Relationship between production of ethylene and a-farnesene in apples, and how it is influenced by the timing of diphenylamine treatment

The relationship between ethylene and peel α-farnesene concentrations was examined by applying diphenylamine (DPA) and the ethylene analogue, propylene at varying times after harvest to superficial scald (scald) susceptible ââ"šÂ¬Ã‹Å“Granny Smithââ"šÂ¬Ã¢"žÂ¢ apples (Malus domestica Borkh.) stored at 10ÃÆ'Ã"šÃ¢â‚¬Å¡ÃƒÆ’‚Ã"šÃ‚°C. Delaying DPA application after harvest had no large effect on ethylene or on peel α-farnesene production. Propylene advanced fruit ripening and promoted an increase in peel α-farnesene concentration before endogenous internal ethylene production, suggesting that ethylene has an important regulatory role in α-farnesene production, but their biosynthetic pathways are controlled independently. The effect of delayed DPA application (4 and 7 days after harvest) on the relationship between ethylene and peel α-farnesene was further examined at both a scald-inducing temperature (0ÃÆ'Ã"šÃ¢â‚¬Å¡ÃƒÆ’‚Ã"šÃ‚°C) and a non-scald-inducing temperature (10ÃÆ'Ã"šÃ¢â‚¬Å¡ÃƒÆ’‚Ã"šÃ‚°C) with ââ"šÂ¬Ã‹Å“Granny Smithââ"šÂ¬Ã¢"žÂ¢ and the scald resistant ââ"šÂ¬Ã‹Å“Croftonââ"šÂ¬Ã¢"žÂ¢ cultivar. Similarly a delayed DPA application had only minor effects on internal ethylene and peel α-farnesene concentrations. The relationship between internal ethylene and peel α-farnesene concentration was dependent on storage temperature, and the type of relationship was independent of cultivar. However, the magnitude of the relationship between cultivars was significantly different (ââ"šÂ¬Ã‹Å“Granny Smithââ"šÂ¬Ã¢"žÂ¢ produced significantly more α-farnesene than ââ"šÂ¬Ã‹Å“Croftonââ"šÂ¬Ã¢"žÂ¢) and may be related to scald development