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100 Ectomycorrhizal Symbioses in Tropical and Neotropical Forests
6
CHAPTER
Abundance, Distribution, and
Function of
Pisolithus albus
and other Ectomycorrhizal
Fungi of Ultramafic Soils in
New Caledonia
Philippe Jourand,1,* Fabian Carriconde,2
Marc Ducousso,3 Clarisse Majorel,1 Laure Hannibal,1
Yves Prin3 and Michel Lebrun4
1. Introduction
Ultramafi c soils, also known as “serpentine soils” in literature, are a
weathered product from ultramafi c bedrock that covers less than 1% of the
earth’s surface (Coleman and Jove 1992). These soils are characterized by
high concentrations of iron oxides (up to 85% w/w), unbalanced calcium-
1IRD, UR040 LSTM, Centre IRD, BPA5, Promenade Roger Laroque, 98848 Nouméa Cedex,
Nouvelle-Calédonie.
2Institut Agronomique néo-Calédonien (IAC), Axe 2 ‘Diversités biologique et fonctionnelle
des écosystèmes terrestres’, Nouméa IRD research centre, BP18239, 98857 Nouméa, Nouvelle-
Calédonie.
3CIRAD, UMR LSTM, TA A-82 ⁄ J Campus International de Baillarguet, 34398 Montpellier
Cedex 5 France.
4Université Montpellier 2, UMR28 LSTM, TA A-82 ⁄ J Campus International deBaillarguet,
34398 Montpellier Cedex 5, France.
*Corresponding author: philippe.jourand@ird.fr
Abundance, Distribution, and Function of Pisolithus albus 101
to-magnesium ratio (up to 1/30 that consequently may infl uence both
Mg and Ca plant nutrition), and the presence of various heavy metals at
high concentrations, such as chromium, cobalt, manganese and nickel,
all of which are mostly toxic for many plants (Brooks 1987). They are
also extremely defi cient in elements that are essential for plant nutrition,
including nitrogen, phosphorus and potassium (Brooks 1987, Chiarucci
and Baker 2007). Previous studies have shown that ultramafi c soils are
characterized by a high biological diversity of plants as described in Proctor
(2003) and micro organisms that use various mechanisms to cope with the
extreme edaphic conditions, in particular adaptation to toxic heavy metals
(Brady et al. 2005, Kazakou et al. 2008, Rajkumar et al. 2009). Recently, major
data about the ecological traits of ultramafi c soils have been reviewed to
propose these soils as a model system in ecology and conservation,mostly
because of their high plant diversity (Harrisson and Rajakaruna 2011).
In ultramafi c ecosystems, it is well known that most plants tolerant to
these extreme soils are involved in mycorrhizal associations, which may
greatly enhance plant nutrition (such as P assimilation) and reduce metal
toxicity on plants (Alexander et al. 2007, Smith and Read 2008). Studies
carried out on ectomycorrhizal (ECM) fungal communities in ultramafi c
soils showed a high diversity of fungal species developing ECM symbioses
with plants growing on these substrates (Moser et al. 2005, Urban et al.
2008). In addition, it was recently demonstrated that ultramafi c soils do not
limit, and can even promote, the ectomycorrhizal fungal diversity (Moser
et al. 2009, Branco and Ree 2010, Branco 2010). However, the comparison of
ECM fungal diversity between serpentine and non-serpentine soils showed
differences within the fungal population structure (Brealey et al. 2006),
sometimes with the presence of unique species (Moser et al. 2005). Moreover,
studies about physiological behaviour such as metal tolerance within a same
fungal species present on both serpentine and non-serpentine soils have
suggested adaptive evolution, raising questions about the adaptation and
evolution of fungal species on these soils (Gonçalves et al. 2007, 2009).
Here, we have presented a review carried out on ECM fungi collected
from ultramafi c soils in New Caledonia, which is a tropical archipelago
located in the South Pacifi c Ocean (Fig. 1). In New Caledonia, these soils
cover one-third of the main island due to geological evolution (Fig. 1). As
a result of the presence of such ultramafi c outcrops, numerous endemic
ecosystems have developed (Jaffré, 1992), making the main island
a biodiversity hot spot (Myers et al. 2000). In the fi rst section, we have
summarized results from existing studies and new results of ECM fungal
diversity found on these extreme soils. In the second section, we have
gathered data about the ECM Pisolithus albus (Cooke and Massee) isolated
from ultramafi c soils in New Caledonia: diversity, metal-tolerance and
symbiotic interactions with its host plant are presented.
102 Ectomycorrhizal Symbioses in Tropical and Neotropical Forests
2. Plant ECM Status and Fungal Diversity in Ultramafi c Soils
of New Caledonia
Considering the vascular plants:fungi ratio of 1:6 as reported by Hawksworth
(1991, 2001) and the number of vascular plants of 3,371 species identifi ed in
New Caledonia (T. Jaffré, personal communication), we could hypothesize
that at least 20,000 fungal species inhabit the archipelago. Referring to
the available literature and herbarium data, the mycologists Horak and
Mouchacca listed about 420 Ascomycota and Basidiomycota taxa in New
Caledonia (Horak and Mouchacca 1998, Mouchacca 1998, Mouchacca and
Horak 1998), which would indicate that approximately 2% of the species
have been inventoried.
The studies undertaken by Perrier, though preliminary, are to date the
only ones that have characterized the ECM status of some New Caledonian
plant species and the related ECM fungal diversity (Perrier 2005, Perrier
et al. 2006a,b). In New Caledonia, two main plant formations are basically
distinguished on ultramafi c rocks: sclerophyllous scrubland formations,
called “maquis” or “maquis minier”, and rain forest formations (Jaffré and
L’Huillier 2010). According to the type of soil, the altitude, and the fl oristic
composition, many groups are further identifi ed. The plant formations
Fig. 1. Geographical map of the New Caledonian archipelago in the South Pacifi c Ocean with
location of ultramafi c massifs (in grey). Data from Perrier et al. (2006a).
Abundance, Distribution, and Function of Pisolithus albus 103
studied by Perrier were located on the ultramafi c Koniambo Massif and
correspond to four distinct vegetation groups (Fig. 2): a maquis with
emerging Araucaria trees, a lingo-herbaceous maquis, a Tristaniopsis spp.
maquis and a rain forest dominated by Nothofagus balansae with patches
of N. codonandra. Investigation of the root systems of 19 species revealed
that two Tristaniopsis species, T. calobuxus and T. guillainii, are involved in
ECM symbioses. These species belong to the Myrtaceae (Leptospermoideae
group), a well-known plant family frequently found to be associated with
ECM fungi (Smith and Read 2008, Wang and Qiu 2006). Nothofagus balansae
and N. codonandra roots were also characterized by the presence of a fungal
mantle and a Hartig net. Another New Caledonian species, N. aequilateralis,
has also been previously shown to be able to develop ECM associations
(McCoy 1991). Nothofagus are indirectly, by the presence of putative ECM
fungal fruit bodies, and/or directly, by investigation of the root system,
defi ned in other regions of the world (i.e., Australia, New Zealand, Papua
New Guinea and South America) as ECM trees (Horak and Wood 1990,
Garnica et al. 2003, Tedersoo et al. 2008, Dickie et al. 2010), and subsequently
recognized as an important ECM genus in the Southern Hemisphere (Smith
and Read 2008).
Fig. 2. Repartition of the four distinct plant formations (sites 1 to 4) on the topographic sequence
studied by Perrier et al. (2006) at the Koniambo Massif. Most abundant and potential species
for restoration purpose within each vegetation type are shown. Plants with ECM structures
or ECM-like-structures on their root systems are indicated by an asterisk or two asterisks,
respectively. The distance in meters (m) from the valley to the plateau and the altitude are
given in abscissa and ordinate, respectively. Modifi ed data from Perrier et al. (2006a).
104 Ectomycorrhizal Symbioses in Tropical and Neotropical Forests
Surprisingly, Perrier et al. (2006a) observed ECM-like structures on
Cyperaceae roots as Costularia arundinacea, with the presence of a fungal
mantle but the absence of a Hartig net. Such observation has already
been done on two other Cyperaceae species belonging to the genus
Carex (Harrington and Mitchell 2002). However, the colonization of C.
arundinacea roots was only observed on sites 3 and 4, dominated by T.
guillainii and N. balansae respectively (Fig. 2). The vicinity of both ECM
plants may thus explain the colonization of C. arundinacea root systems.
