THE MOLECULAR-GENETIC ANALYSIS OF TRITICUM-TAUSCHII, THE D-GENOME DONOR TO HEXAPLOID WHEAT

DNA from Triticum tauschii (the D-genome donor to hexaploid wheat, Triticum aestivum) has been cloned using the restriction endonuclease PstI to generate fragments for insertion into the plasmid pBR322 or pUC118. A total of 143 clones were studied and demonstrated to contain one of the following sequence types: (i) a D-genome amplified repetitive sequence, (ii) polymorphic repetitive sequences ("fingerpring-type" sequences), (iii) polymorphic low to moderately repetitive sequences (PLR sequences), (iv) polymorphic low copy number sequences (PL sequences), and (v) invariant sequences. The D-genome amplified sequence was found to be located on all seven chromosomes. A genetic linkage map using PL and PLR sequences was produced by analysing F2 segregating progeny from crosses between two different taxa of T. tauschii. In addition to using DNA clones from T. tauschii, clones from other laboratories containing either anonymous sequences or genes coding for known products (e.g., 7S globulin, dehydrin, germin, storage protein) were used in the genetic linkage map. Multiple locations were mapped for the PLR sequences and were often clustered on single chromosomes. The restriction fragment length polymorphism markers and isozymes analysed were generally distributed over all the linkage groups that were identified and, when used in conjunction with published markers, provided the basis for a genetic map of T. tauschii.