RFLP ANALYSIS OF NUCLEAR-DNA FOR STUDY OF PHYLOGENY AND DOMESTICATIONOF TETRAPLOID WHEAT

To study the phylogeny and domestication of tetraploid wheat species, variations in nuclear DNA of the cultivated and wild species were inve stigated by RFLP analysis. Twenty-two accessions representing 11 speci es of cultivated tetraploid wheat (Emmer wheat and Timopheevi wheat), 16 accessions of wild Emmer wheat (Triticum dicoccoides Korn.), 14 acc essions of wild Timopheevi wheat (T. araraticum Jakubz.), and an acces sion of common wheat (T. aestivum) were analyzed, using 29 combination s of two restriction enzymes and 20 probes. Based on this result, the genetic distances (d) between all pairs of accessions were estimated. An average d was 0.0189 in the Emmer group and 0.0024 in the Timopheev i group, while that between the groups was 0.0698. Cluster analysis us ing UPGMA, NJ (neighbor joining) and maximum parsimony method showed c lear differentiation of Emmer wheat and Timopheevi wheat. Among the cu ltivated Emmer wheat T. dicoccum Schubl. showed the largest nucleotide diversity (pi:=0.0180) which was close to that (0.0186) in the wild a ncestral species, T. dicoccoides. All the cultivated species, except f or T. dicoccum and T. paleocolchicum Men., were grouped into a distinc t cluster in the phylogenetic trees. All but one accessions of T. dico ccoides were grouped in another. The large genetic diversity in T. dic occum, the non-free threshing species, supports the archeological evid ence that T. dicoccum was the earliest domesticated tetraploid wheat.