ISSN:
1432-2242
Keywords:
Daucus carota L.
;
Tissue culture
;
Differential DNA replication
;
Cell-division growth
;
Cell determination
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Systematic investigations on the occurrence of differential DNA replication in carrot cultures, expressed at the total genome level, were performed. The genome of Daucus carota L. could be characterized by a pattern of repetitive BstNI fragments that was independent of tissue specificity or cultivar differences. Characterization of the genomic DNA of the secondary phloem of carrot roots, in comparison to the DNA of the induced primary cultures at different growth phases, revealed dramatic differences in the copy number of the repetitive fragments. Highly proliferative tissue showed extensive reduction in the proportion of repetitive sequences in the genome in all of the 37 investigated variants. In contrast, during subsequent transition to stationary growth the repetitive fragments re-amplified. The results suggest that the quantitative genome organisation was involved in the regulation of the growth potential of cells. A hypothesis is discussed suggesting a determining influence of the observed differential DNA replication on cell-cycle rates and the cell program of proliferative tissue by structural and positioning effects on DNA loops. To study the causality of somaclonal variation, research on the relationship between physiological genome variability and the induction of heritable changes is recommended.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00220965
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