Polyphasic taxonomy of Penicillium subgenus Penicillium A ... - CBS

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J.C. FRISVAD &R.A.SAMSONExtrolite analysisCYA and YES were used for extrolite analysis. Agarplugs (6 mm diameter) were cut out of 7 days oldcultures and kept in a – 18°C freezer until extraction.The cultures were extracted according to the methodof Smedsgaard (1987) using 500 μl ethylacetate /methanol / dichloromethane 3:2:1 (vol. / vol. / vol.)with 1 % formic acid and ultrasonicated for 10 minutes.The organic solvent was transferred to anothervial and evaporated at 1 mbar in a Rotavapor centrifugeevaporator. The extract was redissolved in 400μl methanol and analysed by HPLC with diode arraydetection (DAD) or electrospray mass spectrometricdetection (ES-MS) (Frisvad and Thrane, 1987; 1993and Smedsgaard, 1997; Nielsen and Smedsgaard,2003). The extrolites were identified by their UVspectra and MS characteristics. Authentic analyticalstandards were employed for retention time andretention index comparison with the extrolites detected.polyphasic approach and mulilocus DNA sequencesis needed to resolve the taxonomy of this teleomorphgenus. Occasionally biverticillate species include P.digitatum, P. sclerotigenum and certain isolates of P.chrysogenum. The extrolites produced by thesespecies, the plant pathogenicity (of P. digitatum andP. sclerotigenum) and DNA sequence data (Peterson,2000) clearly shows that these taxa should be placedin subgenus Penicillium.TaxonomyDelimitation of Penicillium subgenus PenicilliumPenicillium subgenus Penicillium comprises specieswith terverticillate (two stage branched) conidiophores(Fig. 4). They all sporulate heavily and areoften fasciculate. However the subgenus also appearsto be a natural group, i.e. it is both phylogeneticallyand ecologically distinct. All species are related toanimal nutrition and excretion and mans domesticatedlandscapes, e.g. they are found growing andsporulating on plant, algal, animal or fungal raw orprocessed materials and in dwellings of man andother animals. They all grow well at low temperaturesand poorly, if at all, at 37°C. They also grow well atlow water activities and at low pH values (Pitt andHocking, 1998; Frisvad et al., 2000).Excluded taxaSome species in other subgenera with similar penicillior ecology are excluded from subgenus Penicilliumfor the reasons discussed below.Species in the other subgenera are mainly soil orplant root associated (subgenus Aspergilloides andFurcatum) or are often associated with wood andtextiles (subgenus Biverticillium). These ecologicallybased subdivisions are strongly supported by DNAsequence data (Peterson, 2000). DNA sequence dataalso indicate that most species in Eupenicillium seriesCrustacea, except E. shearii, are related to P. chrysogenum(Peterson, 2000). Some species e.g. Eupenicilliumcrustaceum E. egyptiacum and E. molle (Fig.5) have many terverticillate structures, however, andyet should be included in subgenus Penicillium. Inthe present revision we have not included the Eupenicilliumspecies because a major revision using aFig 4. Conidiophore branching patterns in subgenus PenicillliumFig 5. Conidiophores, conidia and ascogenous structures of aEupenicillium crustaceum (A-B), E. egyptiacum (C-D) and E.molle (E).10
P. oxalicum has biverticillate structures, but is pathogenicto cucumbers (Menzies et al., 1995). It showsrich growth at 37 °C and is phylogenetically close tosubgenus Furcatum (Peterson, 2000). On balance,this isolate have been excluded from subgenus Penicilliumin this treatment. Other species in Furcatumare endophytes of plants; e.g. P. nodusitatum formsmyconodules with elder trees (Valla et al., 1989).This species is biverticillate and asymmetric and thusbelong to subgenus Furcatum.Several soil-borne species can produce a fewasymmetric terverticillate conidiophores, but in mostcases, these can be recognized as twice biverticillatestructures. The best examples of this are P. lanosumand P. scabrosum. P. lanosum (Fig. 6) was includedamong the asymmetric terverticillate Penicillia bySamson et al. (1976) and as a synonym of P. puberulumin subgenus Penicillium by Pitt (1979). P. lanosumand P. scabrosum produce extrolites that areboth produced by subgenus Furcatum and subgenusPenicillium species (Frisvad et al., 1990a & b). Basedon phenetic and phylogenetic data we place the lattertwo species in