Date of Award


Degree Type


Degree Name

Master of Science (MS)


Horticulture and Landscape Architecture

First Advisor

Angus S. Murphy

Committee Chair

Angus S. Murphy

Committee Member 1

Peter M. Hirst

Committee Member 2

Gurmukh S. Johal

Committee Member 3

Wendy A. Peer


The plant hormone auxin is a primary regulator of plant growth and development that influences cell division, expansion and elongation, plant patterning and tropic responses. Polar flows generated by cell to cell gradients are essential to auxin action, and these are amplified by asymmetric placement of PIN-FORMED (PIN) auxin efflux carriers on the plasma membrane. In Arabidopsis, five plasma membrane members of the PIN family (PIN1, 2, 3, 4, 7) members exhibit overlapping roles in plant root development. Of these, PIN1 is the most prominent member, as it is required for auxin - mediated shoot organogenesis and phyllotactic patterning. In this thesis, the impact of PIN1 expression in specific cell layers is explored to determine where localized auxin streams directed by PIN1 are essential. Growth phenotypes and localization of PIN1-GFP are examined in Arabidopsis expressing PIN1 under the control of domain-specific and inducible promoters. The results shown herein demonstrate that spatial and temporal regulation of PIN1 expression are required for normal growth and that ectopic PIN1 expression negatively impacts development.