Further investigations led to the identifi cation of other plant species as ECM
(Table 1) (Amir and Ducousso 2010, F. Carriconde personal communication).
Regarding the Myrtaceae, four additional Tristaniopsis species, two
Melaleuca species and the monospecifi c and endemic genus Arillastrum
are involved in such associations (Table 1). The Fabaceae Acacia spirorbis
has also been identifi ed as ECM (Ducousso et al. 2012). Finally, in New
Caledonia, the ECM status has been characterized for only 13 plant species
among Fabaceae, Myrtaceae and Nothofagaceae (Table 1). Giving the large
representation of the Myrtaceae family, especially the Leptospermoidae
group, and the Fabaceae family in New Caledonia (Morat et al. 2012), we
Table 1. Plant families and species in New Caledonia characterized as ECM. The biogeographical
native status is given according to Jaffré et al. (2001) (N: native, i.e., species for which their
natural distribution area extend beyond the boundaries of New Caledonia; E: endemic species;
EE: endemic genus). The types of soils on which species are encountered are also indicated (C:
calcareous; UM: ultramafi c soils; VS: volcano-sedimentary). For species known to be present
on more than one type of soil, the predominant types are highlighted in bold. Modifi ed data
from Amir and Ducousso (2010).
Family Species Biogeographical status Type soil
Fabaceae Acacia spirorbis N C, VS, UM
Myrtaceae
Arillastrum gummiferum EE UM
Melaleuca pancheri EUM
Melaleuca quinquenervia N C, VS, UM
Tristaniopsis calobuxus EUM, VS
Tristaniopsis glauca EUM
Tristaniopsis guillainii EUM
Tristaniopsis macphersonii EUM
Tristaniopsis ninndoensis EVS
Tristaniopsis vieillardii EUM
Nothofagaceae
Nothofagus aequilateralis EUM
Nothofagus balansae EUM
Nothofagus codonandra EUM
Abundance, Distribution, and Function of Pisolithus albus 105
could expect a large number of species to be involved in such mutualistic
interaction. This clear lack of knowledge is furthermore well-illustrated by
the fact that the ECM status remains unknown for two Nothofagus species
in New Caledonia: N. baumanniae and N. discoidea.
The aboveground and belowground fungal diversity has been, to some
extent, investigated on the topographic sequence at the Koniambo Massif
(Fig. 2) by collecting sporocarps, ectomycorrhizal root tips and hyphal mats
in the soil (Table 2, Perrier 2005). Molecular identifi cation has been carried
out by sequencing the nuclear ribosomal DNA (rDNA) internal transcribed
spacer (ITS), a widely used marker in mycology and recently defi ned as the
reference region for fungal DNA barcoding (Schoch et al. 2012). Twenty-
nine sporocarps, 11 ECM root tips and 7 hyphae collected from soil cores
were successfully sequenced (Table 2, Perrier 2005). Comparison of the
generated ITS sequences to the international available database GenBank
using the BLAST algorithm (Altschul et al. 1990) showed the presence
of several genera (Table 2). Interestingly, out of the total of 47 samples,
45 presented a percentage of similarity less than 97% (Table 2), a value
commonly used to differentiate ECM species (e.g., Tedersoo et al. 2003,
Izzo et al. 2005, Smith et al. 2007). Two sporocarps, K66C and KC03C, had
a percentage of similarity >97% with samples from Australia and New
Zealand, respectively. Overall, these results suggest there is a diverse and
unique ECM fungal assemblage at these study sites and possibly across
New Caledonia at a regional scale.
Indeed, the description in the last few years of new putative ECM
species, such as the impressive Podoserpula miranda (Fig. 3), thought to be
associated with Arillastrum gummiferum in the South of New Caledonia
(Ducousso et al. 2009), or the chanterelle, Cantharellus garnieri (Fig. 3)
collected under distinct potential host trees in different localities and type
of soils (Ducousso et al. 2004), strengthened the idea of the high fungal
diversity in the archipelago. Regarding the abundance of the different
fungal genera at Koniambo’s sites, samples belonging to the Cortinarius
genus were largely represented. Indeed, out of the 29 sporocarps, 11 ECM
root tips and 7 hyphal mats collected, 11 (~38%), 6 (~55%), and 5 (~71%)
were assigned to this genus. The large belowground representation of
Cortinarius has already been highlighted in Nothofagus forests in Australia
and New Zealand (Tedersoo et al. 2008, Dickie et al. 2010). Co-evolution
between Cortinariaceae and Nothofagus in Australia has been suggested
(Bougher et al. 1994), and could thus be one of the main driving forces
that may have led to the diversifi cation of this fungal group in the Pacifi c
region.However, the limited sampling size of Perrier’s study (in total only 47
samples), and particularly the very restricted number of studies undergone
to date on fungal diversity, do not allow us to draw any conclusions on
the diversity level and the structure of this diversity on the archipelago.
106 Ectomycorrhizal Symbioses in Tropical and Neotropical Forests
Sample re ference Sample type Plant
form atio n
Host plant
(putative ) † Morpho s pe cie s
Gen Bank
accesion
number
Seque nce
leng ht
(
b
p)
Closest species BLAST match ‡ Bases
matche d % Similarity B est matc h Ge nBank
acce sion numbe r
K66C Sporophore 3 Tristanio psis guillain ii Pisolithus sp FJ656011 527 Pisolithus sp 520/526 99% AF270787
K02C Sporophore 4 Nothofagus balansae Boletus sp FJ656001 609 Boletus sp 384/449 86% EU569234
K05C Sporophore 4 Nothofagus balansae nd FJ656002 551 Cortinarius subgemmeus* 498/561 89% JX000354
K06C Sporophore 4 Nothofagus balansae - FJ656003 605 Phellodon sp 544/597 91% GU222318
K09C Sporophore 4 Nothofagus balansae nd FJ656004 547 Austrogautieria macrospora* 438/504 87% GQ981492
K10C Sporophore 4 Nothofagus balansae nd FJ656005 670 Tricholoma imbricatum 628/668 94% AY573537
K10C Sporophore 4 Nothofagus balansae nd FJ656005 670 Tricholoma imbricatum 626/668 94% AY573537
K12C Sporophore 4 Nothofagus balansae nd FJ656006 572 Cortinarius austrovenetus 534/573 93% GQ890318
K14C Sporophore 4 Nothofagus balansae Inocybe sp FJ 656007 506 Dermocybe largofulgens* 483/504 96% GU233324
K16C Sporophore 4 Nothofagus balansae nd FJ656008 706 La ctarius scro biculatus 660/719 92% EU 597079
K18C Sporophore 4 Nothofagus balansae Lac taroides FJ656009 598 Russula zonaria * 526/569 92% D
Q
421990
KC02C Sporophore 4 Nothofagus balansae nd FJ656012 436 Co rtinarius livid us 390/433 90% A F539734
KC05C Sporophore 4 Nothofagus balansae nd FJ656014 580 Inocybe aeruginascens* 491/569 86% GU 949591
KC08C Sporophore 4 Nothofagus balansae nd FJ656016 670 Lactarius olympianus 624/684 91% EF685079
KC11C Sporophore 4 Nothofagus balansae nd FJ656018 609 Russula sp 577/ 608 95% GU222292
KC12C Sporophore 4 Nothofagus balansae nd FJ656019 518 Co rtinarius f lammulo ides 460/ 540 85% AF539716
KC16C Sporophore 4 Nothofagus balansae nd FJ656020 574 Co rtinarius multif ormis 518/ 589 88% AF389135
