Nucleolar organizer activity and competition in Tricepiro Don Rene INTA, a synthetic forage crop

摘要

The nucleolar organizer activity and the presence of rDNA zones were studied in Tricepiro Don Rene INTA, a synthetic forage crop (2n=42, 6x, AABBRR with introgression of Thinopyrum in 6A chromosome). The use of pTa71 probe revealed the presence of six rDNA zones but Ag-NOR indicated the presence of only four NORs (nucleolus organizer regions). Differential amphiplasty phenomenon could explain the inactivity of some rDNA zones. Simultaneous use of FISH (pTa71 probe) and DAPI banding analysis indicated that the chromosomes with rDNA zones belong to two rye and to four wheat chromosomes. The maximum number of nucleoli observed in somatic cells and the number of chromosomes with secondary constrictions agreed with the four active NORs detected with the Ag-staining method. The use of the pSc119.2 probe allowed to recognize that chromosomes with secondary constrictions are the wheat chromosomes 1B and 6 B.