A new ecological note on Confertobasidium olivaceoalbum (Russulales, Basidiomycota)

Abstract

Confertobasidium olivaceoalbum, a rare corticioid fungus, is recorded for the first time on wood of Eucalyptus globulus in Italy. Since this species has been recorded only on coniferous wood , this finding adds new information to the ecology, geographic distribution and molecular data of corticioid fungi.

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Germany. DOI: 10.1127/nova_hedwigia/2017/0423 0029-5035/2017/0423 $ 2.50
Nova Hedwigia Vol. 105 (2017) Issue 3–4, 425–434
published online May 19, 2017; published in print November 2017 Article
C
A new ecological note on Confertobasidium olivaceoalbum
(Russulales, Basidiomycota)
Elia Ambrosio1,2*, Sergey Volobuev3, Mauro Giorgio Mariotti4–6, Mirca
Zotti2,6, Elena Zappa4–6 and Valeria Agamennone7
1 Via Calamandrei 2, 53035 Monteriggioni, Siena, Italy
2 Laboratory of Mycology, Department of Earth, the Environment and Life Science
(DISTAV), University of Genoa, Corso Europa 26, 16136 Genova, Italy
3 Laboratory of Systematics and Geography of Fungi, Komarov Botanical Institute,
Russian Accademy of Science, Professor Popov str., 2, St. Petersburg, 197376, Russia
4 Polo Botanico "Hanbury", University of Genoa, Corso Dogali, 1 M, 16136 Genova, Italy
5 Hanbury Botanical Gardens, Corso Montecarlo, 43 La Mortola, 18039 Ventimiglia,
Imperia, Italy
6 Department of Earth, the Environment and Life Science (DISTAV), University of Genoa,
Corso Europa 26, 16132 Genoa, Italy
7 Department of Ecological Science, VU University Amsterdam, De Boelelaan
1085-1087, 1081 HV Amsterdam, The Netherlands
With 4 gures
Abstract: Confertobasidium olivaceoalbum, a rare corticioid fungus, is recorded for the first time
on wood of Eucalyptus globulus in Italy. Since this species has been recorded only on coniferous
wood, this finding adds new information to the ecology, geographic distribution and molecular data
of corticioid fungi.
Key words: corticioid fungi, ecology, ITS, exotic plants, botanical gardens.
Introduction
Over the last decades, the classification of corticioid fungi has been challenging for
mycologists, due to the complexity in the species identification, the phylogenetic
relationships and the position of many taxa. Thanks to the progress of the molecular
*Corresponding author: elia.ambrosio.10@gmail.com
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analysis and the acquisition of new sequencing data, there is a relative consensus
that corticioid fungi are distributed among all major clades of Agaricomycetes
(Basidiomycota) (Larsson & Larsson 2003, Larsson 2007).
Among several corticioid fungi, the whole genus Confertobasidium Jülich, and the
species C. olivaceoalbum (Bourdot & Galzin) Jülich, have been subjected to several
phylogenetic misplacements. C. olivaceoalbum was formerly introduced as the type to
identify athelioid species with brownish basal hyphae (Jülich 1972). Later on, Ginns and
Lefebvre (1993) transferred C. olivaceoalbum to Scytinostromella Parmasto because
of the presence of gloeocystidia, skeletal hyphae and an athelioid basidiome. More
recently, Larsson and Larsson (2003), by studying the phylogenetic relationships of
aphyllophoraceous taxa, observed that skeletal hyphae have been overestimated as a
taxonomic character at the generic level and the dimitic hyphal systems have evolved
many times within the russuloid clade. Hence, Confertobasidium has its closest
relative in the monomitic Metulodontia Parmasto rather than genera with a dimitic
hyphal system (e.g. Scytinostromella Parmasto, Wrightoporia Pouzar) within the/
scytinostromella clade.
Currently, the genus Confertobasidium includes two species and two varieties: C. oliva-
ceoalbum, C. montanum (Jülich) Jülich & Stalpers, C. olivaceoalbum var. montanum
Jülich and C. olivaceoalbum var. olivaceoalbum (Bourdot & Galzin) Jülich (www.
mycobank.org, www.indexfungorum.org). Among these, C. olivaceoalbum is described
in the literature being scantly distributed in the world and showing a preference for
growth on certain substrates. In fact, several authors recorded this species only on
stumps of conifers, such as Abies alba Mill., Larix decidua Mill., Picea abies (L.)
