Influence of enhanced temperature on photosynthesis,photooxidative damage,and antioxidant strategies in <Emphasis Type="Italic">Ceratonia siliqua</Emphasis> L. seedlings subjected to water deficit and rewatering |
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Authors: | M L Osório J Osório A C Vieira S Gonçalves A Romano |
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Institution: | 1.Institute for Biotechnology and Bioengineering, Centre of Genomics and Biotechnology (IBB/CGB), Faculty of Sciences and Technology,University of Algarve,Faro,Portugal;2.Institute of Mediterranean Agricultural and Environmental Sciences (ICAAM), Faculty of Sciences and Technology,University of Algarve,Faro,Portugal |
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Abstract: | Predicted future climatic changes for the Mediterranean region give additional importance to the study of photooxidative stress
in local economic species subjected to combined drought and high-temperature conditions. Under this context, the impact of
these stresses on photosynthesis, energy partitioning, and membrane lipids, as well as the potential ability to attenuate
oxidative damage, were investigated in Ceratonia siliqua L. Two thermal regimes (LT: 25/18°C; HT: 32/21°C) and three soil water conditions (control, water stress, and rewetting)
were considered. HT exacerbated the adverse effects of water shortage on photosynthetic rates (P
N) and PSII function. The decrease in P
N was 33% at LT whereas at HT it was 84%. In spite of this, the electron transport rate (ETR) was not affected, which points
to an increased allocation of reductants to sinks other than CO2 assimilation. Under LT conditions, water stress had no significant effects on yield of PSII photochemistry (ΦPSII) and yields of regulated (ΦNPQ) and nonregulated (ΦNO) energy dissipation. Conversely, drought induced a significant decrease of ΦPSII and a concomitant increase of ΦNO in HT plants, thereby favouring the overproduction of reactive oxygen species (ROS). Moreover, signs of lipid peroxidation
damage were detected in HT plants, in which drought caused an increase of 40% in malondialdehyde (MDA) content. Concurrently,
a marked increase in proline content was observed, while the activities of catalase (CAT) and ascorbate peroxidase (APX) were
unaffected. Despite the generation of a moderate oxidative stress response, C. siliqua revealed a great capability for photosynthetic recovery 36 h after rewatering, which suggests that the species can cope with
predicted climate change. |
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