Tissue-specific and pathogen-induced regulation of a Nicotiana plumbaginifolia beta-1,3-glucanase gene.

Abstract

The Nicotiana plumbaginifolia gnl gene encoding a 8-1,3-glucanase isoform has been characterired. The gnl product represents an isoform distinct from the previously identified tobacco 8-1,3-glucanases. By expressing gnl in Escherichia coli, we have determined directly that the encoded protein does, indeed, correspond to a &1,3-glucanase. In N. plumbaginifolia, gnl was found to be expressed in roots and older leaves. Transgenic tobacco plants containing the 5'-noncoding region of gnl fused to the 8-glucuronidase (GUS) repotter gene also showed maximum levels of GUS activity in roots and older leaves. No detectable activity was present in the upper part of the transgenic plants with the exception of stem cells at the bases of emerging shoots. The expression conferred by the gnl promoter was differentially induced in response to specific plant stress treatments. Studies of three plant-bacteria interactions showed high levels of GUS activity when infection resulted in a hypersensitive reaction. lncreased gene expression was confined to cells surrounding the necrotic lesions. The observed expression pattern suggests that the characterized ,í3-1,3-glucanase plays a role both in plant development and in the defense response against pathogen infection.

Developmental, hormonal, and pathogenesis-related regulation of the tobacco class I β-1,3-glucanase B promoter

“…Reporter gene studies have led to similar conclusions for the Nicotiana plumbaginifolia gnl gene [4], and a tobacco gene encoding an extracellular class II /3-1,3-glucanase [39] that differ in regulation from the class I gene described here.…”

Tomato Polyphenol Oxidase (Differential Response of the Polyphenol Oxidase F Promoter to Injuries and Wound Signals)

“…Severa1 physiological and biochemical effects of exogenously applied SA are known, including induction of SAR against a range of pathogens, which may be mediated through induction of defense-related proteins (Castresana et al, 1990;Enyedi et al, 1992;Lyon et al, 1995). Our results suggest that, although PPO is SA-responsive, SA is not likely to be the signal mediating the induction observed in a compatible interaction with either A. solani or P. syringae.…”

Molecular biology of somatic embryogenesis in conifers

“…A more direct role in flower, pollen and embryo development and in seed germination has been suggested for PR-like proteins (Bucciaglia and Smith, 1994;Castresana et at., 1990;de Jong et at., 1992;Fincher, 1989;Hird et at., 1993;Meeks-Wagner et at., 1989;Neale et at., 1990). An extracellular glycosylated 32 kDa protein secreted into culture medium of carrot embryos was found to be a homologue of plant acidic chitinase, which permits the completion of carrot somatic embryo development in the mutant phenotype tsll at nonpermissive temperature (de Jong et ai., 1992(de Jong et ai., , 1995.…”