Analysis of Arabidopsis with Highly Reduced Levels of Malate and Fumarate Sheds Light on the Role of These Organic Acids as Storage Carbon Molecules1[W]
Analysis of Arabidopsis with Highly Reduced Levels of Malate and Fumarate Sheds Light on the Role of These Organic Acids as Storage Carbon Molecules1[W]
复制标题
对苹果酸和富马酸水平高度降低的拟南芥的分析揭示了这些有机酸作为储存碳分子的作用1[W]
作者：
Martina B. Zell;Holger Fahnenstich;Alexander Maier;M. Saigo;E. Voznesenskaya;G. Edwards;C. Andreo;F. Schleifenbaum;C. Zell;M. Drincovich;V. Maurino
虽然苹果酸和富马酸参与了植物代谢的多种途径，但这些有机酸在C3植物中作为碳库的功能尚未得到深入研究。本文以高表达玉米(Zea Mays)胞质NADP-苹果酸酶(Mem)植物为材料，分析了持续低苹果酸和富马酸水平对C3植物生理的影响。短日(SD)生长时，Mem植株表现为淡绿色，生物量减少，比叶面积增加，叶片较薄，光合作用表现较差。这些特征在长时间生长的植物中是不存在的。对转基因植株花环代谢物水平的分析表明，在SD和长日照下都存在类似的干扰，苹果酸和富马酸的水平非常低。夜间结束时对呼吸商的测定表明，野生植物呼吸的主要底物从碳水化合物转变为有机酸，而Mem植物使用更多的还原化合物，如脂肪酸和蛋白质，以促进呼吸。结论是，在SD Mem植物中观察到的变化是长时间黑暗期间碳骨架供应受损的结果。在夜间观察到的这种碳饥饿表型证明了C4酸的生理作用，这可能是植物的一种结构性功能。
While malate and fumarate participate in a multiplicity of pathways in plant metabolism, the function of these organic acids as carbon stores in C3 plants has not been deeply addressed. Here, Arabidopsis (Arabidopsis thaliana) plants overexpressing a maize (Zea mays) plastidic NADP-malic enzyme (MEm plants) were used to analyze the consequences of sustained low malate and fumarate levels on the physiology of this C3 plant. When grown in short days (sd), MEm plants developed a pale-green phenotype with decreased biomass and increased specific leaf area, with thin leaves having lower photosynthetic performance. These features were absent in plants growing in long days. The analysis of metabolite levels of rosettes from transgenic plants indicated similar disturbances in both sd and long days, with very low levels of malate and fumarate. Determinations of the respiratory quotient by the end of the night indicated a shift from carbohydrates to organic acids as the main substrates for respiration in the wild type, while MEm plants use more reduced compounds, like fatty acids and proteins, to fuel respiration. It is concluded that the alterations observed in sd MEm plants are a consequence of impairment in the supply of carbon skeletons during a long dark period. This carbon starvation phenotype observed at the end of the night demonstrates a physiological role of the C4 acids, which may be a constitutive function in plants.