PMID- 15361535
OWN - NLM
STAT- MEDLINE
DCOM- 20050203
LR  - 20231213
IS  - 0022-0957 (Print)
IS  - 0022-0957 (Linking)
VI  - 55
IP  - 406
DP  - 2004 Oct
TI  - Evidence that the hexose-to-sucrose ratio does not control the switch to storage 
      product accumulation in oilseeds: analysis of tobacco seed development and 
      effects of overexpressing apoplastic invertase.
PG  - 2291-303
AB  - Wild-type tobacco (Nicotiana tabacum L.) seed development was characterized with 
      respect to architecture and carbohydrate metabolism. Tobacco seeds accumulate oil 
      and protein in the embryo, cellular endosperm and inner layer of the seed coat. 
      They have high cell wall invertase (INV) and hexoses in early development which 
      is typical of seeds. INV and the ratio of hexose to sucrose decline during 
      development, switching from high hex to high suc, but not until most oil and all 
      protein accumulation has occurred. The oil synthesis which coincides with the 
      switch is mostly within the embryo. INV activity is greater than sucrose synthase 
      activity throughout development, and both activities exceed the demand for 
      carbohydrate for dry matter accumulation. To investigate the role of INV-mediated 
      suc metabolism in oilseeds, genes for yeast INV and/or hexokinase (HK) were 
      expressed under a seed-specific napin promoter, targeting activity to the 
      apoplast and cytosol, respectively. Manipulating the INV pathway in an oilseed 
      could either increase oil accumulation and sink strength, or disrupt carbohydrate 
      metabolism, possibly through sugar-sensing, and decrease the storage function. 
      Neither effect was found: transgenics with INV and/or HK increased 30-fold and 
      10-fold above wild-type levels had normal seed size and composition. This 
      contrasted with dramatic effects on sugar contents in the INV lines.
FAU - Tomlinson, Kim L
AU  - Tomlinson KL
AD  - School of Medicine, Health Policy and Practice, University of East Anglia, 
      Norwich, Norfolk NR4 7TJ, UK. mikib@agr.gc.ca
FAU - McHugh, Sylvia
AU  - McHugh S
FAU - Labbe, Helene
AU  - Labbe H
FAU - Grainger, John L
AU  - Grainger JL
FAU - James, Lisa E
AU  - James LE
FAU - Pomeroy, Keith M
AU  - Pomeroy KM
FAU - Mullin, John W
AU  - Mullin JW
FAU - Miller, Shea S
AU  - Miller SS
FAU - Dennis, David T
AU  - Dennis DT
FAU - Miki, Brian L A
AU  - Miki BL
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20040910
PL  - England
TA  - J Exp Bot
JT  - Journal of experimental botany
JID - 9882906
RN  - 0 (DNA, Bacterial)
RN  - 0 (Hexoses)
RN  - 0 (T-DNA)
RN  - 57-50-1 (Sucrose)
RN  - EC 2.4.1.- (Glucosyltransferases)
RN  - EC 2.4.1.13 (sucrose synthase)
RN  - EC 2.7.1 - (Phosphofructokinases)
RN  - EC 2.7.1.1 (Hexokinase)
RN  - EC 3.2.1.26 (beta-Fructofuranosidase)
SB  - IM
MH  - Carbohydrate Metabolism
MH  - DNA, Bacterial/genetics
MH  - Genetic Vectors
MH  - Glucosyltransferases/metabolism
MH  - Hexokinase/metabolism
MH  - Hexoses/*metabolism
MH  - Phosphofructokinases/metabolism
MH  - Seeds/*growth & development
MH  - Sucrose/*metabolism
MH  - Nicotiana/enzymology/*growth & development
MH  - beta-Fructofuranosidase/*genetics/metabolism
EDAT- 2004/09/14 05:00
MHDA- 2005/02/04 09:00
CRDT- 2004/09/14 05:00
PHST- 2004/09/14 05:00 [pubmed]
PHST- 2005/02/04 09:00 [medline]
PHST- 2004/09/14 05:00 [entrez]
AID - erh251 [pii]
AID - 10.1093/jxb/erh251 [doi]
PST - ppublish
SO  - J Exp Bot. 2004 Oct;55(406):2291-303. doi: 10.1093/jxb/erh251. Epub 2004 Sep 10.