Nor loci analysis in progenies of plants regenerated from the scutellar callus of bread-wheat : A molecular approach to evaluate somaclonal variation.

Progenies of plants regenerated from scutellar callus of bread wheat (Triticum aestivum L.) were analysed for the organization of the intergenic spacer of the rRNA genes, located at the sites of the nucleolar organizer region (Nor loci). Sexual progenies derived from the regenerated plants of three wheat cultivars were subjected to this analysis. The respective DNAs were digested with the restriction endonuclease TaqI, and probed with a specific rDNA fragment by Southern blothybridization. The intergenic rDNA spacer could thus be characterized for each of the three cultivars. Thirty-eight progeny plants of the cultivars 'Chinese Spring' and 'Miriam' were found to be stable in their organisation of the Nor loci: no changes relative to the Nor of control plants from these cultivars were revealed. On the other hand, three progeny plants of 'ND7532' showed reduction in the number of the rDNA spacers. Since no variability in the Nor loci could be revealed among control 'ND7532' plants, this seems to indicate that the changes in the progeny of regenerated plants resulted from the in vitro culture of the scutellar callus. Grain glutenin and gliadin profiles of sexual progenyplants derived from scutellar calli of 'Chinese Spring', of 'Miriam' as well as of 'ND7532' were identical to the respective control plants of these cultivars, indicating low (or no) somaclonal variation in these grain proteins in the analyzed plants.