The enhanced salt tolerance by over-expressing the nhaA gene
in transgenic rice was not confirmed in our study although both
laboratories transformed the same gene into the Japonica rice
strains [9]. The purpose of our study was to optimize the
expression of the nhaA gene under control of the maize ubiquitin
promoter and to use the most relevant control for the experimental
investigations. Control samples were generated containing the GFP
gene and null segregants in regard to salt tolerance. Wild type
seedlings and calli were used as additional controls to minimize
false findings. The use of transgenic calli and transgenic rice
containing the GFP reporter gene further improved the experimental
control and the removed the impact of transgenes, tissue
culture and transformation processes from the study.