caa a22 4500 475795474 CHVBK 20180406123723.0 cr unu---uuuuu 170329e20000201xx s 000 0 eng 10.1007/s001220050047 doi (NATIONALLICENCE)springer-10.1007/s001220050047 Cytological heterozygosity and the hybrid origin of sweet orange [Citrus sinensis (L.) Osbeck] [Elektronische Daten] [A. Pedrosa, D. Schweizer, M. Guerra] Abstract : Citrus sinensis chromosomes, although small in size, present a remarkable differentiation of bands with the fluorochromes CMA and DAPI. These bands suggest that some heteromorphisms are fixed in this species. To investigate the extension of these heteromorphisms, ten cultivars of C. sinenesis were analysed with CMA/DAPI staining and, in some of them, the 18S-5.8S-25S rRNA and 5S rRNA genes were located by in situ hybridization. CMA/DAPI staining showed exactly the same CMA+/DAPI− banding pattern for all cultivars. In situ hybridization revealed three 18S-5.8S-25S rRNA gene sites, two proximally located on two similar chromosomes and one terminally located on a third non-related chromosome. Two 5S rRNA gene sites were observed in this species, with one located proximal to the telomeric 18S-5.8S-25S rDNA site. Both cytological approaches revealed an invariable, heterozygotic karyotype among sweet orange cultivars. Based on these data, the putative hybrid origin of the species is discussed. Springer-Verlag Berlin Heidelberg, 2000 Key words Citrus sinensis nationallicence CMA banding nationallicence FISH nationallicence rRNA genes nationallicence Heterochromatin nationallicence Heterozygosis nationallicence Pedrosa A. Department of Cytology and Genetics, Institute of Botany, University of Vienna, Rennweg 14, A-1030, Vienna, Austria e-mail: apedrosa@s1.botanik.univie.ac.at Fax: +43-1-4277-9541, AT aut Schweizer D. Department of Cytology and Genetics, Institute of Botany, University of Vienna, Rennweg 14, A-1030, Vienna, Austria e-mail: apedrosa@s1.botanik.univie.ac.at Fax: +43-1-4277-9541, AT aut Guerra M. Department of Cytology and Genetics, Institute of Botany, University of Vienna, Rennweg 14, A-1030, Vienna, Austria e-mail: apedrosa@s1.botanik.univie.ac.at Fax: +43-1-4277-9541, AT aut https://doi.org/10.1007/s001220050047 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s001220050047 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pedrosa A. Department of Cytology and Genetics, Institute of Botany, University of Vienna, Rennweg 14, A-1030, Vienna, Austria e-mail: apedrosa@s1.botanik.univie.ac.at Fax: +43-1-4277-9541, AT aut NATIONALLICENCE 700 1- Schweizer D. Department of Cytology and Genetics, Institute of Botany, University of Vienna, Rennweg 14, A-1030, Vienna, Austria e-mail: apedrosa@s1.botanik.univie.ac.at Fax: +43-1-4277-9541, AT aut NATIONALLICENCE 700 1- Guerra M. Department of Cytology and Genetics, Institute of Botany, University of Vienna, Rennweg 14, A-1030, Vienna, Austria e-mail: apedrosa@s1.botanik.univie.ac.at Fax: +43-1-4277-9541, AT aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer