Contrasting Physiological Responses of Jatropha curcas Plants to Single and Combined Stresses of Salinity and Heat
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In this study we evaluated the contrasting major physiological responses of Jatropha curcas L. to salinity alone and in combination with high temperature. The plants were subjected to salinity (100 mM NaCl) before and after exposure to 43 °C (heat stress) for 6 h. The effects of salinity were more harmful than heat stress, and the effects of salt stress were increased when both stress factors were combined. The negative effects of the combined treatments included strong impairment of the CO2 assimilation rate and stomata conductance and increased Na+ and Cl− accumulation in the leaves associated with increased membrane damage and lipid peroxidation. Heat favorably stimulated the accumulation of glycine betaine and chlorophyll in the salt-stressed leaves. Treatments with salt, heat, and their combination stimulated the antioxidant enzymatic defense system, that is, the expression of ascorbate peroxidase (APX) and superoxide dismutase (SOD), whereas the expression of catalase (CAT) was stimulated through treatments with salt alone and in combination with heat; treatment with heat alone did not affect CAT expression. The ascorbate redox state was decreased under salinity stress alone and in combination with heat but remained unaffected when treated with heat alone. Overall, the leaf H2O2 concentration did not change in response to these stresses, but lipid peroxidation and membrane damage was increased. Moreover, high temperature increases the negative effects of salt stress on key physiological processes, but treatment with heat alone is favorable for several metabolic indicators of young J. curcas plants. In contrast with heat, these plants exhibit higher physiological disturbances under isolated salinity stress.
KeywordsHigh temperature Jatropha curcas Osmosolutes Oxidative protection Photosynthesis Salt stress
We thank the Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico - FUNCAP (Project 2155/PRONEX) and the Conselho Nacional de Desenvolvimento Científico e Tecnolígico (CNPq) for financial support. The authors would like to thank the Fazenda Tamanduá for supplying of the Jatropha curcas seeds.
- Chaves MM, Flexas J, Pinheiro C (2009) Photosynthesis under drought and salt stress: regulation mechanisms from whole plant to cell. Ann Bot 125:1–10Google Scholar
- Heath RL, Packer L (1968) Photoperoxidation in isolated chloroplasts. I. Kinetics and stoichiometry of fatty acid peroxidation. Arch Biochem Biophys 125:189–198Google Scholar
- Hoagland DR, Arnon DI (1950) The water culture method for growing plants without soil. Calif Agric Exp Stn Circ 347:1–39Google Scholar
- Nakano Y, Asada K (1981) Hydrogen peroxide is scavenged by ascorbate-specific peroxidase in spinach chloroplasts. Plant Cell Environ 22:1068–1072Google Scholar
- Silva EN, Silveira JAG, Rodrigues CRF, Dutra ATB, Aragão RM (2009a) Ion uptake and growth of physic nut under different salinity levels. Rev Ciênc Agron 40:240–246Google Scholar
- Silva EN, Ferreira-Silva SL, Fontenele AV, Ribeiro RV, Viégas RA, Silveira JAG (2010a) Photosynthetic changes and protective mechanisms against oxidative damage subjected to isolated and combined drought and heat stresses in Jatropha curcas plants. J Plant Physiol 167:1157–1164PubMedCrossRefGoogle Scholar