The National Center for Biotechnology Information (NCBI) provides a data-rich environment in support of genomic research by collecting the biological data for genomes, genes, gene expressions, gene variation, gene families, proteins, and protein domains and integrating the data with analytical, search, and retrieval resources through the NCBI Web site. Entrez, an integrated search and retrieval system, enables text searches across various diverse biological databases maintained at NCBI. Map Viewer, the genome browser developed at NCBI, displays aligned genetic, physical, and sequence maps for eukaryotic genomes including those of many plants. A specialized plant query page allows maps from all plant genomes available in the Map Viewer to be searched to produce a display of aligned maps from several species. Customized Plant Basic Local Alignment Search Tool (PlantBLAST) allows the user to perform sequence similarity searches in a special collection of mapped plant sequence data and to view the resulting alignments within a genomic context using Map Viewer. In addition, pre-computed sequence similarities, such as those for proteins offered by BLAST Link (BLink), enable fluid navigation from un-annotated to annotated sequences, quickening the pace of discovery. Plant Genome Central (PGC) is a Web portal that provides centralized access to all NCBI plant genome resources. Also, there are links to plant-specific Web resources external to NCBI such as organism-specific databases, genome-sequencing project Web pages, and homepages of genomic bioinformatics organizations.