H.Karst. and Pinus pinea L. (Bernicchia & Gorjón 2010, Antonin et al. 2012, Dai et
al. 2013, Prasher & Ashok 2013).
During a mycological study aimed to record macrofungal species in the historical
Hanbury Botanical Gardens (GBHs), located in north-western Italy (Liguria)
(Ambrosio et al. 2015), C. olivaceoalbum, was collected on Eucalyptus globulus Labill.
This plant, commonly named as Tasmanian blue gum, is an evergreen broadleaf tree
native to south-eastern Australia. It was introduced in south-western Europe (in Portugal
and Spain) and Northern Africa in the mid 19th century for industrial purposes, mainly
for timber and paper pulp. Nowadays, in Europe, it is present mainly in Portugal and
in north western Spain. A small number of trees are also distributed in France and in
southern Italy (e.g. in Sicily and Sardinia) (Cerasoli et al. 2016).
Since, to the best of our knowledge, no record exists of C. olivaceoalbum on E. globulus,
the aim of this paper is to identify by morphological and molecular analysis the collected
corticioid specimens in order to: i) update our knowledge on the ecology and geographic
distribution of this species; and ii) increase molecular data on corticioid fungi.
Materials and methods
Study Site: The historical Hanbury Botanical Gardens (GBHs) are located in Liguria (NW Italy)
on the promontory of "Capo Mortola", in the province of Imperia, a few kilometers from the border
between Italy and France (Fig. 1). These gardens cover over 19 hectares with plants from different
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areas with subtropical or warm-temperate climates; semi-natural Mediterranean vegetation (viz. Pinus
halepensis Mill. woods) and the Mediterranean maquis dominated by Quercus ilex L. (Campodonico
2010, Profumo 2010, Ambrosio et al. 2015). GBHs host a high number of plant species (approximately
3500 taxa) and the whole site is declared both Regional Protected Area and Site of Community
Importance (under the Directive 92/43).
The area enjoys a Temperate Mediterranean climate with a hot, dry summer (Rivas-Martinez 2008).
The mean temperature is 22.3°C in July and 8.1°C in January, and the rainfall varies from 117 mm
in November to 20 mm in July (www.climate-data.org). The soil of the area is sandy, formed by
the decomposition of nummulitic limestone of the Lower Eocene period and by a small travertine
deposit (Berger 1912, Ambrosio et al. 2015).
Survey and SpecieS identification: The examined basidiomata were collected on two separate
occasions on the cortex of Eucalyptus globulus (Fig. 2) in October 2013. The identification and
description of the basidioma is based on both morphological and molecular analysis of fresh and dried
specimens. The macroscopic descrip tions were carried out on fresh basidioma while the microscopic
features were observed, under an Olympus BH-2, on dried specimens using a 0.3% KOH solution and
0.1% cotton blue in lactic acid. The spore measurements are based on 50 observations on fresh and
dried samples. For the taxonomical identification the European literature was used (e.g. Hjortstam
et al. 1981, Breitenbach & Kränzlin 1995, Bernicchia & Gorjón 2010).
DNA was extracted from dried specimens using Axygen Genomic DNA Miniprep Kit (Axygen
Biotecnology (Hangzhou) limited, China) according to the manufacturer’s protocol. The primer pair
ITS1F and ITS4B (Gardes & Bruns 1993) was used to amplify the ITS1-5.8S ITS2 region of the
nuclear ribosomal DNA (nrDNA). The PCR products were purified using the Fermentas Genomic
DNA Purification Kit (Thermo Scientific, Lithuania). The sequencing was performed using the
Fig. 1. Geographic localization of the study site.
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BigDieTM Terminator Cycle Sequencing Ready Reaction Kit (Applied Biosystems) on ABI 3140
Sequencer (Applied Biosystems). The obtained sequence alignment contains 771 bp and it has been
deposited to the NCBI GenBank database under the accession number KX355485.
The BLAST algorithm was used to compare the obtained ITS sequence to available sequences in the
GenBank database, and to select sequences of closely related species to be used for the alignment
and phylogenetic analysis.
