Symbiotic Fungi: Principles and Practice (Soil Biology)

14 A. Das and A. Varma
about 1–2 mm in size and appearing on the soil surface. Inside this bladder, the
cyanobacteria are physiologically active and dividing (Schubler and Kluge 2001). It
has been suggested that fungus could provide an important model system for
another symbiosis, the arbuscular mycorrhiza, see Fig. 1.4. Significant differences
between G. pyriforme and lichen are tabulated in Table 1.3.
Fig. 1.4 Schematic drawings of Geosiphon bladder compartmentation. Overview (left) and
detail (right). BLO bacteria like organism, M Mitochondrium, CW cell wall, N nucleus, NC
Nostoc cell, PM plasma membrane, SM symbiosome membrane, V vacuole (cf. Schubler and
Kluge 2001)
Table 1.3 Difference between Geosiphon and lichen (Kluge and Schubler 2002)
Geosiphon Lichen
It represents an endocytobiotic
consortium, with the photobiont living
inside the fungal cell
Mechanism of vegetative propagation of
the entire symbiotic system of
Geosiphon does not exist
There is contact between the two partners
(mycosymbiont and phycosymbioant)
in lichens
Vegetative reproduction through soredia
and isidia by spreading both symbiotic
partners together
Geosiphon does not survive water loss Lichens are robust toward dehydration
Geosiphon is very sensitive toward high
Many lichens are resistant to high
temperature
temperatures
Geosiphon grows only in moderate light It can tolerant high light irradiance