The improvement of salt tolerance in transgenic tobacco by overexpression of wheat F-box gene TaFBA1

- Overexpression of TaFBA1 in tobacco increased seed germination rate and root elongation compared with WT under salt stress. Under long time salt stress, transgenic plants have greater biomass accumulation than WT, and the photosynthesis was more stable than WT. The transgenic plants had higher activity of antioxidant enzymes and less accumulation of ROS under salt stress. Further, the transgenic plants had lower Na+ content and higher K+ content than WT in leaves and roots.
- At the same time, H+-ATPase on Plasma membrane in the transgenic plants were higher than those of WT, accompanied by the net of Na+ efflux rate under salt stress. In tonoplast, the activities of V-ATPase and PPase were also higher than WT, helpful to Na+ maximize intracellular compartmentation.
- The expression of some salt stress related genes were upregulated under salt stress. These results suggested that the improvement of TaFBA1 in plant salt stress tolerance may be associated with the improvement of antioxidative compete and Na+/K+ ion regionalization.

F-box protein is a major subunit of the Skp1-Cullin-F-box (SCF) complex. We previously isolated an F-box gene from wheat, TaFBA1, and here we show that overexpression of TaFBA1 in transgenic plants under salt stress increases germination rate, root elongation, and biomass accumulation compared with WT plants. Improvements in the photosynthetic rate and its corresponding parameters were also found in the transgenic plants. These results suggest that overexpression of TaFBA1 improves salt stress tolerance in transgenic tobacco. Further, the transgenic plants displayed less membrane damage, higher antioxidant enzyme activity, and less accumulation of ROS under salt stress. The transgenic plants also had lower Na+ content and higher K+ content than WT plants in leaves and roots. The activity of H+-ATPase on the plasma membrane in the transgenic plants was higher than in WT plants, and was accompanied by a net Na+ efflux. In the tonoplast, the activity levels of V-ATPase and PPase were also higher in the transgenic plants, thus helping to maximize intracellular Na+ compartmentalization. The expression of some stress-related genes was upregulated by salt stress. This suggests that the enhancement of plant salt stress tolerance may be associated with an improvement in antioxidative competition and Na+/K+ ion regionalization.