During postharvest storage at low temperatures, specific apple cultivars can
develop a physiological disorder known as superficial scald. This disorder results with
the formation of brown or black patches on fruit skin, compromising the entire fruit
marketability. In this work, we investigated the effects of different storage strategies
distinguished by a different regime of oxygen during the storage of two apple cultivars
(‘Granny Smith’ and ‘Ladina’), both susceptible to superficial scald, but with a different
magnitude. More precisely, the apples collected from the two cultivars were stored in
regular and controlled atmosphere, for five and seven months, respectively. The
controlled atmosphere was moreover carried out according to dynamic controlled
atmosphere by means of chlorophyll fluorescence and ultra-low oxygen level strategy.
After cold storage, apples were kept for one week in regular atmosphere at room
temperature, to simulate shelf-life conditions. The apple skin was further collected, and
the total amount of RNA was extracted to assess the global transcriptome. In the cultivar
‘Granny Smith’ it was observed that the storage approach carried out with low level of
oxygen was efficient in preventing the development of scald symptoms, underlying the
central role of the oxidative process in this mechanism. The RNA-Seq analysis
highlighted that the samples subjected to the controlled atmosphere were
characterized by a high expression of genes related to carbohydrate metabolism and
lipid accumulation. ‘Ladina', instead, showed a different behaviour as low oxygen or 1-
MCP was less effective in controlling the development of scald compared to ‘Granny
Smith’. The different physiological response was also distinguished by a different
transcriptional signature, with DEGs more related to ATP biosynthesis, ethylene
production, and oxidative stress response. Comparative transcriptomics carried out
between these two cultivars provides insights into the gene regulatory network
involved in the development of superficial scald in apples.