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Photosynthesis impairment and oxidative stress in Jatropha curcas exposed to drought are partially dependent on decreased catalase activity

Silva, Evandro Nascimento, Silveira, Joaquim A. G., Aragão, Rafael M., Vieira, Cinthya F., Carvalho, Fabrício E. L.
Acta physiologiae plantarum 2019 v.41 no.1 pp. 4
(S)-2-hydroxy-acid oxidase, Jatropha curcas, ascorbate peroxidase, carbon dioxide, catalase, drought, drought tolerance, enzyme activity, hydrogen peroxide, leaves, lipid peroxidation, oxidative stress, photochemistry, photorespiration, photosystem II, superoxide dismutase, water stress
Catalase (CAT) is a crucial enzyme to control the excess peroxisomal H₂O₂ produced during photorespiration. In many plant species, this enzymatic activity decreases in response to drought but its specific role in photosynthesis and redox metabolism is still poorly understood. In this study was tested the hypothesis that photosynthetic and oxidative changes induced by drought are dependent on CAT activity. For this, Jatropha curcas, a drought-tolerant species, was subjected to water deficit and CAT inhibition by a specific pharmacological inhibitor (3-AT), in order to decrease the activity of this enzyme to a similar level as compared to that exhibited by water deficit-treated plants. The CO₂ assimilation and other photosynthetic-related parameters were decreased more intensively by drought as compared to plants exposed to 3-AT, whereas the photochemical efficiency of PSII remained unchanged in both conditions. Non-photochemical quenching was strongly increased in drought-treated plants, but only slightly increased in 3-AT treatment. Membrane integrity and lipid peroxidation were strongly increased in both treatments, while H₂O₂ content was increased only by drought imposition. Ascorbate peroxidase and superoxide dismutase activities were increased in both drought and 3-AT treatments, but glycolate oxidase was strongly increased only in drought-stressed plants. The obtained results evidence that CO₂ assimilation and oxidative protection in leaves of Jatropha curcas plants exposed to water deficit are greatly dependent on drought-induced CAT activity deficiency.