Distribution, colonization and diversity of arbuscular mycorrhizal fungi associated with central...

www.elsevier.com/locate/foreco

Forest Ecology and Management 207 (2005) 315–324

Distribution, colonization and diversity of arbuscular mycorrhizal

fungi associated with central Himalayan rhododendrons

Bhaskar Chaurasiaa, Anita Pandeya,*, Lok Man S. Palnib

aEnvironmental Physiology and Biotechnology, G B Pant Institute of Himalayan Environment and Development,

Kosi-Katarmal, Almora-263 643, Uttaranchal, IndiabState Biotechnology Programme, Govt. of Uttaranchal, Biotech Bhawan, P.O. Haldi, Pantnagar-263 146, India

Received 25 February 2004; received in revised form 16 July 2004; accepted 12 October 2004

Abstract

The objective of the present study was to investigate arbuscular mycorrhizal status of five species of rhododendrons

distributed in Kumaun region of the Indian Central Himalaya. Root and rhizosphere soil samples of all the five species of

rhododendrons, namely, Rhododendron anthopogon, R. arboreum, R. campanulatum, R. barbatum and R. lepidotum were

collected from temperate, sub-alpine to alpine location in altitudinal range from 1500 to 4500 m amsl. The arbuscular

mycorrhizal colonization in root samples ranged from 28 to 42%; and maximum and minimum colonization was observed in R.

arboreum and R. lepidotum, respectively. The highest number of intraradical vesicles (12.5 � 2.8 cm�1 root segment) was

recorded in R. arboreum and the lowest (7.0 � 1.7 cm�1 root segment) in R. barbatum; vesicles were not observed in R.

lepidotum. Spores were extracted from the rhizosphere soil by wet sieving to perform microscopic identification of the species.

The maximum and minimum populations of spores were detected in the rhizosphere soil samples of R. anthopogon

(52.0 � 1.5 spores 25 g�1 soil) and R. lepidotum (32.0 � 2.5 spore 25 g�1 soil), respectively. Spore populations were found

to belong to five genera—Acaulospora, Glomus, Gigaspora, Sclerocystis and Scutellispora; genus Glomus was found to be

dominant in the rhizosphere soil samples of all the rhododendron species. The most frequent and abundant species was G.

fasciculatum, however, this species was not isolated from the rhizosphere soil of R. barbatum. Finger millet (Eleucine coracana)

was used to cultivate the trap culture of arbuscular mycorrhizal fungi to confirm the species identity. Spores of Glomus

pustulatum, not detected in the rhizosphere soil, were recovered from the trap culture. Contrary to this, genus Gigaspora, which

was present in the rhizosphere soil, did not sporulate in the trap culture. Shannon and Wiener index of diversity and Simpson’s

index of dominance indicated that the species richness, dominance and diversity of arbuscular mycorrhizal fungi decrease with

increasing altitude. In two species of rhododendrons, namely R. campanulatum and R. anthopogon, dark septate mycelium was

also observed.

# 2004 Elsevier B.V. All rights reserved.

Keywords: Arbuscular mycorrhizal colonization; Dark septate endophytes (DSE); Glomus; Vesicles; Species richness

* Corresponding author. Tel.: +91 5962 241041; fax: +91 5962 241150.

E-mail addresses: [email protected], [email protected] (A. Pandey).

0378-1127/$ – see front matter # 2004 Elsevier B.V. All rights reserved.

doi:10.1016/j.foreco.2004.10.014

B. Chaurasia et al. / Forest Ecology and Management 207 (2005) 315–324316

1. Introduction

The Indian Himalayan region consists of five

geographical zones i.e., Trans, North West, West,

Central and East Himalaya and covers an area of

approximately 419,873 km2.

Arbuscular mycorrhizal fungi are symbiotic asso-

ciations formed between the members of phylum

Glomeromycota and the roots of most terrestrial

flowering plants (Gianinazzi and Gianinazzi-Pearson,

1986). Arbuscular mycorrhizal fungi are the most

wide spread group (Schubler et al., 2001) found in the

tropics (Chaurasia, 2000), temperate (Vestberg, 1995)

and arctic regions (Dalpe and Aiken, 1998).

