Genetic variation at 27 enzyme loci was studied in 24 Transcaucasian populations of Aegilops squarrosa: 12 ssp. eusquarrosa and 12 ssp. strangulata populations. Most of the genetic variation was among populations: G ST accounted for 0.67 and 0.64 for ssp. eusquarrosa and ssp. strangulata, respectively. The Acph1, Est2, Est5, Got1 and Got2 loci were found to be involved in the adaptive process of Ae. squarrosa subspecies divergence. Allele variation at the Ep locus is most likely to be neutral. The remaining 21 enzyme loci are under purifying selection of different intensities.

All the 79 Aegilops tauschii Coss. accessions of Iranian origin from Prof. Kihara's collection were analyzed electrophoretically. Of 23 enzyme-encoding loci studied, 11 were polymorphic. In Iran Ae. tauschii is presented by ssp. tauschii and ssp. strangulata which distinctly differ genetically, morphologically and ecologically. Variation patterns of low polymorphic locus Aco2 and highly polymorphic Ep are similar in both subspecies. In contrast, variation of Acph1, Ak, Est2, Est5, Got1, Got2, Got3 and Lap is a set of diverse patterns which markedly differ between subspecies and natural regions also, implying that natural selection is involved.

Hexaploid wheat (Triticum aestivum L., genomes AABBDD) originated in South Caucasus by allopolyploidization of the cultivated Emmer wheat T. dicoccum (genomes AABB) with the Caucasian Ae. tauschii ssp strangulata (genomes DD). Genetic variation of Ae. tauschii is an important natural resource, that is why it is of particular importance to investigate how this variation was formed during Ae. tauschii evolutionary history and how it is presented through the species area. The D genome is also found in tetraploid Ae. cylindrica Host (2n = 28, CCDD). The plasmon diversity that exists in Triticum and Aegilops species is of great significance for understanding the evolution of these genera. In the present investigation the complete nucleotide sequence of plasmon D (chloroplast DNA) of nine accessions of Ae. tauschii and two accessions of Ae. cylindrica are presented. Twenty-eight SNPs are characteristic for both TauL1 and TauL2 accessions of Ae. tauschii using TauL3 as a reference. Four SNPs are additionally observed for TauL2 lineage. The longest (27 bp) indel is located in the intergenic spacer Rps15-ndhF of SSC. This indel can be used for simple determination of TauL3 lineage among Ae. tauschii accessions. In the case of Ae. cylindrica additionally 7 SNPs were observed. The phylogeny tree shows that chloroplast DNA of TauL1 and TauL2 diverged from the TauL3 lineage. TauL1 lineage is relatively older then TauL2. The position of Ae. cylindrica accessions on Ae. tauschii phylogeny tree constructed on chloroplast DNA variation data is intermediate between TauL1 and TauL2. The complete nucleotide sequence of chloroplast DNA of Ae. tauschii and Ae. cylindrica allows to refine the origin and evolution of D plasmon of genus Aegilops.

Sequences of four chloroplast DNA noncoding regions, about 3,000 bp in total, were analysed in 112 Aegilops tauschii accessions, 56 of ssp. tauschii and 56 of ssp. strangulata, representing all of the species range. One inversion, 8 insertions/deletions, 18 base pair substitutions and 5 microsatellite loci were found. The data revealed that Ae. tauschii originated in Caucasia. Neither of the two Ae. tauschii subspecies was an ancestor to one another. Aegilops tauschii divided into ssp. tauschii and ssp. strangulata at the very beginning of its existence as a species. Subspecies tauschii was the first to start geographic expansion and relatively rapidly occupied a vast area from Caucasia-eastward up to central Tien Shan and western Himalayas. In contrast to ssp. tauschii, geographic spread of ssp. strangulata was a complicated, multi-stage and slow process. At the beginning of ssp. strangulata evolutionary history its major phylogenetic lineage for a lengthy time span had existed as a small isolated population. Several forms of ssp. strangulata, better adapted to relatively moister and cooler habitats, had originated. Each of these forms has gradually forced out ssp. tauschii from some part of its area in the west, up to central Kopet-Dag.

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