Genome-Wide Characterization of the PLATZ Gene Family in Medicago truncatula and Their Expression Profiles in Response to Abiotic Stress

Plant A/T-rich sequence and zinc-binding protein (PLATZ) transcription factors are pivotal regulators of plant growth, development, and abiotic stress responses. Although PLATZ genes have been extensively studied and functionally characterized in various plant species, little information is available regarding these genes in the legume model plant Medicago truncatula. In this study, a total of 16 PLATZ genes (designated MtPLATZ1 to MtPLATZ16) were identified from the M. truncatula genome and distributed across six of the eight chromosomes. Subcellular localization prediction analysis indicated that all MtPLATZ proteins are localized in the nucleus, with eight representative members experimentally validated by transient expression assays. Collinearity analysis indicated that five segmental duplication pairs were the primary driver of MtPLATZ gene expansion. Based on phylogenetic analysis, these genes were classified into four groups, comprising 6, 2, 4, and 4 genes, respectively. Gene structure analysis demonstrated that these genes possess three or four exons. Most MtPLATZ genes were found to contain at least one ABRE cis-element in their promoter regions, and a few also harbored LTR, CAT-box, ARE, and DRE cis-elements. Expression analysis revealed that MtPLATZ genes exhibit distinct expression patterns across different tissues, suggesting that they may be differentially regulated by abiotic stresses in a tissue-specific manner. Under PEG-induced osmotic stress, acute NaCl shock, acute heat shock, and acute cold shock, the expression levels of these eight genes exhibited significant changes, particularly MtPLATZ2, MtPLATZ6, and MtPLATZ9, indicating that MtPLATZ gene family members may play a broad role in abiotic stress responses. In summary, these findings provide valuable insights for future functional exploration of MtPLATZ genes and contribute to a deeper understanding of their roles in stress responses in M. truncatula.