自然及模拟体系下气压对大花红景天碳同位素组成的作用机制研究

Rhodiola crenulata, mainly growth in the plateau at the altitude above 3000 m, has been used in China as an important traditional herb. In our previous study, Rhodiola crenulata could be differentiated from other species by chemical fingerprints;however,it was extremely difficult to identify the geographical origin by chemical fingerprints.The potential for classifying Rhodiola crenulata based on their geographical origin was investigated by stable carbon isotope composition. The primary results demonstrated that the value of δ13C was increased as the elevation enhanced, but the mechanism is not clear. In the present study, we intend to research the effects of air pressure on the carbon isotope composition of Rhodiola crenulata and its mechanism under natural and simulated systems.The analysis of chemical components and 13C is included to explain the correlation between the two parameters and air pressure. The 13C of polysaccharide is also to be detected in order to clarify the fractional distilation after plant photosynthesis. The change of photosynthesis and stomatal parameters is to be investigated to demonstrate the mechanism during photosynthesis procedure. The development of the project will provide a theoretical basis for the use of stable isotope to identify the provenance of medicinal plants.

大花红景天是传统中药材，生长在海拔3000m以上的高原。本课题组前期研究发现化学指纹图谱无法区分其产地，将稳定碳同位素组成分析(SCIRA)用于大花红景天来源鉴别研究时发现，大花红景天δ13C值随海拔增加而增大，但具体形成机制不明确。气压作为不同海拔下影响δ13C变化的主要因素，本研究拟在自然环境和模拟控制气压体系下，通过测定大花红景天活性成分与δ13C值随气压变化规律，研究活性成分、δ13C随气压的变化规律；比较不同器官δ13C与多糖δ13C在不同气压下的相关性，揭示光合作用后光合产物对13C的吸收和分配机制；研究不同气压下，光合作用参数（光合作用速率、气孔参数等）的变化，阐明影响光合作用过程中碳同位素分馏的机制。本项目的开展可以阐明气压对大花红景天δ13C的影响机制，该研究成果可为δ13C用于中药道地性溯源和质量控制提供基础和理论依据，且δ13C提供的生长习性有助于药用植物优化种植。

关于稳定同位素随海拔的变化规律目前存在一定的争议。本研究创新性的提出了在模拟控制体系下，通过测定植物δ13C、δ15N值，明确了碳、氮同位素组成随气压变化规律；通过比较不同器官δ13C、δ15N在不同气压下的相关性，揭示了光合作用后光合产物对δ13C、δ15N的吸收和分配机制。通过研究不同气压下植物氧化还原体系参数及营养元素的变化，阐明了气压对碳氮同位素分馏的作用机制；通过比较各参数在不同器官中的差异，揭示了δ13C、δ15N值在不同组织中分配的差异机制。研究结果显示，低压可以促进生物量的积累，鲜重和干重均得到了提高；通过对12种矿物元素的分析，显示低压促进了矿物元素的积累；低压条件下的碳稳定同位素比值显著低于常压条件。进一步分析了不同温度下碳、氮稳定同位素的组成差异，从生长发育、营养元素组成及光合作用等方面进一步探索了温度对δ13C、δ15N的影响机制，为δ13C、δ15N用于植物产品溯源和质量控制提供基础和理论依据。