Fig. 2. In situ hybridization of wheat NOR rDNA probe pTa71 to somatic prometaphase or metaphase chromosomes of (a) Arrhenatherum album PI 283189, (b) A. thorei GRA 579/94 and (c) A. elatius PI 251946. The probe was direct-labeled with Alexafluor 488-5-dUTP and cells were counterstained with propidium iodide. Hybridization sites are indicated with arrows.