Plant Signal Transduction and Development

Telephone: (919) 962-5699 (Office);
(919) 962-2161 (Lab)

E-mail: jreed@email.unc.edu

Office: 104 Coker Hall

Mailing Address:
CB# 3280, Coker Hall
The University of North Carolina at Chapel Hill
Chapel Hill, North Carolina 27599-3280

Selected References

Most plant development occurs post-embryonically, and is tied closely to environmental signals. We use techniques of genetics, molecular biology, microscopy, physiology, and biochemistry to study how environmental and endogenous signals regulate plant development. For these studies we use the model plant Arabidopsis thaliana, which has numerous technical advantages (including a completely sequenced genome) that allow rapid experimental progress. We hope in the long run to reconstruct how endogenous developmental programs and exogenous signals cooperate to determine plant form.

We currently focus on how the plant hormone auxin regulates development. Auxin regulates multiple cellular and developmental responses in plants, largely by regulating gene expression. A family of proteins called ARFs (Auxin Response Factors) bind to promoters of auxin-responsive genes and regulate their expression, and proteins of a second family called Aux/IAA can dimerize with ARFs and also thereby affect gene expression. To reveal the roles of these proteins in development, we are characterizing phenotypes of plants with mutations in genes encoding ARF and Aux/IAA proteins. Mutations in different ARF and IAA genes affect various aspects of development, including embryonic patterning, seedling growth, and flower maturation. We are also using these mutants in global gene expression studies to identify regulatory targets of ARF and Aux/IAA proteins, and studying functions of these target genes by reverse genetic methods. To understand the biochemistry of auxin signaling pathways, we are studying interactions among Aux/IAA and ARF proteins, and their modification and stability in plant extracts under different conditions. Several arf and iaa mutants have altered light responses, and we are exploring how light signals modulate auxin signaling.

Auxin and other growth regulators must ultimately affect cell biological processes such as division and expansion. We are also studying potassium transporters of the KT/KUP/HAK family which appear to modulate cell expansion. A mutation in the KUP2 gene of this family decreases cell expansion in several tissues, and we are attempting to understand the developmental functions of KUP2 and other members of this family as well as the biochemical mechanisms by which they transport ions.