Single- and low- copy genes are less likely subject to concerted evolution, thus making themselves ideal tools for studying the origin and evolution of polyploid taxa. Based on the sequences of a single-copy nuclear gene encoding plastid acetyl-CoA carboxylase (Acc-1), a total of 47 accessions Triticum and Aegilops representing diploid, tetraploid and hexaploid were used to estimate the origin of Triticum petropavlovskyi. Phylogenetic analysis was performed based on the intron, intron + sy and exon data sets sequence using maximum likelihood, neighbor-joining and median-joining networks. The A and B genome sequences from Acc-1 loci show that T. petropavlovskyi shares the highest averaged sequence identity with T. polonicum from Xinjiang and exotic landraces of T. aestivum, and reveals specific progenitor-descendant relationships. The D genome sequences of the Acc-1 genes from T. petropavlovskyi are identical to the sequences of the D genome orthologs in T. aestivum, while the relationship of T. petropavlovskyi and Ae. tauschii are most distant. Our findings do not suggest the probability of an independent allopolyploidization event and a single mutation in T. aestivum in the origin of T. petropavlovskyi, but indicate a greater degree of gene flow between T. aestivum and T. polonicum leading to origin of T. petropavlovskyi. It is most likely that T. petropavlovskyi was originated from T. polonicum from Xinjiang to exotic landraces of T. aestivum via a spontaneous introgression or breeding effort.