Structural instability of a transgene locus in tobacco is associated with aneuploidy.
This paper describes molecular and cytogenetic evidence for the stability of a transgene locus that is present on the triplicated chromosome in an aneuploid tobacco line. This instability was manifested in several ways in trisomics including a major chromosome rearrangement that was detectable cytogenetically, smaller scale DNA rearrangements that occurred both germinally and somatically, and methylation/epigenetic silencing. In a deletion derivative of the locus, DNA breakpoints were found in AT-rich regions. One of these regions binds to nuclear scaffolds in vitro, suggesting a possible role for aberrant topoisomerase II cleavage in destabilization of the locus. The implications of increased chromosome instability in aneuploids for plant karyotype evolution and human carcinogenesis are discussed.
Papp
I
I
Institute of Molecular Biology, Austrian Academy of Sciences, Salzburg, Austria.
Iglesias
V A
VA
Moscone
E A
EA
Michalowski
S
S
Spiker
S
S
Park
Y D
YD
Matzke
M A
MA
Matzke
A J
AJ
D000782:Aneuploidy; D001483:Base Sequence; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D019175:DNA Methylation; D004269:DNA, Bacterial / Q000235:genetics; D015321:Gene Rearrangement / Q000235:genetics; D007613:Kanamycin Resistance / Q000235:genetics; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D014026:Nicotiana / Q000235:genetics*; D019076:Transgenes / Q000502:physiology*
D004269:DNA, Bacterial; C036483:T-DNA