PMID- 15361143
OWN - NLM
STAT- MEDLINE
DCOM- 20041216
LR  - 20061115
IS  - 0960-7412 (Print)
IS  - 0960-7412 (Linking)
VI  - 40
IP  - 1
DP  - 2004 Oct
TI  - Citrus fruit bitter flavors: isolation and functional characterization of the 
      gene Cm1,2RhaT encoding a 1,2 rhamnosyltransferase, a key enzyme in the 
      biosynthesis of the bitter flavonoids of citrus.
PG  - 88-100
AB  - Species of the genus Citrus accumulate large quantities of flavanones that affect 
      fruit flavor and have been documented to benefit human health. Bitter species, 
      such as grapefruit and pummelo, accumulate bitter flavanone-7-O-neohesperidosides 
      responsible, in part, for their characteristic taste. Non-bitter species, such as 
      mandarin and orange, accumulate only tasteless flavanone-7-O-rutinosides. The key 
      flavor-determining step of citrus flavanone-glycoside biosynthesis is catalyzed 
      by rhamnosyltransferases; 1,2 rhamnosyltransferases (1,2RhaT) catalyze 
      biosynthesis of the bitter neohesperidosides, while 1,6 rhamnosyltransferases 
      (1,6RhaT) catalyze biosynthesis of the tasteless rutinosides. We report on the 
      isolation and functional characterization of the gene Cm1,2RhaT from pummelo 
      which encodes a citrus 1,2RhaT. Functional analysis of Cm1,2RhaT recombinant 
      enzyme was conducted by biotransformation of the substrates using transgenic 
      plant cell culture. Flavanones and flavones, but not flavonols, were 
      biotransformed into 7-O-neohesperidosides by the transgenic BY2 tobacco cells 
      expressing recombinant Cm1,2RhaT. Immunoblot analysis established that 1,2RhaT 
      protein was expressed only in the bitter citrus species and that 1,6RhaT enzyme, 
      whose activity was previously documented in non-bitter species, was not 
      cross-reactive. Expression of Cm1,2RhaT at the RNA level was prominent in young 
      fruit and leaves, but low in the corresponding mature tissue, thus correlating 
      well with the developmental pattern of accumulation of 
      flavanone-neohesperidosides previously established. Phylogenetic analysis of the 
      flavonoid glycosyltransferase gene family places Cm1,2RhaT on a separate gene 
      cluster together with the only other functionally characterized 
      flavonoid-glucoside rhamnosyltransferase gene, suggesting a common evolutionary 
      origin for rhamnosyltransferases specializing in glycosylation of the sugar 
      moieties of flavonoid glucosides.
FAU - Frydman, Ahuva
AU  - Frydman A
AD  - Institute of Horticulture, The Volcani Center, ARO, PO Box 6, Bet-Dagan 50250, 
      Israel.
FAU - Weisshaus, Oori
AU  - Weisshaus O
FAU - Bar-Peled, Maor
AU  - Bar-Peled M
FAU - Huhman, David V
AU  - Huhman DV
FAU - Sumner, Lloyd W
AU  - Sumner LW
FAU - Marin, Francisco R
AU  - Marin FR
FAU - Lewinsohn, Efraim
AU  - Lewinsohn E
FAU - Fluhr, Robert
AU  - Fluhr R
FAU - Gressel, Jonathan
AU  - Gressel J
FAU - Eyal, Yoram
AU  - Eyal Y
LA  - eng
SI  - GENBANK/AY048882
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - Plant J
JT  - The Plant journal : for cell and molecular biology
JID - 9207397
RN  - 0 (Flavonoids)
RN  - 0 (Plant Proteins)
RN  - 0 (RNA, Messenger)
RN  - EC 2.4.1.- (Hexosyltransferases)
RN  - EC 2.4.1.- (flavonoid 1-2 rhamnosyltransferase)
SB  - IM
MH  - Amino Acid Sequence
MH  - *Citrus/enzymology/genetics
MH  - Cloning, Molecular
MH  - Conserved Sequence
MH  - Flavonoids/*biosynthesis
MH  - Hexosyltransferases/chemistry/*genetics
MH  - Humans
MH  - Molecular Sequence Data
MH  - Plant Leaves/enzymology/genetics/growth & development
MH  - Plant Proteins/chemistry/*genetics
MH  - RNA, Messenger/genetics
MH  - Sequence Alignment
MH  - Sequence Homology, Amino Acid
MH  - Taste
EDAT- 2004/09/14 05:00
MHDA- 2004/12/17 09:00
CRDT- 2004/09/14 05:00
PHST- 2004/09/14 05:00 [pubmed]
PHST- 2004/12/17 09:00 [medline]
PHST- 2004/09/14 05:00 [entrez]
AID - TPJ2193 [pii]
AID - 10.1111/j.1365-313X.2004.02193.x [doi]
PST - ppublish
SO  - Plant J. 2004 Oct;40(1):88-100. doi: 10.1111/j.1365-313X.2004.02193.x.