Effect of different environmental stresses on the expression of oleate desaturase genes and fatty acid composition in olive fruit

Temperature and light regulates olive oleate desaturase genes at transcriptional level, whereas only microsomal oleate desaturase genes are transcriptionally regulated in response to wounding. [Display omitted] ► An olive FAD6 gene was functionally characterized by overexpression in E. coli. ► Temperature and light regulate olive FAD2 and FAD6 genes at transcriptional level. ► Olive FAD2 genes are transcriptionally regulated in response to wounding. The regulation of microsomal and plastidial oleate desaturases by low and high temperature, darkness, and wounding was investigated. To this end, their gene expression levels and the fatty acid composition was determined in the mesocarp tissue of olive fruit from the Picual and Arbequina varieties subjected to the corresponding stress treatments. Firstly, a plastidial oleate desaturase from olive was cloned and its functional identity was confirmed by overexpression in Escherichia coli. The results showed that temperature and light regulate olive oleate desaturase genes at transcriptional level. However, no correlation between their expression levels and the linoleic acid content in microsomal and plastidial lipids was found. In addition, the involvement of microsomal but not plastidial oleate desaturases in the wounding response of olive fruit mesocarp is demonstrated. The fatty acid analysis revealed the appearance of palmitolinoleic acid only in microsomal lipids, reaching a maximum 3 h after wounding.