In olive, breeding programs last about thirty years on average (Lavee et al., 2014; Rallo et al., 2018), while the timing for the selection of new cultivars in other fruit crops has been greatly reduced, also by the application of new efficient genomic tools (Biscarini et al., 2017; Cai et al., 2019; Laurens et al., 2018). In cultivated olives (Olea europaea subsp. europaea var. europaea), the crossbreeding activities have been delayed by the particularly long generation time (Santos-Antunes et al., 2005), the extended juvenile phase and the high demanding nursery practices. This work provides the best candidate genes to construct markers for a fast and reliable genotyping of olive cultivars for their oil quality, offering great opportunities to rapidly screen and planning inter-varietal crosses, and reducing the time for seedling selection. Furthermore, the newly detected candidate genes could be applied as a source for interested traits in genome editing approaches.
The IDR index demonstrated that meta-analysis has good power to identify new differentially expressed genes. Therefore, the low value of IDR indicates a subtly increase in the power of meta-analysis compared to the results obtained in the previously published independent studies (Hong & Breitling, 2008). In addition, the decrease in the number of new differentially expressed genes in the meta-analysis compared to the total genes that were significantly different in comparison between the two developmental stages indicated that the meta-analysis was more efficient than independent studies and provided solid results.