Histochemical Features and Oil Production in Relation to the Reproductive Modes of Physics Nut (Jatropha curcas L.) during in vivo Seed Development and Cell Suspension Culture

Abstract

Physic nut (Jatropha curcas L.) is promising for biodiesel production due to its inedible oil and high oleic acid content which leads to the standard-satisfied biodiesel. However, commercial feasibility has not been achieved due to its low oil content, fruit and seed set ascribed to the lack of crop improvement and incomplete knowledge. Thus, this study aims to fulfill the gap knowledge on 1) development and fertility of male and female gametophytes, 2) relationship between pollination method and oil features and 3) lipid storage in cell suspension. The results showed that bud diameter could be used as criteria for identifying the stages of pollen and embryo sac. The pollen viability and the stigma receptivity were high at anthesis. There was no significant difference of seed oil content after open-, cross-, self-pollination and non- pollination (apomixis). However, the open-pollination provided maximal fruit, seed set and oleic acid content. Besides, the endosperm reserved greater oil and oleic than the embryo. The seed oil bodies were mainly composed of triacylglycerol (TAG) and integral proteins named caleosin and oleosins (both high and low molecular weight isoforms). Cell suspension was established, from the compact callus, in liquid MS media added with 1 mg L-1 2, 4-dichlorophenoxyacetic acid (2,4-D) and 0.5 mg L-1 kinetin (KN). This study revealed that both oil content and oleic acid were lower in the cell suspension than in the seed. However, the cell suspension accumulated higher oleic acid than all other fatty acid types found within the cell, indicating its potential for using as a source of oil for producing the standard-satisfied biodiesel. Further improvement, nevertheless, is needed in order to increase the biomass and oil content of the cell suspension - for meeting the commercial demand.