Characterization of abiotic stress-responsive Arabidopsis thaliana RD29A and XXXX genes and evaluation of transgenes.

@entity48904 @entity7352 @entity72958 @entity22715
Abiotic stresses have adverse effects on plant growth and productivity. The homologous RD29A and @entity22715 genes are exquisitely sensitive to various abiotic stressors. Therefore, @entity72958 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 @entity22715 are available in the literature. To understand how these proteins function, we used reverse genetic approaches, including identifying @entity72958 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 @entity72958 promoters upstream of the cognate @entity72958 cDNAs and as chimeric genes with noncognate promoters were used to transform @entity72958 plants. Cold, drought, and salt induced both genes; the promoter of @entity48904 was found to be more responsive to drought and cold stresses, whereas the promoter of @entity22715 was highly responsive to salt stress. Morphological and physiological responses of @entity72958 plants to salt stress were further investigated. Root growth, and photosynthetic properties declined significantly, while solute concentration (    ), water use efficiency (WUE) and   @entity7352 ratio increased under salt stress. Unexpectedly, the @entity72958 knockout mutant lines maintained greater root growth, photosynthesis, and WUE under salt stress relative to control. We conclude that the RD29A and @entity22715 proteins are unlikely to serve directly as protective molecules.
