Abstract:
examined in Choanephora cucurbita rum during the early stages
of infection by Piptocephalis virginiana » There was a small
but consistent increase in the leakage of electrolytes, amino
acids and sugars as a result of infection. These low levels
of differential leakage in infected tissues are explained on
the basis of the nature of this obligate, biotrophic, mycoparasitic
system. Quantitative analysis of the twenty six
amino acids and amino compounds detected in the leacheates —
showed similar profiles in infected and control host and no
new species of amino acids or amino compounds were detected
in either infected or control host leacheates. Comparatively
high amounts of aspartic acid, glutamic acid and alanine were
found in the leacheates of host and infected host . Analyses
of the sugars comprising the leacheates of infected and
control host showed the presence of eight sugars, among which
glucose was found in significant amounts (50-53%) ' The
nutritional implication of this preferential leakage is
discussed. No significant difference was observed in the
leacheates of infected host sugar profiles compared with that
of the control host. Profiles of the internal pool sugars of
infected and control host did not reflect that obtained from
the leacheate data, perhaps owing to leakage of sugars in a
selective manner
.
Membrane lipid analyses yielded higher levels of lipid
in infected host compared with the control, both at the 24 h
and 36 h analyses. In addition, preliminary investigations
of phosphorous-32 incorporation and turnover in phospholipids
showed higher levels of 32p incorporation and turnover in
infected host compared with the control. No apparent
difference was noted in the profiles of the neutral lipid
classes and the polar lipid classes of the membrane lipids as
determined by one and two dimensional thin-layer chromatography
respectively. However, a small but consistently higher degree
of unsaturation was detected in the fatty acids of infected
tissue compared with the control. Also, '^''-^^''^^'-'-^'^^c acid, a
polyunsaturated fatty acid previously reported to show a
direct correlation during the early stages of infection and
the degree of parasitism of P. virginiana on C. cucurbitarum ,
was found in higher amounts in infected host membrane lipids
compared with that of the control host. The implications of
these membrane lipid alterations are discussed with particular
reference to the small but consistently higher leakage of
electrolytes, amino acids and sugars observed during infection
in this study.
