title: Expression of wheat Na(+)/H(+) antiporter TNHXS1 and H(+)- pyrophosphatase TVP1 genes in tobacco from a bicistronic transcriptional unit improves salt tolerance.
abstract: Abiotic stress tolerance of plants is a very complex trait and involves multiple physiological and biochemical processes. Thus, the improvement of plant stress tolerance should involve pyramiding of multiple genes. In the present study, we report the construction and application of a bicistronic system, involving the internal ribosome entry site (IRES) sequence from the 5'UTR of the heat-shock protein of tobacco gene NtHSF-1, to the improvement of salt tolerance in transgenic tobacco plants. Two genes from wheat encoding two important vacuolar ion transporters, Na(+)/H(+) antiporter (TNHXS1) and H(+)-pyrophosphatase (TVP1), were linked via IRES to generate the bicistronic construct TNHXS1-IRES-TVP1. Molecular analysis of transgenic tobacco plants revealed the correct integration of the TNHXS1-IRES-TVP1construct into tobacco genome and the production of the full-length bicistronic mRNA from the 35S promoter. Ion transport analyses with tonoplast vesicles isolated from transgenic lines confirmed that single-transgenic lines TVP1cl19 and TNHXS1cl7 had greater H(+)-PPiase and Na(+)/H(+) antiport activity, respectively, than the WT. Interestingly, the co-expression of TVP1 and TNHXS1 increased both Na(+)/H(+) antiport and H(+)-PPiase activities and induced the H(+) pumping activity of the endogenous V-ATPase. Transgenic tobacco plants expressing TNHXS1-IRES-TVP1 showed a better performance than either of the single gene-transformed lines and the wild type plants when subjected to salt treatment. In addition, the TNHXS1-IRES-TVP1 transgenic plants accumulated less Na(+) and more K(+) in their leaf tissue than did the wild type and the single gene-transformed lines. These results demonstrate that IRES system, described herein, can co-ordinate the expression of two important abiotic stress-tolerance genes and that this expression system is a valuable tool for obtaining transgenic plants with improved salt tolerance.
authors.affiliation: Laboratory of Plant Protection and Improvement, Center of Biotechnology of Sfax, University of Sfax, Route Sidi Mansour Km 6, B.P'1177', 3018 Sfax, Tunisia.
authors.forename: Sandra
authors.initials: S
authors.lastname: Gouiaa
authors.forename: Habib
authors.initials: H
authors.lastname: Khoudi
authors.forename: Eduardo O
authors.initials: EO
authors.lastname: Leidi
authors.forename: Jose M
authors.initials: JM
authors.lastname: Pardo
authors.forename: Khaled
authors.initials: K
authors.lastname: Masmoudi
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D002374:Catalase / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D002934:Cinnamates / Q000494:pharmacology; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics; D006921:Hygromycin B / Q000031:analogs & derivatives / Q000494:pharmacology; D043564:Inorganic Pyrophosphatase / Q000235:genetics*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified; D011188:Potassium / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D055049:Salt Tolerance / Q000187:drug effects / Q000235:genetics*; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics*; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D014026:Nicotiana / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D014158:Transcription, Genetic / Q000187:drug effects; D014908:Triticum / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D014617:Vacuoles / Q000187:drug effects / Q000201:enzymology
chemical_list: D002934:Cinnamates; D018076:DNA, Complementary; D010940:Plant Proteins; D017923:Sodium-Hydrogen Exchangers; D002734:Chlorophyll; D006921:Hygromycin B; C026273:hygromycin A; D012965:Sodium Chloride; D012964:Sodium; D002374:Catalase; D043564:Inorganic Pyrophosphatase; D011188:Potassium