Localization and composition of seed oils of Crithmum maritimum L. (Apiaceae)

The use of some halophytes for rehabilitation of salt affected area has been reported. Crithmum maritimum L. halophyte and apiaceae can tolerate high levels of salt. Their seed was endospermic and had a suitable size for oil extraction. The aim of this report is to localize the lipids in the seed and determine their oils composition. The results showed that the lipids were accumulated in endosperm tissue as oil globoids. The percentage of oils was 44.4% dry weight basis. The C. maritimum L. seed oil was rich with oleic acid (78.6%), low level of palmitic acid (4.8%) and non negligible amount of linoleic acid (15.4%). This composition is similar to olive oil and canola oil. These results confirmed the good quality of C. maritimum L. seed oils.Keys word: Halophytes; Crithmum maritimum L.; seed oils

Effect of phosphorus limiting on phytase activity, proton efflux and oxygen consumption by nodulatedroots of common bean (Phaseolus vulgaris)

This work intended to measure the nodulated-roots oxygen consumption, proton efflux and phytase activity in 2 lines of common bean (Phaseolus vulgaris) (115, 147) at 2 levels of P supply. Rooted seedlings were inoculated with Rhizobium tropici CIAT 899 in hydroaeroponic cultivation under glasshouse. Phosphorus was supplied as KH2PO4 at 15 and 250 ìmol pl-1 week-1 (15P and 250P, respectively). Our results showed that plant growth nodulation and symbiotic nitrogen fixation were significantly affected by P limiting (15P) for the both lines, but this adverse effect was more pronounced in 147 than in 115. For the both lines, the phytase activity, higher in roots than in nodules, was significantly increased by P limiting, but 115 maintained higher values as compared to 147 line. Incotyledons, the phytase activity was higher in 115 than in 147. Phosphorus shortage increased the cumulated proton release only in 115, whereas it was lowered for 147. In this line, the proton release was linked to symbiotic nitrogen fixation. Under 15P, the proton efflux per unit of nodulated-root biomass was 25% greater for 115 than 147, suggesting that under P limitation, proton efflux may constitute an efficient way to increase P uptake in the tolerant line (115). 15P increased significantlynodulated-root O2 consumption per g nodule DW and nodule conductance, but to a higher extent in 147. As a whole, bean plants at P-deficient conditions increased the activity of phytases and proton efflux, thus maintaining the oxygen diffusion in nodules. This may represent an adaptive mechanism for N2- fixing legumes to respond to P deficiency, by increasing the utilisation and the uptake of phosphorus for symbiotic nitrogen fixation

Composition and Stability of the Oxidative Phosphorylation System in the Halophile Plant Cakile maritima

Mitochondria play a central role in the energy metabolism of plants. At the same time, they provide energy for plant stress responses. We here report a first view on the mitochondrial Oxidative Phosphorylation (OXPHOS) system of the halophile (salt tolerant) plant Cakile maritima. Mitochondria were purified from suspension cultures of C. maritima and for comparison of Arabidopsis thaliana, a closely related glycophyte (salt sensitive) plant. Mitochondria were treated with digitonin and solubilized protein complexes were analyzed by 2D Blue native/SDS polyacrylamide gel electrophoresis. The OXPHOS systems of the two compared plants exhibit some distinct differences. C. maritima mitochondria include a very abundant respiratory supercomplex composed of monomeric complex I and dimeric complex III. At the same time the complexes II and IV are of reduced abundance. The stability of the OXPHOS complexes was investigated by combined salt and temperature treatments of isolated mitochondria. ATP synthase (complex V) is of increased stability in C. maritima. Also, the I + III2 supercomplex is present in high abundance during stress treatments. These results give insights into the mitochondrial contribution to the plant salt stress response

Proline priming: An efficient strategy to mitigate salinity impact at early developmental stages of the oilseed halophyte Cakile maritima

Seed germination is a vital process, yet extremely sensitive to salinity. This is particularly true for coastal halophytes like the annual oilseed species Cakile maritima, which faces the simultaneous impact of wind, salt-spray and seawater inundations in its natural biotopes. At the early developmental stages, this may jeopardize seed germination, plant establishment capacity and hence its development and persistence. Osmopriming is a pre-sowing approach aiming to improve seedling emergence and establishment in adverse environments. Here, we investigate the effect of proline (at 0, 1, 5, and 20 mM) pre-treatment on salt tolerance of C. maritima at the juvenile stage under salinity (0, 100, and 200 mM NaCl). Proline seed priming enhanced the germination rate (28% to 92%) and promoted seedling establishment of C. maritima by stimulating α-amylase activity even at the highest salinity (+55 %). Besides, after transfer of non-germinated seeds on distilled water, salt impact was fully reversible. At the seedling stage, chlorophyll fluorescence parameters showed that this osmoticum increased the maximal quantum yield of PSII photochemistry (Fv/Fm) and the quantum yield of photochemical energy conversion [Y(II)]. In contrast, the quantum yield of nonregulated nonphotochemical energy dissipation [Y(NO)] and the quantum yield of regulated nonphotochemical energy dissipation [Y(NPQ)], which might be correlated to the mitigation of the salt deleterious effects on PSII. Proline and carbohydrate concentrations also increased following priming. Overall, our data provide strong arguments for using proline at low doses (1 and 5 mM) as a successful priming agent to alleviate salinity-induced adverse effect on plants

