Carbon Isotope Fractionation in Plants: Annual Technical Progress Report

摘要

Plants fractionate carbon isotopes during photosynthesis in ways which reflect photosynthetic pathway and environment. The fractionation is product of contributions from diffusion, carboxylation and other factors which can be understood using models which have been developed in the work. The object of the work is to use this fractionation to learn about the factors which control the efficiency of photosynthesis. Unlike previous studies, the authors do not rely principally on combustion methods, but instead develop more specific methods with substantially higher resolving power. The authors have recently developed a new short-term method for studying carbon isotope fractionation which promises to provide a level of detail about temperature, species, and light intensity effects on photosynthesis which has not been available until now. The authors are studying the isotopic compositions of metabolites (particularly aspartic acid) in C sub 3 plants in order to determine the role of phosphoenolpyruvate carboxylase in C sub 3 photosynthesis. The authors are studying the relative roles of diffusion and carboxylation in nocturnal CO sub 2 fixation in CAM plants. The authors are studying the use of isotopic content as an index of water-use efficiency in C sub 3 plants. We are developing new methods for studying carbon metabolism in plants. 3 refs. (ERA citation 13:031182)