Phenotyping plants under real world conditions is highly challenging. The Frommer lab (Stanford) developed a suite of genetically encoded biosensors that report subcellular levels of ions or metabolites (e.g. ions, sugars) or that report the activity of particular transporters with high temporal resolution. Typically, plants expressing these sensors are analyzed using fluorescence microscopy. This project will explore whether ion levels can be quantified (here the signaling intermediate calcium as a proof of concept) in specific regions of plant leaves using a remote imaging system. The Kramer lab at MSU developed a growth chamber that can mimic and replay field conditions and simultaneously phenotype photosynthetic parameters using a fluorescence imaging system. This collaboration brings together these two innovative platforms: the dynamic environmental imaging system (DEPI), and genetically encoded ultrasensitive fluorescent biosensor technology. The project aims to develop a novel system that can monitor genetically encoded sensors in intact plants with unprecedented depth and the parallel option for high throughput phenotyping of photosynthesis. The project will lay the groundwork for establishing systems and tools as community resources with the potential to transform photosynthesis research programs around the world. This high-risk project will lay the basis for phenotyping genetic variants in Arabidopsis as well as crops and expand the usefulness of genetically encoded biosensors to large scale screening. In addition, this project will train a postdoctoral scientist with experience in physical chemistry in phenotyping. The project will also train high school students and undergraduate students, and where possible minority students will be engaged in this endeavor.
Such an imaging system would present a completely novel tool for phenotyping molecular events in intact plants and thus present a new tool for screening genetic variants and to discover new biology at the whole plant level. The project will demonstrate the potential of this technology by monitoring novel ultrasensitive calcium sensors to test long-standing hypotheses regarding the role of calcium in signaling processes and the response patterns in leaves in fluctuating environmental conditions and specific signaling processes. One of the challenges is the sensitivity of the combined plant-imaging system. The Frommer lab developed novel ultrasensitive calcium sensors that will be used here and that may enable us to observe calcium dynamics over the whole growth cycle in populations of 100s of plants simultaneously. This approach, if successful, could be expanded to other fluorescent biosensors and implemented for crop plant screening. At the same time, such a system may uncover new biology in the areas of plant cell signaling and chloroplast ion dynamics.