The mycorrhizal status from different ecological

regions i.e. aquatic and marshy habitats (Sengupta and

Chaudhuri, 1990), tropical plains (Ragupathy and

Mahadevan, 1993), tropical forests (Chaurasia, 2000),

sand dunes (Mohankumar et al., 1988), mangroves

(Mohankumar and Mahadevan, 1986) and the Western

Ghat region (Muthukumar and Udaiyan, 2000) of the

Indian sub-continent has been investigated.

Dark septate endophytes (DSE) are a miscella-

neous group of ascomycetous fungi that colonize roots

of many plants, both intracellularly and intercellularly

(Christie and Nicolson, 1983; O’Dell et al., 1993;

Ahlich and Sieber, 1996; Jumpponen, 2001). These

fungi were first described as Mycelium radicis

atrovirens (Smith and Read, 1997) and were found

to melanize hyphae and colonized the roots, occa-

sionally forming microsclerotia and sometimes a weak

hartig net in conifers (O’Dell et al., 1993; Ahlich and

Sieber, 1996).

The available information on mycorrhizal associa-

tions of rhododendrons indicates a number of

mycorrhizal partners (Largent et al., 1980); the main

associates appear to be ericoid in nature (Read and

Stribley, 1975; Duddrige and Read, 1982). However,

arbuscular mycorrhizal status of the rhododendron

species has received little attention (Cross, 1975;

Dighton and Coleman, 1992). Dighton and Coleman

(1992) reported the presence of intracellular arbus-

cules, vesicles and intraradical spores of arbuscular

mycorrhizal fungi in the roots of R. maximum. In the

present study the occurrence, colonization and the

diversity of arbuscular mycorrhizal fungi associated

with all the five species of rhododendrons found on an

altitudinal range from 1500 to 4500 m amsl in

Kumaun region of Indian Central Himalaya have

been investigated.

2. Materials and methods

2.1. Site description

The present study was conducted in the temperate,

sub-alpine and alpine zones of Pindari Glacier region

(33850–308100N to 798480–798520E) of Kumaun

Himalaya in the Indian Central Himalaya. A total

of five species of rhododendrons (family Ericaceae),

distributed from 1500 to 4500 m amsl (up to timber-

line), are found in this region. R. arboreum is most

widely distributed and starts appearing around 1500 m

elevation; it increases in importance with elevation

especially in oak dominated forests. Beyond 2800 m it

is replaced by R. barbatum in the birch forest.

Eventually, vegetation is represented by scrubs or

heaths (above 3400 m amsl), where R. campanulatum

and R. anthopogon are the sole representatives of

woody vegetation, and R. lepidotum forms sparse

bushy appearance in the alpine meadows. The general

description of the study sites is presented in Table 1.

2.2. Collection of soil and root samples

The rhizosphere soil and root samples were

collected from all the five species of rhododendrons,

preferably from the sites where the species were

found to grow in form of a pure stand or pure patch in

natural forest. The samples were taken after

removing the top litter layer (5–10 cm) and digging

out an appropriate amount of soil close to the roots of

the host plant from a depth of 10–15 cm. The samples

were collected in triplicate. Soil particles attached to

fine feeder roots were removed by generous shaking.

The soil samples brought to the laboratory were

stored at 4 8C to sustain the viability of arbuscular

mycorrhizal spores and to lower the activity of the

rhizosphere micro flora.

2.3. Assessment of arbuscular mycorrhizal

colonization

The root samples were rinsed thoroughly with

running tap water several times to remove the debris

B. Chaurasia et al. / Forest Ecology and Management 207 (2005) 315–324 317

Table 1

Distribution of rhododendrons found in Indian Central Himalaya and the study locations

