Molecular Cloning of Osmotin and Regulation of Its Expression by ABA and Adaptation to Low Water Potential

Abstract

In response to adaptation to NaCI, cultured tobacco cells (Nicotiana tabacum L. cv Wisconsin 38) synthesize a major 26 kilodalton protein which has been named osmotin due to its induction by low water potentials. To help characterize the expression of osmotin in adapted cells, a cDNA clone for osmotin has been isolated. Abscisic acid induces messenger RNA encoding osmotin. Levels of this mRNA in adapted cells are approximately 15-fold higher than in unadapted cells. Message for osmotin is present at constant levels through the growth cycle of adapted cells, while in unadapted cells, the level decreases during exponential phase of growth and increases again when the cells approach stationary phase. While abscisic acid induces the message for osmotin, a low water potential environment appears to be required for accumulation of the protein. An osmotin mRNA, a low water potential environment is required for preferential translation of osmotin mRNA or to reduce osmotin turnover (21).We report here the isolation of a cDNA clone encoding osmotin. We confirm the hypothesis that ABA induces transcription or stabilization of osmotin mRNA. We also confirm that some posttranscriptional event allows the enhanced accumulation of osmotin after adaptation to osmotic stress. We show that the stable altered expression of osmotin is not related to gene amplification or rearrangement and compare the complete amino acid sequence of osmotin with four other homologous proteins.

Colonization of the Arabidopsis rhizosphere by fluorescent Pseudomonas spp. activates a root-specific, ethylene-responsive PR-5 gene in the vascular bundle

“…The alignment shows the amino acid sequences of several PR-5 type proteins. Sequences are from Arabidopsis AtTLP1 (AGI number At4g24180), Arabidopsis AtPR-5 (AGI number At1g75040; Uknes et al (1992)), Arabidopsis AtTLI (AGI number At4g38660), tobacco NtOsmotin (GeneBank accession number X95308; Singh et al (1989)), and LePR-5x (GeneBank accession number AAM23272; Rep et al (2002)). Numbers above the alignments correspond to amino acid positions in AtTLP1.…”

“…Three Arabidopsis proteins that have a central hydrophobic region and a C-terminal protein kinase domain characteristic of receptor protein kinases group together based on their PR-5 core sequence. Published sequences are referred to by protein names: PR-5 (Uknes et al, 1992), PR-5K , OSM34 (Capelli et al, 1997), LP-1 (Hu and Reddy, 1995), LP-3 (Hu and Reddy, 1997) from Arabidopsis; Olp1 (Chen et al, 1996), NP24 (King et al, 1988), AP24 (Ruiz-Medrano et al, 1992) and PR-5x (Rep et al, 2002) from tomato; Osmotin (Singh et al, 1989), SE39b (Kuboyama et al, 1997), PR-R1 (Payne et al, 1988), and PR-R2 (Cornelissen et al, 1986) from tobacco; Zeamatin (Richardson et al, 1987) from maize; PpAZ44 (Ruperti et al, 2002) from peach; MdPR-5a (Oh et al, 2000) from apple; VvTL1 (Tattersall et al, 1997) from grape. All sequence names are preceded by species abbreviations (At: Arabidopsis, Le: tomato, Md: apple, Nt: tobacco, Pp: peach, Vv: grape, Zm: maize).…”

“…Comparison of the predicted amino acid sequence with sequences in the databank revealed that it shares highest homology with the predicted amino acid sequence of the thaumatin-like isolog gene AtTLI (At4g38660; 70% identity) ( Figure 5). AtTLP1 shares 56% identity at the amino acid level with the previously identified Arabidopsis AtPR-5 protein that is associated with SAR (Uknes et al, 1992), and is homologous to other proteins belonging to the PR-5 family, including tobacco NtOsmotin (Singh et al, 1989) (40% identity) and the tomato LePR-5x protein (39% identity), which was found to accumulate in the xylem sap of F. oxysporum-infected tomato plants (Rep et al, 2002). The homology with the previously characterized PR-5 type proteins NtOsmotin and LePR5x is relatively low.…”

Activation of Two Osmotin-Like Protein Genes by Abiotic Stimuli and Fungal Pathogen in Transgenic Potato Plants

“…Among stress proteins are osmotin and osmotin-like proteins that have also been classified as members of plant PR type-5 proteins (Singh et al, 1989;BOI et al, 1990;Zhu et al, 1993Zhu et al, , 1995. It has been demonstrated that tobacco osmotin gene expression is activated by ABA, NaC1, wounding, vira1 infection, and ethylene (LaRosa et al, 1992;Nelson et al, 1992).…”

Cloning of cDNAs for genes that are specifically or preferentially expressed during the development of tobacco genetic tumors

“…The sequence of TIDO-2 appeared to be a counterpart of the gene for glucan endo-l,3-~-glucosidase that was isolated from N. tabacum (92% identity at the amino acid level; Shinshi et a/., 1988). TID23, TID44, TID89, TID91, TID481 and TID853 seemed to be related to a 14 kDa protein of carrot (Aleith and Richter, 1990, unpublished; EMBL accession number X15436), wound-induced proteinase inhibitor I of tomato (Wingate etal., 1989), pathogenesis-related (PR) protein 1 a from tobacco (Cornelissen et a/., 1986b), miraculin from miracle fruit (Theerasilp et a/., 1989), osmotin (Singh et a/., 1989) and the basic form of PR-1 (Payne et a/., 1989), respectively. TID301 was 30% identical at the amino acid level to the gene for the major allergenic protein, Lo/ pl, of rye grass pollen (Griffith etal., 1991).…”