An assessment of the phylogenetic relationship among sugarcane and relatedtaxa based on the nucleotide sequence of 5S rRNA intergenic spacers

5S rRNA intergenic spacers were amplified from two elite sugarcane (Sacchar um hybrids) cultivars and their related taxa by polymerase chain traction ( PCR) with 5S rDNA consensus primers. Resulting PCR products were uniform in length fi om each accession but exhibited some degree of length variation among the sugarcane accessions and related tars. These PCR products did not always cross hybridize in Southern blot hybridization experiments. These P CR products were cloned into a commercial plasmid vector PCR(TM) 2.1 and se quenced. Direct sequencing or cloned PCR products revealed spacer length of 231-237 bp for S. officinarum, 233-237 for sugarcane cultivars, 228-238 bp for S. spontaneum, 239-252 bp for S. giganteum, 385-410bp for Erianthus sp p., 226-230 bp for Miscanthus sinensis Zebra, 206-207 bp for M. sinensis IM P 3057, 207-209 bp for Sorghum bicolor, and 247-249 bp for Zea mays. Nucleo tide sequence polymorphism were found at both the segment and single nucleo tide level. A consensus sequence fur each taxon was obtained by Align X. Mu ltiple sequences were aligned and phylogenetic trees constructed using Alig n X, CLUSTAL and DNAMAN programs. In general, accessions of the following t axa tended to group together to form distinct clusters: S. giganteum, Erian thus spp., M, sinensis, S. bicolor, and Z. mays. However, the two S. offici narum clones and two sugarcane cultivars did not form distinct clusters but interrelated within the S. spontaneum cluster. The disclosure of these 5S rRNA intergenic spacer sequences will facilitate marker-assisted breeding i n sugarcane.