causes disease in birch trees, including B. ermanii. According to Yamaguchi (1989),
the white-rot fungus Inonotus obliquus, the causal microorganism of canker disease
in Japanese birch, has been found in Honshu and northern Japan, especially in
Hokkaido. Hattori (1990) isolated I. obliquus from the sclerotial tissue collected
from Betula platyphylla var. japonica (Miq.) H. Hara in Tochigi, northern Japan.
This finding suggests that Inonotus sp. isolated from Mt. Iwaki sclerotia may be a
pathogen of the birch trees at the study site.
The final fungus identified, Phyllactinia sp. (Ascomycota: Erysiphales), causes
powdery mildew on the leaves and stems of a broad range of host plants, including
Q. serrata (Homma 1937).
Contrary to our expectations, C. geophilum was not detected at either site. The
T-RFLP method is capable of detecting the presence of a species but cannot
unequivocally indicate the absence of a species (Dickie et al. 2002). Other species,
including C. geophilum, may have been present in sclerotia, but amplification may
have been insufficient for detection. However, the results of our study suggest that:
(i) sclerotia collected at Mt. Chokai were formed by A. arundinis and those at
Mt. Iwaki were formed by Inonotus sp.; or (ii) sclerotia were originally formed by
C. geophilum, but were subsequently occupied by other species. Obase et al. (2014)
reported that sclerotia-associated fungi may be specialized mycoparasites or
saprobes that preferentially decay fungal tissues or act as endophytes that colonize
C. geophilum sclerotia without any aggressive interactions. However, given that we
found no evidence of C. geophilum, the sclerotia observed may have been formed by
A. arundinis on Mt. Chokai and by Inonotus sp. on Mt. Iwaki. Further investigation
is required.
Our current data could not clearly show the details of the interaction of
C. geophilum with other fungi for the formation of sclerotia, but recent developments in molecular biology techniques will shed light on this interaction.
2.3 Fungal Community Analysis by Culture and Molecular
Methods in Sclerotia from Forest Soil on Mt. Ontake,
Gifu Prefecture, Japan
2.3.1 Material and Methods
2.3.1.1 Soil Sampling and Collection of Sclerotia
We sampled surface soil (Andic Podzols, WRB/FAO-Unesco) on 24 June 2006 from
Yunohana Pass on Mt. Ontake in Gifu Prefecture (35
55
0 14
00 N, 137
27
0 47
00 E,
elevation 2103 m) in a grove of northern Japanese hemlock (Tsuga diversifolia).
The soil in this location has previously been reported to contain large numbers of
sclerotia (Sakagami 2009b). Surface soil (0–5 cm depth) was collected using a
trowel and stored at 4
C. According to wet sieving method (Brundrett 1996),
24
K. Narisawa et al.
the white-rot fungus Inonotus obliquus, the causal microorganism of canker disease
in Japanese birch, has been found in Honshu and northern Japan, especially in
Hokkaido. Hattori (1990) isolated I. obliquus from the sclerotial tissue collected
from Betula platyphylla var. japonica (Miq.) H. Hara in Tochigi, northern Japan.
This finding suggests that Inonotus sp. isolated from Mt. Iwaki sclerotia may be a
pathogen of the birch trees at the study site.
The final fungus identified, Phyllactinia sp. (Ascomycota: Erysiphales), causes
powdery mildew on the leaves and stems of a broad range of host plants, including
Q. serrata (Homma 1937).
Contrary to our expectations, C. geophilum was not detected at either site. The
T-RFLP method is capable of detecting the presence of a species but cannot
unequivocally indicate the absence of a species (Dickie et al. 2002). Other species,
including C. geophilum, may have been present in sclerotia, but amplification may
have been insufficient for detection. However, the results of our study suggest that:
(i) sclerotia collected at Mt. Chokai were formed by A. arundinis and those at
Mt. Iwaki were formed by Inonotus sp.; or (ii) sclerotia were originally formed by
C. geophilum, but were subsequently occupied by other species. Obase et al. (2014)
reported that sclerotia-associated fungi may be specialized mycoparasites or
saprobes that preferentially decay fungal tissues or act as endophytes that colonize
C. geophilum sclerotia without any aggressive interactions. However, given that we
found no evidence of C. geophilum, the sclerotia observed may have been formed by
A. arundinis on Mt. Chokai and by Inonotus sp. on Mt. Iwaki. Further investigation
is required.
Our current data could not clearly show the details of the interaction of
C. geophilum with other fungi for the formation of sclerotia, but recent developments in molecular biology techniques will shed light on this interaction.
2.3 Fungal Community Analysis by Culture and Molecular
Methods in Sclerotia from Forest Soil on Mt. Ontake,
Gifu Prefecture, Japan
2.3.1 Material and Methods
2.3.1.1 Soil Sampling and Collection of Sclerotia
We sampled surface soil (Andic Podzols, WRB/FAO-Unesco) on 24 June 2006 from
Yunohana Pass on Mt. Ontake in Gifu Prefecture (35
55
0 14
00 N, 137
27
0 47
00 E,
elevation 2103 m) in a grove of northern Japanese hemlock (Tsuga diversifolia).
The soil in this location has previously been reported to contain large numbers of
sclerotia (Sakagami 2009b). Surface soil (0–5 cm depth) was collected using a
trowel and stored at 4
C. According to wet sieving method (Brundrett 1996),
24
K. Narisawa et al.