Abstract:
In plants,
γ
-aminobutyric acid (GABA) is synthesized by polyami
ne degradation
pathway besides GABA shunt. Aminoguanidine (AG) is
a specific inhibitor of the key
enzyme (diamine oxidase, DAO) for GABA formation in
polyamine degradation pathway.
In this study, AG was applied to study the function
s of polyamine degradation pathway
on growth and GABA accumulation in germinating fava
bean under hypoxia-NaCl stress.
The results showed that 5.0 mmol L
-1
of AG inhibited DAO activity maximally but not
entirely, and inhibited the growth of sprouts simul
taneously. Hence, blocking polyamine
degradation pathway significantly affected the grow
th of germinating fava bean.
Polyamine degradation pathway provided 26.9 and 29.
3%
of GABA in cotyledon and
embryo, respectively, because DAO activity was not
inhibited entirely. Polyamine,
especially putrescine (Put), accumulated after poly
amine degradation pathway was
blocked, indicating that Put was the main substrate
of GABA in polyamine degradation
pathway.
Keywords
: Aminoguanidine, Diamine oxidase, Putrescine,
γ
-aminobutyric acid.
