Submitted to: Applied Genomics and Proteomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2003
Publication Date: 11/1/2003
Citation: Horvath, D.P., Schaffer, R. 2003. Urg1, a conserved and previously uncharacterised gene expressed preferentially in growing shoots of arabidopsis and leafy spurge. Applied Genomics and Proteomics. 2(3):169-179. Interpretive Summary: This paper characterizes the regulation of a novel leafy spurge gene that is induced concomitantly with the induction of growth (breaking of dormancy) in its underground buds and germinating seeds, and by the plant hormone gibberellic acid. Expression of this gene was inhibited by drought stress, but not by cold stress. This gene was identified using Arabidopsis microarrays that were probed with all of the expressed genes from growing shoot apices of leafy spurge, wild oat and poplar. This suggests that there are similar genes in most (if not all) plants which are also turned on in growing tissues. A search of the GenBank database identified similar genes from other plants, animals and fungi. Nothing was previously known about the function or regulation for any of these genes in other organisms.
Technical Abstract: Recent studies have demonstrated the applicability of Arabidopsis microarrays to identify conserved and differentially-expressed genes from other plant species. One finding from these studies indicated the Arabidopsis clone designated 195F3T7 was preferentially expressed in growing shoot apices of leafy spurge, poplar and wild oat. This clone has homology to genes from mammals, worms, insects and yeast as well as to those of several plant species. However, no function has been attributed to this gene. We have used this Arabidopsis clone to study the expression pattern of its corresponding gene in leafy spurge. Clone 195F3T7 hybridizes to a small gene family in leafy spurge. One or more members of this gene family are induced preferentially in growing tissue. It is coordinately up-regulated concomitantly with the induction of S-phase of the cell cycle. Its expression is positively regulated by treatments that induce initiation of the cell cycle and growth in underground adventitious buds of leafy spurge including exogenous GA3 treatment and defoliation. It is negatively regulated by drought stress, but only marginally down-regulated by cold stress, in the shoot apices. It is not substantially induced in underground buds by loss of auxin- producing organs such as growing apices and axillary buds, but is induced by application of the polar auxin transport inhibitor NPA.