Plant species/habit and height Locationa (m) Soil pH Other associates

R. anthopogon Don, shrub, 0.18–0.95 m Phurkia forest, 3000–4500 5.12 R. lepidotum, R. campanulatum,

Cotoneaster microphyllus, Pyrus foliolosa

R. arboreum Sm, tree, 7.62–12.20 m Khaljhuni forest, 1500–3000 5.32 Quercus semicarpifolia, Q. floribunda,

Lyonia ovalifolia, Symplocos chinensis,

Litsea umbrosa

R. barbatum G. Don, tree, 6.09–7.62 m Sundardunga forest, 2600–3200 4.74 Prunus cornuta, Acer accuminatum, Abies

pindrow, R. arboreum, Q. semicarpifolia

R. campanulatum Don, shrub, 3.04–4.57 m Phurkia forest, 2800–4000 4.60 Rosa sericea, R. anthopogon, Lonicera

angustifolia, Betula utlis, Prunus cornuta,

Pyrus foliolosa, Syringa emodi

R. lepidotum Wall ex G. Don, shrub, 0.30–0.61 m Phurkia forest, 3300–4500 4.62 R. anthopogon, Pyrus foliolosa

a All located in district Bageshwar, Kumaun region of Uttaranchal in the Indian Central Himalaya.

and adhering soil particles. Roots were cut into 1 cm.

segments for cleaning and staining. Root segments

were cleared in KOH (10%,w/v; 90 8C, 2 h) and

stained with acid fuschin (0.01%, w/v; Kormanik

et al., 1980).

The assessment of root colonization by arbuscular

mycorrhizal fungi was done by the slide method; root

segments were selected randomly from the stained

samples and observed for the presence or absence of

functional structures (mycelium, vesicles and arbus-

cules) of arbuscular mycorrhizal fungi. A minimum

of 100 root segments were used for this enumeration,

and the colonization by arbuscular mycorrhizal

fungi was calculated using the following formula:

%Colonization¼ total number of root segments colonizedtotal number of root segments studied �100

2.4. Extraction and identification of arbuscular

mycorrhizal spores from the rhizosphere soil

Extraction of arbuscular mycorrhizal spores was

carried out following the wet-sieving and decanting

method (Gerdemann and Nicolson, 1963). The soil–

water mixture (25:1000; w/v) was decanted through

stacked sieves (the coarse sieve on the top and the

finest sieve at the bottom). The sieve sizes ranged from

36 to 420 mm. Population of arbuscular mycorrhizal

spores was estimated by the method of Gour and

Adholeya (1994). Spores were separated into groups

according to their size and the general morphological

similarities recorded under a stereomicroscope

(Nikon). The slides were prepared using PVL

(polyvinyl alcohol + lactophenol) or PVLG (polyvinyl

alcohol + lactic acid + glycerol) for the identification

of arbuscular mycorrhizal species. Spores were

identified up to species level according to Schenck

and Perez (1990). Observations on the size, wall and

other spore structures were carefully recorded with an

optiphot-2 (Nikon) and the micrographs were taken

with fx35 dx (Nikon) camera.

2.5. Trap cultures

Since arbuscular mycorrhizal fungi do not grow

independently on routine culture media, greenhouse

pot cultures were established with the soil samples to

recover spores of arbuscular mycorrhizal fungal

species present in the soil, including those that may

not have sporulated at the time of sampling. A mixture

of soil and sand (3:1) (autoclaved three times at 121 8Cand 1.1 kg/cm2 for 1 h) was used for pot cultures

(30 cm height � 25 cm diameter) for providing a

suitable host, the seeds of a local finger millet (E.

coracana) previously surface sterilized with 0.01%

HgCl2 for 2 min and washed several 3–4 times with

sterilized distilled water, were sown in the pots (20

seeds per pot). Approximately 50 g of rhizosphere soil

was mixed with the seeds at the time of sowing. The

spores were extracted after 3–4 months, as described

earlier.

2.6. Data analysis

Shannon and Wiener index of diversity (Hutch-

enson, 1970), Simpson’s index of dominance (Simp-

son, 1949), similarity index, and species richness

(Franke-Synder et al., 2001) were calculated for the


Fig. 1. Arbuscular mycorrhizal colonization in rhododendrons of Kumaun, Indian Central Himalaya. (A) Extraradical chlamydospore and

vesicles (bar = 100 mm). (B) Intraradical vesicles (bar = 100 mm). (C) Intraradical chlamydospore of Glomus sp. (bar = 50 mm). (D) Hyphal

coiling inside the cell (bar = 40 mm). (E) Constriction in the mycelium and intraradical vesicles in the root (bar = 20 mm). (F) Dark septate

mycelium (bar = 40 mm).

distribution and diversity of arbuscular mycorrhizal

fungi.

