The tolerance of Jatropha curcas seedlings to NaCl: an ecophysiological analysis.

Jatropha curcas L. is a biodiesel crop that is resistant to drought stress. However, the salt tolerance of this plant has not yet been studied. To address this question, J. curcas seedlings were grown in a fertilised substrate to evaluate the effects of salinity stress on growth, leaf water relation and organic solutes, leaf and root mineral concentrations, chlorophyll fluorescence parameters, and carbohydrate concentration. The experiment consisted of six treatments with different concentrations of NaCl in the irrigation water: 0 (control), 30, 60, 90, 120 and 150 mM. The total biomass exhibited a salt-induced decrease in the 60 mM or higher NaCl concentrations. The Cl(r) concentration was higher than the Na(+) concentration in all of the plant tissues. The water potential and relative water content of the leaves were not affected by any of the salt treatments. However, salinity induced a decline in the leaf K(+) concentration, together with a significant enhancement in the leaf P, S, Fe, Zn, Mn and Cu levels. The net assimilation of CO₂ also decreased with the salt treatment, due in part to non-stomatal limitation from the increase in C(a)/C(i) and a decrease in the maximum quantum efficiency (F(v)/F(m)) of photosystem II and soil plant analysis development (SPAD) units. This work suggests that J. curcas seedlings exhibit a moderate tolerance to salinity, as the plants were able to tolerate up to 4 dS m(-1) (EC water irrigation; 30 mM NaCl). The negative influences of salinity in this crop are mainly due to Cl(r) and/or Na(+) toxicity and to a nutritional imbalance caused by an increase in the Na(+)/K(+) ratio. The osmotic effect of salinity in this species is negligible, perhaps due to its strong control of leaf transpiration, which reduces water loss.

Díaz-López L ，Gimeno V ，Lidón V ，Simón I ，Martínez V ，García-Sánchez F ... -  《-》

Physiological adjustment to salt stress in Jatropha curcas is associated with accumulation of salt ions, transport and selectivity of K+, osmotic adjustment and K+/Na+ homeostasis.

This study assessed the capacity of Jatropha curcas to physiologically adjust to salinity. Seedlings were exposed to increasing NaCl concentrations (25, 50, 75 and 100 mm) for 15 days. Treatment without NaCl was adopted as control. Shoot dry weight was strongly reduced by NaCl, reaching values of 35% to 65% with 25 to 100 mm NaCl. The shoot/root ratio was only affected with 100 mm NaCl. Relative water content (RWC) increased only with 100 mm NaCl, while electrolyte leakage (EL) was much enhanced with 50 mm NaCl. The Na(+) transport rate to the shoot was more affected with 50 and 100 mm NaCl. In parallel, Cl(-) transport rate increased with 75 and 100 mm NaCl, while K(+) transport rate fell from 50 mm to 100 mm NaCl. In roots, Na(+) and Cl(-) transport rates fell slightly only in 50 mm (to Na(+)) and 50 and 100 mm (to Cl(-)) NaCl, while K(+) transport rate fell significantly with increasing NaCl. In general, our data demonstrate that J. curcas seedlings present changes in key physiological processes that allow this species to adjust to salinity. These responses are related to accumulation of Na(+) and Cl(-) in leaves and roots, K(+)/Na(+) homeostasis, transport of K(+) and selectivity (K-Na) in roots, and accumulation of organic solutes contributing to osmotic adjustment of the species.

Silva EN ，Silveira JA ，Rodrigues CR ，Viégas RA ... -  《-》

Leaf water relations and net gas exchange responses of salinized Carrizo citrange seedlings during drought stress and recovery.

Pérez-Pérez JG ，Syvertsen JP ，Botía P ，García-Sánchez F ... -  《-》

Exogenous nitric oxide improves salt tolerance during establishment of Jatropha curcas seedlings by ameliorating oxidative damage and toxic ion accumulation.

Jatropha curcas is an oilseed species that is considered an excellent alternative energy source for fossil-based fuels for growing in arid and semiarid regions, where salinity is becoming a stringent problem to crop production. Our working hypothesis was that nitric oxide (NO) priming enhances salt tolerance of J. curcas during early seedling development. Under NaCl stress, seedlings arising from NO-treated seeds showed lower accumulation of Na+ and Cl- than those salinized seedlings only, which was consistent with a better growth for all analyzed time points. Also, although salinity promoted a significant increase in hydrogen peroxide (H2O2) content and membrane damage, the harmful effects were less aggressive in NO-primed seedlings. The lower oxidative damage in NO-primed stressed seedlings was attributed to operation of a powerful antioxidant system, including greater glutathione (GSH) and ascorbate (AsA) contents as well as catalase (CAT) and glutathione reductase (GR) enzyme activities in both endosperm and embryo axis. Priming with NO also was found to rapidly up-regulate the JcCAT1, JcCAT2, JcGR1 and JcGR2 gene expression in embryo axis, suggesting that NO-induced salt responses include functional and transcriptional regulations. Thus, NO almost completely abolished the deleterious salinity effects on reserve mobilization and seedling growth. In conclusion, NO priming improves salt tolerance of J. curcas during seedling establishment by inducing an effective antioxidant system and limiting toxic ion and reactive oxygen species (ROS) accumulation.

Gadelha CG ，Miranda RS ，Alencar NLM ，Costa JH ，Prisco JT ，Gomes-Filho E ... -  《-》

Evaluating the Contribution of Growth, Physiological, and Ionic Components Towards Salinity and Drought Stress Tolerance in Jatropha curcas.

Abrar MM ，Saqib M ，Abbas G ，Atiq-Ur-Rahman M ，Mustafa A ，Shah SAA ，Mehmood K ，Maitlo AA ，Ul-Hassan M ，Sun N ，Xu M ... -  《Plants-Basel》