MOLECULAR CYTOGENETICS OF THE GENUS ARABIDOPSIS - IN-SITU LOCALIZATION OF RDNA SITES, CHROMOSOME-NUMBERS AND DIVERSITY IN CENTROMERIC HETEROCHROMATIN

We have used in situ hybridization to determine the number of sites of rDNA in species in the genus Arabidopsis. A. wallichii (2n = 16) has one major pair of sites and one minor pair of sites, while A. pumila and A. griffithiam (both In-32) have six major and two minor rDNA sites. A. thaliana (2n = 10) is known to have two pairs of rDNA sites. A highly repeated para-centromeric sequence from A. thaliana, pALl, is absent in the other three species. Hence the A. thaliana genome is not present (or the centromeric DNA has evolved substantially) in the polyploid species A. pumila and A. griffithiana. Analysis of Arabidopsis species is a valuable complement to the large programmes for genetic analysis of A. thaliana. © 1993 Annals of Botany Company.