Transcriptome analysis of the influence of CPPU application for fruit setting on melon volatile content

Abstract

In fruit production, the application of the plant growth regulator 1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU) dulls the fruit aroma. Gas chromatography–mass spectrometry and transcriptome analyses were performed on CPPU-treated and pollinated fruits to determine how CPPU affects the production of aroma in melon fruit. The results showed that the contents of two important esters (benzyl acetate and phenethyl acetate) in the CPPU-treated fruits were significantly lower than those in the pollinated fruits. Transcriptome sequencing data revealed that most differentially expressed genes were involved in “phenylalanine metabolism” pathway, and their expression was significantly decreased in the CPPU-treated fruits. Further analysis showed that the phenylalanine content in the CPPU-treated fruits was significantly higher than that in the pollinated fruits. In summary, CPPU application interferes with phenylalanine metabolism in melon fruits and affects the production of aromatic esters.