Poster: Transcription Regulation

Abs # 1060: Regulation of the expression of polyamine biosynthetic genes: arginine decarboxylase (ADC) and S-adenosylmethionine decarboxylase (SAMDC)

Presenter:	Minocha, Subhash C, sminocha@christa.unh.edu
Authors	Minocha, Subhash C (A)   Mitchell, Jeffrey J (A)   Nuzzi, Paul  (A)
Affiliations:	(A): University of New Hampshire

Polyamines (putrescine, spermidine, and spermine) are low molecular weight cations implicated in many important physiological phenomena in plants. Three enzymes, namely arginine decarboxylase (ADC), ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC), regulate the biosynthesis of polyamines in a tissue-specific manner, and in response to various environmental stimuli, including stress. In order to delineate the regulation of the expression of polyamine biosynthetic genes during development, we used the approach of promoter-reporter gene fusion. Arabidopsis thaliana plants were transformed with plasmid DNA constructs that contained the putative promoter and 5’-UTR regions from adc-2 and samdc-1 genes fused to the b-glucuronidase (GUS) reporter gene. The plants selected on hygromycin were selfed to produce T1 seeds, which produced plants (T2) that were used for analysis of GUS activity at different stages of development. The results show that SAMDC expression was stronger than ADC in most tissues of the plant at most stages of development. A strong expression of SAMDC was seen in the roots, the cotyledons, and the upper and lower thirds of the hypocotyls. The middle part of the hypocotyls showed the weakest expression. On the other hand, ADC expression was notably weaker in most parts of the plant, and was predominant in the vascular tissues.