HIGH CHROMOSOMAL INSTABILITIES IN SOMACLONES OF TWO INTERSPECIFIC ALLIUM-HYBRIDS
Multiple fluorescence in situ hybridization (FISH) and genomic in situ hybridization (GISH) were used in the karyotype analysis of Allium cepa (2n=2x=16; CC), A. ampeloprasum (2n=4x=32; AAAA), A. tuberosum (2n=4x=32; TTTT), and the hybrids onion x leek and onion x Chinese chive as well as somaclones of hybrids. Chromosomes were characterized after multiple FISH of 5S and 25S rDNA-gene specific probes, an onion-specific DNA probe of telomeric repeats and GISH of labelled onion-DNA. The measurement of chromosome length and position of FISH signals were done with a computer-aided image analysis. FISH signals of both rDNA probes showed species-specific positions and patterns in the classified chromosome types of number 6 (25S), 7 (5S) and 8 (25S) in A. ampeloprasum, A. tuberosum and their hybrids with A. cepa. Investigations on vegetative propagated descendants of two plants (sublines) derived from callus of a 24-chromosomic onion-leek hybrid (AAC) showed in subline 84/1d many chromosomal aberrations (deletions and translocations) predominantly in the two leek genomes of 30 analysed plants. Some abberations originated newly in a second somaclonal generation. In the second subline 84/1a a translocation between chromosome 8AS of leek and 2CL of onion was found to be stable in 5 somaclones of second generation. In all somaclones of the hybrid A. cepa x A. tuberosum (CTT) the numbers of chromosomes 3C, 5C and 6C were doubled and that of chromosomes 6T and 8T high variable. The use of these chromosome aberrations for physical localization of RAPD marker was discussed.
Schrader, O., Ahne, R., Budahn, H., Peterka, H. and Zhao, H. (2005). HIGH CHROMOSOMAL INSTABILITIES IN SOMACLONES OF TWO INTERSPECIFIC ALLIUM-HYBRIDS. Acta Hortic. 688, 85-92
onion, leek, chinese chive, interspecific hybrid, somaclone, FISH, GISH, tandem repeat, chromosome aberration