Hydrogen peroxide is involved in the acclimation of the Mediterranean shrub, Cistus albidus L., to summer drought |
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Authors: | Jubany-Mari Tana; Munne-Bosch Sergi; Lopez-Carbonell Marta; Alegre Leonor |
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Abstract: | This study evaluated the possible role of hydrogen peroxide(H2O2) in the acclimation of a Mediterranean shrub, Cistus albidusL., to summer drought growing under Mediterranean field conditions.For this purpose, changes in H2O2 concentrations and localizationthroughout a year were analysed. H2O2 changes in response toenvironmental conditions in parallel with changes in abscisicacid (ABA) and oxidative stress markers, together with ligninaccumulation, xylem and sclerenchyma differentiation, and leafarea were also investigated. During the summer drought, leafH2O2 concentrations increased 11-fold, reaching values of 10µmol g–1 dry weight (DW). This increase occurredmainly in mesophyll cell walls, xylem vessels, and sclerenchymacells in the differentiation stage. An increase in ABA levelspreceded that of H2O2, but both peaked at the same time in conditionsof prolonged stress. C. albidus plants tolerated high concentrationsof H2O2 because of its localization in the apoplast of mesophyllcells, xylem vessels, and in differentiating sclerenchyma cells.The increase in ABA, and consequently of H2O2, in plants subjectedto drought stress might induce a 3.5-fold increase in ascorbicacid (AA), which maintained and even decreased its oxidativestatus, thus protecting plants from oxidative damage. Afterrecovery from drought following late-summer and autumn rainfall,a decrease in ABA, H2O2, and AA to their basal levels (60 pmolg–1 DW, 1 µmol g–1 DW, and 20 µmol g–1DW) was observed. Key words: Abscisic acid, ascorbate, ascorbate oxidative status, Cistus albidus, hydrogen peroxide, leaf plasticity, lignin, Mediterranean shrubs, oxidative markers, summer drought
Received 29 July 2008; Revised 15 September 2008 Accepted 8 October 2008 |
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