PMID- 10938841
OWN - NLM
STAT- MEDLINE
DCOM- 20000907
LR  - 20190513
IS  - 0022-0957 (Print)
IS  - 0022-0957 (Linking)
VI  - 51 Spec No
DP  - 2000 Feb
TI  - Control of C4 photosynthesis: effects of reduced activities of 
      phosphoenolpyruvate carboxylase on CO2 assimilation in Amaranthus edulis L.
PG  - 339-46
AB  - Heterozygous mutants of Amaranthus edulis deficient in PEP carboxylase (PEPC) 
      have been used to study the control of photosynthetic carbon assimilation. A 
      reduction in PEPC activity led to a decrease in the initial slope of the 
      relationship between the CO2 assimilation rate and the intercellular CO2 
      concentration and to a decrease in photosynthesis at high light intensities, 
      consistent with a decrease in the capacity of the C4 cycle in high light. PEPC 
      exerted appreciable control on photosynthetic flux in the wild-type, with a 
      relatively high flux control coefficient of 0.35 in saturating light and ambient 
      CO2. The flux control coefficient was decreased in low light or increased in low 
      CO2 or in plants containing lower PEPC activity. However, the rate of CO2 
      assimilation decreased down to about 55% PEPC, followed by an up-turn in the 
      light-saturated photosynthetic rate as PEPC was further reduced, suggesting the 
      existence of a mechanism that compensates for the loss of PEPC activity. The 
      amounts of photosynthetic metabolites, including glycine and serine, also showed 
      a biphasic response to decreasing PEPC. There was a linear relationship between 
      the activity of PEPC and the activation state of the enzyme. A possible mechanism 
      of compensation involving photorespiratory intermediates is discussed.
FAU - Bailey, K J
AU  - Bailey KJ
AD  - Robert Hill Institute, University of Sheffield, UK.
FAU - Battistelli, A
AU  - Battistelli A
FAU - Dever, L V
AU  - Dever LV
FAU - Lea, P J
AU  - Lea PJ
FAU - Leegood, R C
AU  - Leegood RC
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - J Exp Bot
JT  - Journal of experimental botany
JID - 9882906
RN  - 142M471B3J (Carbon Dioxide)
RN  - EC 4.1.1.31 (Phosphoenolpyruvate Carboxylase)
SB  - IM
MH  - Carbon Dioxide/*metabolism
MH  - Crosses, Genetic
MH  - Electrophoresis, Polyacrylamide Gel
MH  - Immunoblotting
MH  - Magnoliopsida/enzymology/genetics/*physiology
MH  - Phosphoenolpyruvate Carboxylase/*metabolism
MH  - Photosynthesis/*physiology
MH  - Plants, Genetically Modified/genetics/physiology
EDAT- 2000/08/12 11:00
MHDA- 2000/09/09 11:01
CRDT- 2000/08/12 11:00
PHST- 2000/08/12 11:00 [pubmed]
PHST- 2000/09/09 11:01 [medline]
PHST- 2000/08/12 11:00 [entrez]
AID - 10.1093/jexbot/51.suppl_1.339 [doi]
PST - ppublish
SO  - J Exp Bot. 2000 Feb;51 Spec No:339-46. doi: 10.1093/jexbot/51.suppl_1.339.