植物叶片水平δ^(13)C与水分利用效率的研究进展

Review on carbon isotope composition(δ^(13)C) and its relationship with water use efficiency at leaf level

水分限制可能因全球气候变化加剧成为限制植物生产力的主要原因,因此,如何提高植物水分利用效率(WUE)是未来一个主要研究目标。WUE能够反映植物-土壤-大气之间的碳水循环的耦合状况,研究WUE有助于了解陆地生态系统碳水耦合机制。稳定性碳同位素技术已成为研究生态系统养分循环最有效的方法之一,也被利用到植物水分利用效率中。研究表明,植物叶片的稳定碳同位素比值(δ^(13)C)是植物长期水分利用效率(WUE)的良好指标。本文综述了δ^(13)C表征WUE的机制,植物δ^(13)C和WUE的影响因子(包括:叶片结构性状、植物生理生态、气候因子、基因控制和遗传变异),分析了水分胁迫及酸沉降条件下植物的δ^(13)C和WUE变化特征,并对全球气候变化下植物δ^(13)C和WUE的研究进行了展望。指出气孔导度、比叶面积、叶片氮含量、细胞间CO2浓度和大气CO2浓度等因子可直接或间接作用植物的光合速率和蒸腾速率,从而引起WUE的变化。一般情况下,植物在干旱条件下具有更高的WUE和更低的δ^(13)C,长期酸沉降下植物的气孔导度和光合作用均会下降,氮的输入可以通过改善水分利用效率来提高植物的生产力。建议为更清晰地认识全球气候变化,在利用稳定性同位素技术进行WUE研究过程中,需要突出数量性状基因座(QTL)、碳酸酐酶、水孔蛋白和光合羧化酶的大小亚基基因在遗传控制方面起到的关键作用,加强多时空尺度的关联研究,探索双重稳定同位素(δ^(13)C、δ18O)概念模型的应用。

Water deficiency is a major global constraint for plant productivity that is likely to be exacerbated by climate change. Hence, improving plant water use efficiency （WUE） has become a major goal in the near future. WUE reflects the coupling of carbon and water cycles in plant-soil-atmosphere continuum. Analyzing WUE can improve our understanding of the interaction between carbon and water cycles in terrestrial ecosystems. Stable carbon isotope analysis has become the most effective techniques in plant ecological research. As an indicator,foliar carbon isotope discrimination （δ^13CC） is often used to evaluate long-term WUE in C3 plants. Study of δ^13CC and WUE can help to reveal and predict the response and adaptation of forest vegetation to global climate change. In this paper, the mechanism of characterization of g＇3 C and WUE, the factors influencing plant 8~3 C and WUE, including leaf traits, plant ecophysiology, climate factors, genetic control and genetic variation were summarized. The impacts of water stress and acid deposition on plantδ^13CC and WUE were also discussed. Plant stomatal conductance, specific leaf area, leaf nitrogen content, intercellular CO2 concentration, and atmospheric CO2 concentration were proposed to be the dominant factors influencing WUE variations due to their direct or indirect effects on plant net photosynthesis and transpiration rate. Generally, plants display higher WUE and lower δ^13CC when exposed to drought stress, and lower stomatal conductance and photosynthesis under long-term acid deposition. Nitrogen input will enhance plant productivity by improving water use efficiency. We suggest that the key role of quantitative trait loci, carbonic anhydrase, aquaporins, large and small subunits gene of Rubisco in the process of WUE genetic control must be highlighted when using stable isotope technique to study plant WUE. Finally, we must strengthen the study of multiple temporal and spatial scale variation and explore the application of combing analysis of δ^C and δ^SO on the dual isotope conceptual model.