3. Results

Colonization by the arbuscular mycorrhizal fungi

was observed in the root samples of different species

of rhododendrons. Extraradical spore and vesicles

(Fig. 1A) as wall as intraradical vesicles (Fig. 1B) and

spore (Fig. 1C) were observed during the study.

Extraradical as well as intraradical spores and vesicles

varied from spherical to ellipsoidal in shape.

Colonization of arbuscular mycorrhizal fungi was

almost similar in all rhododendron species. Maximum

arbuscular mycorrhizal percent colonization was

observed in R. arboreum (42%) followed by R.

barbatum (40%), R. anthopogon (37%), R. campa-

nulatum (33%) and R. lepidotum (28%). Intraradical

vesicles were not observed in R. lepidotum samples.

Arbuscules were not detected in the root segments of

all the species, however, the hyphal coiling (Fig. 1D)

and constriction in hyphae (Fig. 1E) were observed.

The results indicated that there was no correlation

between the arbuscular mycorrhizal colonization and

spore population. The number of species of arbuscular

mycorrhizal fungi associated with the rhizosphere soil

samples of all the rhododendrons showed a limited


Fig. 2. Arbuscular mycorrhizal colonization (%) and number of arbuscular mycorrhizal species found in rhizosphere soil (RS) of rhododen-

drons.

correlation with arbuscular mycorrhizal colonization

(Fig. 2). The rhizosphere soil of R. arboreum was found

to harbor maximum number of arbuscular mycorrhizal

fungal species (12) followed by R. barbatum (9), R.

anthopogon (8), R. campanulatum (8) and R. lepidotum

(6). Maximum spore population in rhizosphere soil were

found in R. anthopogon (52.0 � 1.5 spores 25 g�1) and

minimum in R. lepidotum (32.0 � 2.5 spores 25 g�1).

Maximum and minimum number of vesicles per

centimeter root segment was recorded in R. arboreum

(12.5 � 2.8) and R. barbatum (7.0 � 1.7), respectively,

while vesicles were not observed in the roots of R.

lepidotum (Fig. 3).

A total of 16 spore forming arbuscular mycorrhizal

fungi were observed. Among these seven species

belonged to the genus Glomus, three each to

Gigaspora and Scutellispora, two to Sclerocystis

Fig. 3. Spore population in rhizosphere soil and number of vesicles in root

mean value).

and one to Acaulospora. Out of the total 16, 8 could be

identified up to species level (Table 2; Fig. 4).

The rhizosphere soil of all the five species of

rhododendrons appeared to be dominated by the species

of Glomus. G. fasciculatum was found to be the most

abundant and common species except in R. barbatum

where it was not observed. Genus Gigaspora was found

to occur frequently associated with R. campanulatum

along with the genus Glomus. Acaulospora foveata was

absent from the soil samples of R. anthopogon and R.

lepidotum. Acaulospora sp., Gigaspora sp., and

Sclerocystis sp. were not detected in the rhizosphere

soil samples of R. lepidotum (Table 2). A number of

other species belonging to different genera of arbuscular

mycorrhizal fungi, which could not be identified due to

the lack of appropriate number of propagules and their

absence in trap cultures, were observed in the rhizo-

segments of rhododendrons (vertical bar represent standard error of

B.

Ch

au

rasia

eta

l./Fo

restE

colo

gy

an

dM

an

ag

emen

t2

07

(20

05

)3

15

–3

24

32

0Table 2

Synoptic key characters of arbuscular mycorrhizal species and their distribution in the rhizosphere soil

Species Sporocarp colour

and size (mm)

Spore colour

and size (mm)

Suspensor

diameter

(mm)

Wall

thickness

(mm)

R. anthopogon R. arboreum R. barbatum R. campanulatum R. lepidotum

Acaulospora Gerd. & Trappe

emend. Berch

A. foveata Trappe & Jonos – Y–Br; 85–310– (–410)

� 215–350– (–480)

� 14–18 � + ++ + –

Gigaspora Gerd. & Trappe

Gigaspora sp. Aa – Y; 190–250 15–20 3–10 � ++ +++ + –

Gigaspora sp. Ba – Y–Br; 220–260 25–40 2–8 ++ ++ � ++ –

Gigaspora sp. Ca – PY; 260–350 � � � � + ++ –

Glomus Tul. & Tul.

