The two cultivars of Digitaria eriantha: cv. Sudafricana (a cold-sensitive cultivar) and cv. Mejorada INTA (a cold-resistant cultivar) were exposed to low temperature and compared in terms of the involvement of abscisic acid (ABA) and catabolites, jasmonates, and antioxidant defense in cold tolerance. Cold stress caused a greater ABA increase in cv. Mejorada INTA than in cv. Sudafricana. In both cultivars abscisic acid glucose ester and dihydrophaseic acid were the most abundant catabolites. Cold treatment decreased JA in leaves of both cultivars. In cv. Sudafricana, 12-hydroxyjasmonate (12-OH-JA) decreased and 12-oxophytodienoic acid increased. In regard to antioxidant defense, both cultivars increased the non-protein thiols in response to cold stress. However, reduced glutathione (GSH) level was higher in leaves of cv. Mejorada INTA than cv. Sudafricana. Cold-treated leaves of cv. Sudafricana increased thiobarbituric acid-reactive substances (TBARS), but cv. Mejorada INTA leaves showed no such increase. Superoxide dismutase activity decreased and ascorbate peroxidase activity increased in cold-treated leaves of cv. Sudafricana. No significant change of these enzymes was observed for cv. Mejorada INTA. The cold tolerance of cv. Mejorada INTA could be related to JA, 12-OH-JA and GSH high basal contents, ABA increase, and TBARS stability after cold treatment.

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Our main objective was to analyze the protection provided by Mycorrhiza (Rhizophagus intraradices) to Jatropha curcas plants under cold stress, through the analysis of physiological and oxidative stress parameters. Mycorrhizal (AM) and non-mycorrhizal (nonAM) plants were exposed to cold stress 4±1 ºC temperature for 72 h. The control plant grow at 25 ±1 ºC. Under cold stress, the stomata conductance decreased both AM and nonAM plants and photosynthetic efficiency only in non AM plants. The CAT activity increased in AM plants independently of stress conditions. GR activity shows a typical rise to cold stress in nonAM plants and decreased in AM ones. With cold stress, the APX activity was reduced in all treatments and SOD activity was not affected in all treatment The MDA content increased in nonAM plants while in AM plants it was unaffected by low temperature. This study reported on the regulation of antioxidant compounds, their relationship to the AM symbiosis and cold stress in Jatropha curcas L.

J. curcas and J. macrocarpa are useful for restoring degraded areas and their seeds contain oils for biodiesel production. The aim of the work was to determine the reserve substances in the endosperm and the embryo of J. curcas and J. macrocarpa which is important in understanding the germination process, the establishment of these species and its industrial employment. Seeds were imbibed in distilled water for 24 h, to facilitate removal of seed coat with the aim to separate the embryo and nutritive tissues. In both species, the endosperm contained aleurone grains consisting of a crystalloid and globoid, lipids of red color and the starch was not observed. Four major fatty acids were determined in J. curcas seed: oleic, palmitic, stearic, palmitoleic and oleic fatty acid represents about 70% oil content. Oleic acid was the most abundant in J. macrocarpa seeds, while, there was not palmitoleic acid. Seed with predominantly unsaturated fatty acids is ideal for biodiesel industry. The means of the sugar content were: 14.3 µg/mg in endosperm and 104.76 µg/mg in embryo of J. curcas and 6.48 µg/mg in endosperm and 59.20 µg/mg in embryo of J. macrocarpa. The means of the protein content were: 4.2 µg/mg in endosperm and 45.02 µg/mg in embryo of J. curcas and 3.26 µg/mg in endosperm and 31.08 µg/mg in embryo of J. macrocarpa. Sugar and protein contents of Jatropha seeds were significantly higher in embryo in both species