Cyto-histological analysis and mobilization of riserve in Jatropha curcas L.

Jatropha curcas L. is gaining interest as a promising energy crop whose oil is suitable for biodiesel production. The aim of our investigation was to study the type, localization, and dynamics of the reserves in J. curcas seed, which is considered the principal product of this species, utilized for biodiesel production. We investigated the cyto-anatomical structure of the mature and germinating seeds and the storage substances localization in their different tissues. To this aim different techniques of light and electron microscopy were utilized (toluidine blue and periodic acid-Schiff [PAS] staining and transmission electron microscope [TEM] observations). The results showed that, in mature seeds, protein vacuoles and oil bodies were present in the endosperm, embryo, and cotyledons. During germination the endosperm reserves were mobilized and the endosperm was characterized by vacuolated cells without protein and oil reserves; the oil and protein content also decreased in the cotyledons where, at this stage, starch grains appeared. Starch grains were also detected in the hypocotyl, where oil and protein reserves were not observed. Our studies confirmed that all portions of the mature seed (except the seed coat) contributed to store reserves and were a good source of oil, while immediately after germination the distribution of reserves was significantly modified and seeds were not a good source of the oil.