G. aggregatum Scenck &

Smith emend. Koske

– Y–Br; (20–)

40–85 (–120)

� � ++ +++ + –

G. ambisporum Scenck

& Smith

Br–DBr–BL;

315–690 �424–776

DBr–BL; 85–157;

98–166 � 93–157

� 3–9 ++ + + � –

G. fasciculatum

(Thaxter) Gerd.

& Trappe emend.

Walker & Koske

– H–Y–Br; 50–149

� 65–140

– (2.3–) 7–12

(–16.10)

++ +++ � ++ +

G. pustulatum-like (spB) – PY–YBr; 40 � 55 – 1–5 – – ++ – ++

Glomus sp. Aa – PY–Y; 120–124

� 124–135

– 2–4 + + – ++ –

Glomus sp. Ba Y–YBr–Br,

>300 � 200

Y–YBr; 22–29

� 29–35

– 2 + ++ – – +

Glomus sp. Ca DBr, P+; 390 � 500 DBr; 140–150 � 2–3 ++ – + – +

Sclerocystis Gerd. & Trappe

S. sinuosa Gerd. & Baksh. Br, P+, 6–20:

248–412

PY–YBr; 45–

118 � 30–83

– 1.3–4.9 – + – – +

S. rubiformis Gerd.

& Trappe

DBr, P�; 180 �180 –375 � 675

DBr; 37–125

� 29–86

– 3–7.6 ++ + – – –

Scutellispora Walker

& Senders

S. nigra (Redhead) Walker

& Sanders

– YBr–Br–BL, 297–500

(–1050)

40–60 �80–120

7–10 � + +++ – –

Scutellispora sp. Aa – Br–BL; 430–490 62 � 86 4–8 – + ++ – +

Scutellispora sp. Ba – Br, 250–260 35 � 53 3–7 + � � + –

a Measurement of species are based on the spores extracted from rhizosphere soil; H—hyaline; DBr—dark brown; Br—brown; Bl—black; YBr—yellow brown; PY—pale yellow;

P+—peridium present; P�—peridium absent, + Poor, ++ moderate, +++ frequent.


Fig. 4. Arbuscular mycorrhizal species found in rhizosphere soil of rhododendrons of Indian Central Himalaya. (A) Azygospore of Acaulospora

foveata (bar = 50 mm). (B) Outer ornamented surface of azygospore of A. foveata (bar = 30 mm). (C) Loose sporocarp of Golmus aggregatum

(bar = 100 mm). (D) Sporocarp of G. ambisporum (bar = 250 mm). (E) Sporocarp of Sclerocystis rubiformis (bar = 250 mm). (F) Chlamydospore

of G. fasciculatum (bar = 100 mm). (G) A portion of sporocarp of Sclerocystis sinuosa (bar = 250 mm). (H) A portion of the sporocarp of S.

sinuosa showing peridium and spores (bar = 100 mm). (I) Chlamydospore of Scutellispora nigra (bar = 250 mm).

sphere soil samples during this study. Contrary to this, a

few species, e.g., G. pustulatum like spores were

isolated from the trap cultures; this was absent from the

rhizosphere soil samples.

Distribution pattern on the occurrence of arbuscular

mycorrhizal species showed that maximum similarity

Table 3

Similarity matrix for the occurrence of arbuscular mycorrhizal fungi asso

Central Himalaya

R. anthopogon R. arboreum

R. anthopogon 100.00 60.00

R. arboreum 100.00

R. barbatum

R. campanulatum

R. lepidotum

(60%) was found between R. arboreum and R.

anthopogon, and between R. arboreum and R.

campanulatum, and the least (14.28%) between R.

campanulatum and R. lepidotum (Table 3). It was

evident from the dominance and diversity indices of

arbuscular mycorrhizal fungi that R. arboreum was the

ciated with rhizosphere soil of rhododendrons of Kumaun, Indian

R. barbatum R. campanulatum R. lepidotum

23.52 50.00 42.85

57.14 60.00 44.44

100.00 47.05 40.00

100.00 14.28

100.00


Table 4

Dominance and diversity indices of arbuscular mycorrhizal fungi associated with rhizosphere soil of rhododendrons of Kumaun, Indian Central

Himalaya

Host plants Species richness (%) Shimpson’s index of dominance Shannon–Weiner index

R. anthopogon 50 (8 sp.) 0.1360 2.0315

R. arboreum 75 (12 sp.) 0.0987 2.3991

R. barbatum 56.25 (9 sp.) 0.1296 2.1099

R. campanulatum 50 (8 sp.) 0.1388 2.0228

R. lepidotum 37.5 (6 sp.) 0.1836 1.7478

species where arbuscular mycorrhizal species were

dominant with the highest diversity (2.3991) and the

least dominance (1.7478) and diversity of arbuscular

mycorrhizal fungi (Table 4) in respect to R. lepidotum.

