Woody plants provide critical sources of energy and building materials and play important roles in carbon sequestration, hydrologic cycles, and habitat assemblies. Despite the many services provided by woody plants, very little is known about how woody stems develop and how vascular connections are formed between the older woody portions of a stem and the younger, non-woody growth. The main objective of this project is to determine how movement of the plant hormone auxin controls vascular development in a woody plant using the model species Populus tremula x alba. By using a combination of chemical analyses, genetic modification and microscopy, the movement of auxin will be tracked from the young developing leaves to the woody stem below and related to the time course of vein formation. The movement of auxin will also be disrupted with chemical inhibitors in order to determine the effects of auxin transport on wood structure. This work is expected to shed light on how the vasculature -- the network of veins that supply leaves with water and distribute sugars to the rest of the plant -- is established in woody plants and how the hormone auxin determines important physical properties of the stem. In particular, liquid permeability is important for improved utilization of plant materials (e.g., wood) as well as plant survival and is determined during vascular development, a process that may be regulated by auxin flow. This project also provides multiple training opportunities for undergraduates interested the sciences both during the academic year and through summer internships. It is expected that this project will encourage ten or more undergraduates to pursue careers in science related to plant biology including forestry, carbon cycling and the development of new raw materials for biofuels.