KC17C Sporophore 4 Nothofagus balansae nd FJ656021 574 Leratiomyces ceres 394/411 96% HQ604750
KC19C Sporophore 4 Nothofagus balansae nd FJ656022 583 Cortinarius sin
g
ularis* 508/584 87% J
Q
287672
KC22C Sporophore 4 Nothofagus balansae nd FJ656023 528 Austrogautieria macrospora* 442/503 88% GQ981492
KD37C Sporophore 4 Nothofagus codonandra nd FJ656038 582 Co rtinarius eu tactus* 559/582 96% JX000366
KC23C Sporophore 4 Tristaniop sis guillainii nd FJ656024 414 Cortinarius elaiops* 241/262 92% JX000369
K01C Sporophore 4 Nothofagus balansae nd FJ656000 701 Tricholoma ustale 632/713 89% AF458435
K22C Sporophore 4 Nothofagus balansae nd FJ656010 582 Inocybe aeruginascens* 491/569 86% GU949591
KC03C Sporophore 4 Nothofagus balansae nd FJ656013 612 Russula sp 593/ 613 97% GU222292
KC06C Sporophore 4 Nothofagus balansae nd FJ656015 436 Phaeocollybia redheadii 394/411 96% J N102541
KC10C Sporophore 4 Nothofagus balansae nd FJ656017 447 Cortinarius aff. austrosanguineus 427/454 94% GQ890317
KD36C Sporophore 4 Nothofagus codonandra nd FJ656037 585 Cortinarius elaiops* 554/586 95% JX000369
KD42C Sporophore 4 Nothofagus codonandra nd FJ656039 485 Tricholoma ustale 402/455 88% AF458435
KE01-2M ECM 3 Tristanio psis guillain ii - FJ 656040 457 Piloderma sp 400/450 89% JQ711951
KE02M E CM 3 Tr istaniopsis g uillainii - FJ656041 511 Cortinarius vernicifer* 387/449 86% JX000370
KE04M E CM 3 Tr istaniopsis g uillainii - FJ656042 438 Piloderma sp 383/430 89% JQ711951
KD10M ECM 4 Nothofagus balansae - FJ656025 552 Oidiodendron chlamydosporicum 477/519 92% AF062789
KE06M E CM 4 Nothofagus balansae - FJ656043 584 Cortinarius amoenus 544/590 92% AF389160
KE12-1M ECM 4 Nothofagus balansae - FJ656045 620 Tricholoma ustale 557/640 87% AF458435
KD18M ECM 4 Nothofagus codonandra nd FJ656026 474 Cortina rius calyp tratus* 425/476 89% EU525980
Table 2. Sporocarps, ECM root tips and hyphae samples collected in the Tristaniopsis spp. maquis (site 3) and the rain forest dominated by Nothofagus
balansae (site 4), located on the topographic sequence at the Koniambo Massif and genotyped by sequencing of the ITS region. The host plant (putative),
the morphospecies when available, the ITS sequence length, the closest BLAST match and the related information are presented. ITS sequence data
generated by Perrier (2005) were recently analyzed.
Abundance, Distribution, and Function of Pisolithus albus 107
fg yp
KD29-2M ECM 4 Nothofagus codonandra - FJ 656033 608 Cortinarius elaiops* 558/606 92% J X000369
KD31'' -2M EC M 4 Nothofagus codonandra - FJ656034 570 Cortinarius elaiops* 518/600 86% JX000369
KD31'M ECM 4 Nothofagus codonandra - F J656035 682 Tomente llopsis submollis 642/684 94% JQ 711898
KD36-2M E CM 4 Nothofagus codonandra - FJ656036 584 Cortinarius singularis* 509/584 87% JQ287672
KD19_ 1S Hyphae 3 Tristanio psis guillain ii - FJ 656027 698 Lycoperdon sp 682/726 94% JX029934
KD19_ 2S Hyphae 3 Tristanio psis guillain ii nd FJ656028 592 Cortin arius euta ctus* 560/597 94% H Q533023
KD19_ 9S Hyphae 3 Tristanio psis guillain ii - FJ 656029 410 Cortinarius sp 350/402 87% JQ287690
KD20_ 5S Hyphae 3 Tristanio psis guillain ii - FJ 656031 585 Cortinarius sp 543/594 91% JN942302
KD20_ 6S Hyphae 3 Tristanio psis guillain ii nd FJ656032 615 Cortinarius sp 552/621 89% JN942302
KE12_2S H yphae 4 Nothofagus balansae - FJ 656046 608 Tricholoma ustale 554/ 629 88% AF458435
KE18
_
2S H
yp
hae 4 Notho
f
a
g
us codonandra - FJ 656047 540 Cortinarius sub
g
emme us* 477/ 560 85% JX000354
† ECM root tips were sampled by tracing the roots from the tree trunks.
‡ Voucher specimens are indicated by an asterisk.
108 Ectomycorrhizal Symbioses in Tropical and Neotropical Forests
Although preliminary analysis of the ECM diversity has been achieved, a
thorough description of ECM and fungal communities and the interaction
with host-plants in New Caledonia should be carried out. In order to really
investigate such fungal diversity and better understand the mechanisms
involved, molecular ecology studies on ECM communities by sequencing
sporocarps and ectomycorrhizas using the classical Sanger approach,
complemented by the use of next generation sequencing on soil cores,
should be undertaken.
Fig. 3. Two new fungal species recently identifi ed in New Caledonia: (A) Podoserpula miranda
(Atheliaceae) and (B) Cantharellus garnierii (Cantharellaceae). Photos provided: courtesy Ducousso
Marc, CIRAD.
Color image of this figure appears in the color plate section at the end of the book.
A
B
Abundance, Distribution, and Function of Pisolithus albus 109
3. Pisolithus albus from Ultramafi c Soils in New Caledonia:
Diversity and Physiological Response to Nickel
Pisolithus albus (Cooke and Massee) is a fungal species belonging to Pisolithus
Alb. and Schwein known to be one of the major ectomycorrhizal Boletale
distributed on a worldwide scale that forms ectomycorrhizal symbioses
with a broad range of angiosperm and gymnosperm tree species (Marx
1977, Martin et al. 2002). Pisolithus is also regarded as an early colonizer
that persists on sites subject to edaphic stresses (Anderson et al. 1998).
In New Caledonia, P. Albus fruit bodies are very abundant. The species
also develops ectomycorrhizal associations with many endemic plants
belonging to various genera of the Myrtaceae such as Melaleuca, Tristaniopsis
and Sannantha, and one Mimosaceae, i.e., Acacia spirorbis (Perrier 2005). In
New Caledonia most of the plants able to form ECM with P. albus dominate
specifi c zones in their respective ecosystem: for example, Tristaniopsis genus
colonizes specifi c zones of the ultramafi c ecosystem at an altitude from 400
to 900 meters (L’Huillier et al. 2010). Altogether, the abundance of P. albus
and its ability to develop ECM symbioses with endemic plants that colonize
specifi c ecosystems in New Caledonia has led to the study of the genetic
diversity of P. albus in New Caledonia.
3.1 Diversity of Pisolithus albus and their symbioses in New
Caledonia
Isolates of ectomycorrhizal P. albus were sampled from both ultramafi c
and non-ultramafic soils in New Caledonia in order to investigate
the relationships between (i) genetic diversity and (ii) the edaphic
constraintssuch as the defi ciency of major nutrient elements (N, K and
P), the unbalanced Ca/Mg ratio and the presence of heavy metals at high
concentrations (Jourand et al. 2010a). Fruiting body description, spore
morphology (Fig. 4) and phylogenetic analysis based on internal transcribed
spacer (ITS) rDNA (as previously reported by Martin et al. 2002) sequences
confi rmed that all isolates belong to P. albus and are closely related to
other Australasian specimens (Fig. 5). In addition, the ecology of P. albus
isolated from New Caledonia confi rmed the dominant association with
endemic plants belonging to genera of the Myrtaceae family (e.g., Melaleuca,
Sannantha, Tristaniopsis) or the Fabaceae family (e.g., Acacia).
