Advisor(s)
Abstract(s)
Allopolyploidy is a significant evolutionary process, resulting in
new species with diploid or greater chromosome complements
derived from two or more progenitor species. We examined the
chromosomal consequences of genomic merger in Arabidopsis
suecica, the allotetraploid hybrid of Arabidopsis thaliana and
Arabidopsis arenosa. Fluorescence in situ hybridization with centromere,
nucleolus organizer region (NOR), and 5S rRNA gene
probes reveals the expected numbers of progenitor chromosomes
in natural A. suecica, but one pair of A. thaliana NORs and one pair
of A. arenosa-derived 5S gene loci are missing. Similarly, in newly
formed synthetic A. suecica-like allotetraploids, pairs of A. thaliana
NORs are gained de novo, lost, and or transposed to A. arenosa
chromosomes, with genotypic differences apparent between F3
siblings of the same F2 parent and between independent lines.
Likewise, pairs of A. arenosa 5S genes are lost and novel linkages
between 5S loci and NORs arise in synthetic allotetraploids. By
contrast, the expected numbers of A. arenosa-derived NORs and A.
thaliana-derived 5S loci are found in both natural and synthetic A.
suecica. Collectively, these observations suggest that some, but not
all, loci are unstable in newly formed A. suecica allotetraploids and
can participate in a variety of alternative rearrangements, some of
which resemble chromosomal changes found in nature.
Description
Keywords
plant polyploidy speciation translocation
Pedagogical Context
Citation
"PNAS". 101: 52 (2004). 18240-18245