Mercury (0.01-1.0 mM) inhibited
chlorophyll formation in greening
maize leaf segments. However, supplementing incubation medium with
2-oxoglutarate, maintained substantially higher level of
chlorophyll in absence of
metal after an initial period of 8 hr. On preincubation of leaf segments with
HgCl2, per cent inhibition of
chlorophyll synthesis by
metal was same in the presence and absence of
2-oxoglutarate.
Supply of
2-oxoglutarate (0.1-10.0 mM) exerted concentration dependent effect on
chlorophyll formation in absence or presence of
metal. Increase in
delta-amino levulinic
acid dehydratase as well as
NADH-glutamate synthase activity and decrease in
NADH-
glutamate dehydrogenase activity by
2-oxoglutarate in the presence of Hg suggested that
glutamate for
delta-amino levulinic
acid synthesis could be made available from NH4+ assimilation via.,
glutamine synthetase/
glutamate synthase pathway during
mercury toxicity.