Genome-Wide Identification of Peanut Pyruvate Kinase Gene Family and Their Potential Roles in Seed Germination and Drought Stress Responses

Pyruvate kinase (PK), a pivotal enzyme in glycolysis, serves as a multifunctional regulator of plant growth, development, and stress adaptation. Despite its significance, the functional roles of PKs in peanut remain largely unexplored. Here, we performed a genome-wide identification and systematic characterization of PK genes in cultivated peanut, identifying 21 AhPK genes (AhPK1–AhPK21). Phylogenetic classification divided these genes into two subfamilies: PKc (comprising PKc-1 and PKc-2 subgroups) and PKp (comprising PKp-α and PKp-β subgroups). AhPK members within the same subfamily shared similar motif composition patterns, while genes from different subgroups showed significantly different exon–intron organizations. Collinearity analysis indicated that segmental duplication events and purifying selection predominantly drove the expansion and evolution of the AhPK family. Evolutionary analysis further indicated closer evolutionary relationships between peanut PKs and those of Arabidopsis than with rice. Predicted protein interaction networks suggested that AhPKs can form polymeric protein complexes (e.g., PKp-α and PKp-β) or interact with some important proteins, including FBA4, F14O13.7, APY, DLD, and T16L4.190. Promoter analysis identified abundant cis-regulatory elements associated with light responses, stress responses, hormone responses, and development. Expression pattern analysis demonstrated the significant induction of multiple AhPK genes during seed germination and under polyethylene glycol (PEG)-induced drought stress or abscisic acid (ABA) treatment. Collectively, these findings provide critical insights into the functional roles of AhPK genes in seed germination and drought stress responses, establishing a foundation for future mechanistic studies.