Phylogenetic analysis was conducted with MEGA6 (Tamura et al. 2013): sequences were aligned using
the ClustalW algorithm, and a maximum likelihood analysis was performed to obtain a phylogenetic
tree (Tamura et al. 2004, Hall 2013). Gamma distribution of rates was used to calculate the genetic
distance between ITS sequences of C. olivaceoalbum and closely related species in MEGA6. Standard
error estimates were obtained by a bootstrap procedure (500 replicates).
The studied specimens are deposited in the Herbarium at the Komarov Botanical Institute in St.
Petersburg, Russia (det. S.Volobuev; coll. num. LE 303396) and in the personal Herbarium collected
by E.Ambrosio (coll. num. 20131001).
Systematic classification followed Hibbet et al. (2007) and Kirk et al. (2008). Nomenclature and
author abbreviations were used in accordance with CABI (www.indexfungorum.org), CBS (www.
cbs.knaw.nl) and IMA (www.mycobank.org).
Results
As a result of the macro- and microscopic examination, the species Confertobasidium
olivaceoalbum was identified. The detailed morphological characteristics of the
specimens follows the nomenclature citation provided below.
Confertobasidium olivaceoalbum (Bourdot & Galzin) Jülich, Willdenowia Beiheft
7: 167 (1972)
≡ Corticium olivaceoalbum Bourdot & Galzin, Bulletin de la Société Mycologique de France 27
(2): 239 (1911)
Fig. 2. Different view of Eucalyptus globulus in the study site: a. canopy; b. trunk; c. fallen cortex.
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≡ Athelia olivaceoalba (Bourdot & Galzin) Donk, Fungus 27: 12 (1957)
≡ Gloeocystidiellum olivaceoalbum (Bourdot & Galzin) Tellería, Nova Hedwigia 53 (1–2): 237 (1991)
≡ Scytinostromella olivaceoalba (Bourdot & Galzin) Ginns & M.N.L.Lefebvre, Mycologia Memoirs
19: 141 (1993)
≡ Amylocorticium olivaceoalbum (Bourdot & Galzin) Boidin, Lanq. & Gilles, Bulletin de la Société
Mycologique de France 113 (1): 76 (1997)
= Scytinostromella fallax Burds. & Nakasone, Mycologia 73: 469 (1981)
= Gloeocystidiellum parvisporum Manjón & G.Moreno, Anales del Jardín Botánico de Madrid 38
(2): 334 (1982)
Basidiomata resupinate, effused, crustaceous or membranaceous to pellicular, hymeno-
phore smooth, whitish to pale yellow, margin usually rhizomorphic (Fig. 3).
Hyphal system dimitic, generative hyphae with clamps, thin-walled, 3–4.5 µm wide,
hyaline to pale yellow, skeletal hyphae originated from thin-walled clamped hyphae,
narrow, thick-walled.
Gloeocystidia positive to the reaction with sulpho-aldehydes (viz. SA+), fusiform or
cylindrical, sinuous and constricted, 20–25 × 3–5 µm.
Basidia cylindrical, 15–20 × 3.5–5 µm, with 4 sterigmata and a basal clamp.
Basidiospores ovoid, broadly ellipsoid, 4–4.5(5) × 2–2.5 µm, smooth, thin-walled,
weakly amyloid, acyanophilous.
The morphological identification was supported by molecular data. We used BLAST to
compare the ITS sequence of C. olivaceoalbum to sequences in the GenBank database.
To estimate the phylogenetic relationships by evolutionary distance we selected ITS
nrDNA sequences deposited in NCBI GenBank database of C. olivaceoalbum from
other geographic regions of the world and we also selected some sequences of the
closest phylogenetic species and genera (e.g. Scytinostromella spp., Metulodontia
nivea) based on the most recent study (Larsson & Larsson 2003; Larsson 2007).
Phanerochaete livescens (P.Karsten) S.Volobuev & V.Spirin was selected as outgroup.
The result of the phylogenetic analysis (Fig. 4) shows that all the C. olivaceoalbum
specimens form a separate and distinctive group from the other closest systematic
relatives (e.g. the Scytinostromella group).
