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Plants use water and the energy from sunlight to make energy-dense sugars. After production in the leaves, the sugar needs to be moved to other parts of the plant where this energy is consumed. These consuming tissues are termed 'sinks'. Analogous to our circulatory systems, plants have a network of cells called the phloem that allow the movement of sugars from source (leaves) to the sink tissues. Scientists have long sought to increase the yield of crops by regulating the movement of sugars, the theory being that if supplies are increased, yield can be increased while the input of costly and environmentally problematic fertilizers is diminished. Previous work has identified a transporter within the phloem and this proposal aims to characterize the function of this key regulator in sugar transport. Specifying how this transporter moves sugar to various tissues within the plant will allow scientists to develop strategies to optimize sugar translocation in crops that increase yield while reducing the environmental impacts of production agriculture. The Hispanic roots of the lead scientist for this project give this team an edge in engaging Hispanic audiences by communicating complex scientific topics in Spanish to ignite interest in science among the general public and among students. The scientists involved in this project will organize an international meeting on agricultural biotechnology and society, and will also develop bilingual web-based teaching tools to promote scientific literacy.

The partitioning of photoassimilates between their sites of production and utilization is a key determinant of plant growth and development. Emerging evidence suggests regulation of photoassimilate partitioning is mediated in part by a type I H+-PPase. A role for this transporter has been established at the tonoplast; however, this exclusive function has been unsettled by recent work showing plasma membrane (PM) localization of this transporter and establishing that it is prominently expressed in phloem companion cells (CC). The researchers propose this enzyme has two opposing roles, PPi hydrolysis and synthesis that contribute to a cascade of events that energize plant growth. They will test the capacity of the Arabidopsis thaliana H+-PPase to synthetize PPi in a heterologous system (Saccharomyces cerevisiae) and in plants. Concurrently, a series of genetic, immunohistochemical and physiological experiments will determine how this pump affects the partitioning of assimilates. This fundamental research will catalog that H+-PPases as a central mediator involved in the allocation and metabolism of photosynthates.



National Science Foundation, Division of Integrative Organismal Systems


March 2016 — February 2019