Poster: Intracellular Signaling

Abs # 818: Analysis of Inositol 5-Phosphatase gene expression in Arabidopsis thaliana

Presenter:	Gunesekera, Bhadra M, bgunesek@vt.edu
Authors	Gunesekera, Bhadra M (A)   burnette, Ryan  (A)   Gillaspy, Glenda  (A)
Affiliations:	(A): Department of Biochemistry ,Virginia Tech

Inositol 5-Phosphatases (5PTases) are thought to terminate signal transduction events in animal, yeast and plant cells. Yeast contains 4 5PTase genes, whereas animals contain >30. The At5PTase gene family of Arabidopsis consists of 15 genes. To understand whether the multiplicity of At5PTase genes is required for signal termination within different tissues, we analyzed the expression patterns of all 15 At5PTase genes using RT- PCR analysis. We found that, expression of these genes was not restricted to certain tissues. At5PTase4, 8 and 9 are detected only in roots and seedlings. In contrast, At5PTase1,2,3,5,6,7,10,12,13,14, and15 are expressed at a similar level in leaves, roots, bolts, flowers and seedlings. At5PTase11 transcript is not detected in root tissue, but is expressed in all other tissues tested. We conclude that restriction of expression does not account for the multiplicity of At5PTase genes. The presence of putative regulatory elements in all 15 gene promoters suggested that signaling may regulate expression of At5PTases. To test this, we examined expression of all 15 At5PTase genes in seedlings stimulated by light or abscisic acid (ABA) for various times. Preliminary RT-PCR results show that all 15 At5PTases are detected at a low level in dark-grown seedlings. Upon light treatment, expression of a subset of At5PTase transcripts is transiently up-regulated with different kinetics. Similar results were observed with ABA. We conclude that light and ABA signaling regulate specific subsets of these signal terminator genes. These findings indicate that the multiplicity of At5PTase genes may reflect the function of individual genes in different signaling pathways.