Plastidic phosphate transport and plant biomass allocation

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Plastids are a defining feature of plant cells. These diverse organelles are the sites of a wide array of essential processes that include photosynthesis and the subsequent partitioning of carbon between sugars for immediate use throughout the plant, and starch for temporary storage that is reclaimed during the night. Phosphate concentrations strongly influence these processes, but understanding of the transport proteins needed to coordinate plastidic phosphate levels with environmental and metabolic conditions is incomplete. The objectives of this project are to determine the transport mechanism and physiological role of phosphate transporters that reside in either chloroplasts or non-photosynthetic plastids of the model plant Arabidopsis thaliana. Loss-of-function mutants for these transporters display unique growth and metabolic phenotypes that suggest distinct roles. Notably, a mutant for a root plastid transporter exhibits increased cell proliferation in leaves with a corresponding increase in leaf biomass. Grafting studies combined with genetic and biochemical studies will be used to test the hypothesis that carbon allocation between root and shoot tissues influences mitotic activity in leaves. This project will provide new insight into how plants integrate phosphate and carbon metabolism at the cellular level to control the physiology of photosynthetic and non-photosynthetic tissues. Moreover, these studies may have practical implications for agriculture. Graduate and undergraduate students will receive multidisciplinary research training, formal teaching opportunities, and will participate in the development and implementation of undergraduate biology education workshops.