Hartwell J
School of Biological Sciences, University of Liverpool, Biosciences Building, Liverpool L69 7ZB, UK.
Biochem Soc Trans. 2005 Nov;33(Pt 5):945-8. doi: 10.1042/BST20050945.
A circadian clock optimizes many aspects of plant biology relative to the light/dark cycle. One example is the circadian control of primary metabolism and CO2 fixation in plants that carry out a metabolic adaptation of photosynthesis called CAM (crassulacean acid metabolism). These plants perform primary CO2 fixation at night using the enzyme phosphoenolpyruvate carboxylase and exhibit a robust rhythm of CO2 fixation under constant conditions. Transcriptomic analysis has revealed that many genes encoding enzymes in primary metabolic pathways such as glycolysis and starch metabolism are under the control of the circadian clock in CAM plants. These transcript changes are accompanied by changes in metabolite levels associated with flux through these pathways. The molecular basis for the circadian control of CAM remains to be elucidated. Current research is focusing on the identity of the CAM central oscillator and the output pathway that links the central oscillator to the control of plant metabolism.
生物钟相对于光/暗循环优化了植物生物学的许多方面。一个例子是在进行一种称为景天酸代谢（CAM）的光合作用代谢适应的植物中，生物钟对初级代谢和二氧化碳固定的控制。这些植物在夜间使用磷酸烯醇式丙酮酸羧化酶进行初级二氧化碳固定，并在恒定条件下表现出强劲的二氧化碳固定节律。转录组分析表明，许多编码初级代谢途径（如糖酵解和淀粉代谢）中酶的基因在CAM植物中受生物钟控制。这些转录变化伴随着与这些途径通量相关的代谢物水平的变化。CAM生物钟控制的分子基础仍有待阐明。目前的研究集中在CAM中央振荡器的身份以及将中央振荡器与植物代谢控制联系起来的输出途径上。
