J. Jansa, M. Vos´atka Applied Soil Ecology 15 2000 125–136 129
2.5. Statistical evaluation of the data One-way ANOVA was used for evaluation of the
effect of different fungal isolates on plant growth. G
-test was used only to estimate significant differences in mortality rates. The statistical evaluation was per-
formed using SOLO statistical package BMDP Soft- ware, Los Angeles, CA, 1991. G-test was calculated
using CoStat package.
3. Results
Almost all roots of ericoid plants collected from the natural habitats were found to have some kind of in-
timate hyphal association within cortical cells of their roots Fig. 1a and b. Mycorrhizal colonization was
well developed in the whole range of habitats and alti- tudes from 400 to 1200 m above sea level. High col-
onization rate of roots sampled in nature was detected different cultivars of Rhododendron sp., Vaccinium
Table 1 Isolates of ericoid mycorrhizal fungi used for experimental work and their origin
Isolate Description
Host plant and origin O1
Oidiodendron sp.
Rhododendron sp., 100 years old, Pruhonice
O2 Oidiodendron
sp. Rhododendron
sp., 100 years old, Pruhonice O3
Oidiodendron sp.
Vaccinium myrtillus , K. Stud´anka
O4 Oidiodendron
sp. Vaccinium myrtillus
, K. Stud´anka O5
Oidiodendron sp.
Rhododendron sp., 120 years old, Pruhonice
O6 Oidiodendron
sp. Rhododendron
sp., 40 years old, Pruhonice O7
Oidiodendron sp.
Vaccinium myrtillus , Jesen´ıky Mts.
O8 Oidiodendron
sp. Vaccinium myrtillus
, Jesen´ıky Mts. O9
Oidiodendron sp.
Empetrum hermaphroditum , Oulu, Finland
O10 Oidiodendron
sp. Rhododendron
, 100 years old, Pruhonice O11
Oidiodendron sp.
Rhododendron , 40 years old, Pruhonice
D1 Dark sterile mycelium
Vaccinium myrtillus , Oulu, Finland
D2 Dark sterile mycelium
Vaccinium myrtillus , Oulu, Finland
D3 Dark sterile mycelium
Empetrum sp., Oulu, Finland
D4 Dark sterile mycelium
Loisaleuria procumbens , Ukraine
D5 Dark sterile mycelium
Rhododendron sp., Karlova Stud´anka
D6 Dark sterile mycelium
Vaccinium myrtillus , Jesen´ıky Mts.
D7 Dark sterile mycelium
Rhododendron sp., 30 years old, Pruhonice
D8 Dark sterile mycelium
Gaultheria procumbens , Ukraine
D9 Dark sterile mycelium
Rhododendron sp., 30 years old, Pruhonice,
D10 Dark sterile mycelium
Rhododendron sp., 100 years old, Pruhonice
D11 Dark sterile mycelium
Vaccinium myrtillus , Karlova Stud´anka
D12 Dark sterile mycelium
Vaccinium myrtillus , Karlova Stud´anka
D13 Dark sterile mycelium
Rhododendron sp., 100 years old, Pruhonice
D14 Dark sterile mycelium
Vaccinium myrtillus , Karlova Stud´anka
D15 Dark sterile mycelium
Rhododendron sp., 100 years old, Pruhonice
myrtillus , Calluna vulgaris, Gaultheria procumbens,
and Empetrum hermaphroditum. More than 200 strains of endophytic fungi belong-
ing to Oidiodendron sp. and dark sterile ascomyce- tous mycelia were isolated from the roots of different
host plants Table 1. Satisfactory growth was obtained on MEA medium, of slowly growing, dark and sterile
mycelia, revealed to develop from hyphal coils inside cortical cells and were supposed to be the symbiotic
fungi. During their growth, they were usually masked by rapidly growing saprophytes.
Using our isolation technique, a trend was observed in distribution of symbionts amongst different host
plants, a higher number of Oidiodendron sp. were iso- lated from Vaccinium plants than from Rhododendrons
Table 2. Majority of root-endophytic fungal popu- lations by other plants make fungi belonging to dark
sterile mycelium group.
In vitro mycorrhization of Azalea plantlets exper- iment 1 showed stimulation of rooting by Oidioden-
dron strains O4 and O6. Fungal isolates inoculated
130 J. Jansa, M. Vos´atka Applied Soil Ecology 15 2000 125–136
Table 2 Numbers of morphologically different colonies of fungal endo-
phytes obtained by isolation from root samples of Calluna vul- garis
, different Rhododendrons, Vaccinium myrtillus, Gaultheria procumbens
and Empetrum hermaphroditum collected in natural habitats
Plant sample Dark sterile
mycelium Oidiodendron
sp. Calluna
3 Rhododendron 1
14 2
Rhododendron 2 12
2 Rhododendron 3
15 Rhododendron 4
8 2
Rhododendron 5 3
Rhododendron 6 6
4 Rhododendron 7
13 Vaccinium 1
4 6
Vaccinium 2 4
5 Vaccinium 3
4 7
Vaccinium 4 6
2 Vaccinium 5
3 3
Gaultheria 10
Empetrum 1 2
2 Empetrum 2
5
into the system developed structures typical of ericoid mycorrhizas Fig. 2a and b. However, the majority
of fungi appeared to grow too fast in relation to the plants and after harvest, inhibitory effect of fungal
growth on root development was observed. There appeared to be a competition for mineral sources, as
the plants were showing symptoms of deficiencies. In prolonged cultivation, after another 4 weeks, the
plants were overgrown by fungi. Not enough roots for evaluation of infection were obtained, therefore
only presence–absence of mycorrhizal structures were recorded Table 3.
Post vitro mycorrhization of Rhododendrons in ex- periment 2 showed that there was only one isolate D4
significantly stimulating plant growth. However, there were no inhibitiory effects of any inoculated fungus
Table 4, Fig. 3. Similarly, in experiment 3, two O6, O9 of 20 strains of ERM showed consistent positive
effects on plant growth Table 5, Fig. 4. Root biomass was generally reduced by inoculation in experiment
2, but such an effect was not observed in experiment 3, probably due to prolonged cultivation time. Most
apparent stimulation of plant development due to in- oculation was observed using isolate O6 in both post
vitro experiments significant leaf number increase in experiment 2, significant stem dry weight and leaf area
stimulation in experiment 3. Increase in some of the parameters describing plant growth were also observed
for fungal isolate D6 in both experiments.
4. Discussion
