Abstract :
A GUS-transformed strain of B. sorokiniana was used
to study the relationship between futigal growth, lesion
development and natural root cortical cell death (RCD)
in roots of different cereals. Roots of 10-day-old seedlings,
grown on filter paper, were inoculated with the
fungtis and at different time intervals lesion size and
GUS-activity in the roots were determined. A sigtiificant,
positive correlation was found between GUS-activity and
ergosterol content in barley roots infected with this transformed
strain and these results indicate that GUS can be
used as a marker to study fungal growth in plant tissue.
The fungus had a slower growth rate in resistant barley
varieties, i.e., those producing smaller lesions, than in
more susceptible varieties.
In wheat and triticale, the fungal growth was faster
than in barley, despite the smaller atid lighter coloured
lesions in these species. This may be explained by the fact
that wheat and triticale have a faster rate of root cortical
senescetice than barley. Presumably, dying cortex cells
cannot respond to the fungal invasion by producing phenolic
compounds that cause browning of the tissue.
Among seven investigated cereal species, there was a positive
correlation between the degree of RCD and fungal
biomass increase in roots after inoculation
