ISSN:
1573-6849
Keywords:
fluorescencein situ hybridization (FISH)
;
geminivirus-related DNA (GRD) sequences
;
Nicotiana tabacum L.
;
phylogeny
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract TheN. tabacum (tobacco) nuclear genome carries approximately 25 multiple direct repeats of a geminivirus-related DNA (GRD) sequence that probably arose by illegitimate recombination, following geminivrus infection, duringNicotiana evolution. Each GRD repeat carries sequences similar to the geminiviralAL1 gene of the tomato golden mosaic virus (TGMV), encoding a protein required for viral DNA replication, plus thecis-essential replication origin. Using a cloned 14-kb GRD repeat sequence as a probe for fluorescencein situ hybridization (FISH), we identified a unique tobacco chromosome carrying GRD. Translocations between chromosomes of the tobacco S and T genomes were used as physical markers by sequentially hybridizing chromosomes with labelled GRD and total genomic DNA fromN. sylvestris (equivalent to the S genome). The 25S, 18S and 5.8S ribosomal gene clusters were detected in double-labelling experiments for use as additional markers to identify the chromosomal location of GRD. GRD occupies one site on a homologous pair of small submetacentrics from the T genome characterized by a lack of either translocated segments from the S genome or ribosomal genes. GRD provides an additional marker for the small chromosomes of the T genome and a useful phylogenetic tool.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00710015
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