Characterization of abiotic stress-responsive <Emphasis Type="Italic">Arabidopsis thaliana RD29A</Emphasis> and <Emphasis Type="Italic">RD29B</Emphasis> genes and evaluation of transgenes |
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Authors: | Joseph Msanne Jiusheng Lin Julie M Stone Tala Awada |
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Institution: | (1) School of Natural Resources, University of Nebraska-Lincoln, 3310 Holdrege Street, Lincoln, NE 68583, USA;(2) Department of Biochemistry, University of Nebraska-Lincoln, 1901 Vine Street, Lincoln, NE 68588, USA; |
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Abstract: | 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. |
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