plant surface microbiology.pdf

30 Axenic Culture of Symbiotic Fungus Piriformospora indica 597
Fig. 3. An overall view of the molecular taxonomic position of P. indica (modified
after Schüßler et al. 2001)
4 Chlamydospore Formation and Germination
The fungus produces chlamydospores at the apex of hyphae, which were
mostly irregular undulated in shape. These chlamydospores can be easily germinated
on various synthetic media (Verma et al. 1998). On solidified agar
(2 %) medium, a tendency for cluster formation of chlamydospores was
observed. Temperature (low to high and/or vice versa), pH (alkaline to acid or
vice versa), and shock treatment also induced excessive sporulation. These
spores were viable for over a year when preserved at room temperature. Loss
in viability of the dormant spores was the least when germinated after 1 year.
Dormant spores germinated within 1 day of their placement on nutrient agar
medium and incubated at 40 °C under high humidity (>90 %). The first step of
germination was the formation of germ tubes at the protruded zone of the
spore, followed by hyphal emergence. Most of the nuclei followed the hyphae
and seldom were one or two nuclei left behind in the spore. Soon branching
appeared with a short and long branch (Fig. 4).
5 Cultivation
Fungi are heterotrophic for carbon compounds and these serve two essential
functions in fungal metabolism. The first function is to supply the carbon
needed for the synthesis of compounds which comprise living cells. Proteins,