Diversity in Iranian wheats, particularly Triticum (Aegilops) tauschii (squarrosa; D genome)

Dr Hojjatollah Saeidi and Professor Mohammad Reza Rahiminejad, Isfahan University, Iran and

Pat Heslop-Harrison and Trude Schwarzacher, University of Leicester

Left: The distribution of the repetitive DNA sequence dpTa1 (DNA most diverse on D genome) using florescent in situ hybridization on the chromosomes (stained blue with DAPI) in accession At524 of Aegilops tauschii.

Iran, as a part of the Fertile Crescent, is within the centre of diversity and centre of origin of most of Triticeae plants. Thus, the study of biodiversity of this group within this area is important, giving information about the range of genes present, origin of species, and origin of the polyploid species such as bread wheat. Because of the contribution of the D genome to bread wheat, the genetic diversity present within Ae. tauschii is of considerable interest for finding new genes for exploitation in agriculture, and for tracking the origins of crop domestication. It has been reported that the T. aestivum D-genome originated from the SE or SW Caspian Sea in Iran. Ae. tauschii has resistance to various pests and pathogens which are significant in agriculture, and there are reports of useful physiological traits such as resistance to low temperature, tolerance to salt, and good performance in low-yielding, drought-stressed environments.

We are exploiting microsatellite markers, fluorescent in situ hybridization (FISH) using repetitive DNA, inter retroelement amplified polymorphisms (IRAP) and some other molecular markers and morphological characters to estimate genetic diversity and relationships within and between different genus and species of Triticeae, specially Aegilops tauschii, (diploid, D genome) across Iran.

The diploid goatgrassAe. tauschii Coss. [Syn. Triticum tauschii (Coss.) Schmal., Aegilops squarrosa auct. non L., 2n=2x=14] contains the D genome of Triticeae cereals, and is considered the progenitor of the D genome in bread wheat (Triticum aestivum L., 2n=6x=42, genome composition AABBDD).

In our study on biodiversity of Aegilops tauschii in Iran using microsatellite markers, IRAP and FISH, all this markers revealed high level of polymorphism between populations of this species in Iran, but no clear groupings supporting the taxonomic groping were detected that can be a consequence of high gene flow between populations in this area.

Polymorphism pattern from 20 Aegilops tauschii populations generated by IRAP using Sukula and LTR6150 primers, showing high level of polymorphism between populations.







January 2006