Dark septate endophytes (DSE) were found to

occur frequently along with arbuscular mycorrhizal

mycelium in R. campanulatum and R. anthopogon

(Fig. 1F). Roots of both the hosts were found sparsely

colonized by hyphae of DSE without appressoria in

the root segments. Primordia for microsclerotia were

also recorded in some of the root segments of R.

campanulatum. These structures were, however, not

observed in other species of rhododendrons.

4. Discussion

Due to their non-specific nature, arbuscular

mycorrhizae represent widely spread symbiotic

associations both geographically and in terms of the

number of plant host species involved. There are a few

reports on the occurrence of arbuscular mycorrhizae

(Cross, 1975; Koske et al., 1990; Dighton and

Coleman, 1992; Blaszkowski, 1994) in plants belong-

ing to the order Ericales, where ericoid type of

mycorrhizae is commonly found in their roots

(Duddrige and Read, 1982).

Mycorrhizal flora of rhododendrons, e.g., R.

ponticum, R. simsii, and the occurrence of arbuscular

mycorrhizal fungi and their use as inoculum for

enhancing their growth have been reported from

Europe (Cross, 1975; Dighton and Coleman, 1992).

The present study would appear to be the first detailed

report on the mycorrhizal associations found in all the

five species of rhododendrons found in Kumaun

region of the Indian Central Himalaya, representing

temperate to alpine locations.

This study describes the distribution of arbuscular

mycorrhizal fungi in the rhizosphere soil of rhodo-

dendrons along with details of externally associated

functional structures (extra radical mycelium, vesicles

and chlamydospores) as well as internal associations

(intraradical hyphal coiling, intraradical vesicles and

chlamydospores), except the arbuscules. The presence

of arbuscules in roots is generally used to associate

plants with functional arbuscular mycorrhizae. While

the arbuscules were almost absent in the root samples,

hyphal coils were commonly seen. The amount of

internal colonization by arbuscular mycorrhizal fungi

might depend on differences in the root morphology.

Smith and Smith (1997) reviewed structural diversity

of arbuscular mycorrhizal fungi and recognized two

types of colonizing pattern, viz., Arum-type and Paris-

type. In the Arum-type, extensive intercellular hyphae

and arbuscules develop, while in the Paris-type these

structures are absent and hyphal coils occur com-

monly. In the present investigation the Paris-type

colonization of arbuscular mycorrhizal fungi was

found to be prominent in all the five species of

rhododendrons. These structures may have a role in bi-

directional transfer of nutrients in the absence of

arbuscules.

The frequent occurrence of intraradical vesicles

(ellipsoid) indicated that a large part of the arbuscular

mycorrhizal fungi belonged to order Glomerales

(Schubler et al., 2001). Approximately 50% of total

isolated species were identified as species of Glomus;

G. fasciculatum being the most dominant. Predomi-

nance of G. fasciculatum, under various climatic

conditions, tropical to high arctic has been reported by

several workers (Dalpe and Aiken, 1998; Ragupathy

and Mahadevan, 1993; Chaurasia, 2000). The depen-

dence of spore population on pH of the soil was also

reflected in the present study. The spore population of


the total arbuscular mycorrhizal fungi was lower in

alpine region where the soil pH was relatively lower.

Although genus Glomus has been found to

dominate in the rhizosphere soil, the species

composition of arbuscular mycorrhizal fungi varies

in different rhododendrons. The study also reflected a

trend indicating decrease in the richness and diversity

of arbuscular mycorrhizal fungi with the increasing

altitude. It coincides with decreased richness and

diversity in the vegetational flora along an increase in

the altitude. The diversity of several groups of

terrestrial organisms has been found to be inversely

related with altitude (Gentry, 1988; Stevens, 1992).

