Sucrose / H+ symporters in plants for targeted biomass partitioning

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Sucrose / H+ symporters in plants for targeted biomass partitioningPlant productivity has increased dramatically over the last century due in part to breeding practices that divert resources to harvested organs. Sucrose (Suc) is produced in leaves by photosynthesis and is transported to tissues that are growing or accumulating storage reserves. Understanding Suc transport is thus essential to understanding growth and yield. Suc may move passively from cell to cell through specialized channels called plasmodesmata or may be accumulated across plasma membranes by Suc/proton (H+) symporter enzymes. Suc/H+ symporters are therefore fundamental to carbohydrate distribution and to coordinating disparate organs into a whole entity. Suc/H+ symporters form a small gene family, but the physiological functions of most members is poorly resolved. A better understanding of their function would help clarify their respective roles in whole-plant nutrient partitioning, and would enable their manipulation to target biomass to harvested organs. This project will 1) establish the capacity of representative symporters for moving Suc across membranes in whole plants by assessing their ability to complement a defined Suc-transport-defective mutant, and 2) establish the potential of ectopically expressed symporters to target carbohydrate and biomass to specific tissues to enhance plant productivity. Broader Impacts: By building on strengths established during prior support, this project will efficiently contribute to our understanding of nutrient partitioning in relation to whole-plant physiology and provide transformative strategies to increase productivity; provide interdisciplinary training for high-school, undergraduate, graduate, and postdoctoral scholars from diverse backgrounds; and engage students from at-risk groups by coordinating with organizers of the UNT FOCUS scholarship program (Fostering Outstanding Cohorts in Undergraduate Science, NSF program 07-524, Scholarships in Science, Technology, Engineering, and Mathematics [S-STEM], Project #0807128), which promotes success by fostering cohorts of science majors and promoting interaction with science mentors.