Altogether, the ecological and molecular data of P. albus isolated
in New Caledonia were in agreement with the phylogeography of the
ectomycorrhizal Pisolithus genus inferred from rDNA-ITS sequences,
suggesting that (1) evolutionary lineages within Pisolithus are related to
the biogeographical origin of their plant hosts (Martin et al. 2002) and (2)
a long-distance dispersal event of ectomycorrhizal fungi from Australia
110 Ectomycorrhizal Symbioses in Tropical and Neotropical Forests
might explain the introduction of Pisolithus species in the South Pacifi c
zone (Moyersoen et al. 2003). Interestingly, the use of other molecular
tools such as ITS-restriction fragment length polymorphism (Fig. 6A)
and amplifi ed fragment length polymorphism markers (AFLP) (Fig. 6B),
showed the existence of one genotype within P. albus grouping isolates from
ultramafi c soils (Jourand et al. 2010a). Such results raised the question of
the presence a fungal ecotype on ultramafi c soils, as described for plants
found on these soils (Harrison and Rajakaruna 2011). They also contribute
to the hypothesis of a link between the phylogenetic population structure
and the ecological adaptation due to the particular mineral constraints,
Fig. 4. Pisolithus albus from New Caledonia. A: Pisolithus albus MD07-117 from the Koniambo
massif; B: Pisolithus albus MD07-228 from the Ouen-Toro, Noumea; C: cross section of Pisolithus
albus MD07-166 from Pindjen water-fall and D: globose spores (8.77 to 9.62 µm) of Pisolithus
albus MD06-379 from Poum, erected spines (1.2 µm) are clearly visible. From Jourand et al.
(2010a).
Color image of this figure appears in the color plate section at the end of the book.
B
Abundance, Distribution, and Function of Pisolithus albus 111
in particular ultramafi sm, as observed in ectomycorrhizal communities
from other ultramafi c soils (Urban et al. 2008). To further investigate this
hypothesis, considering that nickel is one of the most toxic and bioavailable
metal found at high concentrations in these soils (Echevarria et al. 2006),
P. albus molecular and physiological responses to nickel were assessed in
a further study.
Fig. 5. Phylogenetic synthetic relationships among representative Pisolithus sp. from New
Caledonia collection sites and worldwide reference isolates. The phylogeny is based on the
analysis of the rDNA ITS1, 5.8S and ITS2 sequences. The tree was rooted with Suillus luteus
ITS sequences. Signifi cant bootstrap frequencies are indicated. Abbreviations: S America:
South America; SE Asia: South East Asia; W Africa: West Africa, E Africa: East Africa. From
Jourand et al. (2010a).
112 Ectomycorrhizal Symbioses in Tropical and Neotropical Forests
Fig. 6. A) Representative patterns of ITS restriction fragment length polymorphism (RFLP)
profi les of Pisolithus albus isolates from both ultramafi c and volcano sedimentary soils compared
to both undigested amplifi ed ITS and 100 pb DNA Ladder (Promega). Arrows highlight
major differences between profi les. B) Genetic relationship within P. albus isolates from New
Caledonia according to AFLP analysis. Bootstrap consensus UPGMA tree obtained for 882
AFLP scored fragments obtained with the 9 selective primers pairs on the 27 P. albus isolates
(100 replicates). Data from Jourand et al. (2010a).
A) P. albus ITS RFLP profi les
B) P. albus AFLP profi le relationship
Abundance, Distribution, and Function of Pisolithus albus 113
3.2 Tolerance and adaptation to nickel of Pisolithus albus from New
Caledonia
In ultramafi c soils, nickel (Ni) is one the most bioavailable and phytotoxic
element: nickel content may reach up to 10 g/kg in ultramafi c soils when
compared with the average 50 mg/kg in cultivated soils (Wenzel and
Jockwer 1999, Echevarria et al. 2006). This mineral element is a crucial
selecting factor for plant survival on ultramafi c soils: to grow on such
high concentrations of nickel as found in serpentine environments (often
coinciding with high concentrations of other heavy metals), plants had to
develop major adaptations that include exclusion of the absorption of the
toxic metal by the roots and/or metal hyperaccumulation with internal
complexation and compartmentation (Kazakou et al. 2008). In addition,
ECM symbioses might contribute to limit the metal accessibility and uptake
by the plant (Colpaert et al. 2011).
3.2.1 Pisolithus albus nickel content and in vitro tolerance
In the previous study, the nickel concentration in fruiting body tissues
of Pisolithus albus isolates from New Caledonia was assessed, as well as
the in vitro nickel tolerance of cultivated mycelia from isolates collected
from soil type (ultramafi c vs non-ultramafi c) where P. albus were collected
(Jourand et al. 2010a). In fruiting bodies of P. albus from ultramafi c soils,
the nickel concentration reached an average of 5.7µg/g of dried tissue. In
contrast, tissue of carpophores of isolates collected from non-ultramafi c soils
contained 2.5 times less nickel. In addition, P. albus mycelia from ultramafi c
soils included isolates with high variations of in vitro nickel-tolerance, with
both nickel-tolerant isolates (with an average that half the maximal effective
concentration of Ni that reduced fungal growth by 50% was 575 mM) and
nickel-sensitive isolates (average Ni EC50 37 mM). In contrast, all isolates
from non-ultramafi c soils were found to be nickel-sensitive (average Ni
EC50 at 32 mM).
Within Pisolithus spp., previous studies have showed that some isolates
were able to tolerate high concentrations of nickel. For example isolates of
Pisolithus tinctorius were found to tolerate nickel with a Ni EC50 ranging
from 126 to 170 mM (Tam 1995). Aggangan et al. (1998) also described one
isolate of P. tinctorius from ultramafi c soils in New Caledonia able to grow
on nickel from 20 to 200 µM. More recently, Blaudez et al. (2000) and Ray et
al. (2005) reported isolates of P. tinctorius that are able to grow on medium
with nickel concentrations ranging from 17 to 350 µM. The mycelia from
P. albus isolates from New Caledonian ultramafi c soils displayed both
in vitro nickel-sensitive and nickel-tolerant phenotypes. In addition, the
nickel-tolerant isolates presented a noteworthy tolerance to Ni with an
114 Ectomycorrhizal Symbioses in Tropical and Neotropical Forests
average Ni EC50 two to three times higher than the Ni EC50 already reported
for other Pisolithus spp. mentioned above. To explain the high variability in
nickel-tolerance observations, it was fi rst hypothesized that such variations
could be correlated to high real fl uctuations of bioavailable nickel content
in ultramafi c soils, which is assessed as the DTPA-Ni fraction according to
Echevarria et al. (2006). Perrier et al. (2006a) reported that the nickel-DTPA
concentrations in ultramafi c soils varied in a range from 17 to 980 µmol/
kg. Assuming that the average nickel-DTPA concentration does not refl ect
real fl uctuations of bioavailable nickel in ultramafi c soils, and considering
the range of nickel-DTPA concentrations in ultramafi c soils reported by
Perrier et al. (2006a,b), it is not surprising to fi nd isolates of P. albus with high
variations in nickel tolerance from the same ultramafi c site. Similar variations
in metal-tolerant fungal populations in correlation to metal-soil content have
already been reported. For instance, in Suilloid fungi, populations displayed
zinc tolerance relative to zinc concentrations in polluted soils, suggesting
an evolutionary adaptation of fungi to the soil environment (Colpaert et
al. 2004). More recently, evidence of adaptation to nickel was provided in
isolates of Cenococcumgeophilum from ultramafi c soils in Portugal and the
USA (Gonçalves et al. 2009). No clear relationship between the phenotypic
physiological response to nickel and the population genetic differentiation
observed within P. albus from soils could be established as the nickel-tolerant
isolates from ultramafi c soils did not cluster in a homogeneous group. It
was thus tempting to speculate that the capacity of some P. albus to tolerate
high nickel concentrations refl ects the expression of an adaptive response
to high concentrations of bioavailable nickel in soils as suggested for other
fungi in response to high heavy metal levels (Hartley et al. 1997, Colpaert
et al. 2004, Gonçalves et al. 2009). However, if New Caledonian population
of P. albus seems to be structured into one ecotype, nickel tolerance alone
might not be a suffi cient feature to explain such results. Thus, the ultramafi c
constraint should be considered as a whole, even if each factor (N, P, K
contents, Ca/Mg imbalance, heavy metal presence) is studied separately,
as suggested by Kazakou et al. (2008).
3.2.2 Pisolithus albus transcriptomic response to nickel
In another study on nickel-tolerant Pisolithus albus isolated from ultramafi c
soils in New Caledonia, the comparison of the transcriptomes of a nickel-
tolerant isolate in the presence and absence of nickel was monitored by
using pyrosequencing and quantitative polymerase chain reaction (qPCR)
approaches in order to identify genes involved in the specifi c molecular
response to nickel and to quantify their expression (Majorel et al. 2012).
As a result of the experiment, two non-normalized cDNA libraries were
obtained from one nickel-tolerant P. albus isolate grown in the presence and
Abundance, Distribution, and Function of Pisolithus albus 115
absence of nickel. A total of 19,518 genes could be obtained through the de
novo assembly of the sequence reads from the two non-normalized cDNA
libraries. The expression of 30% of these genes was regulated by nickel.
Further analysis identifi ed 4,211 genes (21%) that were up-regulated by
nickel and 1763 genes (9%) that were down-regulated by nickel. The global
statistical distribution of these 19,518 genes is presented on a scatter plot
in Fig. 7A. The genes, for which expression was induced most markedly
by nickel, encoded products that were putatively involved in a variety of
biological functions, such as the modifi cation of cellular components (53%)
and the regulation of biological processes (27%) and molecular functions
(20%) (Fig. 7B). Compared to most previous studies conducted on ECM
samples isolated from soils polluted with heavy metals as a result of human
activities (Jacob et al. 2004, Muller et al. 2007, Ruytinx et al. 2011), this study
was the fi rst repository of its kind. These results clearly suggested a positive
transcriptomic response of the fungus to nickel-rich environments, which
may contribute to the tolerance of the fungus to the extreme conditions as
found in New Caledonia. The analysis of the results based on gene ontology
(GO) analysis and functional genetic tools also suggests the role of these
genes as putative adaptive mechanisms of nickel tolerance in P. albus. The
majority of genes up-regulated by nickel belonged to the GO category
‘cellular component’. Information on the annotations of these genes is
valuable for the further investigation of gene functions, cellular structures
and biological processes that might be involved in the tolerance of fungi
to nickel via extracellular and intracellular mechanisms, as suggested by
Bellion et al. (2006).
In the second step of the experiment, ten genes that were analyzed as
the most nickel-induced in pyrosequencing were characterized by qPCR
analysis in both nickel-tolerant and nickel-sensitive P. albus isolates from
ultramafi c soils. Among them, six genes were expressed exclusively in nickel-
tolerant isolates as well as in ECM samples in situ. In addition, in the nickel-
tolerant isolates, the presence of nickel increased their level of expression by
between one- and nine-fold (Fig. 8). Their functional classifi cation showed
that these genes encoded for putative proteins involved either in chitin
cell wall rearrangements as GPI-anchor-like protein and class III chitinase,
or biological regulations as vacuolar protein sorting and APC amino acid
permease, suggesting a possible role of fungi in metal immobilization and
consequently in reducing metal toxicity when in symbiosis with plants. In
previous studies involving fungi, many genes involved in the response to
stress induced by heavy metals were found to encode proteins that function
as metal transporters or metal-binding proteins (Jacob et al. 2004, Bellion
et al. 2006, Bolchi et al. 2011). However, in Majorel et al. (2012), most of the
genes overexpressed in the presence of nickel did not encode proteins that
are generally involved in metal-stress responses. This suggested that the
116 Ectomycorrhizal Symbioses in Tropical and Neotropical Forests
Fig. 7. A) Scatter plot presenting gene expression levels in Pisolithus albus Ni-tolerant
ecotypefree-living mycelium grown without or with Ni at 250 µM. The expression levels of
genes were normalized using a scale of 0 to 10,000. Each circle in the plot represents expression
of one gene. B) Functional GO terms assignment and distribution of total sequences of two
transcriptomes of Ni-tolerant P. albus with (+250 µM) and without nickel, among Gene
Ontology (GO) biological process, molecular function and cellular component. From Majorel
et al. (2012).
A) Gene expression level repartition in Ni-tolerant Pisolithus albus
B) Gene functional GO terms assignment and distribution in Ni-tolerant P. albus
Abundance, Distribution, and Function of Pisolithus albus 117
Fig. 8. Comparison of mRNA accumulation profi les for six selected Ni up-regulated genes in
fi ve P. albus isolates from ultramafi c soil in presence of nickel 50 µM (black columns) and in
absence of nickel (grey columns). Three nickel-tolerant isolates (MD06-337, MD09-045, and
MD07-001) and two nickel-sensitive isolates (MD09-078 and MD09-063) were compared.
Transcript accumulation was quantifi ed by qPCR using 2-ΔΔCT method with normalization to
two reference genes, GAPDH and EF4α, and is expressed as arbitrary units. The data indicate
mean values ± S.D. values, calculated from three technical replicates with triplicate biological
samples. The fold induction by nickel is presented above the black columns in italics. ND:
mRNA non-detected (Ct values >37). From Majorel et al. (2012).
0
10
20
30
40
50
60
70
80
MD06 - 337 MD09 - 001 MD09 - 045 MD09 - 063 MD09 - 078
Gene N°
1 (GPI- anchor-like)
0
1
2
3
4
MD06 - 337 MD09 - 001 MD09 - 045 MD09 - 063 MD09 - 078
Gene N° 2 (predicted protein)
0
1
2
3
4
5
MD06
- 337 MD09 - 001 MD09 - 045 MD09 - 063 MD09 - 078
Gene N°
5 (vacuolar protein sorting)
0
5
10
15
20
25
30
MD06 - 337 MD09 - 001 MD09 - 045 MD09 - 063 MD09 - 078
Gene N°
6 (S
- adenosylmethionine transferase
)
0
0,2
0,6
1
1,4
MD06 - 337 MD09 - 001 MD09 - 045 MD09 - 063 MD09 - 078
Gene N°
7 (class III chitinase)
0
20
40
60
300
400
MD06 - 337 MD09 - 001 MD09 - 045 MD09 - 063 MD09 - 078
Gene N°
9 (APC amino acid permease)
mRNA accumulation
(Arbitrary units)
mRNA accumulation
(Arbitrary units)
mRNA accumulation
Arbitrary units
mRNA accumulation
Arbitrary units
mRNA accumulation
Arbitrary units
mRNA accumulation
Arbitrary units
Ni-tolerant Ni-sensitive
Ni-tolerant Ni-s ensitive
Ni-tolerant Ni-s ensitive Ni-tolerant Ni-sensitive
Ni-tolerant Ni -sensitive Ni-tolerant Ni-sens itive
ND ND ND ND
ND ND ND ND
ND ND ND ND
9x
1.3x
1.3x
1.6x
1x
1.2x
3.6x
1x
1.4x
2.5x
1x
1x
2.2x
1.2x
1.4x
1.5x 1x
1.2x
118 Ectomycorrhizal Symbioses in Tropical and Neotropical Forests
mechanisms that underlie the nickel tolerance in P. albus from ultramafi c
soils might differ from those of other fungi. In particular, that might
refl ect a long-term adaption to nickel in natural environment, in contrast
to short-term adaptation on metal contaminated soils. Among the genes
in which expression was remarkably induced in presence of nickel, and
exclusively expressed in nickel-tolerant, it was interesting to identify genes
that encode chitinase-like and glycosylphosphatidylinositol (GPI) cell-wall
structural proteins that are involved in extracellular processes and encode
putative cell-wall proteins. Recently, it was suggested that modifi cations
of structural elements of the cell wall, such as the rearrangement of chitin
and biosynthesis of glucan- or galactosamine-containing polymers, might
play a key role in modulating the integrity of the cell wall and its capacity
to immobilize heavy metals. In this way, such modifi cations could confer
tolerance to metals and affect the ability of fungi to survive in stressful
environments (Meharg 2003, Bellion et al. 2006, Fuchs and Mylonakis
2009).
Altogether, these results evidenced a strong and specifi c transcriptomic
response to nickel of ultramafi c-adapted P. albus both in vitro and in situ.
This led the authors to hypothesize that the presence of both nickel-tolerant
and nickel-sensitive fungal phenotypes in ultramafi c soils might refl ect
environment-dependent phenotypic responses to variations in the effective
concentrations of nickel in heterogeneous ultramafi c habitats (Majorel et
al. 2012).
