INSTABILITY OF THE BLUE GRAIN COLOR IN A STRAIN OF TRITICUM-AESTIVUM L

The blue-grained wheat accession TRI 2401 (Triticum aestivum var. tschermakianum Mansf.) from the gene bank in Gatersleben was confirmed to be an alien disomic substitution for wheat chromosome 4A(a), which confers blue aleurone. Reciprocal hybrids with 'Chinese Spring' had nonblue (red) seeds in F1 and segregated on average 74% nonblue and 26% blue in F2. This segregation is not necessarily monogenic. In selfed progeny of TRI 2401 about 1.4% of the seeds were nonblue (red). Most of these aberrant seeds were monosomic for the alien chromosome. The seed from selfing of the monosomics segregated in a ratio of 67% nonblue (2n = 41) to 33% blue (2n = 42). The nonblue seeds undoubtedly arose from aneuploid gametes originating by nondisjunction during gametogenesis. Since 20-chromosome male gametes rarely function, it was assumed that the deficiency was mostly transmitted through the egg cells. In addition, spotting of the blue aleurone was observed with a frequency of 0.017%. Size and pattern of the spots varied considerably. It is thus likely that the loss of the blue color in the aleurone cells resulted from the loss of the alien chromosome during endosperm development. On the basis of the behavior mentioned, it was concluded that the gene(s) for blue aleurone in the European wheat accession TRI 2401 seem to be different from the analogous gene, Ba, in the blue-grained derivatives of wheat x Elytrigia pontica crosses.