Generation of marker free salt tolerant transgenic plants of Arabidopsis thaliana using the gly I gene and cre gene under inducible promoters (original) (raw)
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Characterization of a T-DNA insertion mutant for NaCl-hypersensitivity in Arabidopsis thaliana
Salinity is a major abiotic stress which reduces crop productivity. Determination of the molecular components involved in salinity stress signaling and understanding the mechanisms of adaptation to salinity is essential for genetic improvement of crop plants. Forward genetics, using the model plant Arabidopsis thaliana, has been and will continue to be a powerful method to identify the determinants of salt stress adaptation. Several families of T-DNA insertional mutagenesis of Arabidopsis was generated by Agrobacterium-mediated transformation. Genetic characterization of a subset of the transformants indicates that they have in average 1.35 inserts each, as assayed by kanamycin resistance segregation. These lines have been screened under varying growth conditions for the monitoring of visible alterations (phenotype). Several putative mutants were observed, including a NaCl-hypersensitive mutant (mut-46). This mutant exhibited a salt-sensitive phenotype manifested as reduction in primary root growth, and exhibited reduced length as well as density of root hairs in the presence of NaCl. However, the phenotype of the non-stress mut-46 root hairs is similar as the WT under salt stress. The fresh weight of wild-type and mut-46 seedlings was reduced by exposure to NaCl. Western blot analysis indicated that salinity reduced the expression of actin proteins in both wild-type and mut-46 compared with control Arabidopsis seedlings.
Planta, 2011
Abiotic stresses have adverse effects on plant growth and productivity. The homologous RD29A and RD29B genes are exquisitely sensitive to various abiotic stressors. Therefore, RD29A and RD29B gene sequences have potential to confer abiotic stress resistance in crop species grown in arid and semi-arid regions. To our knowledge, no information on the physiological roles of the proteins encoded by RD29A and RD29B are available in the literature. To understand how these proteins function, we used reverse genetic approaches, including identifying rd29a and rd29b T-DNA knockout mutants, and examining the effects of complementing transgenes with the genes under control of their native promoters and chimeric genes with the native promoters swapped. Four binary vectors with the RD29A and RD29B promoters upstream of the cognate RD29A and RD29B cDNAs and as chimeric genes with noncognate promoters were used to transform rd29a and rd29b plants. Cold, drought, and salt induced both genes; the promoter of RD29A was found to be more responsive to drought and cold stresses, whereas the promoter of RD29B was highly responsive to salt stress. Morphological and physiological responses of rd29a and rd29b plants to salt stress were further investigated. Root growth, and photosynthetic properties declined significantly, while solute concentration (Ψπ), water use efficiency (WUE) and δ13C ratio increased under salt stress. Unexpectedly, the rd29a and rd29b knockout mutant lines maintained greater root growth, photosynthesis, and WUE under salt stress relative to control. We conclude that the RD29A and RD29B proteins are unlikely to serve directly as protective molecules.
Transgenic approaches to increase dehydration-stress tolerance in plants
Molecular Breeding, 1999
Plant productivity is strongly influenced by abiotic stress conditions induced by drought, high salt and low temperature. Plants respond to these conditions with an array of biochemical and physiological adaptations, at least some of which are the result of changes in gene expression. Transgenic approaches offer a powerful means of gaining valuable information to better understand the mechanisms governing stress tolerance. They also offer new opportunities to improve dehydration-stress tolerance in crops by incorporating a gene involved in stress protection into species that lack them. In this review, we discuss progress made towards understanding the molecular elements involved in dehydration-stress responses that have been used to improve salt or drought tolerance following several transgenic approaches. Further, we discuss various strategies being used to produce transgenic plants with increased tolerance to dehydration stress. These include the overproduction of enzymes responsible for biosynthesis of osmolytes, late-embryogenesis-abundant proteins and detoxification enzymes. At this time, there is a need for a careful appraisal of the genes to be selected and promoter elements to be used, because constitutive expression of these genes may not be desirable in all applications. In this context, the advantages and limitations of transgenic approaches currently being used are discussed together with the importance of using stress-inducible promoters and the introduction of multiple genes for the improvement of dehydration-stress tolerance.