Poster: Hormones

Abs # 649: Auxin/gibberellin interaction in Arabidopsis

Presenter:	Sponsel, Valerie , vsponsel@utsa.edu
Authors	Sponsel, Valerie  (A)   Desgagne-Penix, Isabel  (A)   Ritter, Laurie  (A)   Upadhaya, Pratistha  (A)
Affiliations:	(A): University of Texas at San Antonio

The potential interaction of auxin and gibberellins (GAs) in Arabidopsis is being examined in several ways. The expression of genes encoding GA 20-oxidase enzymes has been measured in young seedlings and constituent parts of mature, wild-type plants which have been treated with auxins, auxin transport inhibitors, GAs, and GA biosynthesis inhibitors. In addition, GA 20-oxidase expression is being compared in the semi-dwarf big mutant, which has reduced auxin transport, is resistant to auxin transport inhibitors, and responds to applied C₁₉-GAs. GA 20-oxidase expression is being measured using northern blot analysis, RTPCR, and GA20ox1-GUS reporter lines (originally obtained from Drs. Peter Hedden and Andy Phillips). In addition, the distribution of auxin in similarly treated plants is being estimated using seedlings expressing DR5-GUS (originally obtained from Dr. Tom Guilfoyle). Progress in comparing auxin distribution and GA20-oxidase expression under conditions in which auxin status has been altered genetically or pharmacologically will be described. This work is supported by NSF award IBN 0080934.