Flavell RB 1986
- Authors:
Flavell RB.
- Title:
Repetitive DNA and chromosome evolution in plants.
- Reference location:
Philosophical Transactions of the Royal Society of London - Series B:
Biological Sciences. 312(1154):227-42, 1986 Jan 29.
- Abstract:
Most higher plant genomes contain a high proportion of repeated sequences.
Thus repetitive DNA is a major contributor to plant chromosome structure.
The variation in total DNA content between species is due mostly to
variation in repeated DNA content. Some repeats of the same family are
arranged in tandem arrays, at the sites of heterochromatin. Examples from
the Secale genus are described. Arrays of the same sequence are often
present at many chromosomal sites. Heterochromatin often contains arrays
of several unrelated sequences. The evolution of such arrays in
populations is discussed. Other repeats are dispersed at many locations in
the chromosomes. Many are likely to be or have evolved from transposable
elements. The structures of some plant transposable elements, in
particular the sequences of the terminal inverted repeats, are described.
Some elements in soybean, antirrhinum and maize have the same inverted
terminal repeat sequences. Other elements of maize and wheat share
terminal homology with elements from yeast, Drosophila, man and mouse. The
evolution of transposable elements in plant populations is discussed. The
amplification, deletion and transposition of different repeated DNA
sequences and the spread of the mutations in populations produces a
turnover of repetitive DNA during evolution. This turnover process and the
molecular mechanisms involved are discussed and shown to be responsible
for divergence of chromosome structure between species. Turnover of
repeated genes also occurs. The molecular processes affecting repeats
imply that the older a repetitive DNA family the more likely it is to
exist in different forms and in many locations within a species. Examples
to support this hypothesis are provided from the Secale genus.
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