M. Gryndler et al., EFFECT OF GLUCOSE ON THE DEVELOPMENT OF GLOMUS-FISTULOSUM COLONIZATION AND EXTRARADICAL MYCELIUM ON MAIZE ROOTS, Folia microbiologica, 43(6), 1998, pp. 635-643
Various doses of glucose were added weekly to pots with maize growing
in a mixture of soil and Perlite inoculated with the arbuscular mycorr
hizal (AM) fungus Glomus fistulosum to define the effects of an additi
onal carbon source on plant growth, mycorrhizae and other microbial fe
atures of the cultivation substratum. Higher doses of glucose (100 and
300 mg per pot) decreased plant growth and abundance of root hairs af
ter 6 weeks of cultivation. Lower doses of glucose (10 and 30 mg per p
ot) had a positive effect on some characteristics of the development o
f the arbuscular fungus, e.g. root colonization, abundance of arbuscul
es, the length of extraradical mycelium associated with root surface,
length of mycelium in the substratum as well as the length of both myc
elia showing dehydrogenase activity as compared with variants not supp
lied with glucose solution. Glucose did not affect the number of spore
s of AM fungus. No effect of glucose was found on substratum respirati
on but glucose amendment increased microbial biomass and particularly
the occurrence of saprophytic fungi. In a subsequent experiment focuse
d on nonsymbiotic phase of fungal life cycle, the mycorrhizal root seg
ments were incubated for 6 weeks in Petri dishes on membranes covered
with a soil layer and supplied weekly with four glucose concentrations
from 0.3 to 10 mg. Highest total length of hyphae associated with the
root surface and the length of hyphae showing dehydrogenase activity
was found when the lowest dose of 0.3 mg glucose was added to the soil
weekly, whereas a 10 mg dose increased the length and activity of hyp
hae associated with a membrane. The possible mechanisms of the effects
of additional labile carbon pool on the development of mycorrhizal fu
ngus are discussed.