C. Barroso et al., Salt-specific regulation of the cytosolic O-acetylserine(thiol)lyase gene from Arabidopsis thaliana is dependent on abscisic acid, PLANT MOL B, 40(4), 1999, pp. 729-736
The expression of Atcys-3A gene coding for cytosolic O-acetylserine(thiol)l
yase, a key enzyme in cysteine biosynthesis, from Arabidopsis thaliana is s
ignificantly induced by exposure to salt and heavy-metal stresses. Addition
of NaCl to mature plants induced a rapid accumulation of the mRNA througho
ut the leaf lamina and roots, and later on in stems, being mainly restricte
d to vascular tissues. The salt-specific regulation of Atcys-3A was also me
diated by abscisic acid (ABA) since: (1) exogenous addition of ABA to the c
ulture medium mimicked the salt-induced plant response by raising the level
of Atcys-3A transcript, and (2) Arabidopsis mutants aba-1 and abi2-1 were
not able to respond to NaCl. Our results suggest that a high rate of cystei
ne biosynthesis is required in Arabidopsis under salt stress necessary for
a plant protection or adaptation mechanism. This hypothesis was supported b
y the observation that intracellular levels of cysteine and glutathione inc
reased up to 3-fold after salt treatment.