Plant rDNA database: ribosomal DNA loci information goes online.

Number, position and structure of the 5S and 18S-5.8S-26S ribosomal DNA (rDNA) loci are important species characteristics. In recent decades, we have witnessed accumulation of rDNA data, and there is a need to compile, store and analyse this information, and to make it accessible to a broader scientific community. An online resource, accessible at www.plantrdnadatabase.com , has been developed to accomplish these goals. Current knowledge regarding chromosomal rDNA sites is provided for more than 1,000 plant species (including more than 1,400 different accessions). The data comes from fluorescent in situ hybridisation experiments (FISH) from more than 300 publications. Additional information is also displayed, such as ploidy level, mutual arrangement of rRNA genes, genome size and life cycle. The webpage is intuitive and user-friendly, including different search options, and currently holds information published (or in press) up until January 2011; frequent updates are planned. We expect this database to be used for data-mining, analysing rDNAs from different angles, unit organisation, distribution, evolution and linkage of rDNA patterns with phylogenetic relationships.