Tung tree stearoyl-acyl carrier protein Δ9 desaturase improves oil content and cold resistance of Arabidopsis and Saccharomyces cerevisiae

The seed oil of tung tree is rich in a-eleostearic acid (ESA), which endows tung oil with the characteristic of an excellently dry oil. The stearoyl-acyl carrier protein δ9 desaturase (SAD) is a rate-limiting enzyme that converts the stearic acid to the oleic acid, the substrate for the production of the α-ESA. However, the function of the two predicted and genes in the tung tree has not been determined. In this study, quantitative real-time PCR (qRT-PCR) analysis showed that and were expressed in multiple organs of tung tree but were highly expressed in the seed during the oil rapid accumulation period. Heterologous expression of and could promote the production of oleic acid and its derivatives in Arabidopsis thaliana and yeast BY4741, indicating that and possess the stearoyl-ACP desaturases function. Furthermore, both and could significantly improve seed oil accumulation in Arabidopsis. VfSAD1 could also significantly promote the oil accumulation in the yeast BY4741 strain. In addition, overexpression of and enhanced the tolerance of yeast and Arabidopsis seedlings to low temperature stress. This study indicates that the two genes play a vital role in the process of oil accumulation and fatty acid biosynthesis in the tung tree seed, and both of them could be used for molecular breeding in tung tree and other oil crops.