特定化合物同位素分析技术在树木非结构性碳水化合物研究中的应用

特定化合物同位素分析(CSIA)可以实现对复杂基质中特定化合物稳定碳同位素组成(δ¹³C)的精确测定。应用此方法测定树木非结构性碳水化合物(NSC)中特定成分(如糖类、有机酸和糖醇)的δ¹³C,不仅能够追踪新同化的光合产物在树木中的运移及与外界的碳交换,还能够更敏感地指示树木生理状况对环境变化的响应。本文首先系统介绍了CSIA从样品采集、处理到δ¹³C测定的方法,然后综述了树木NSC中各成分之间及各成分在不同器官之间的δ¹³C差异,阐述了树木NSC的δ¹³C时间动态变化特征及内在机制,最后分析了NSC作为主要呼吸底物,其δ¹³C与树木呼吸释放CO₂的δ¹³C(δ¹³C_R)之间的联系,并针对CSIA分析技术在后光合分馏、树木逆境生理和年轮δ¹³C形成机制等研究的应用前景提出了展望。

Applications of compound-specific isotope analysis in tree non-structural carbohydrates research: A review.

Compound-specific isotope analysis (CSIA) can precisely determine the carbon isotopic composition (δ¹³C) of specific compounds in a complex substrate. The δ¹³C values in tree non-structural carbohydrates (NSC) compounds, e.g. sugars, organic acids, and sugar alcohols, measured via CSIA could help tracing the newly assimilated photosynthate during carbon transfer and exchange with atmosphere. Further, they can act as sensitive indicators of the physiological response of trees to environmental change. In this review, we first systematically introduced the methods of CSIA with respect to sampling, purification, and analysis. Then, compound-specific δ¹³C difference among different NSCs and across tree carbon pools, as well as temporal pattern and mechanism underlying the variation of δ¹³C were described. Finally, we discussed the interaction between δ¹³C in tree NSCs, the main substrates of respiration, and respired CO₂(δ¹³C_R). Further studies on the post-photosynthetic discrimination, tree stress physiology, and tree-ring δ¹³C formation with the promising applications of CISA were suggested.