3.3 Role of ECM symbiose between nickel-tolerant Pisolithus albus
and its host plant Eucalyptus globulus exposed at toxic nickel
concentrations
As ECM symbioses are known to play a major role in the fi tness of plants
in the presence of heavy metals (Jentschke and Godbold 2000), experiments
were carried out to analyse the symbiotic interactions between P. albus
and one of its host plants in the presence of nickel. Ectomycorrhizal
Pisolithus albus isolated in nickel-rich ultramafi c soils from New Caledonia
and showing in vitro adaptive nickel tolerance were inoculated to
Eucalyptus globulus Labill used as a Myrtaceae plant-host model to study
ectomycorrhizal symbiosis. Plants were then exposed to a nickel dose-
response experiment with increased nickel treatments up to 60 mg/kg soil
as maximum extractable nickel content found in ultramafi c soils (Perrier
et al. 2006a). Results showed that plants inoculated with ultramafi c ECM
P. albus were able to tolerate high and toxic concentrations of Ni (up to
60 mg/kg) while uninoculated controls were not (Fig. 9). At the highest
nickel concentration tested, root growths were more than 20-fold higher
and shoot growths more than 30-fold higher in ECM plants compared with
Abundance, Distribution, and Function of Pisolithus albus 119
control plants. Ergosterol was also measured in roots as it is a major sterol
in fungi and is a good indicator of the level of mycorrhizal colonization of
roots (Martin et al. 1990). Without nickel, roots had a mean level of 19.7%
ectomycorrhization. At low nickel concentrations (0.6 and 6 mg/kg), the
level of root ECM colonization varied from 15.6 to 27.8%. At high and toxic
nickel concentrations (30 and 60 mg/kg), the level of root colonization was
signifi cantly reduced to around 9%, but confi rmed the presence of viable
ECM. At the highest nickel concentration tested, the improved growth in
ECM plants was also associated witha 2.4-fold reduction in root nickel
concentration but a massive 60-fold reduction in transfer of nickel from root
to shoots, while for all other major plant nutrient elements analyzed, i.e., N,
P, K, Ca and Mg, no signifi cant differences in concentration were noted in
either shoots or roots in response to nickel treatments or fungal treatment.
To determine whether nickel tolerance was related to the release of metal
binding compounds, exudates from roots were analyzed. The two principal
chemical components of the exudate solution were non-protein thiols and
oxalate. Control plants excreted signifi cantly more thiols and oxalate than
plants developing ECM symbiose with P. albus, with the increase being more
Fig. 9. Eucalyptus globulus seedlings after 12-weeks growth. A and A’ mycorrhizal; B and B’:
non-mycorrhizal (controls). A and B: no nickel added; A’ and B’ seedlings treated with Ni.
From Jourand et al. (2010b).
Color image of this figure appears in the color plate section at the end of the book.
120 Ectomycorrhizal Symbioses in Tropical and Neotropical Forests
evident at higher nickel concentrations: control plants released 5-fold more
thiols at 30 and 60 mg/kg of nickel, and 12- and 8-fold more oxalate at 30
and 60 mg/kg nickel, respectively. All these results confi rmed that the nickel
tolerance of the ECM has a substantial benefi cial effect on the plant host.
Ultramafi c ECM isolates produced signifi cant increases in growth in both the
absence and low concentrations of nickel (from 0.6 to 6 mg/kg). Plant root
surface was greatly increased, and the high level of mycorrhizal colonization
is consistent with previous data on the interaction between Pisolithus
and Eucalyptus (Martin et al. 1990, Brundrett et al. 1996). At low nickel
concentrations, the increase in both shoot and root biomass observed in ECM
plants compared with non-inoculated plants is probably a consequence of
better mineral nutrition (Marschner 1995, Finlay 2004). However, at toxic
levels of nickel the contribution of the ECM symbiosis with ultramafi c P.
albus to host nickel tolerance was more substantial. Interestingly, P. albus
isolates could withstand in vitro high nickel concentrations but accumulated
very little nickel in its tissue (Jourand et al. 2010b). The lower nickel uptake
by mycorrhizal plants could not be explained by increased release of metal-
complexing chelates since these were 5- to 12-fold lower in mycorrhizal
plants at high nickel concentrations. It was proposed that the fungal sheath
covering the plant roots acts as an effective barrier to limit transfer of nickel
from soil into the root tissue.
4. Conclusions
Overall, the observations about ECM diversity found on ultramafi c soils
in New Caledonia raise very compelling questions about the evolutionary
processes involved in fungal diversifi cation in New Caledonia and at a
regional scale. The focus on ECM Pisolithus albus isolated from soils in New
Caledonia highlighted the identifi cation of an ultramafi c nickel-tolerant
ecotype as reported in Jourand et al. (2010a), showing specifi c and adaptive
molecular response to this metal (Majorel et al. 2012), and having a key role
in plant host adaptation to toxic nickel concentrations as found in these soils
(Jourand et al. 2010b). Together, these results constitute an important step in
evaluating the potential of ECM symbioses for plant adaptation to ultramafi c
soils containing high concentrations of heavy metals, which is a prerequisite
for their use in strategies for ecological restoration of mine sites as suggested
by Reddell et al. (1999), Perrier et al. (2006a) and, more recently, Khosla and
Reddy (2008). Further characterization of ECM fungal communities in New
Caledonia would increase knowledge about fungal diversity and identify
fungal species that might be relevant for plant inoculation purpose and
their direct implications in restoration strategies.
Abundance, Distribution, and Function of Pisolithus albus 121
Acknowledgements
Most of these studies were supported by (i) the GIP CNRT “Nickel and its
Environment” [grant number GIPCNRT98] and (ii) the ANR ECCO2005
and BIODIV2007 research programs entitled “Niko” and “Ultrabio”
respectively. The authors wish to thank Pr R. Reid (University of Adelaide,
South Australia), Dr T. Jaffré (IRD, Nouméa, New Caledonia), S. Santoni
(INRA, Montpellier, France), M.E. Soupe, J. Riss, C. Richert for their
respective contributions and/orsuggestions. They are also thankful Mr.
Pierrick Gailhbaud and Mr Antoine Leveau of Koniambo Nickel Society
(KNS), Vavouto, Koné, New Caledonia.The authors thank the anonymous
referees for their valuable comments on this study, and Krista L. Mc
Guire for improving the language.
References
Alexander, E., R. Coleman, T. Keeler-Wolfe and S. Harrison. 2007. Serpentine Geoecology
of Northern North America. Geology, Soils, and Vegetation. Oxford University Press,
New York.
Aggangan, N., B. Dell and N. Malajczuk. 1998. Effects of chromium and nickel on growth of
the ectomycorrhizal fungus Pisolithus and formation of ectomycorrhizas on Eucalyptus
urophylla S.T. Blake. Geoderma 84: 15–27.
Altschul, S.F., W. Gish, W. Miller, E.W. Myers and D.J. Lipman. 1990. Basic local alignment
search tool. J. Mol. Biol. 215: 403–10.
Amir, H. and M. Ducousso. 2010. Les bactéries et les champignons du sol sur roches
ultramafi ques. In: L. L’huillier, T. Jaffré and A. Wulff (eds.). Mines et environnement en
Nouvelle-Calédonie: les milieux sur substrats ultramafi ques et leur restauration. IAC,
Nouméa, Nouvelle-Calédonie, pp. 129–145.
Anderson, I.C., S.M. Chambers and J.W.G. Cairney. 1998. Use of molecular methods to estimate
the size and distribution of mycelial individuals of the ectomycorrhizal basidiomycete
Pisolithus tinctorius. Mycol. Res. 102: 295–300.
Bellion, M., M. Courbot, C. Jacob, D. Blaudez and M. Chalot. 2006. Extracellular and cellular
mechanisms sustaining metal tolerance in ectomycorrhizal fungi. FEMS Microbiol. Let.
254: 173–181.
Blaudez, D., C. Jacob, K. Turnau, J.V. Colpaert, U. Ahonen-Jonnarth, R. Finlay, B. Botton and
M. Chalot. 2000. Differential responses of ectomycorrhizal fungi to heavy metals in vitro.
Mycol. Res. 104: 1366–1371.
Bolchi, A., R. Ruotolo, G. Marchini, E. Vurro, L. Sanità di Toppi, A. Kohler, E. Tisserant, F.
Martin and S. Ottonello. 2011. Genome-wide inventory of metal homeostasis-related
gene product including a functional phytochelatin synthase in th hypogeous mycorrhizal
fungus Tuber melanosporum. Fungal Genet. Biol. 48: 573–584.
