Nucleolar activity in Triticum x Thinopyrum hybrids with different ploidy level

Abstract

The activity of nucleolar organizer regions (NORs) and the presence of ribosomal DNA (rDNA) zones were studied in two Triticum x Thinopyrum hybrids: a hexaploid hybrid with 2n = 42 chromosomes, named trigopiro SH16 INTA, and a decaploid hybrid with 2n = 56 chromosomes, named trigopiro Don Noé INTA. The use of the pTa71 probe revealed the presence of 10 rDNA signals in both hybrids, whereas the Ag-NORs technique showed 10 signals in SH16 and 8 in Don Noé. We concluded that all trigopiro SH16 INTA NORs are active and that the activity of one NOR pair of trigopiro Don Noé INTA is suppressed. Therefore, the amphiplasty phenomenon is present in trigopiro Don Noé INTA but not in trigopiro SH16 INTA.