Nucleolar organizer activity in wheat,rye and derivatives analyzed by a silver-staining procedure

Nucleolar activity was analyzed in wheat (Triticum sp.), rye (Secale cereale) and several types of wheat-rye derivatives using a modified, highly reproducible, silver staining procedure (Lacadena et al. 1984). A comparative analysis of the nucleolar organizer regions (NORs) of somatic metaphase chromosomes was made by phase contrast, C-banding, and silver staining. The frequency distribution of the number of nucleoli visualized at interphase by silver staining was also used to infer the activity of NORs. The results agree quite well with data from in situ hybridization reported by other authors. The behavior of euploid, ditelosomic and nulli-tetrasomic plants of common wheat showed the relative nucleolar activity of the four organizer chromosomes to be: 6B > 1B > 5D > 1A. — Several types of wheat-rye derivatives were analyzed: interspecific hybrid, triticale, addition and substitution lines, and plants with the genome constitutions, AABBDR, ABDR + 5D, ABRR, and ABRRR. In all cases the nucleolar organizer chromosome 1R of rye was suppressed by the presence of wheat chromosomes.