PMID- 15095130
OWN - NLM
STAT- MEDLINE
DCOM- 20040519
LR  - 20131121
IS  - 1435-8603 (Print)
IS  - 1435-8603 (Linking)
VI  - 6
IP  - 1
DP  - 2004 Jan-Feb
TI  - Induction of poplar leaf nitrate reductase: a test of extrachloroplastic control 
      of isoprene emission rate.
PG  - 12-21
AB  - Several recent studies have suggested that control of isoprene emission rate is 
      in part exerted by supply of extrachloroplastic phosphoenolpyruvate to the 
      chloroplast. To test this hypothesis, we altered PEP supply by differential 
      induction of cytosolic nitrate reductase (NR) and PEP carboxylase (PEPC) in 
      plants of Populus deltoides grown with NO3- or NH4+ as the sole nitrogen source. 
      Growth with 8 mM NH4+ produced a high leaf nitrogen concentration, compared with 
      8 mM NO3-, as well as slightly elevated rates of photosynthesis and significantly 
      enhanced rates of isoprene emission and content of dimethylallyl diphosphate 
      (DMAPP, a precursor to isoprene biosynthesis), chlorophyll (a+b) and carotenoids. 
      Growth with 8 mM NO3- resulted in parallel reductions in both leaf isoprene 
      emission rate and DMAPP. The differential effects of growth with NH4+ or NO3- 
      were not observed when plants were grown with 4 mM nitrogen. The effects of 
      reduced DMAPP availability were specific to isoprene emission and were not 
      propagated to higher isoprenoids, as the correlations between nitrogen content 
      and either leaf chlorophyll (a+b) or total carotenoids were unaffected by 
      nitrogen source. Biochemical analysis revealed significantly higher levels of NR 
      and PEPC activity in leaves of 8 mM NO3- -grown plants, consistent with their 
      fundamental roles in nitrate assimilation. Taken together, these results support 
      the hypothesis that foliar assimilation of NO3- reduces isoprene emission rate by 
      competing for carbon skeletons (mediated by PEPC) within the cytosol and possibly 
      reductant within the chloroplast. Cytosolic competition for PEP is a major 
      regulator of chloroplast DMAPP supply, and we offer a new "safety valve" 
      hypothesis to explain why plants emit isoprene.
FAU - Rosenstiel, T N
AU  - Rosenstiel TN
AD  - Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, 
      CO 80309, USA. todd.rosenstiel@colorado.edu
FAU - Ebbets, A L
AU  - Ebbets AL
FAU - Khatri, W C
AU  - Khatri WC
FAU - Fall, R
AU  - Fall R
FAU - Monson, R K
AU  - Monson RK
LA  - eng
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - England
TA  - Plant Biol (Stuttg)
JT  - Plant biology (Stuttgart, Germany)
JID - 101148926
RN  - 0 (Butadienes)
RN  - 0 (Hemiterpenes)
RN  - 0 (Organophosphorus Compounds)
RN  - 0 (Pentanes)
RN  - 0A62964IBU (isoprene)
RN  - 358-72-5 (3,3-dimethylallyl pyrophosphate)
RN  - 73-89-2 (Phosphoenolpyruvate)
RN  - 7440-44-0 (Carbon)
RN  - EC 1.7.- (Nitrate Reductases)
RN  - EC 1.7.99.4 (Nitrate Reductase)
RN  - N762921K75 (Nitrogen)
SB  - IM
MH  - Butadienes
MH  - Carbon/metabolism
MH  - Chloroplasts/metabolism
MH  - Cytosol/metabolism
MH  - Enzyme Induction
MH  - Hemiterpenes/*biosynthesis/metabolism
MH  - Kinetics
MH  - Models, Biological
MH  - Nitrate Reductase
MH  - Nitrate Reductases/*biosynthesis
MH  - Nitrogen/metabolism
MH  - Organophosphorus Compounds/metabolism
MH  - Pentanes
MH  - Phosphoenolpyruvate/metabolism
MH  - Plant Leaves/enzymology/metabolism
MH  - Populus/enzymology/*metabolism
EDAT- 2004/04/20 05:00
MHDA- 2004/05/20 05:00
CRDT- 2004/04/20 05:00
PHST- 2004/04/20 05:00 [pubmed]
PHST- 2004/05/20 05:00 [medline]
PHST- 2004/04/20 05:00 [entrez]
AID - 10.1055/s-2003-44722 [doi]
PST - ppublish
SO  - Plant Biol (Stuttg). 2004 Jan-Feb;6(1):12-21. doi: 10.1055/s-2003-44722.