Seed priming mitigates high salinity impact on germination of bread wheat (Triticum aestivum L.) by improving carbohydrate and protein mobilization

Salinity is increasingly considered as a major environmental issue, which threatens agricultural production by decreasing yield traits of crops. Seed priming is a useful and cost-effective technique to alleviate the negative effects of salinity and to enable a fast and uniform germination. In this context, we quantified the effects of priming with gibberellic acid (GP), calcium chloride (CP), and mannitol (MP) on seed germination of three bread wheat cultivars and investigated their response when grown at high salinity conditions (200 mM NaCl). Salt exposure strongly repressed seed imbibition and germination potential and extended germination time, whereas priming enhanced uniformity and seed vigor. Seed preconditioning alleviated the germination disruption caused by salt stress to varying degrees. Priming mitigating effect was agent-dependent with regard to water status (CP and MP), ionic imbalance (CP), and seed reserve mobilization (GP). Na+ accumulation in seedling tissues significantly impaired carbohydrate and protein mobilization by inhibiting amylase and proteases activities but had lesser effects on primed seeds. CP attenuated ionic imbalance by limiting sodium accumulation. Gibberellic acid was the most effective priming treatment for promoting the germination of wheat seeds under salt stress. Moreover, genotypic differences in wheat response to salinity stress were observed between varieties used in this study. Ardito, the oldest variety, seems to tolerate better salinity in priming-free conditions; Aubusson resulted the most salt-sensitive cultivar but showed a high germination recovery under priming conditions; Bologna showed an intermediate behavior

Comparative study of the effect of salt stress, Alternaria alternata attack or combined stress on the Cakile maritima growth and physiological performance

Cakile maritima is a halophytic plant model that is well known by its ability to tolerate high salt concentrations. Salinity was reported to improve the tolerance of halophytes to several abiotic stresses; however, the involvement of salt in the tolerance to biotic stress is still scant. In the present work, the effect of salt on C. maritima responses towards the pathogenic Alternaria alternata was investigated. For that, C. maritima seeds were germinated for four weeks. Plants were then divided into four groups: i) Plants irrigated with salt (200mM NaCl); ii) Plants infested by fungus; iii) Plants irrigated with salt and infested by fungus and finally control plants (0mM NaCl, without inoculation). Our results showed that upon salt stress or fungal attack, plants reduced biomass production, hydration status and photosynthetic performance which were associated with a decrease in the gas exchange and chlorophyll fluorescence parameters, with a more pronounced effect upon fungal attack. However, under combined stress, a significant increase of these parameters was noticed, with a level close to that of control. Concerning nutrient contents, K, Zn, Fe, Cu and Mg decreased in the C. maritima leaves exposed to both stresses applied individually. In contrast, all these nutrients were increased in plants grown under combined stress. Taken together, we can conclude that plants grown under combined stresses had better growth rate and physiological performance compared to all other treated plants, and that salt may be the key in improving the C. maritima ability to tolerate fungal attack

Comparative responses to water deficit stress and subsequent recovery in the cultivated beet Beta vulgaris and its wild relative B. macrocarpa

The effects of water deficit stress and recovery on growth, photosynthesis, physiological and biochemical parameters were investigated in the cultivated Beta vulgaris and in two Tunisian provenances (Soliman and Enfidha) of its wild relative B. macrocarpa. Seedlings were cultivated for 4 weeks under optimal or limiting water supply (respectively, 100% and 25% of field capacity, FC). After 2 weeks of treatment, a lot of stressed plants were rehydrated to 100% FC. In the Control, B. vulgaris was more productive than B. macrocarpa, whereas Enfidha provenance showed the highest biomass production (1.6- and 3-fold compared with B. vulgaris and Soliman, respectively), under water deficit stress. A partial re-establishment of growth occurred in both species upon recovery at 100% FC. The sensitivity of B. vulgaris and Soliman provenance to drought was associated with the disturbance of leaf water status and the sharp decrease in net CO2 assimilation (–66% and –82% as compared with the Control, respectively). On the contrary, the better behaviour of Enfidha provenance was related to its better photosynthetic capacity and leaf relative water content, along with a higher accumulation of amino acids (proline, glycine, and glutamine) implied in the osmotic adjustment. Leaf hexose concentration increased significantly under drought stress in both species whereas leaf sucrose concentration declined only in drought-stressed B. vulgaris and Soliman provenance. Leaf glutamate dehydrogenase activity increased under water deficit in both species despite to a higher extent in B. vulgaris. As glutamate dehydrogenase is implied in catabolism of glutamate to oxoglutarate, it might contribute to provide stressed plants with carbon skeletons. Enfidha provenance of the spontaneous species B. macrocarpa could be used in the marginal arid ecosystems in order to limit the deficit in fodder and to improve the pastoral value of these regions. In addition, this species could serve as a source of genes for genetic improvement to water deficit stress

