Ex vitro assessment of increased salt tolerance in tobacco constitutively expressing the Vitis vinifera dehydration responsive gene
2017
Jardak, R. | El Abbassi, M. M. | Ben Jouira, H. | Hanana, M. | Ben Salem-Fnayou, A. | Mliki, A. | Ghorbel, A.
Threats against grapevine productivity in Tunisia include several climatic constraints, namely salinity. In order to achieve an effective salt stress tolerance through genetic engineering, the constitutive expression effect of the candidate Vitis vinifera dehydration responsive gene (Vvrd22) was examined in the tobacco model plant. After genetic transformation, two T2 transgenic lines (L15 and L20) were selected for a greenhouse assay for growth, water status and biochemical assessment under salinity conditions. According to the ex vitro trial, the transgenic lines did not exhibit any phenotypic difference compared to wild type (WT) under control conditions (0 mM NaCl). When subjected to a salt stress treatment (400 mM NaCl) for six weeks, better leaf and shoot fresh weights were registered within the transgenic lines than in WT plants. However, root fresh weights did not display any differences between both wild and transgenic lines. Considering water status, a lower decrease of the water content (WC) was revealed in the transgenic lines' leaves and shoots compared to WT at the end of the assay. Moreover, in contrast to WT, WC in the roots was lower than that in the leaves and shoots within L15 and L20 lines. With regard to the soluble sugar content, an overproduction was detected in Vvrd22-expressing plants but not within WT. However, proline content increased similarly in both lines. Our results suggest that Vvrd22 expression contributes to the protection of the vegetative part and maintaining of the water status to counteract salt stress. However, further physiological studies are still required for the settlement of reliable conclusions regarding the enhancement of salt tolerance in transgenic tobacco.
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