Journal of Experimental Botany, Vol 50, 373-381, Copyright © 1999 by Oxford University Press
G Bartoli, M Simontacchi, E Tambussi, J Beltrano, E Montaldi and S Puntarulo
The purpose of the present work was to evaluate both oxidative stress and
the antioxidant response system in leaves from wheat (Triticum
aestivum cv. Buck Poncho) subjected sequentially to drought and
watering. Drought was imposed by withholding water until soil water
potential reached -2.0 MPa and maintained under those conditions for 24 h.
DCFDA oxidation by wheat leaves was not significantly affected by drought,
but watering led to an approximately 2-fold increase in DCFDA oxidation
rate. However, no significant effect either on lipid radical content or on
hydroperoxide content was measured after drought and drought followed by
watering. Microsomes isolated from leaves exposed to drought, and from
leaves exposed to drought followed by watering, generated a significantly
higher amount of hydroxyl radical as compared to microsomes isolated for
control leaves suggesting a higher production of hydroxyl radical in the
cellular water soluble phase, after drought and watering as compared to
control values. The content of
ARTICLES
Drought and watering-dependent oxidative stress: effect on antioxidant content in Triticum aestivum L. leaves
Plant Physiology Institute (INFIVE), School of Agronomy and Natural Sciences, National University of La Plata, La Plata, Argentina; Department of Physical Chemistry, School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina; Corresponding author e-mail: susanap@huemul.ffyb.uba.ar
-tocopherol
in wheat leaves was increased 2.4-fold after drought and
-carotene content was increased by 2.6-fold after
drought. Hydration lowered lipid-soluble antioxidant content to control
values. Total thiol content as increased by 70% after drought, and watering
did not significantly alter the enhanced values. Drought decreased by 28.5%
the content of reduced ascorbic acid. Taken as a whole, active species
formed at wheat membranes after exposure to moderate water stress, are
efficiently removed upon rehydration by reaction with an increased content
of
-tocopherol and
-carotene. Moreover a co-ordinated response
involving glutathione reductase activity, thiols and ascorbic acid is
triggered to limit free radical dependent effects.Key
words: Antioxidants, lipid radicals, oxygen radicals, water
stress, wheat
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