Collaborative Research: Light Enhanced 13C Enrichment of Dark Respired CO2: Implications for Leaf Internal CO2 Conductance and Respiration in the Light

限制光合作用吸收CO2的叶片内部阻力影响作物和其他植物利用水和肥料的效率。 这种效率也受到光合作用和呼吸作用如何通过共享反应物和产物相互作用的影响。 该项目将通过分析叶片如何区别使用CO2中碳的重同位素和轻同位素来研究叶片中CO2扩散的阻力以及光合作用和呼吸作用之间的相互作用，随着可调谐二极管激光光谱仪（TDL）的发展，这项任务变得更容易，更快，更便宜。 最近的发现表明，在黑暗时期之前立即向叶子提供高强度的光可以对黑暗期间的同位素交换产生很大的影响。 这意味着磷酸烯醇式丙酮酸羧化酶（PEPC）的作用比预期的更大，这可能会影响用于测量内部叶片对CO2扩散的阻力以及光合作用和呼吸作用之间的相互作用的同位素数据的解释。 将沿着分析木本和草本植物碳同位素利用的每日和季节变化以及含有大量PEPC的植物。这项研究将有助于确定PEPC在控制植物的同位素使用及其对光合和呼吸interactions.broader影响的作用：除了潜在的作物改良，增加了解叶片内的同位素交换将完善用于了解生态系统代谢的基本假设，并产生所需的数据来模拟区域碳循环。 TDL是直接和廉价的使用，使其成为理想的课堂教育和实验室培训的研究生和本科生在新墨西哥州大学（少数民族服务机构，UNM生物学的1300个专业中有36%是西班牙裔，另外7%是美洲土著）和波特兰州立大学（许多学生是家庭中第一个上大学的成员，或者是非传统的重返校园的学生）。 使用这种设备的经验将有助于学生为大学，国家实验室和私营部门的研究事业做好准备。

The resistances inside leaves that restrict the uptake of CO2 by photosynthesis impact how efficiently crops and other plants use water and fertilizers. This efficiency is also impacted by how photosynthesis and respiration interact through sharing of reactants and products. This project will examine the resistances to CO2 diffusion in leaves and interactions between photosynthesis and respiration through analyses of how leaves differentially use heavy and light isotopes of carbon in CO2, a task that has become easier, faster, and less expensive with the development of a new technology - the tunable diode laser spectrometer (TDL). Recent discoveries suggest that providing high light intensities to a leaf immediately preceding a dark period can have a large effect on the exchange of isotopes during darkness. This implies a larger role of the enzyme phosphoenolpyruvate carboxylase (PEPC) than is expected and this could impact interpretation of isotopic data used to measure internal leaf resistance to CO2 diffusion and interactions between photosynthesis and respiration. Daily and seasonal variation in carbon isotope usage by woody and herbaceous species will be analyzed along with plants containing high amounts of PEPC. This study will help to define the role of PEPC in controlling isotopic usage by plants and its influence on photosynthetic and respiratory interactions.Broader impacts: In addition to potential crop improvements, increases in understanding of isotopic exchange within leaves will refine the fundamental assumptions used to understand ecosystem metabolism and generate data needed to model regional carbon cycles. The TDL is straightforward and inexpensive to use making it ideal for classroom education and laboratory training of graduate and undergraduate students at the University of New Mexico (a Minority Serving Institution where 36% of UNM Biology's 1300 majors are Hispanic and another 7% are Native American) and at Portland State University (where many students are the first member of their family to attend college or are non-traditional re-entry students). Experience with this equipment will help prepare students for research careers at universities, national labs, and in the private sector.