LOCATING THE ALIEN CHROMATIN SEGMENT IN COMMON WHEAT - AEGILOPS-LONGISSIMA MILDEW RESISTANT TRANSFERS

By use of the Chinese Spring ph1b mutant, recombination was induced between the 3S1 short arm telosome of Ae. longissima and its group-3 wheat homoeologues. Transfer was thus obtained of chromosomal segments bearing the alien Pm13 mildew resistance gene into several common wheat lines. To identify the wheat chromosome involved in each transfer, these were subjected to monosomic and C-banding analyses. Probably due to preferential 3B-3S1 pairing, irrespective of the group-3 wheat chromosome present as monosome in the critical steps of the transfer work, in 2/3 of the cases 3B turned out to be the recipient chromosome, whereas 3D was the one involved in the remaining ones. Assessment of the residual pairing ability of the recombinant chromosomes in F1's between four 3B and three 3D transfer lines and their corresponding wheat ditelosomic as well as 3S1 substitution lines, indicated about coincident values (about 40 % pairing with DT3BS) in three of the 3B recombinants, a significantly different pattern in the fourth one (10 %) and a more continuous variation among the 3D ones. An overall prevailing terminal location of the wheat-alien chromatin exchange points is tentatively hypothesized.