Discussion
Available ecological data state that Confertobasidium olivaceoalbum was recorded only
on dead stump of conifers, such as Abies, Cedrus, Larix, Pinus and Picea (Bernicchia
& Gorjón 2010, Antonin et al. 2012, Dai et al. 2013, Prasher and Ashok 2013). To
the best of our knowledge, no record is available of C. olivaceoalbum on Eucalyptus
globulus. Hence, with this finding we can confirm its presence on a different known
substratum.
Moreover, current references point out that the geographical distribution of C. oliva-
ceoalbum is fragmented and its presence is recorded in few areas in the Northern
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Hemisphere, such as in Russia (Ghobad-Nejhad 2011, Filippova & Zmitrovich 2013),
in Europe (in Italy by Bernicchia & Gorjón 2010; in Austria by Von Harald & Willibald
1993; in Czech Republic by Antonín et al. 2012; in Germany by Grosse-Brauckmann
1989), in America (in USA by Burdsall and Nakasone 1981), and in the tropical zone (in
India by Prasher & Ashok 2013, Ranadive 2013; in China by Dai et al. 2004). In Italy,
according to Bernicchia and Gorjón (2010) C. olivaceoalbum is scarcely distributed.
They recorded this species only in four regions, viz. Trentino Alto-Adige, Veneto,
Emilia Romagna, Tuscany and Lazio. Hence, our finding can be considered the first
record for the region of Liguria (Zotti & Orsino 2001, Onofri et al. 2005, Zotti et al.
2008, Ambrosio et al. 2014). Moreover, the new collection of a rare corticioid species
in Italy enriches the mycological national dataset (Onofri et al. 2005, Bernicchia &
Gorjòn 2010, Venturella et al. 2011) and highlights the presence in this country of a
high number of rare wood decaying fungi (Saitta et al. 2011, 2017).
Consistently with the study by Larsson and Larsson (2003), our analysis supports
the hypothesis that C. olivaceoalbum is not the sister group of Scytinostromella
heterogenea (Bourdot & Galzin) Parmasto, the generic type of Scytinostromella, but
rather it constitutes a separate group (see Fig. 4).
Fig. 3. Macroscopical pictures of Confertobasidium olivaceoalbum at necked eye in the study site.
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It is also interesting to observe that this fungus has been found on a plant that is exotic
for the Italian flora. This should encourage us to broaden our investigations on the
presence of macrofungal species in sites of conservative interest (e.g. botanical gardens),
since a large number of fungi are adapted to grow as parasites on plants, sometimes
causing extensive damage that can be very costly from a natural conservative perspective
(Deacon 2006, Mueller 2004). Alternatively, in extreme cases, the exotic plants can also
be a vector for invasive organisms such as fungi, thus becoming extremely dangerous
for the autochthonous flora. In fact, plant conservation actions cannot be implemented
without a complete knowledge of the diversity and the interactions between plants and
other living organisms, in particular fungi (Ambrosio et al. 2015).
Finally, the recording and the identification, by both morphological and molecular
analysis, of C. olivaceoalbum on E. globulus allow us to expand our knowledge on the
geographic distribution and ecology of this species. In addition, from a systematic point
of view, our results increase the dataset on corticioid fungi, although new morphological
and molecular studies need to be carried out to deepen our knowledge on the systematic
and the phylogenetic relationships of this group of fungi. Future studies should be
addressed to investigate less or never studied areas in order to increase our knowledge
on the macrofungal species diversity.
Fig. 4. ITS-based phylogenetic tree showing the phylogenetic relationships between Confertobasidium
olivaceoalbum and closely related species and genera.
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Acknowledgments
Authors would like to thank K.-H.Larsson for his support in the species identification, and A.Saitta
for his collaboration in sharing comparative specimens. We also would like to thank V.Barra for the
help with the English revision of the manuscript and G.Nardi for the support in the graphic images.
This study was carried out in the framework of a PhD project in Applied Botany to the Agriculture
and the Environment, University of Genoa, Italy. E.Ambrosio was supported by MIUR (Ministry of
Education, Universities and Research – Italy) doctoral fellowship (2012–2014). Molecular analysis
was performed at the Komarov Botanical Institute, Russian Accademy of Science (St. Petersburg,
Russia).
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