, Volume 5, Issue 7, pp 451-456

Karyotype analysis of Helianthus annuus using Giemsa banding and fluorescence in situ hybridization

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Abstract

The karyotype of H. annuus was analysed by computer-aided image processing with respect to the chromosome length, arm ratio, occurrence and chromosomal position of intercalary heterochromatin and the location of 18S/25S and 5S ribosomal RNA genes. The karyotype was subdivided into a group of four acrocentric chromosome pairs, of which two were distinguishable by HKG (HCl, KOH, Giemsa) banding and a group of 13 meta- to submetacentric pairs. The latter could be subdivided into seven pairs with one and six pairs with two HKG bands. Three pairs of submetacentric satellite chromosomes revealed 18S/25S rDNA loci after fluorescence in situ hybridization (FISH) and silver staining . A fourth, smaller and possibly inactive, locus occurred in the terminal position on a metacentric pair. One submetacentric satellite chromosome pair revealed a 5S rRNA gene locus in the pericentromeric position; a second locus marked a submetacentric pair with one HKG band. The C-banding technique marks exclusively centromeric heterochromatin. Measurements of chromosomes in combination with Giemsa banding and FISH enabled the discrimination of most chromosome pairs of the sunflower.

This revised version was published online in November 2005 with corrections to the Cover Date.