Affordable Access

Flavonoid biosynthesis in barley primary leaves requires the presence of the vacuole and controls the activity of vacuolar flavonoid transport.

Authors
Type
Published Article
Journal
PLANT PHYSIOLOGY
0032-0889
Publisher
American Society of Plant Biologists
Publication Date
Volume
144
Issue
1
Pages
432–444
Identifiers
PMID: 17369433
Source
Medline

Abstract

Barley (Hordeum vulgare) primary leaves synthesize saponarin, a 2-fold glucosylated flavone (apigenin 6-C-glucosyl-7-O-glucoside), which is efficiently accumulated in vacuoles via a transport mechanism driven by the proton gradient. Vacuoles isolated from mesophyll protoplasts of the plant line anthocyanin-less310 (ant310), which contains a mutation in the chalcone isomerase (CHI) gene that largely inhibits flavonoid biosynthesis, exhibit strongly reduced transport activity for saponarin and its precursor isovitexin (apigenin 6-C-glucoside). Incubation of ant310 primary leaf segments or isolated mesophyll protoplasts with naringenin, the product of the CHI reaction, restores saponarin biosynthesis almost completely, up to levels of the wild-type Ca33787. During reconstitution, saponarin accumulates to more than 90% in the vacuole. The capacity to synthesize saponarin from naringenin is strongly reduced in ant310 miniprotoplasts containing no central vacuole. Leaf segments and protoplasts from ant310 treated with naringenin showed strong reactivation of saponarin or isovitexin uptake by vacuoles, while the activity of the UDP-glucose:isovitexin 7-O-glucosyltransferase was not changed by this treatment. Our results demonstrate that efficient vacuolar flavonoid transport is linked to intact flavonoid biosynthesis in barley. Intact flavonoid biosynthesis exerts control over the activity of the vacuolar flavonoid/H(+)-antiporter. Thus, the barley ant310 mutant represents a novel model system to study the interplay between flavonoid biosynthesis and the vacuolar storage mechanism.

There are no comments yet on this publication. Be the first to share your thoughts.

Statistics

Seen <100 times
0 Comments