Results of the present study showed that higher

arbuscular mycorrhizal diversity supports higher

aboveground diversity, as also proposed by van der

Heijden et al. (1998). According to them the below-

ground diversity of vesicular arbuscular mycorrhizal

fungi is a major factor in the maintenance of plant

diversity and ecosystem functioning.

In two rhododendron species, namely R. campa-

nulatum and R. anthopogon, presence of dark septate

fungi was also observed. Functional role of DS fungi

in rhododendrons is a matter of investigation. As in

the present work, DS fungal structures (intra cellular

mycelium, microsclerotium primordial) were also

reported from antarctic and sub-arctic sites (Christie

and Nicolson, 1983; Treu et al., 1996). The

occurrence of DS fungi in high stress environments

such as the alpine and arctic habitats strongly

suggests a more mutualistic role of these fungi

(Jumpponen, 2001).

The present study confirms the wide occurrence of

arbuscular mycorrhizal fungi in members of Erica-

ceae. It also extends the range of host plants of

arbuscular mycorrhizae which may play essential

ecological role in highly stressed environments like

arctic and alpine habitats where plant communities

experience short growing period, low temperature,

low nutrient status and low decomposition rates.

Acknowledgements

The Council of Scientific and Industrial Research

(CSIR), and the Union Ministry of Forests and

Environment, Government of India, New Delhi, are

thanked for the financial support.

References

Ahlich, K., Sieber, T.N., 1996. The profusion of dark septate

endophytic fungi in non-ectomycorrhizal fine roots of forest

trees and shrubs. New Phytol. 132, 259–270.

Blaszkowski, J., 1994. Arbuscular fungi and mycorrhizae (Glo-

males) of the Hel Peninsula, Poland. Mycorrhiza 5, 71–88.

Chaurasia, B., 2000. Ecological study of tropical forest trees with

special reference to vesicular–arbuscular-mycorrhizal (VAM)

association. Ph.D. Thesis. Dr. H. S. Gour University Sagar,

M.P., India, 172 pp.

Christie, P., Nicolson, T.H., 1983. Are mycorrhizas absent from the

Antarctic? Trans. Brit. Mycol. Soc. 80, 557–560.

Cross, J.R., 1975. Biological flora of the British Isles: Rhododendron

ponticum L. J. Ecol. 63, 345–364.

Dalpe, Y., Aiken, S.G., 1998. Arbuscular mycorrhizal fungi asso-

ciated with Festuca species in the Canadian High Arctic. Can. J.

Bot. 76, 1930–1938.

Dighton, J., Coleman, D.C., 1992. Phosphorus relations of roots and

mycorrhizas of Rhododendron maximum L. in the southern

Appalachians, North Carolina. Mycorrhiza 1, 175–184.

Duddrige, J., Read, D.J., 1982. An ultrastructural analysis of the

development of mycorrhizas in Rhododendron ponticum. Can. J.

Bot. 60, 2345–2356.

Franke-Synder, M., Douds Jr., D.D., Galvez, l., Phillips, J.G.,

Wagoner, P., Drinkwater, L., Morton, J.B., 2001. Diversity of

communities of arbuscular mycorrhizal (AM) fungi present in

conventional verses low-input agricultural sites in eastern Penn-

sylvania, USA. Appl. Soil Ecol. 16, 35–48.

Gerdemann, J.W., Nicolson, T.H., 1963. Spores of mycorrhizal

Endogone species extracted from soil by wet sieving and

decanting. Trans. Brit. Mycol. Soc. 46, 235–244.

Gentry, A.H., 1988. Changes in plant community diversity and

floristic composition on environmental and geographical gradi-

ent. Ann. Misso. Bot. Gard. 75, 1–34.

Gianinazzi, S., Gianinazzi-Pearson, V., 1986. Progress and head-

aches in endomycorrhiza biotechnology. Symbiosis 2, 139–149.

Gour, A., Adholeya, A., 1994. Estimation of VAMF spores in soil: a

modified method. Mycorrhiza News 6 (1), 10–11.

Hutchenson, K., 1970. A test for comparing diversities based on the

Shannon formula. Theor. Biol. 29, 151–154.

