Autor(es):
Silva, Manuela 
; Viegas, Wanda ; Bento, Miguel ; Pereira, H. Sofia ; Rocheta, Margarida ; Gustafson, Perry
Data: 2008
Identificador Persistente: http://hdl.handle.net/10400.5/2411
Origem: Repositório da UTL
Assunto(s): triticale; genome; polyploidization
Descrição
Background. Polyploidization is a major evolutionary process in plants where hybridization and chromosome doubling induce
enormous genomic stress and can generate genetic and epigenetic modifications. However, proper evaluation of DNA
sequence restructuring events and the precise characterization of sequences involved are still sparse. Methodology/Principal
Findings. Inter Retrotransposons Amplified Polymorphism (IRAP), Retrotransposons Microsatellite Amplified Polymorphism
(REMAP) and Inter Simple Sequence Repeat (ISSR) largely confirmed the absence of any intraspecific variation in wheat, rye
and triticale. The comparative analysis of banding profiles between wheat and rye inbred lines revealed 34% of monomorphic
(common to both parental species) bands for the ten different primer combinations used. The analysis of triticale plants
uncovered nearly 51% of rearranged bands in the polyploid, being the majority of these modifications, due to the loss of rye
bands (83%). Sequence analysis of rye fragments absent in triticale revealed for instance homology with hydroxyproline-rich
glycoproteins (HRGP), a protein that belongs to a major family of inducible defence response proteins. Conversely, a wheatspecific
band absent in triticale comprises a nested structure of copia-like retrotransposons elements, namely Claudia and
Barbara. Sequencing of a polyploid-specific band (absent in both parents) revealed a microsatellite related sequence.
Cytological studies using Fluorescent In Situ Hybridization (FISH) with REMAP products revealed a widespread distribution of
retrotransposon and/or microsatellite flanking sequences on rye chromosomes, with a preferential accumulation in
heterochromatic sub-telomeric domains. Conclusions/Significance.. Here, we used PCR-based molecular marker techniques
involving retrotransposons and microsatellites to uncover polyploidization induced genetic restructuring in triticale. Sequence
analysis of rearranged genomic fragments either from rye or wheat origin showed these to be retrotransposon-related as well
as coding sequences. Further FISH analysis revealed possible chromosome hotspots for sequence rearrangements. The role of
chromatin condensation on the origin of genomic rearrangements mediated by polyploidization in triticale is also discussed
