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Reprogramming of rye rDNA in triticale during microsporogenesis
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Orientador(es)
Resumo(s)
To test the hypothesis that interspecific genomic and
chromosome interactions leading to nucleolar dominance
could be reprogrammed in meiosis, we compared
the expression of distinct nucleolar
organizing region (NOR) loci in hexaploid triticale root
tip meristematic cells, pollen mother cells and young
pollen grains. Interphase and metaphase cells were
silver stained to quantify nucleoli and active NOR loci
respectively. A marked difference in the ribosomal
RNA gene activity of each locus was observed when
different types of cells were compared: in somatic and
pollen mother cells, rRNA gene activity was mainly
restricted to major wheat NORs (1B and 6B) with only
a small contribution from rye NORs (1R). In contrast, in
young pollen grains, all NORs present, including the
1R NORs, were consistently active. The expression of
all NORs just after meiosis is considered to be a consequence
of meiotic reprogramming of rye origin
rDNA. Gene reprogramming mediated by the resetting
of methylation patterns established early in embryogenesis
is suggested to be responsible for the differential
expression of the NORs of rye origin in distinct
developmental stages of triticale.
Descrição
Palavras-chave
meiotic reprogramming microspores nucleolar dominance rDNA expression rye NOR
Contexto Educativo
Citação
"Chromosome Research". ISSN 0967-3849. 3 (1995). 492-496