Differential rRNA Genes Expression in Hexaploid Wheat Related to NOR Methylation

作者：Carvalho Ana; Polanco Carlos; Lima Brito Jose^*; Guedes Pinto Henrique

来源：Plant Molecular Biology Reporter, 2010, 28(3): 403-412.

DOI：10.1007/s11105-009-0165-5

• Cytosine methylation
• Epigenetics
• NOR polymorphism
• Ribosomal DNA (rDNA
• Triticum aestivum L.

Ribosomal RNA genes expression was analysed in 18 Portuguese bread wheat accessions (Triticum aestivum L. em Thell.), and the number of argyrophilic-nucleolar organiser regions (Ag-NORs) per cultivar was scored. Ten accessions presented six Ag-NORs per metaphase and six nucleoli per interphase, and eight accessions presented four Ag-NORs per metaphase and four nucleoli per interphase. Fluorescent in situ hybridisation with the 45S rDNA sequence pTa71 and genomic DNA from Aegilops tauschii (2n = 2x= 14, DD) confirmed the Ag-NOR location and identified the six satellited chromosomes as being the chromosome pairs 1B, 6B and 5D. The methylation pattern of the NOR region was studied by Southern blot using pTa71 as probe, which represented a complete rDNA unit of bread wheat. DNA digestions performed by MspI and HpaII resulted in different patterns revealing the high level of cytosine methylation at their recognition sequences. The total percentage values of NOR methylation indicated that wheat accessions with a maximum of four Ag-NORs were more heavily methylated at the NOR region than accessions with a maximum of six Ag-NORs.

• 出版日期2010-9