To validate if the salt tolerance related gene, nhaA, can confer rice more salt tolerance, gene function was tested in transgenic rice calli and transgenic plants. The nhaA gene was driven under the control of the maize ubiquitin promoter in Construct 19308 (Fig. 1). The gene was expected to render salt tolerance to transgenic calli and plants. Construct 17933 containing the GFP gene (Green fluorescence protein) was used as a gene control (Fig. 1) and coloured transgenic calli carrying GFP were visibly selected. Contructs 19308 and 17933 also contain a manA gene, encoding the phosphomannose isomerase (PMI) protein under the control of the rice actin promoter. Expression of the manA gene was used as a selection marker during plant transformation. Transgenic rice calli were selected by adding mannose into the selection medium so that the putative transformants could proliferate due to the capacity to utilize mannose as a carbon source [5,24].