植物呼吸释放CO2碳同位素变化研究进展

摘要

Stable carbon isotopes have become an important tool to advance our understanding of carbon cycle processes.The carbon isotope signature of plant-respired CO2 (δ13 CR) is widely used for disentangling key physiological processes,carbon allocation,and responses to changing environmental conditions.In this review,we summarize short-term dynamics of δ13CR.Plant organs differ in both their δ13CRvalues and the magnitude of their diel variation:leaf ＞ root ＞ trunk and stem.Plant functional types differ in the magnitude of the diurnal shift in δ13CR.The correlation between the diel variation of δ13 CR and the isotopic signature of the substrate is not consistent across various studies.The isotopic signature of respired CO2 is determined by the isotope effects of photosynthetic carbon assimilation,respiratory substrate availability,the utilization of respiratory intermediates,and respiratory enzymes in connection with different carbon metabolic pathways,light enhanced dark respiration (LEDR),species-specific genetic characteristics,and changes in environmental factors.Despite recent advances in the understanding of the potential mechanisms driving short-term variation in plant δ13 CR,more research is required to unravel the underlying respiratory metabolic mechanisms.Stable isotope techniques have been employed in various ecological and environmental studies in China.However,not much work has been done in the field of plant δ3CR and its physiological mechanisms.We hope this review will strength our understanding of the recent advances in plant δ13CR research and promote the progress of in-depth research on plant respiratory metabolism in China.%稳定性碳同位素是研究碳循环的有效手段.植物呼吸释放CO2的碳同位素(δ13CR)变化是研究植物或生态系统与大气碳交换的重要方法,并可以揭示植物的生理过程、碳分配方式及其对环境变化的响应.介绍了目前国内外关于植物δ13CR变化的研究概况,植物不同器官δ13CR值及其日变化幅度趋势一致:叶片＞根系＞树干/茎,不同功能群植物其呼吸释放CO2碳同位素组成存在差异.但植物δ13CR值日变化与呼吸底物的相关性在不同的研究中结果并不一致.导致植物呼吸δ13CR发生变化的主要原因为光合同位素效应、呼吸底物的供给及呼吸代谢中间产物利用、碳代谢相关酶的活性、LEDR(light enhanced dark respiration)、植物的遗传特性及外部环境改变.目前国际上已有较多关于导致植物呼吸δ13CR发生变化原因的研究,但内在机制的研究尚未完善.该领域研究在国内鲜有报道,因此,亟需加强我国关于植物δ13CR短期变化及其潜在呼吸代谢机制的研究.