A visit to PhenotypeDB is like a tour through a seed catalogue full of bizarre and unusual maize mutants. But, to maize geneticists, these mutants are more than curiosities; they are the tools of their trade. At PhenotypeDB, researchers can shop for the kinds of plants that will further their particular research goals. To see how a researcher might patronize this online store, try the following exercises:

• Check out some tassel mutants
• Find all adult dwarf mutants
• Find plants with mutant ear, seedling and adult traits
• Access genetic sequence data for a mutant

A researcher interested in maize reproduction might want to peruse the bizarre male flowers photographed by the MGDP team. First, go to the ZmDB Mutant Phenotype Browser page Scroll down to the area titled "Adult Mutant Phenotype Categories." Under "phenotype," select tassel; check the "picture" box, and click "Search." Up pops a table with photos of plants with mutant tassels. Click on a photo to enlarge it. The tassel of the Grid A, row 60, column 5 plant droops; that from Grid C, row 33, column 18 has no branches low down; the one from Grid C row 34, column 4 has small or short tassel branches; and the Grid E, row 19, column 35 tassel is unbranched. The genes for these kinds of traits can help researchers understand maize flowering.

Rather than researching mutations in one plant part, a researcher might want to find all plants exhibiting a very specific mutation. To do so, she would start at the Phenotype Lists page of PhenotypeDB. This index defines the terms and abbreviations used to describe all the mutant phenotypes in the database. Select Adult Vegetative Abbreviations, and find the dwarf phenotypes. Clicking on the highlighted phenotype "dwf" transports you to the Locations Search page. Clicking on "start search" builds a table of all the plants carrying the dwf descriptor. From this result, a researcher could order seed for dwarf plants or refine the search to only specific types of dwarf plants.

Some plants exhibit unusual traits at every stage of development – seed, seedling, and adult. Such plants interest researchers because, if a single mutation causes all the observed traits, the altered gene is likely important throughout the plant's lifetime. To find such plants, start at the Location Search page. Check the boxes for "Seed URM," "Seedling URM," and "Adult URM." A table pops up listing several plants that have unique recessive mutations at each of these stages. Click on the grid letter to see a description of the mutations. For definitions of the various abbreviations, hop to the Phenotype Lists page.

PhenotypeDB also connects genetic sequences to rows and columns of grid plants. In the Mutant Browser, under Seed and Ear Mutant Phenotype Categories, scroll to "Defective Size or Kernel," and Grid "G." Check the "picture" box, and click search. The resulting table shows defective kernels in Grid G (one of the grids for which sequencing has been completed). Clicking on the grid letter for one of the items opens a table describing that plant. At the bottom of that table, hit "Click to search all RescueMu GSS generated from this row." Up pops a list of several hundred GenBank identifiers. These are the genomic survey sequences (GSSs) found when the MGDP sequenced RescueMu-tagged DNA from leaves of plants in this row of Grid G (learn more).

Clicking on any of the GenBank numbers will bring up a table describing the source of that data. Click on the GenBank number in that page and you'll get the actual genetic sequence (Cs, Gs, As and Ts). This sequence can be copied and pasted into various database tools that will compare it to other sequences of interest. For example, a researcher interested in all waxy seeds might compare all the sequences for such seeds found in PhenotypeDB. Such a comparison might turn up a common sequence that explains the mutant trait.

In cases where columns have been sequenced (in addition to rows), researchers can match RescueMu-tagged DNA to a specific plant (a row/column address) -- useful information if the RescueMu tag caused an observed mutant trait (learn more).