Jumpponen, A., 2001. Dark septate endophytes—are they

mycorrhizal? Mycorrhiza 11, 207–211.

Kormanik, P.P., Bryan, W.C., Schultz, R.C., 1980. Procedure and

equipment for staining large number of plant roots for endo-

mycorrhizal assay. Can. J. Microbiol. 26, 536–538.

Koske, R.E., Gemma, J.N., Englander, L., 1990. Vesicular–arbus-

cular mycorrhizae in Hawaiian Ericales. Am. J. Bot. 77, 64–68.

Largent, D.L., Sugihara, N., Wishner, C., 1980. Occurrence of

mycorrhizae on ericaceous and pyrolaceous plants in Northern

California. Can. J. Bot. 58, 2275–2279.

Mohankumar, V., Mahadevan, A., 1986. Survey of vesicular–arbus-

cular mycorrhizae in mangrove vegetation. Curr. Sci. 55,

936.

Mohankumar, V., Ragupathy, S., Nirmala, C.V., Mahadevan, A.,

1988. Distribution of vesicular–arbuscular mycorrhizae (VAM)

in the sandy beach soil of Madras coast. Curr. Sci. 57, 367–368.


Muthukumar, T., Udaiyan, K., 2000. Arbuscular mycorrhizas of

plants growing in the Western Ghat region, southern India.

Mycorrhiza 9, 297–313.

O’Dell, T.E., Massicotte, H.B., Trappe, J.M., 1993. Root coloniza-

tion of Lupinus latifolius Agardh. and Pinus contorta Dougl. by

Phialocephala fortinii Wang & Wilcox. New Phytol. 124, 93–

100.

Ragupathy, S., Mahadevan, A., 1993. Distribution of vesicular–

arbuscular mycorrhizae in plants and rhizosphere soils of

the tropical plains, Tamilnadu, India. Mycorrhiza 3, 123–

136.

Read, D.J., Stribley, D.P., 1975. Some mycological aspects of the

biology of mycorrhiza in the Ericaceae. In: Sanders, F.E.,

Mosse, B., Tinker, P.B. (Eds.), Endomycorrhizas. Academic

Press, London, pp. 105–117.

Schenck, N.C., Perez, Y., 1990. A manual for identification of

vesicular–arbuscular mycorrhizal fungi. INVAM University of

Florida, Gainesville, FL, 286 pp.

Schubler, A., Schwarzott, D., Walker, C., 2001. A new fungal

phylum, the Glomeromycota: phylogeny and evolution. Mycol.

Res. 105 (12), 1413–1421.

Sengupta, A., Chaudhuri, S., 1990. Vesicular–arbuscular mycorrhi-

zal (VAM) fungi in pioneer salt marsh plants of the Ganges river

delta in West Bengal (India). Plant Soil 122, 111–113.

Simpson, E.H., 1949. Measurement of diversity. Nature 163–168.

Smith, F.A., Smith, S.E., 1997. Structural diversity in vesicular–

arbuscular mycorrhizal symbioses. New Phytol. 137, 373–388.

Smith, S.E., Read, D.J., 1997. Mycorrhizal Symbiosis, 2nd ed.

Academic Press, San Diego, 605 pp.

Stevens, G.C., 1992. The elevational gradient in altitudinal range: an

extension of Papoport’s latitudinal rule of altitude. Am. Nat. 140,

893–911.

Treu, R., Laursen, G.A., Stephenson, S.L., Landolt, J.C., Densmore,

R., 1996. Mycorrhizae from Denali National Park and Preserve,

Alaska. Mycorrhiza 6, 21–29.

van der Heijden, M.G.A., Klironomos, J.M., Ursie, M., Moutoglis,

P., Streitwolf-Engel, R., Boller, T., Wiemken, A., Sanders, I.R.,

1998. Mycorrhizal fungal diversity determines plant biodiver-

sity, ecosystem variability and productivity. Nature 396 (5), 69–

72.

Vestberg, M., 1995. Occurrence of some Glomales in Finland.

Mycorrhiza 5, 329–336.

Distribution, colonization and diversity of arbuscular mycorrhizal fungi associated with central...

Documents

Transcript of Distribution, colonization and diversity of arbuscular mycorrhizal fungi associated with central...