Labelling plants with radioactive 11CO2 for noninvasive 3D imaging with PET

Abstract

Plant carbon dioxide fixation and subsequent photoassimilates allocation are fundamentally important for survival, growth and yield of plants. Since carbon distribution in a plant is highly dynamic its investigation is a unique challenge. Radiotracers, such as radioactive carbon dioxide 11CO2 can be administered to a leaf or canopy for tracing photoassimilate distribution within a plant. The 3D distribution of the 11C tracer can be monitored with a positron emission tomograph (PET) in order to obtain carbon transport parameters for functional phenotyping. For labelling plants we established a gas exchange system for both measuring gas exchange of leaves and administering 11CO2 to the plant. Handling the radioactive carbon dioxide safely requires special precautions which are implemented in the system. Here, we present results of the first gas exchange measurements of pea (Pisum sativum) under drought stress as well as images of 11C allocation into the root measured with the PET system ‘PlanTIS’. For an improved 3D visualization of 11C transport a new PET system (phenoPET) was constructed, which is currently under evaluation. First experimental results on plants with both phenoPET and the gas exchange system are expected by mid of 2016. In future, it is planned to automatize plant transport, labeling and tracer measurement. All installations combined will facilitate dynamic monitoring and quantification of carbon assimilation with regards to different phenotypes and under controlled environmental conditions