Overexpression of the Tobacco Tsi1 Gene Encoding an EREBP/AP2-Type Transcription Factor Enhances Resistance against Pathogen Attack and Osmotic Stress in Tobacco

Abstract

Using mRNA differential display analysis, we isolated a salt-induced transcript that showed a significant sequence homology with an EREBP/AP2 DNA binding motif from oilseed rape plants. With this cDNA fragment as a probe, cDNA clone Tsi1 (for Tobacco stress-induced gene1 ) was isolated from a tobacco cDNA library. RNA gel blot analysis indicated that transcripts homologous with Tsi1 were induced not only in NaCl-treated leaves but also in leaves treated with ethephon or salicylic acid. Transient expression analysis using a Tsi1 :: smGFP fusion gene in BY-2 cells indicated that the Tsi1 protein was targeted to the nucleus. Fusion protein of Tsi1 with GAL4 DNA binding domain strongly activated transcription in yeast, and the transactivating activity was localized to the 13 C-terminal amino acids of Tsi1. Electrophoretic mobility shift assays revealed that Tsi1 could bind specifically to the GCC and the DRE/CRT sequences, although the binding activity to the former was stronger than that to the latter. Furthermore, Agrobacteriummediated transient expression and transgenic plants expressing Tsi1 demonstrated that overexpression of the Tsi1 gene induced expression of several pathogenesis-related genes under normal conditions, resulting in improved tolerance to salt and pathogens. These results suggest that Tsi1 might be involved as a positive trans -acting factor in two separate signal transduction pathways under abiotic and biotic stress. INTRODUCTIONPlants respond to adverse environmental stress and pathogen attack by expressing specific genes and synthesizing a large number of stress proteins that have putative roles in stress adaptation and plant defense (Skriver and Mundy, 1990;Reymond and Farmer, 1998). The signals that mediate systemic responses must be transmitted rapidly throughout the plant and may involve cell-to-cell signaling. Putative systemic signals include ethylene (Ecker and Davis, 1987), salicylic acid (Durner et al., 1997), jasmonic acid (Farmer and Ryan, 1990), and abscisic acid (Zeevaart and Creelman, 1988). Communication between these plant hormones might modulate the expression of abiotic and biotic stress-responsive genes in plants. However, the interactions between these hormone-mediated signal pathways and molecular mechanisms governing their cross-regulation have remained generally unresolved.Ethylene is a phytohormone that affects virtually all stages of plant development, including seed germination, cell elongation, cell fate, fruit ripening, senescence, and abscission.Ethylene also is a key regulator that mediates a plant's response to biotic and abiotic stresses (O'Donnell et al., 1996; Lund et al., 1998). Both ethylene and salicylic acid, a plant defense signal, accumulate in plants during pathogen infection (Penninckx et al., 1996). Among the different classes of ethylene-responsive genes, the most extensively studied are those activated by ethylene in response to pathogen attack. This class includes basic chitinase, ␤ -1,3-glucanases, defensins, and other pathogenesis-related (PR)...

Analysis of mRNA Levels of Ten Genes Under Water Stress in Triticum turgidum subsp. durum

“…These divergent results could be explained by differences of stress response in the plant tissue studied, the specific stress condition or even the species studied. In other studies, some members of ERF respond to abiotic stresses, such as drought and high salinity (Fujimoto et al, 2000;Park et al, 2001), and can confer tolerance to these stresses by overexpression in transgenic plants (Park et al, 2001). …”

Tomato TERF1 modulates ethylene response and enhances osmotic stress tolerance by activating expression of downstream genes

“…There is evidence that ERF proteins, such as CBF1, Tsi1 and DREB proteins, can bind to DRE [15,21,22]. In order to test whether TERF1 interacts with DRE, we tested the binding affinity of TERF1 with DRE using an electrophoresis mobility shift assay.…”

“…Tomato Pti4 can mediate cross-talk between SA and ethylene/JA pathways and regulate defense-related gene expression via GCC box and non-GCC box genes [12,14]. Overexpression of tobacco Tsi1 results in improved tolerance to salt and resistance to pathogen, suggesting that Tsi1 might be involved in two separate signal transduction pathways under abiotic and biotic stress [15]. In this paper, we report a novel member of ERF proteins from tomato that we designated tomato ethylene responsive factor 1 (TERF1), since it was found to bind to the ethylene responsive element GCC box.…”

Overexpressing a NAM, ATAF, and CUC (NAC) transcription factor enhances drought resistance and salt tolerance in rice

“…Two well characterized dehydration stress-related cis-elements bound by transcription factors are the drought-responsible element (DRE) recognized by DREB or CBF transcription factors (15) and the abscisic acid (ABA)-responsive element (ABRE) recognized by bZIP domain transcription factors (16)(17)(18). Numerous reports suggest that overexpression of some stress-inducible transcription factors, such as DREB1A (19), CBF4 (20), SCOF (21), Tsi (22), and OSISAP1 (14), can increase the tolerance to drought, salinity, or low temperature in Arabidopsis or other plant species.…”