title: Intergenic spacer length variants in Old Portuguese bread wheat cultivars.
abstract: The intergenic spacer of the ribosomal DNA is highly variable, but is location specific in the nucleolar organizer region of the chromosomes. This study provides an event of high level of polymorphism / size variation and occurrence of 14 unique phenotypes in 48 landraces of Portuguese bread wheat cultivars for IGS-amplified products obtained by PCR-RFLP technique performed with TaqI. The attendant IGS polymorphism has been used to deduce affinities between landraces. Some of the high molecular weight IGS allelic variants were also probed for their chromosomal localization by sequential silver nitrate staining and fluorescence in situ hybridization. However, only the intergenic spacer allelic variant of 3.1 kb could be successfully hybridized, and was observed to be physically located on the chromosome pair 1B in the NOR loci of the cultivar 'Magueija'.
authors.affiliation: Institute of Biotechnology and Bioengineering, Centre of Genomics and Biotechnology,University of Tras-os-Montes and Alto Douro, PO Box 1013, 5001-801 Vila Real, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Carvalho
authors.forename: Henrique
authors.initials: H
authors.lastname: Guedes-Pinto
authors.forename: José
authors.initials: J
authors.lastname: Lima-Brito
mesh_terms: D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics*; D015252:Deoxyribonucleases, Type II Site-Specific; D014644:Genetic Variation; D017404:In Situ Hybridization, Fluorescence; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length; D014908:Triticum / Q000235:genetics*
chemical_list: D021903:DNA, Ribosomal Spacer; D015252:Deoxyribonucleases, Type II Site-Specific; C027046:TCGA-specific type II deoxyribonucleases