The Impacts of -Overexpression on Growth and Photosynthetic Parameters.

Background: TRR14 protein is a small protein, a member of a multigene family in Arabidopsis which was found as the fi rst protein during screening seedlings for their resistant to the trehalose sugar.

Objectives: A number of TRR14-overexpressing plants were subjected to the characterization in the present research, among which, the associated morphological features and changes accompany growth pattern and photosynthesis related parameters.

Materials And Methods: gene was isolated from and cloned into the pBin-35S vector. Recombinant vector was transferred to the (Col-0) via using the Floral Dipping method. Seeds from the overexpressed (TRR14) and the Col-0 wild-type (WT) plants were shown on soil under long day conditions. Several measurements were then performed including determination of the fresh and dry weights, leaf area, chlorophyll a and b (Chl a and Chl b) content, Chl a/b ratio, total chlorophyll and carotenoids content, soluble and insoluble sugars content, total and soluble protein content, the Hill reaction rate, chlorophyll fl uorescence, as well as photorespiration rate. Meanwhile, the chloroplastic proteins were investigated by SDS-PAGE analysis.

Results: TRR14 plants showed a signifi cant increase in fresh and dry weights, leaf area, and total and soluble protein content along with a signifi cant decrease in the insoluble sugar contents was observed in comparison to the WT plants. Chl a, Chl b, total chlorophyll content, Chl a/b ratio, carotenoids content, Hill reaction rate, and chlorophyll fl uorescence didn't show a signifi cant diff erence between TRR14 and WT plants. The SDS-PAGE gel electrophoresis of the chloroplastic proteins showed a thick band with a molecular mass of 25 kDa in -overexpressed plants, compared to the WT plants. Remarkably, photorespiration rate was decreased in TRR14 plants compared to WT plants.

Conclusion: The increased biomass of TRR14 transformed plants might be due to its ability in reducing photorespiration through concentrating CO in the leaf's intercellular spaces.