C-BANDING AND FLUORESCENCE IN-SITU HYBRIDIZATION STUDIES OF THE WHEAT-ALIEN HYBRID AGROTANA

'Agrotana', a wheat-alien hybrid (2n = 56), is a potential source of r esistance to common root rot, stem rust, wheat streak mosaic virus, an d the wheat curl mite. However, the origin of 'Agrotana', reported to be durum wheat X Agropyron trichophorum (pubescent wheatgrass), is unc ertain. The objective of this investigation was to determine the chrom osome constitution of 'Agrotana' using C-banding and fluorescence in s itu hybridization techniques. The F-1 hybrid of 'Agrotana' x 'Chinese Spring' wheat showed 7 I + 21 II in 14.9% of the pollen mother cells, evidence of the presence of the A, B, and D genomes in 'Agrotana'. The hybrid had 16 heavily C-banded chromosomes, namely 4A, and 1-7B of wh eat, and a translocation that probably involved wheat chromosomes 2A a nd 2D. In situ hybridization using biotinylated genomic DNA of Ag. tri chophorum cv. Greenleaf blocked with CS DNA failed to identify the ali en chromosomes in 'Agrotana', indicating that the alien chromosomes we re not likely derived from pubescent wheatgrass. In situ hybridization using labelled wheat genomic DNA blocked with 'Agrotana' DNA revealed that 'Agrotana' had 40 wheat, 14 alien, and 2 (a pair) wheat-alien tr anslocated chromosomes. There was no homology between wheat and the al ien chromosomes or chromosome segments Involved in the wheat-alien rec ombinant. Two of the seven pairs of alien chromosomes were homoeologou s to each other. The ability to identify alien chromatin in wheat usin g labelled wheat DNA instead of labelled alien DNA will be particularl y useful in chromosome engineering of wheat germplasms having alien ch romatin of unknown origin.