Bougher, N.L., B.A. Fuhrer and E. Korak. 1994. Taxonomy and biogeography of Australian
Rozites species mycorrhizal with Nothofagus and Myrtaceae. Aust. J. Bot. 7: 353–375.
Brady, K., A. Kruckberg and H. Bradshaw. 2005. Evolutionary ecology of plant adaptation to
serpentine soils. Ann. Rev. Ecol. Evol. Syst. 36: 243–266.
Branco, S. 2010. Serpentine soils promote ectomycorrhizal fungal diversity. Mol. Ecol. 19: 5566–5576.
Branco, S. and R.H. Ree. 2010. Serpentine soils do not limit mycorrhizal fungal diversity. PLoS One 5:e11757.
Brearley, FQ. 2006. Differences in the growth and ectomycorrhizal community of Dryobalanops lanceolata
(Dipterocarpaceae) seedlings grown inultramafic and non-ultramafic soils. Soil Biol. Biochem. 38:3407–3410.
122 Ectomycorrhizal Symbioses in Tropical and Neotropical Forests
Brooks, R. 1987. Serpentine and its vegetation. Dioscorides Press, Portland.
Brundrett, M., N. Bougher, B. Dell, T. Grove and N. Malajczuk. 1996. Working with mycorrhizas
in forestry and agriculture. ACIAR Monogr. 32. Australian Centre for International
Agricultural Research, Canberra, Australia, p. 374.
Chiarucci, A. and A.J.M. Baker. 2007. Advances in the ecology ofserpentine soils. Plant Soil
293: 1–217.
Coleman R.G. and C. Jove. 1992. Geological origin of serpentinites. In: A.J.M. Baker, J. Proctor
and R.D. Reeves (eds.). The Vegetation of Ultramafi c (Serpentine) Soils. Proceedings of
the First International Conference on Serpentine Ecology. Intercept, Hampshire, UK,
pp. 1–17.
Colpaert, J.V., L.A.H. Muller, M. Lambaerts, K. Adriaensen and J. Vangronsveld. 2004.
Evolutionary adaptation to Zn toxicity in populations of Suilloid fungi. New Phytol.
162: 549–560.
Colpaert, J.V., J. Wevers, E. Krznaric and K. Adriaensen. 2011. How metal-tolerant ecotypes
of ectomycorrhizal fungi protect plants from heavy metal pollution. Annals of Forest
Science 68: 17–24.
Dickie, I.A., N. Bolstridge, J.A. Cooper and D.A. Peltzer. 2010. Co-invasion by Pinus and its
mycorrhizal fungi. New Phytol. 187: 475–484.
Ducousso, M., C. Contesto, M. Cossegal and Y. Prin. 2004. Cantharellus garnierii sp. nov., une
nouvelle chanterelle des maquis nickélifères de Nouvelle-Calédonie. Cryptogamie
Mycol. 25: 135–145.
Ducousso, M., S. Proust, V. Denis and G. Eyssartier. 2009. Podoserpula miranda nom prov., une
nouvelle espè ce de champignon trè s spectaculaire dé couverte en Nouvelle-Calé donie.
Bois et Forêts des Tropiques 302: 73–75.
Ducousso, M., F. Carriconde, E. Frischt, F. Juillot, L. Hannibal, C. Majorel and Jourand P.
2012. Diversité des champignons ectomycorhiziens d’Acaciaspirorbis dans des habitats
très contrastés en Nouvelle-Calédonie. Journées Francophones Mycorhizes, troisième
édition, 5-7 septembre 2012, Nancy, France.
Echevarria, G., S. Massoura, T. Sterckeman, T. Becquer, C. Schwartz and J.L. Morel. 2006.
Assessment and control of the bioavailability of Ni in soils. Environ. Toxicol. Chem. 25:
643–651.
Finlay, R.D. 2004. Mycorrhizal fungi and their multifunctional roles. Mycol. 18: 91–96.
Fuchs, B.B. and E. Mylonakis. 2009. Our paths might cross: the role of the fungal cell wall
integrity pathway in stress response and cross talk with other stress response pathways.
Eukaryot. Cell 8: 1616–1625.
Garnica, S., M. Weib and F. Oberwinkler. 2003. Morphological and molecular phylogenetic
studies inSouth American Cortinarius species. Mycol. Res. 107: 1143–1156.
Gonçalves, S.C., A. Portugal, M.T. Goncalves, R. Vieira, M.A. Martins-Loucao and H.
Freitas. 2007. Genetic diversity and differential in vitro responses to Ni in Cenococcum
geophilumisolates from serpentine soils in Portugal. Mycorrhiza 17: 677–686.
Gonçalves, S.C., M.A. Martins-Louçao and H. Freitas. 2009. Evidence of adaptative tolerance
to nickel in isolates of Cenococcum geophilum from serpentine soils. Mycorrhiza 19:
221–230.
Harrington, T.J. and D.T. Mitchell. 2002. Colonisation of root systems of Carex fl acca and C.
pilulifera by Cortinarius (Dermocybe) cinnamomeus. Mycol. Res. 106: 452–459.
Abundance, Distribution, and Function of Pisolithus albus 123
Harrison, S. and N. Rajakaruna. 2011. Serpentine: the Evolution and Ecology of a Model System.
The University of California Press, Berkeley and Los Angeles, CA.
Hartley, J., J.W.G. Cairney and A.A. Meharg. 1997. Do ectomycorrhizal fungi exhibit adaptive
tolerance to potentially toxic metals in the environment? Plant Soil 189: 303–319.
Hawksworth, D.L. 1991. The fungal dimension of biodiversity: magnitude, signifi cance, and
conservation. Mycol. Res. 95: 641–655.
Hawksworth, D.L. 2001. The magnitude of fungal diversity: the 1.5 million species estimate
revisited. Mycol. Res. 105: 1422–1432.
Horak, E. and J. Mouchacca. 1998. Annoted checklist of New Caledonian Basidiomycota. I.
Holobasidiomycetes. Mycotaxon 68: 75–129.
Horak, E. and A.E. Wood. 1990. Cortinarius Fr. (Agaricales) in Australasia. 1. Subgen. Myxacium
and subgen. Paramyxacium. Sydowia 42: 88–168.
Izzo, A., J. Agbowo and T.D. Bruns. 2005. Detection of plot-level changes in ectomycorrhizal
communities across years in a old-growth mixed-conifer forest. New Phytol. 166:
619–630.
Jacob, C., M. Courbot, F. Martin, A. Brun and M. Chalot. 2004. Transcriptomic responses to
cadmium in the ectomycorrhizal fungus Paxillus involutus. FEBS Letters 576: 423–427.
Jaffré, T. 1992. Floristic and ecological diversity of the vegetation on ultramafi c rocks in New
Caledonia. In: A.J.M. Baker, J. Proctor and R.D. Reeves (eds.). The Vegetation of Ultramafi c
Soils. Intercept Ltd, Andover, UK, pp. 101–107.
Jaffré, T., Morat P., Veillon J.M., Rigault F., Dagostini G. 2001.Composition and characterisation
of the native flora of New Caledonia. Documents Scientifiques et Techniques - IRD : II, 121 p.
Jaffré, T. and L. L’Huillier. 2010. La végétation des roches ultramafi ques ou terrains miniers.
In: L. L’huillier, T. Jaffré and A. Wulff (eds.). Mines et environnement en Nouvelle-
Calédonie: les milieux sur substrats ultramafi ques et leur restauration. IAC, Nouméa,
Nouvelle-Calédonie, pp. 45–103.
Jentschke, G. and D.L. Godbold. 2000. Metal toxicity and ectomycorrhizas. Physiol. Plant
109: 107–116.
Jourand, P., M. Ducousso, C. Loulergue-Majorel, L. Hannibal, S. Santoni, Y. Prin and M. Lebrun.
2010a. Ultramafi c soils from New Caledonia structure Pisolithus albus in ecotype. FEMS
Microbiol. Ecol. 72: 238–249.
