Biodiesel is an alternative to petroleum diesel fuel. It is a renewable, biodegradable, and nontoxic biofuel. Interest in the production of biodiesel from Jatropha curcas L. seeds has increased in recent years, but the ability of J. curcas to grow in salt-prone areas, such as the Caatinga semiarid region, has received considerably meager attention. The aim of this study was to identify the main physiological processes that can elucidate the pattern of responses of J. curcas irrigated with saline water, which commonly occurs in the semiarid Caatinga region. This study measured the activity of the antioxidant enzymes involved in the scavenging of reactive oxygen species, which include catalase (CAT) and ascorbate peroxidase (APX), as well as malondialdehyde (MDA) levels. The levels of chlorophyll (Chl), carotenoids, amino acids, proline, and soluble proteins were also analyzed. The net carbon assimilation rate (P N ), stomata conductance (g s ), and transpiration rate (E) decreased with salt stress. The activities of CAT and APX were decreased, while H 2 O 2 and MDA levels as well as electrolyte leakage were significantly increased in salt-stressed plants compared to the untreated ones. These observations suggest that the ability of J. curcas plants resist to salt stress is associated with the activities of protective enzymes and their defensive functions. However, our results indicate that the reactive oxygen species scavenging system is not sufficient to protect J. curcas leaves against oxidative damage caused by salt stress, and, therefore, it cannot be treated as a salt tolerant plant species.

The present study investigated the influence of two Brazilian environments on the physico-chemical and physiological properties of Jatropha curcas L. (physic nut) – an oilseed plant of great potential in biodiesel production. Fruits and seeds of plants grown in the Brazilian Atlantic rainforest (AF) and in the semiarid climate of Caatinga (SA) were compared. Fruits from the SA were longer, wider and heavier than those from the AF. In contrast, the AF seeds were larger and heavier than the SA seeds. Soluble sugars, protein, relative water content and electrical conductivity of the SA seeds significantly exceeded that of the AF seeds by 28%, 23%, 32% and 94%, respectively. Seeds of the AF had a significantly greater percentage germination (17.5%) and needed less time to germinate (10%) than did the SA seeds. Shoot dry biomass of seedlings grown from the AF seeds significantly exceeded that of the SA by 18.5%. Results suggest this pattern may be due to the higher carbon storage (i.e. sugars, proteins and oil) in the AF than SA seeds. Further studies are warranted to verify whether the differences observed between the seed sources investigated in the present study could be due to varietal or biotype factors.

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ABSTRACT. Sugarcane culture is an important source of income for the Brazilian economy. The aim of this study was to identify somaclonal variation in sugarcane varieties RB943365 and RB92579 arising from micropropagation using inter-simple sequence repeat (ISSR) DNA markers. The evaluated plants were generated from the in vitro propagation of shoot tips grown in MS medium supplemented with vitamins, myoinositol, glycine, and sucrose, without the use of growth regulators. Fifteen consecutive subcultures with intervals of 14 days were carried out, and DNA was extracted from young leaves obtained from each of the subcultures. The DNA was amplified with ISSR markers and separated by electrophoresis on 2% agarose gels. No evidence of polymorphism was observed in subcultures of the varieties analyzed, suggesting the absence of somaclonal variants. In this way, the ISSR marker was efficient at analyzing somaclonal variation, and in vitro propagation of sugarcane can be considered efficient for 15 consecutive subcultures of the varieties analyzed.