Evolutionary History of Triticum petropavlovskyi Udacz. et Migusch. Inferred from the Sequences of the 3-Phosphoglycerate Kinase Gene

Single- and low-copy genes are less likely to be subject to concerted evolution. Thus, they are appropriate tools to study the origin and evolution of polyploidy plant taxa. The plastid 3-phosphoglycerate kinase gene ( Pgk-1 ) sequences from 44 accessions of Triticum and Aegilops , representing diploid, tetraploid, and hexaploid wheats, were used to estimate the origin of Triticum petropavlovskyi . Our phylogenetic analysis was carried out on exon+intron, exon and intron sequences, using maximum likelihood, Bayesian inference and haplotype networking. We found the D genome sequences of Pgk-1 genes from T. petropavlovskyi are similar to the D genome orthologs in T. aestivum , while their relationship with Ae. tauschii is more distant. The A genome sequences of T. petropavlovskyi group with those of T. polonicum , but its Pgk-1 B genome sequences to some extent diverge from those of other species of Triticum . Our data do not support for the origin of T. petropavlovskyi either as an independent allopolyploidization event between Ae. tauschii and T. polonicum , or as a monomendelian mutation in T. aestivum . We suggest that T. petropavlovskyi originated via spontaneous introgression from T. polonicum into T. aestivum . The dating of this introgression indicates an age of 0.78 million years; a further mutation event concerning the B genome occurred 0.69 million years ago.