Fróðskaparrit - 01.07.2004, Side 40

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HABITAT PREFERENCES OF THE ARBUSCULAR MYCORRHIZAL FUNGI
OF THE FAROES COMPARED WITH OTHER PLACES
Object Scores Labeled by SITE
ngland Fciroes □ Panama □
Sourhc □ © Q.
-1,0 -,5 0,0 ,5 L0 1,5 2,0
Dimension 1
Cases weighted by number of objects.
Fig. 3. Homogeneity analysis ofthe data summarised in
Table 3. The calculations are donefrom present/absent
values. Sourhope: Scottish grassland with Agrostis ca-
pillaris (1 site). Faroes: Faroese grasslands with Agros-
tis capillaris (8 sites). Panama: Tropicalforest (2 sites).
England: Englishforest (3 canopies)
Results from T-RFLP
A more direct (and efficient) method to es-
timate diversity is to use the T-RLFP tech-
nique. This method allows assessment of
diversity without identifying the single
types by cloning. One peak can be assumed
to be one type - although there might be
overlaps with restriction sites at the same
place.
Vandenkoornhuyse et al. (2003) used T-
RFLP analysis to estimate AM fungal di-
versity in Agrostis capillaris, which was
7.54 fungal types per sample. They used 2
PCR amplifications of each sample and 2
enzymes, Hinfl and Hsp92\l and ran each
digest twice on the analyser. This method
allowed them to distinguish between very
small peaks and background noise. The
present study was not as thorough, so the
data are probably more reliable if cutting
off peak height - for example only accept-
ing peaks larger than 3% of the total fluo-
rescence. However, the number of types
Vandenkoornhuyse et al. found fits well
with what this study would get if most of
the peaks were valid (Table 3, cut-off peak
height 0%). The table indicates that the di-
versity in Faroese sites is high; even the
most restricted criterion (cut-off peak
height 5%) indicates a higher number of
AM fungal types at low altitude than at the
the Scottish low altitude site. This result is
in reasonable accordance to the finding
from the clonal work, that there are more
types at low altitude compared with high
(Table 2), especially when considering the
limited number of clones from low altitude.
Peak height
Cut-off peak height >0% >1% >3% >5%
Sornfelli 13.75 6.75 3.75 3.25
Velbastað 10 10 8,25 4,75
Sourhope 7.875 5.75 4.625 3.875
Table 4. Mean number of peaks above a minimal-cut-
off peak lieight. Each peak indicates a possible AM
fungal type.
Conclusion and further discussion
The question raised in this paper is whether
the main factor determining the nature of
the arbuscular fungal flora is the plant host