Characterization of Arabidopsis thaliana Line with T-DNA Insertion in the Inositol Polyphosphate 5-Phosphatases8 Gene

Inositol polyphosphate 5-phosphatases (5Tase) are the important enzymes of the phosphatidylinositol (PI) signaling pathway and have been found to play important roles in plant growth, development, and stress responses. Most of the Arabidopsis genes encoding Inositol polyphosphate 5-phosphatases have been characterised. However, promoters of genes encoding Inositol polyphosphate 5-phosphatases of plants have not been characterized so far. Here, we report the characterization of Arabidopsis thaliana SALK mutant lines having T-DNA insertion in the upstream intergenic region of the Inositol polyphosphate 5-phosphatases8 (At5Tas8) gene. The location of T-DNA insertion in the SALK line was confirmed by PCR, and plant homozygous and hemizygous for the T-DNA insertion were identified. The homozygous plants were observed for the morphological difference as well as for the root phenotype. However, no significant morphological differences were observed in the mutant and wild-type plants. The expression analysis using qRT-PCR revealed a similar level of At5Tase8 transcript in the mutant and wild-type plants suggesting T-DNA insertion lies beyond the At5Tase 8 promoter. In silico analysis of the 3000 bp sequence upstream of the translation start site covering the T-DNA insertion site has revealed the presence of potential cis-regulatory elements for heat, light, drought, salt, sugar, and hormone. Besides, most predicted cis-elements were located downstream of the T-DNA insertion site, further supporting that the promoter of At5Tase8 lies within the 2738 bp sequence upstream of the translation start site. Further study is required to delineate the At5Tase8 promoter using promoter-reporter fusion in the transgenic Arabidopsis.