Poster: Hormones

Abs # 607: Hormonal regulation of GA 3b-hydroxylase gene expression in pea fruit as measured by real-time RT-PCR

Presenter:	Reinecke, Dennis M, dennis.reinecke@ualberta.ca
Authors	Reinecke, Dennis M (A)   Ozga, Jocelyn A (A)   Yu, Jody  (A)
Affiliations:	(A): University of Alberta

To understand further how seeds, auxin (4-chloroindole-3-acetic acid [4-Cl-IAA]), and gibberellins (GAs) regulate GA biosynthesis in pea (Pisum sativum) fruit, we studied expression of the gene PsGA3ox1 that codes for the enzyme that converts GA₂₀ to biologically active GA₁ using real-time reverse transcription-polymerase chain reaction analysis. The effects of seeds and hormones on the expression of pericarp PsGA3ox1 were investigated over a 24-h treatment period. Pericarp PsGA3ox1 mRNA levels gradually increased from 2 to 3 DAA when seeds were present; however, when the seeds were removed, the pericarp transcript levels dramatically declined. When 2-DAA deseeded pericarps were treated with 4-Cl-IAA, PsGA3ox1 mRNA levels peaked 4 h after hormone treatment (270-fold increase), then decreased. PsGA3ox1 mRNA levels in deseeded pericarps treated with indole-3-acetic acid or GA₃ were the same or lower than deseeded controls. These data also show that pericarp PsGA3ox1 expression is hormonally regulated and suggest that the conversion of GA₂₀ to GA₁ occurs in the pericarp and is regulated by the presence of seeds and 4-Cl-IAA for fruit growth. Supported by NSERC grant #138166-02.