subgenus Furcatum. This is in agreementwith Domsch et al. (1980). These authorsplaced P. scabrosum (listed as P. atrovenetum, p.545) and P. lanosum (p. 584) close to soil-bornePenicillia in subgenus Furcatum, P. herquei and P.jensenii, respectively.Fig. 6. Conidophores and conidia of Penicillium lanosum.POLYPHASIC TAXONOMY OF SUBGENUS PENICILLIUMP. arenicola was so different from all other Penicilliumspecies that Pitt (1979) set it apart in sectionInordinate Pitt, series Arenicola Pitt, with P. canadenseas a synonym. The very irregular penicilli, thegolden blonde to olive brown conidia, the dark brownreverse, the production of canadensolide and thespecific occurrence in forest soil all suggest an entirelyunique placement in Penicillium and no links toany species in subgenus Penicillium. The only featuresin common with species in subgenus Penicilliumare the often terverticillate Penicilli and theproduction of the extrolite asperphenamate. We havetherefore omitted P. arenicola in this monograph.Species conceptMany controversies exist regarding the infraspecificranks of variety and subspecies. We have chosen touse only the species rank following the idea thatvarieties and subspecies are usually based on theneodarwinian idea that populations and races willgradually turn into new species, for example, aftergeographical separation and selection. As we do notsubscribe to that mechanism as the only cause ofspeciation, in agreement with Schlichting andPigliucci (1998), we here adopt the species level asthe lowest formal taxonomic level.We here adopt a phenotypic species concept inwhich each species is a homogeneous and distinctcluster in phenotypic space with a large distance toany other such cluster. Species discovered this wayhave proven to agree with other species conceptssuch as those based on ecology or phylogeny. Thecriteria applied are a combination of micromorphological,macromorphological, physiological andextrolite characters. Classifications and identificationsbased on any of those types of characters alonehave been unsatisfactory among others because of themany taxa in Penicillium.We will exemplify this with Penicillium crustosum.P. crustosum was described in 1930 by Thomand accepted in the P. expansum series by Raper andThom (1949), even though a synonym of it, P. terrestreJensen, was placed in the P. terrestre seriesbased on slightly different colony texture. Samson etal. (1976) placed P. crustosum in synonomy with P.verrucosum var. cyclopium based on micromorphologicalsimilarities. Fassatiova (1977) placed P.crustosum close to P. expansum and reduced it tovariety status as P. expansum var. crustosum. Pitt(1979b) accepted P. crustosum, but included isolatesof P. aurantiogriseum (P. australicum) and P. solitum(P. verrucosum var. melanochlorum), inconsistentwith the high growth rate claimed to be characteristicfor P. crustosum, while P. solitum and P.aurantiogriseum grow very slowly. Other strains ofP. solitum and P. aurantiogriseum were placed underthe latter species by Pitt (1979b). Bridge et al. (1989)reduced P. crustosum to a variety of P. solitum as P.solitum var. crustosum. Frisvad and Filtenborg (1989)accepted P. crustosum based on its consistent productionof penitrem A, roquefortine C, terrestric acid andcyclopenol in combination with its high growth rateand extraordinarily high production of conidia. Someof the similar and dissimilar features of the speciesabove (see also page 50) show why it is important to11
Page 2 and 3: J.C. FRISVAD &R.A.SAMSONcies is not
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Page 19 and 20: dipodomyis are mainly distinguished
Page 21 and 22: species of the Claviformia by the m
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Page 25 and 26: Ex type cultures of P. granulatum (
Page 27 and 28: = P. terraconense Ramírez & Martí
Page 29 and 30: Two names, P. aurantiocandidum and
Page 31 and 32: (except P. allii and P. albocoremiu
Page 33 and 34: species on cheese (Lund et al., 199
Page 39 and 40: List of accepted species in subgenu
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POLYPHASIC TAXONOMY OF SUBGENUS PEN
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Smedsgaard J. (1997b) Terverticilla
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Polyphasic taxonomy of Penicillium subgenus Penicillium A ... - CBS

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