Genome-Wide Identification of the TIFY Family in Longan and Their Potential Functional Analysis in Anthocyanin Synthesis

TIFY is one of the plant-specific transcription factors, which is extensively involved in regulating plant development, stress response, and biosynthesis of secondary metabolites. In this study, we identified 19 <i>DlTIFY</i> genes from the longan genome data. All of them contained the conserved TIFY domain, and these 19 <i>DlTIFYs</i> were distributed on 9 out of the 15 chromosomes of longan. A phylogenetic tree was constructed based on the TIFY protein sequences from <i>Arabidopsis</i>, rice, orange, and grape. They were clustered into six groups, with the TIFYs from longan showing the closest homology to those from orange. Duplication events were present between <i>DlTIFY1</i> and <i>DlTIFY5</i>, <i>DlTIFY4</i> and <i>DlTIFY6</i>, and <i>DlTIFY16</i> and <i>DlTIFY17</i>. There are several light-responsive elements, Abscisic Acid (ABA)-, Gibberellic Aci (GA)-, and Methyl Jasmonate (MeJA)-responsive elements, in the promoter regions of longan <i>TIFY</i> genes. Additionally, the flavonoid biosynthetic gene regulation elements were presented in the promoter of <i>DlTIFY7</i>, <i>DlTIFY10</i>, and <i>DlTIFY11</i>, suggesting their involvement in flavonoid synthesis regulation of longan. We also found that the expression of <i>DlTIFY7</i> in the stem and pericarp was significantly higher than that in other tissues. Interestingly, the outer edge of the corolla exhibited a green hue with a faint reddish tint across the corolla in transgenic tobacco plants overexpressing <i>DlTIFY7</i>. Subcellular localization experiments confirmed that DlTIFY7 is expressed in the nucleus. These findings suggest that <i>DlTIFY7</i> may serve as a novel candidate transcription factor negatively regulating anthocyanin synthesis in longan. This study provides valuable insights into the functional characterization of longan <i>DlTIFY</i> genes and lays a foundation for future research on their roles in regulating plant development and secondary metabolism.