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Manipulation of flavour and aroma compound sequestration and release using a glycosyltransferase with specificity for terpene alcohols
Author(s) -
Yauk YarKhing,
Ged Claire,
Wang Mindy Y.,
Matich Adam J.,
Tessarotto Lydie,
Cooney Janine M.,
Chervin Christian,
Atkinson Ross G.
Publication year - 2014
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12634
Subject(s) - geraniol , aroma , glycoside , actinidia deliciosa , terpene , chemistry , ripening , hexanol , biochemistry , food science , botany , biology , stereochemistry , alcohol , essential oil
Summary Glycosides are an important potential source of aroma and flavour compounds for release as volatiles in flowers and fruit. The production of glycosides is catalysed by UDP ‐glycosyltransferases ( UGT s) that mediate the transfer of an activated nucleotide sugar to acceptor aglycones. A screen of UGT s expressed in kiwifruit ( Actinidia deliciosa ) identified the gene Ad GT 4 which was highly expressed in floral tissues and whose expression increased during fruit ripening. Recombinant Ad GT 4 enzyme glycosylated a range of terpenes and primary alcohols found as glycosides in ripe kiwifruit. Two of the enzyme's preferred alcohol aglycones, hexanol and ( Z )‐hex‐3‐enol, contribute strongly to the ‘grassy‐green’ aroma notes of ripe kiwifruit and other fruit including tomato and olive. Transient over‐expression of Ad GT 4 in tobacco leaves showed that enzyme was able to glycosylate geraniol and octan‐3‐ol in planta whilst transient expression of an RNA i construct in Actinidia eriantha fruit reduced accumulation of a range of terpene glycosides. Stable over‐expression of Ad GT 4 in transgenic petunia resulted in increased sequestration of hexanol and other alcohols in the flowers. Transgenic tomato fruit stably over‐expressing Ad GT 4 showed changes in both the sequestration and release of a range of alcohols including 3‐methylbutanol, hexanol and geraniol. Sequestration occurred at all stages of fruit ripening. Ripe fruit sequestering high levels of glycosides were identified as having a less intense, earthier aroma in a sensory trial. These results demonstrate the importance of UGT s in sequestering key volatile compounds in planta and suggest a future approach to enhancing aromas and flavours in flowers and during fruit ripening.