Abstract:To understand the function of phosphoenolpyruvate carboxylase (PEPC) in peanut, PEPC sequences of the diploid progenitor Arachis duranensis genome database were analyzed. Nine gene family members were found, and their sequence lengths ranged from 3 584 to 12 956 bp with 702-3 168 bp open reading frame (ORF), distributed in the 3, 5, 7, 8, 9, and 10th chromosomes. In the amino acid sequences of AdPEPC proteins, there were conserved domains, such as HCO3- binding sites and PEP binding sites, et al. According to the sequence characteristics, AdPEPC proteins could be divided into 3 groups as plant type, bacterium type and short sequence type. Protein homologies of the same type were high, and the number of intron and exon in gene structures was similar. Gene expression analysis showed that the expressions of most members were high in flowers or stems. AdPEPC1;2 and AdPEPC4;2 had the highest expression in stem. Other family members, especially AdPEPC2, AdPEPC1;5 and AdPEPC1;3, expressions were significantly higher in flower than other tissues. AdPEPC1;5 expression was not detected in leaf. No expression of AdPEPC3 was detected in root, stem, leaf and flower, and it was presumed to be pseudogenes based on its gene structure. These would lay a foundation for further study on the functions of AdPEPC family genes.