Presence of proline in salinized nutrient solution re-enforces the role of this amino acid in osmoregulation and protects lipid membrane peroxidation in Arabidopsis thaliana

Abstract Very little is known about the effect of proline addition on the accumulation of inorganic solutes (Na ) and soluble sugars in the model plant Arabidopsis thaliana. Therefore, the aim of the present study was to assess the effect of 10 mM proline (P) supply in the culture medium on water status and solute accumulation of Arabidopsis thaliana seedlings exposed to 50 mM NaCl (S). The decrease of leaf osmotic potential was more pronounced in P+S as compared to S plants, indicating that former plants were able to accumulate more compounds involved in the osmotic adjustment process. Leaf potassium concentration was reduced by 15, 21 and 25% in P, S and P+S plants respectively, as compared to the control. When compared to S or P treatments, leaf proline and soluble sugar were more accumulated under P+S treatment. Under saline conditions, exogenous proline increased leaf Na + , Ca 2+ and Mg 2+ concentrations by 27, 281 and 252%, respectively, as compared to the control. Interestingly, proline addition mitigated significantly the deleterious effects of salt on lipid membrane peroxidation. Regarding the contribution of soluble sugars to osmotic adjustment (OA), it amounted to 6% in S or P+S, plants. For proline, its contribution to OA did not exceed 3.4% under salinity (S), whereas in (P+S) treatment, it increased to 14.7%. As a whole, the positive effect of proline exogenous application under saline conditions could be partly explained by the enhanced role of this organic compound in osmoregulation and its likely protective effect against membrane lipid peroxidation

Seed Germination Strategies of Mediterranean Halophytes Under Saline Condition

The study of the ecological strategies adopted by seed plants to ensure their success in different environments is closely related to germination ecology. This implies a careful knowledge of ecophysiology of seeds and, therefore, also of interaction between plants and the complexity of external factors. In particular, the environmental conditions of the area where a plant grows and produces seeds represent the main factors that influence successful seedling establishment. The physical-chemical features of habitats, and therefore their heterogeneity, affect the behavior of seeds in different ways. In addition to the timing of seed production, they can induce or terminate dormancy and/or germination and influence the germination pattern of different seeds in the same plant and so the composition and dispersal of soil seed banks. Salinity is a major abiotic stress affecting growth and plant productivity worldwide, constituting one of the main topics of study in the field of plant physiology. Halophytes are the plants that have the availability to survive and develop in different types of saline habitats. In this chapter, we consider some examples to illustrate the main adaptive strategies used by the seeds of halophytes on ecophysiological perspectives to survive in habitats affected by high levels of salinity. The focus is on the species that live in the brackish or salt coastal areas of the Mediterranean Basin. On these environments, the salt stress may act synergistically with intense anthropic pressure, generating profound alterations in the ecosystem and threatening the survival of the plant species very sensitive to the effects of climate change also. The results show the main diverse strategies, such as dormancy cycling, seed heteromorphism, and recovery capacity, from saline shock, favoring the chances of seed survival. The interaction between temperature and salinity during germination was also discussed assessing its crucial role as an ecological strategy

Cross-tolerance to abiotic stresses in halophytes: Application for phytoremediation of organic pollutants

International audienceHalopytes are plants able to tolerate high salt concentrations but no clear definition was retained for them. In literature, there are more studies that showed salt-enhanced tolerance to other abiotic stresses compared to investigations that found enhanced salt tolerance by other abiotic stresses in halophytes. The phenomenon by which a plant resistance to a stress induces resistance to another is referred to as cross-tolerance. In this work, we reviewed cross-tolerance in halophytes at the physiological, biochemical, and molecular levels. A special attention was accorded to the cross-tolerance between salinity and organic pollutants that could allow halophytes a higher potential of xenobiotic phytoremediation in comparison with glycophytes