Developmental and pathogen-induced activation of an msr gene, str246C, from tobacco involves multiple regulatory elements

Abstract

A family of genes, the so-called msr genes (multiple stimulus response), has recently been identified on the basis of sequence homology in various plant species. Members of this gene family are thought to be regulated by a number of environmental or developmental stimuli, although it is not known whether any one member responds more specifically to one stimulus, or whether each gene member responds to various environmental stimuli. In this report, we address this question by studying the tobacco msr gene str246C. Using transgenic tobacco plants containing 2.1 kb of 5' flanking DNA sequence from the str246C gene fused to the beta-glucuronidase (GUS) coding region, the complex expression pattern of the str246C promoter has been characterized. Expression of the str246C promoter is strongly and rapidly induced by bacterial, fungal and viral infection and this induction is systemic. Elicitor preparations from phytopathogenic bacteria and fungi activate the str246C promoter to high levels, as do wounding, the application of auxin, auxin and cytokinin, salicylic acid or copper sulfate, indicating the absence of gene specialization within the msr gene family, at least for str246C. In addition, GUS activity was visualized histochemically in root meristematic tissues of tobacco seedlings and is restricted to roots and sepals of mature plants. Finally, analysis of a series of 5' deletions of the str246C promoter-GUS gene fusion in transgenic tobacco plants confirms the involvement of multiple regulatory elements. A region of 83 bp was found to be necessary for induction of promoter activity in response to Pseudomonas solanacearum, while auxin inducibility and root expression are apparently not controlled by this element, since its removal does not abolish either response. An element of the promoter with a negative effect on promoter activation by P. solanacearum was also identified.

Physiological and Molecular Characteristics of Elicitin-Induced Systemic Acquired Resistance in Tobacco

“…A similar multiple component responsiveness is discussed for the basic /3-1,3-glucanase gene of Nicotiana plumbaginifolia (Alonso et al, 1995). Recently, activation of str 246 expression in tobacco either by infection with Pseudomonas solanacearum or by treatment with auxin was correlated with multiple regulatory elements in the promoter region of this gene (Gough et al, 1995). The further dissection of promoter regions exhibiting specific responsiveness to defined stimuli will clearly help to extend our current knowledge about the regulation of gene expression during resistance induction.…”

“…To compare elicitin-dependent acquired resistance to SAR at the molecular level, induced transcript accumulation was analyzed in northern hybridization experiments using SAR gene-specific probes from tobacco. In addition, a probe for the str 246 gene, whose expression after fungal, bacterial, and viral infection was reported to be systemic (Gough et al, 1995), was included. For these experiments, stem and leaf tissues were analyzed separately after migration of elicitins via the vascular system, as was the infiltrated tissue and the zone surrounding it after infiltration of cryptogein in tobacco leaves.…”

Regulation of Sesquiterpene Cyclase Gene Expression (Characterization of an Elicitor- and Pathogen-Inducible Promoter)

“…Among these, promoters for the CHS15 gene from bean (Dron, 1988;Harrison, 1991), the PAL-l (Lois et al, 1989) and PR2 (van de Locht et al, 1990) genes from parsley, a PRlOa gene from potato (Despres et al, 1995), an IFR gene from alfalfa (Oommen et al, 1994), and the str246c (Gough et al, 1995) and several PR Eyal et a\., 1993;Shinshi et al, 1995) genes from tobacco have been examined in detail for cis-sequences controlling gene expression patterns. The CHS15 promoter, for example, contains G-and H-box elements that have been correlated with defense gene expression as well as proper developmental expression of the CHS gene in flowers and root tissues.…”

“…GST is induced by H,O, (Levine et al, 1994), PAL and other phenylpropanoid biosynthetic genes are activated by MJ (Ellard-Ivey and Douglas, 1996), and many of the PR genes are defined by their SA inducibility (Ward et al, 1991;Ryals et al, 1994 some tissues o r cell types. The IFR promoter directs strong expression i n root meristem, cortex, a n d nodules of transgenic alfalfa plants (Oommen et al, 1994), whereas the str246c promoter directs very high levels of root a n d sepal expression in transgenic plants (Gough et al, 1995). Except for a low leve1 of wound-inducible expression, we have not detected any EAS4 promoter-directed GUS expression in any plant tissues, including flowers and a11 reproductive structures (S. Yin and J. Chappell, unpublished data), throughout plant development other than in those challenged wíth elicitors or pathogens.…”

Characterization of hsr201 and hsr515, two tobacco genes preferentially expressed during the hypersensitive reaction provoked by phytopathogenic bacteria

“…The hsr (hypersensitivity-related) genes are preferentially expressed during HR. Transcripts corresponding to the str (sensitivity-related) genes accumulate strongly during interactions leading to the disease or the H R although temporal and spatial differences are detected during both types of responses [23]. One of the hsr genes, hsr203J, has been characterized and presents a novel pattern of activation [37].…”