Phylogeny and taxonomy of Phaeoacremonium and its relatives

L. Mostert

Research output: Thesisexternal PhD, WU


Species of Phaeoacremonium are known vascular plant pathogens causing wilt and dieback of woody hosts.  The most prominent diseases in which they are involved are Petri disease and esca, which occur on grapevines and are caused by a complex of fungi, including Phaeomoniella chlamydospora and several species of Phaeoacremonium . Various Phaeoacremonium species are also opportunistic on humans, where they are known to cause phaeohyphomycosis. 

The genus Togninia was confirmed as the teleomorph of Phaeoacremonium by means of morphology, sexual compatibility, and DNA phylogeny. Subsequently, the genus Togninia was monographed along with its Phaeoacremonium anamorphs. Ten species of Togninia and 22 species of Phaeoacremonium were treated. Several new species of Togninia were found during the course of the study, namely T. argentinensis , T. austroafricana , T. krajdenii , T.parasitica , T.rubrigena and T. viticola . New species of Phaeoacremonium includePm. alvesii, Pm. amstelodamense,Pm. argentinense ,Pm. australiense,Pm. austroafricanum, Pm. griseorubrum,Pm.krajdenii,Pm. novae-zealandiae , Pm . iranianum ,Pm. scolyti, Pm. sphinctrophorum,Pm.subulatum,Pm. tardicrescens,Pm . theobromatisandPm. venezuelense . Species were identified based on their cultural and morphological characters, supported by DNA data derived from partial sequences of the actin and β-tubulin genes. Phylogenies of the SSU and LSU rRNA genes were used to determine whether Togninia has more affinity with the Calosphaeriales or the Diaporthales . These results confirmed that Togninia had a higher affinity to the Diaporthales than the Calosphaeriales . Examination of type specimens revealed that T.cornicola , T.vasculosa , T . rhododendri, T . minima var. timidula and T.villosa , were not members of Togninia . New combinations such as Calosphaeria cornicola,Calosphaeriarhododendri , Calosphaeriatransversa , Calosphaeriatumidula,Calosphaeriavasculosa and Jattaeavillosawere therefore proposed to accommodate these species.

The correct and rapid identification of Phaeoacremonium species is important tofacilitate the understanding of their involvementin plant as well as human disease. A rapid identification method was developed for the 22 species of Phaeoacremonium currently recognised. It involved the use of 23 species-specific primers, including 20 primers targeting the β-tubulin gene and three targeting the actin gene. These primers can be used in 14 multiplex reactions. Additionally a multiple-entry electronic key based on morphological, cultural andb-tubulin sequence data was developed to facilitate routine species identification. This database can be accessed online at With this identification tool phenotypic and sequence data can be used to identify the different Phaeoacremonium species. Separate dichotomous keys were provided for the identification of the Togninia and Phaeoacremonium species based on phenotypic characters. Additionally, keys for the identification of Phaeoacremonium -like fungi and the genera related to Togninia were also provided. 

The mating strategy of several Togninia species was investigated with ascospores obtained from fertile perithecia produced in vitroTogninia argentinensis and T.novae-zealandiae have homothallic mating systems, whereas T. austroafricana , T. krajdenii , T. minima , T.parasitica , T. rubrigena and T. viticola are heterothallic. The species predominantly isolated from diseased grapevines are Pm. aleophilum , Pm. parasiticum and Pm. viticola . Perithecia of two of these species, T. minima and T. viticola , have been found on grapevines in the field, indicating that these species recombine in vineyards. 

The genetic diversity among isolates ofPa.chlamydospora on grapevines was investigated by means of Amplified Fragment Length Polymorphisms (AFLPs). Phaeomoniellachlamydospora isolates were collected from different positions on the same vine, different vines within a vineyard and different vineyards withinSouth Africa. Selected isolates from various grape producing countries, namelyAustralia,France,Italy,Iran,New Zealand,SloveniaandU.S.A.were also included. The overall low level of genetic variation confirmed asexual reproduction to be dominantin the field. Different genotypes were found among isolates ofPa.chlamydospora within the same grapevine, suggesting multiple infections from different inoculum sources. Isolates from different countries had a high percentage of similarity and clustered together, indicating the absence of genotype-geographic structure. The presence of the same genotype in different vineyards and production areas suggests that long-range dispersal through aerial inoculum or infected plant material played an important role in genotype distribution. 

Seven species of Togninia and 15 species of Phaeoacremonium were newly described during the course of this study. The data obtained in this study, as well as the newly developed dichotomous and online polyphasic keys will enable scientists to correctly identify all the known species and also provide a reference database to which new species can be added in future. The newly reported host ranges and distributions, together with pathogenicity data, will enable scientists to identify species of possible quarantine concern.

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
  • Crous, Pedro, Promotor
  • Abeln, E.C.A., Co-promotor, External person
Award date23 Jun 2006
Place of Publication[S.l.]
Print ISBNs9789085044604
Publication statusPublished - 2006


  • diaporthales
  • pezizomycotina
  • deuteromycotina
  • phylogeny
  • taxonomy
  • keys
  • phaeohyphomycosis
  • human diseases
  • medical mycology
  • plant pathogenic fungi


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