A CONSERVED SEQUENCE IN INTERNAL TRANSCRIBED SPACER-1 OF PLANT NUCLEAR RIBOSOMAL-RNA GENES

A highly conserved sequence was found in rRNA gene internal transcribe d spacer 1 (ITS1) among flowering plant species. The sequence, GGCRY-( 4 to 7 n)-GYGYCAAGGAA (where Y = C or T; R = G or A) is located in the central region of ITS1, and is present in published sequences from a wide range of flowering plants. The rest of ITS 1 is highly variable i n sequence. Therefore, the conserved motif within ITS 1 may have a key function in the processing of rRNA gene transcripts. Furthermore, ide ntification of such a conserved motif will help facilitate alignment o f sequences for phylogenetic analysis.