Jourand, P., M. Ducousso, R. Reid, C. Majorel, C. Richert, J. Riss and M. Lebrun. 2010b. Nickel-
tolerant ectomycorrhizal Pisolithus albus ultramafi c ecotype isolated from nickel mines
in New Caledonia strongly enhance growth of the host plant Eucalyptus globulus at toxic
nickel concentrations. Tree Physiol. 30: 1311–1319.
Kazakou, E., P.G. Dimitrakopoulos, R.D. Reeves, A.J.M. Baker and A.Y. Troumbis. 2008.
Hypotheses, mechanisms, and trade-offs of tolerance and adaptation to serpentine soils:
from species to ecosystem level. Biol. Rev. 83: 495–508.
Khosla, B. and M.S. Reddy. 2008. Response of ectomycorrhizal fungi on the growth and
mineral nutrition of eucalyptus seedlings in bauxite mined soil. Amer-Eurasian J. Agri.
Environ. Sci. 3: 123–126.
L’Huillier, L., T. Jaffré and A. Wulf. 2010. Mines et environnement en Nouvelle-Calédonie
: les milieux sur substrats ultramafi ques et leur restauration. IAC Ed, Noumea, New
Caledonia.
Majorel, C., L. Hannibal, M.E. Soupe, F. Carriconde, M. Ducousso, M. Lebrun and P. Jourand.
2012. Tracking nickel adaptive biomarkers in Pisolithus albus from New Caledonia using
a transcriptomic approach. Mol. Ecol. 21: 2208–2223.
Martin, F., C. Delaruelle and J.L. Hilbert. 1990. An improved ergsoterol assay to estimate fungal
biomass in ectomycorrhizas. Mycol. Res. 94: 1059–1064.
Martin, F., J. Diez, B. Dell and C. Delaruelle. 2002. Phylogeography of the ectomycorrhizal
Pisolithus species as inferred from ribosomal DNA ITS sequence. New Phytol. 153:
345–357.
Marschner, H. 1995. Mineral nutrition of higher plants 2nd edn. Academic Press, London,
UK, p. 889.
Marx, D.H. 1977. Tree host range and world distribution of the ectomycorrhizal fungus
Pisolithus tinctorius. Can. J. Microbiol. 23: 217–223.
124 Ectomycorrhizal Symbioses in Tropical and Neotropical Forests
McCoy, S.G. 1991. Edaphic controls infl uencing the distribution of Nothofagus aequilateralis
on ultrabasic soils at the Col the Mouirange, New Caledonia, Australian National
University.
Meharg, A.A. 2003. The mechanistic basis of interactions between mycorrhizal associations
and toxic metal cations. Mycol. Res. 107: 1253–1265.
Morat, P., T. Jaffré, F. Tronchet, J. Munzinger, Y. Pillon, J.-M. Veillon and M. Chalopin. 2012.
The taxonomic database “FLORICAL” and characteristics of the indigenous fl ora of New
Caledonia. Adansonia 34, in press.
Moser, A.M., C.A Petersen, J.A. D’Allura and D. Southworth. 2005. Comparison of
ectomycorrhizas of Quercus garryana (Fagaceae) on serpentine and non serpentine soils
in southwestern Oregon. Am. J. Bot. 92: 224–230.
Moser, A.M., J. Frank, J.A. D’Allura and D. Southwood. 2009. Ectomycorrhizal communities
of Quercus garryana are similar on serpentine and non serpentine soils. Plant Soil 315:
185–194.
Mouchacca, J. 1998. Ascomycetes described from New Caledonia, South Pacifi c region.
Mycotaxon 67: 99–121.
Mouchacca, J. and E. Horak. 1998. Annotated cheklist of New Caledonia Basidiomycota. II.
Rusts and Smuts. Mycotaxon 69 : 13–30.
Moyersoen, B., Beever, R.E. and F. Martin 2003. Genetic diversity of Pisolithus in New-Zealand
indicates multiple long-distance dispersal from Australia. New Phytol. 160: 569–579.
Muller, L.A., J. Vangronsveld and J.V. Colpaert. 2007. Genetic structure of Suillus luteus
populations in heavy metal polluted and non-polluted habitats. Mol. Ecol. 16: 4728–
4737.
Myers, N., R.A. Mittermeier, C.G. Mittermeier, G.A.B. da Fonseca and J. Kent. 2000. Biodiversity
hotspots for conservation priorities. Nature 403: 853–858.
Perrier, N. 2005. Bio-géodiversité fonctionelle des sols latéritiques miniers: application à
la restauration écologique (Massif du Koniambo, Nouvelle-Calédonie). PhD thesis.
University of New Caledonia, New Caledonia.
Perrier, N., H. Amir and F. Colin. 2006a. Occurrence of mycorrhizal symbioses in the metal-rich
lateritic soils of the Koniambo Massif, New Caledonia. Mycorrhiza 16: 449–458.
Perrier, N., J.P. Ambrosi, F. Colin and R.J. Gilkes. 2006b. Biogeochemistry of a regolith: the New
Caledonian Koniambo ultramafi c massif. J. Geochem. Explor. 88: 54–58.
Proctor, J. 2003. Vegetation and soil and plant chemistry on ultramafi c rocks in the tropical
Far East. Perspect. Plant Ecol. 6: 105–124.
Rajkumar, M., M.N.V. Prasad, H. Freitas and N. Ae. 2009. Biotechnological applications of
serpentine soil bacteria for phytoremediation of trace metals. Crit. Rev. Biotechnol. 2:
120–130.
Ray, P., R. Tiwari, G.U. Reddy and A. Adholeya. 2005. Detecting the heavy metal tolerance
level in ectomycorrhizal fungi in vitro. World J. Microb. Biot. 21: 309–315.
Reddell, P., V. Gordon and M.S. Hopkins. 1999. Ectomycorrhizas in Eucalyptus tetrodonta
and E. miniata forest communities in tropical Northern Australia and their role in the
rehabilitation of these forests following mining. Aust. J. Bot. 47: 881–907.
Ruytinx, J., A.R. Craciun, K. Verstraelen, J. Vangronsveld, J.V. Colpaert and N. Verbruggen.
2011. Transcriptome analysis by cDNA-AFLP of Suillus luteus Cd-tolerant and Cd-sensitive
isolates. Mycorrhiza 21: 145–154.
Schoch, C.L., K.A. Seifert, S. Huhndorf, V. Robert, J.L. Spouge, C.A. Levesque, W. Chen and
F.B. Consortium. 2012. Nuclear ribosomal internal transcribed spacer (ITS) region as a
universal DNA barcode marker for Fungi. P. Natl. Acad. SCI USA 109: 6241–6246.
Smith, S. and D. Read. 2008. Mycorrhizal Symbiosis, 2nd edn. Academic Press, London.
Smith, M.E., G.W. Douhan and D.M. Rizzo. 2007. Ectomycorrhizal community structure in
a xeric Quercus woodland based on rDNA sequence analysis of sporocarps and pooled
roots. New Phytol. 174: 847–863.
Tam, P.C.F. 1995. Heavy metal tolerance by ectomycorrhizal fungi and metal amelioration by
Pisolithus tinctorius. Mycorrhiza 5: 181–187.
Abundance, Distribution, and Function of Pisolithus albus 125
Tedersoo, L., U. Kõljalg, N. Hallenberg and K.-H. Larsson. 2003. Fine scale distribution of
ectomycorrhizal fungi and roots across substrate layers including coarse woody debris
in a mixed forest. New Phytol. 159: 153–165.
Tedersoo, L., T. Jairus, B.M. Horton, K. Abarenkov, T. Suvi, I. Saar and U. Koljalg. 2008. Strong
host preference of ectomycorrhizal fungi in a Tasmanian wet sclerophyll forest as revealed
by DNA barcoding and taxon specifi c primers. New Phytol. 180: 479–490.
Urban, A., M. Puschenreiter, J. Strauss and M. Gorfer. 2008. Diversity and structure of
ectomycorrhizal and co-associated fungal communities in a serpentine soil. Mycorrhiza
18: 339–354.
Wang, B. and Y.-L. Qiu. 2006. Phylogenetic distribution and evolution of mycorrhizas in land
plants. Mycorrhiza 16: 299–363.
Wenzel, W.W. and F. Jockwer. 1999. Accumulation of heavy metals in plants grown on
mineralised soils of the Austrian Alps. Environ. Pollut. 104: 145–15.
