Cloning and sequencing of the ribosomal RNA genes in maize: the 17S region.

The maize genes for the 17S, 5.8S, and 26S ribosomal RNAs (rRNAs) are located on chromosome 6 and consist of 9-kb sequences repeated about 5,000-10,000 times per 2C. One of these sequences was isolated from a lambda library containing maize Eco RI genomic segments. The sequence of the small-subunit (17S) RNA was determined using the M13 shotgun-dideoxy sequencing approach. The maize sequence was compared with nuclear rRNAs from yeast, Xenopus, and rat. Using these sequences, it is possible to identify tentatively the start and the end points of the sequence of the maize nuclear small subunit rRNA. This RNA has a length of 1809 nucleotides. The alignment of all four sequences for maximal homology allows us to identify regions within the rRNA that have been conserved during eukaryotic evolution.