Effect of trifluoroacetate, a persistent degradation product of fluorinated hydrocarbons, on Phaseolus vulgaris and Zea mays.
The aim of this study was to quantify the effect of the pollutant, trifluoroacetate (TFA), on growth and photosynthesis of Phaseolus vulgaris (C(3)) and Zea mays (C(4)) in order to elucidate the physiological and biochemical basis of its inhibitory action. In whole plant studies, photosynthetic gas exchange, fast phase fluorescence kinetics and Rubisco activity were measured in parallel over a 14-day period in plants cultivated in a water culture system with NaTFA added at concentrations ranging from 0.625 to 160mgl(-1). Although initial stimulation of some photosynthetic parameters was observed at low TFA concentrations early on in the experiment, marked inhibition occurred at higher concentrations. In general Z. mays was affected more severely than P. vulgaris showing a large TFA-induced decrease in both apparent carboxylation efficiency (ACE) and in vitro Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase; EC 4.1.1.39) activity. Analysis of photosynthetic gas exchange revealed that besides constraints on mesophyll processes such as Rubisco activity, stomatal limitation also increased with increasing TFA concentration, especially in P. vulgaris. In depth analysis of the fast phase fluorescence transients pointed at TFA-induced uncoupling of the oxygen evolving complex (OEC) and inhibition of electron transport beyond Q(a) including possible constraints on the reduction of end electron acceptors of photosystem I.
Smit
Martin F
MF
School of Environmental Sciences and Development, Potchefstroom Campus, North-West University, Potchefstroom 2520, North-West Province, South Africa.
van Heerden
Philippus D R
PD
Pienaar
Jakobus J
JJ
Weissflog
Ludwig
L
Strasser
Reto J
RJ
Krüger
Gert H J
GH
D002245:Carbon Dioxide / Q000378:metabolism*; D004579:Electron Transport / Q000187:drug effects / Q000502:physiology; D006845:Hydrocarbons, Fluorinated / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D027805:Phaseolus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects* / Q000502:physiology; D045332:Photosystem II Protein Complex / Q000378:metabolism; D054046:Plant Stomata / Q000502:physiology*; D012273:Ribulose-Bisphosphate Carboxylase / Q000037:antagonists & inhibitors*; D014269:Trifluoroacetic Acid / Q000633:toxicity*; D003313:Zea mays / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
D006845:Hydrocarbons, Fluorinated; D045332:Photosystem II Protein Complex; D002245:Carbon Dioxide; D014269:Trifluoroacetic Acid; D012273:Ribulose-Bisphosphate Carboxylase; D010100:Oxygen