Functional prediction of a T-DNA tagged gene of Arabidopsis thaliana by in silico analysis.

We have employed a gene-knockout approach using T-DNA tagging and in vivo gene fusion in Arabidopsis thaliana for identification and isolation of specific plant genes. Screening of about 3,000 T-DNA tagged lines resulted in identification of a mutant line (no. 197) exhibiting a significant delay in flowering. From this line a 600-bp plant DNA fragment downstream of the left T-DNA junction was cloned by inverse PCR. BLAST searching in the A. thaliana genomic database indicated a putative gene, frf (flowering regulating factor), with unknown function downstream of the T-DNA insert. Bioinformatic tools were used to predict possible protein structure and function. The protein structure predicted by fold recognition indicates that frf is a transcriptional regulator, a ligand-binding receptor responsive to steroids and hormones. Analyzing the predicted results and the phenotype of the T-DNA tagged plant we hypothesized that FRF might be involved in hormone response in A. thaliana. For verification of this hypothesis we exposed the plants of line no. 197 to gibberellic acid (GA3), a potential growth regulator in higher plants. This treatment resulted in an earlier onset of flowering, almost similar to that in wild type control plants.