A xenobiotic-stress-activated transcription factor and its cognate target genes are preferentially expressed in root tip meristems

Citation
S. Klinedinst et al., A xenobiotic-stress-activated transcription factor and its cognate target genes are preferentially expressed in root tip meristems, PLANT MOL B, 42(5), 2000, pp. 679-688
Citations number
39
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Plant Sciences","Animal & Plant Sciences
Journal title
PLANT MOLECULAR BIOLOGY
ISSN journal
0167-4412 → ACNP
Volume
42
Issue
5
Year of publication
2000
Pages
679 - 688
Database
ISI
SICI code
0167-4412(200003)42:5<679:AXTFAI>2.0.ZU;2-Y
Abstract
In plants, as-1-type cis elements and their trans-acting factors confer tis sue-specific and signal-responsive activities to the promoters of several g lutathione S-transferase (GST) genes. Regulation of as-1 is widely thought to involve trans-acting factors that belong to a family of basic/leucine-zi pper `TGA factors' that selectively bind this element. We have previously s hown that TGA1a, a highly conserved TGA factor of tobacco, enhances transcr iption through as-1 in response to xenobiotic-stress cues. To better unders tand the functional contribution of this transcription factor to the expres sion of as-1-regulated genes, we have studied its tissue- and cell-specific localization in tobacco seedlings. We show here that the relative amount o f TGA1a transcripts expressed in roots and shoots correlate with the as-1-r egulated, basal-level expression of a GUS transgene and two putative target GST genes. In situ hybridization of intact seedlings demonstrated that TGA 1a and these GST genes are preferentially expressed in root tip meristems. Similar findings were made with a gene-specific probe for PG13, a homologue of TGA1a, demonstrating that both factors are likely to be present in the same root meristem cells. Furthermore, TGA1a protein was immunologically de tected exclusively in the primary root and its meristem. Collectively, thes e studies suggest that TGA1a, and perhaps PG13, may contribute to the expre ssion of GST isoenzymes, especially in root tip meristems. The biological s ignificance of these observations is discussed.