The Impact of Seasonal Temperature Fluctuations on Genotype x Phenotype Interactions in <em>Malus domestica</em> Borkh.

Environmental and agronomic factors strongly affect the development and quality of apple fruits. The presented study explain the genotype(G) x phenotype(P) x environment(E) relationships, shaping the fruit development phases and features of four apple cv.. We assessed the three-dimensional data concerning: expression profiles (fold change, in qPCR reaction) of eight genes related to fruit ripeness regulation; seasonal temperatures variation (year-to-year 2018-2020) and variation of fruit parameters: FW, IEC, TSS, TA and FF. The effects of each component GxPxE were calculated according to the Pearson correlation parameters (Log(p-value) plots). We observed that low temper-atures (especially before reaching the apple ripening phase), promoted an increase of gene activity and improve the fruit quality of four cultivars with different flowering/ripening dates: ‘Ligol’ (early flowering/late ripening reference cultivar), &#039;Pink Braeburn&#039;, &#039;Pinokio&#039; and &#039;Ligolina&#039;. We also found positive effect of low temperatures on the activity of AAAA1, AALA1, StG and AAXA genes as well as on the evaluated fruit quality parameters, and confirmed their dependence on genotype of the studied cultivars. The obtained results shed light to understand the complexity of mechanism of variability of fruit features and fruit harvest date. This knowledge may improve breeding programs on production of better quality of apple fruits.