DNA sequence and expression variation of hop (Humulus lupulus) valerophenone synthase (VPS), a key gene in bitter acid biosynthesis.

Background: The hop plant (Humulus lupulus) is a source of many secondary metabolites, with bitter acids essential in the beer brewing industry and others having potential applications for human health. This study investigated variation in DNA sequence and gene expression of valerophenone synthase (VPS), a key gene in the bitter acid biosynthesis pathway of hop.

Methods: Sequence variation was studied in 12 varieties, and expression was analysed in four of the 12 varieties in a series across the development of the hop cone.