Cloning and characterization of a Tyrosine Aminotransferase (TAT) Gene in Gerbera hybrida

In our previous study, a gene predicted to encode a tyrosine aminotransferase (TAT) was found to be significantly up-regulated in root rot diseased Gerbera by transcriptome sequencing. To confirm the genes and investigate the function, we cloned the gene by RT-PCR and then conduct bioinformatic analyses. In this study, a 1537 bp long cDNA sequence of thisgene (named as GhTAT) was firstly cloned, which containeda coding region of 1 233 bp, which was predicted to encode a protein of 410 amino acids. Bioinformatic analysis showed that theGhTAT was a stable hydrophobic protein without signal peptide. Subcellular location prediction result indicated that this protein located in chloroplast, which is the biosynthesis position of tyrosine and the derived products of tyrosine biosynthesis pathway. Moreover, typical tyrosine aminotransferase domain was found in this protein, indicating that it is a TAT. According to the TAT-based phylogenetic analysis and similarity analysis, the closest relationship and highest similarity was found between GhTAT and Halianthus annuus TAT, which again verified the TAT property of GhTAT. Tyrosine aminotransferase (TAT) is the first enzyme in tyrosine biosynthesis pathway, whose products include many antioxidant substances such as tocopherols and tocotrienols. The up-regulation of GhTAT in root rot diseased gerbera suggest that it may play important role in response to the root rot pathogen infection. In addition, 60 phosphorylation sites (accounting for 14.6%) were found in this protein, suggesting that the expression of this protein and its encoding gene were greatly influenced by the phosphorylation reactions.