Unveiling the Wheat NTP Gene Family: Insights from Genome-Wide Identification and TaNTP6 Haplotype Analysis

Background Nucleotidyl transferase proteins (NTPs) regulate RNA homeostasis by mediating templated-independent nucleotide additions to RNA termini, thereby being implicated in crucial roles during plant growth, development, and stress responses. However, investigations of the NTP gene family have been limited to Arabidopsis , rice, maize, and soybean, with NTP genes in wheat remaining uncharacterized. Results In this study, we identified 34 TaNTP genes in wheat and classified them into three phylogenetic groups (G1–G3). All 20 segmental duplication events occurred specifically in G3. Motif and domain analyses showed distinct features: G3 TaNTPs contain unique motifs, while G1 members possess an extra PAP_assoc domain absent in G2 and G3. Protein interaction networks further supported group divergence, with G1 and G3 proteins forming separate modules (Module Ⅰ and Ⅱ), and G2 distributed across both, suggesting functional specialization or dual roles. Expression profiling revealed that most TaNTPs are lowly expressed in leaves but upregulated under heat-drought stress. Many are also responsive to salt, ABA, and SA, supporting roles in stress adaptation. Notably, TaNTP6A/B/D show high expression levels in grains. Significant associations were observed between specific TaNTP6A/B/D haplotypes and thousand-kernel weight (TKW), implying a crucial regulatory role in grain development. Through haplotype analysis, we identified superior haplotypes associated with increased grain yield: TaNTP6A-Hap1 , TaNTP6B-Hap2 , and TaNTP6D-Hap5 / 6 . Additionally, subcellular localization analysis revealed that TaNTP4A and TaNTP1A, the orthologs of AtHESO1 and AtURT1, are detectable in both the nucleus and cytoplasm, but exhibit predominant nuclear localization. Conclusions These results provide pivotal insights into the NTP family in wheat. Importantly, the identification of superior TaNTP6A/B/D haplotypes offers valuable genetic resources for facilitating high-yield wheat breeding programs.