Genome-Wide Identification and Expression Profiling of the Di19 Gene Family in Sweet Potato and Its Two Diploid Relatives

Background: Di19 (drought-induced 19)proteins belong to the C2H2-type zinc-finger family and play a crucial role in regulating plant growth, developmental processes, hormone signal transduction, and abiotic stress adaptation. However, research on the Di19 gene family in sweet potato and its diploid relatives remains relatively limited. Methods: At the whole-genome level, members of the Di19 gene family in sweet potato (Ipomoea batatas, 2n = 6x = 90) and its two diploid relatives, Ipomoea trifida (2n = 2x = 30) and Ipomoea triloba (2n = 2x = 30) were systematically identified, and multi-dimensional bioinformatics analyses were carried out. Results: Seven Di19 genes were identified per species, with the family’s overall evolutionary characteristics conserved. Some IbDi19s showed species-specific structural variations, mainly manifested as an increase in the number of exons, loss or substitution of conserved motifs. The expression patterns of Di19s of two diploid relatives are highly conserved. IbDi19s are mainly expressed in leaves and roots. Most members respond significantly to JA treatment, but hardly respond to IAA. The expression of IbDi19-1 was significantly up-regulated by 336-fold and 68-fold under GA3 and cold treatments, respectively. Based on bioinformatics and expression data, a hypothesis was proposed that IbDi19-1 may be involved in the regulation of low-temperature response and gibberellin signaling pathways. Conclusions: This study provides candidate genes and a theoretical basis for evolutionary analysis, stress-resistant molecular breeding of the Di19 gene family in sweet potato and its two diploid relatives.