Germinabilidade de sementes de pinhão manso (Jatropa curcas L.) sob restrição hídrica: aspectos fisiológicos, moleculares e citológicos

Abstract

Physic nut (Jatropha curcas L.) is a high oil content Euphorbiaceae seed species renowned for its apparent tolerance to environmental stresses, besides being used by local communities for treating various diseases, having some pharmacological properties being scientifically proven. It is nowadays considered a possible source of renewable feedstock for biofuel production. The physiological behavior of seeds under normal conditions of water availability differs when compared to restrictive water conditions. Nevertheless, it is necessary to conduct studies to better understand the mechanisms of recovery of seed germination and physiological quality under adverse environmental conditions which may allow the establishment of protocols for optimizing the germination process. The present study describes the physiological, molecular and cytological profiles of seeds of physic nut during imbibition in water and in osmotic water restriction conditions. The seeds were derived from Brazilian semiarid regions, Janaúba (MG) e Irará (BA). The bioassays were executed in the Laboratory of Biochemistry, Biotechnology and Bioproducts at the Federal University of Bahia. Seeds were characterized by volume, weight and moisture content, germination, tubulin accumulation and appearance of microtubular cytoskeleton. Seeds from Irará showed better physiological quality than those of Janaúba. This result reflects an apparent higher degree of deterioration of Janaúba seeds. Cytological analysis revealed observed accumulation of β-tubulin and reactivation of the cell cycle during imbibitions in water. Mitotic microtubules configurations appeared only after radicle protrusion whereas it did not appear in seed under osmotic water restriction. In this researche, Jatropha seeds appeared to have little tolerance to drought.