Isolation and expression analysis of organelle genes involved in the development of olive flowers (Olea europaea L.)

Recent research demonstrated that in olive, hermaphrodite and staminate flowers show a different starch content. The low RuBisCO activity and chlorophyll content suggested the secondary origin of this starch, so differences between these two kinds of flowers could be related to a different sink capability. To highlight the origin of starch and understand how photosynthetic activity and energetic metabolism are involved in flower abortion, the expression of two organelles genes, psbA and F1-ATPase, were characterized by RT-PCR and in situ hybridization. Data obtained showed that psbA and ATPase genes are differentially expressed in Leccino and Dolce Agogia cultivars and in hermaphrodite and staminate flowers. RT-PCR experiments demonstrated that transcript levels of psbA and F1-ATPase genes were higher in Leccino which is richer in hermaphrodite flowers than in Dolce Agogia. The in situ hybridization experiments, moreover, showed that the expression of these genes was modulated during flower development and confirmed the presence of higher transcript levels in hermaphrodite flowers. These results highlighted the role of energetic metabolism in the flower development.