specialized functions of olive fad2 gene family members related to fruit development and the abiotic stress response three different cdna sequences designated oepfad23 oepfad24 and oepfad25 encoding three microsomal oleate desaturases fad2 have been isolated from olive olea europaea cv picual sequence analysis and functional expression in yeast of the corresponding cdnas confirm that they encode microsomal oleate desaturases gene expression and lipid analysis indicate that these three genes are not involved in the linoleic acid present in seed lipids while oefad25 together with oefad22 contributes mostly to the linoleic acid present in the mesocarp and therefore in the olive oil our results have also shown that olive fad23 fad24 and fad25 gene expression is not only spatially and temporally regulated in olive fruit but also is cultivardependent as well as regulated by water regime temperature light and wounding all these data suggest specialized physiological roles for the olive fad2 gene family members with respect to both aspects of the biosynthesis of the linoleic acid either present in storage lipids that constitute the olive oil or being part of membrane lipids which are involved in the response to abiotic stresses and highlight the differences on fad2 gene regulation between oilseeds and oil fruits