically important crops, such as Coffea arabica and Eucalyptus spp.…”

“…C. cacaofunesta is indigenous to Central and South America [1,2]. In Brazil, this pathogen was first reported in the Amazon region [7].…”