Smit Martin F, van Heerden Philippus D R, Pienaar Jakobus J, Weissflog Ludwig, Strasser Reto J, Krüger Gert H J
School of Environmental Sciences and Development, Potchefstroom Campus, North-West University, Potchefstroom 2520, North-West Province, South Africa.
Plant Physiol Biochem. 2009 Jul;47(7):623-34. doi: 10.1016/j.plaphy.2009.02.003. Epub 2009 Feb 21.
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.
本研究的目的是量化污染物三氟乙酸（TFA）对菜豆（C3植物）和玉米（C4植物）生长及光合作用的影响，以阐明其抑制作用的生理生化基础。在全株研究中，在添加浓度范围为0.625至160mg l-1的NaTFA的水培系统中培养的植物，在14天内同时测量光合气体交换、快速相荧光动力学和Rubisco活性。尽管在实验早期低TFA浓度下观察到一些光合参数的初始刺激，但在较高浓度下出现了明显的抑制。总体而言，玉米比菜豆受到的影响更严重，表现出TFA诱导的表观羧化效率（ACE）和体外Rubisco（核酮糖-1,5-二磷酸羧化酶/加氧酶；EC 4.1.1.39）活性大幅下降。光合气体交换分析表明，除了对叶肉过程如Rubisco活性的限制外，气孔限制也随着TFA浓度的增加而增加，尤其是在菜豆中。对快速相荧光瞬变的深入分析表明，TFA诱导了放氧复合体（OEC）的解偶联，并抑制了超过Q(a)的电子传递，包括对光系统I末端电子受体还原的可能限制。
