Articles
Genetic variations within the promoters of the genes for bitter acid and flavonoid biosynthesis of hop partly explain different levels of bitter acids between cultivars
Article number
1328_10
Pages
75 – 80
Language
English
Abstract
The hop derived bitter acids are fundamental for the bitter taste of most beer styles.
Bitter acids are produced in the glands of the female inflorescences (cones) of hop.
Three enzymes are mainly responsible for the bitter acid production, valerophenone synthase (VPS) as well as prenyltransferases 1 and 2 (PT1 and PT2). Furthermore, hop cones contain pharmacologically interesting flavonoids, which also rely on the PT1 activity.
This shows that the bitter acid and flavonoid pathways are not independent.
Additionally, some transcription factors (TFs) are known to co-regulate the bitter acid and the flavonoid biosynthesis.
TFs regulate genes by binding to promoter elements and thereby altering the corresponding gene expression.
Consequently, mutations within promoters are likely to have considerable impact on the gene function.
Therefore, variants of promoter elements of bitter acid genes might be associated with bitter acid concentrations in hop cones.
In this study, promoter elements of the bitter acid biosynthesis and related genes have been sequenced.
It was demonstrated that sequence variations between hop cultivars were associated with variations in alpha acid concentration.
These results showed that knowledge-based targeted sequencing is a suitable method for identifying associations between genetic variants and traits.
Furthermore, a significant trait association was identified for promoters of the prenyltransferases and bitter acid concentrations.
Interestingly, the strongest association was identified for the promoter of dihydroflavanol 4-reductase gene from the flavonoid biosynthetic pathway.
Bitter acids are produced in the glands of the female inflorescences (cones) of hop.
Three enzymes are mainly responsible for the bitter acid production, valerophenone synthase (VPS) as well as prenyltransferases 1 and 2 (PT1 and PT2). Furthermore, hop cones contain pharmacologically interesting flavonoids, which also rely on the PT1 activity.
This shows that the bitter acid and flavonoid pathways are not independent.
Additionally, some transcription factors (TFs) are known to co-regulate the bitter acid and the flavonoid biosynthesis.
TFs regulate genes by binding to promoter elements and thereby altering the corresponding gene expression.
Consequently, mutations within promoters are likely to have considerable impact on the gene function.
Therefore, variants of promoter elements of bitter acid genes might be associated with bitter acid concentrations in hop cones.
In this study, promoter elements of the bitter acid biosynthesis and related genes have been sequenced.
It was demonstrated that sequence variations between hop cultivars were associated with variations in alpha acid concentration.
These results showed that knowledge-based targeted sequencing is a suitable method for identifying associations between genetic variants and traits.
Furthermore, a significant trait association was identified for promoters of the prenyltransferases and bitter acid concentrations.
Interestingly, the strongest association was identified for the promoter of dihydroflavanol 4-reductase gene from the flavonoid biosynthetic pathway.
Publication
Authors
P. Seeburger, M.H. Hagemann, U. Born, G. Weber, K. Kammhuber, A. Lutz, E. Seigner, J.N. Wünsche
Keywords
Humulus lupulus L., genotypic variation, amplicon sequencing, molecular marker development
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