Identification of C-genome chromosomes involved in intergenomic translocations in Avena sativa L., using cloned repetitive DNA sequences

Four anonymous non-coding sequences were isolated from an Avena strigosa (A genome) genomic library and subsequently characterized. These sequences, d esignated As14, As121, As93 and As111, were 639, 730, 668, and 619 bp long respectively, and showed different patterns of distribution in diploid and polyploid Avena species. Southern hybridization showed that sequences with homology to sequences As14, and As121 were dispersed throughout the genome of diploid (A ge nome), tetraploid (AC genomes) and hexaploid (ACD genomes) Avena species but were absent in the C-genome diploid species. In contrast , sequences homologous to sequences As93 and As111 were found in diploid (A and C genomes), tetraploid (AC genomes) and hexaploid (ACD genomes) specie s. The chromosomal locations of the 4 sequences in hexaploid oat species we re determined by fluorescent in situ hybridization and found to be distribu ted over the length of the 28 chromosomes (except in the telomeric regions) of the A and D genomes. Furthermore, 2 C-genome chromosome pairs with the As14 sequence, and 4 with As121. were discovered to be involved in intergen omic translocations. These chromosomes were identified as 1C, 2C, 3C and 16 C by combining the As14 or As121 sequences with two ribosomal sequences and a C-genome-specific sequence as probes in fluorescence in situ hybridizati on. These sequences offer new tools for analyzing possible intergenomic tra nslocations in other hexaploid oat species.