Submission of gene expression data to the Gene Expression Omnibus is now a requirement of publication in most journals, so it is an extremely valuable resource. It is also extremely big, and full of data that isn’t relevant to your question or task at hand – but it is easy to find the right data using the search bar if you follow a few rules. There are example searches on the GEO homepage.
To find data relating to Arabidopsis thaliana, search: (Arabidopsis thaliana[organism])
To find Arabidopsis microarray data, search: (Arabidopsis thaliana[organism]) AND “expression profiling by array”
The easiest way to find other Arabidopsis datasets is to search: (Arabidopsis thaliana[organism]). On the left hand side of the window, there is a ‘Study type’ section. If you click on ‘More…’ a list of study types pops up from which you can select the data type you are looking for (see screen shot below).
You can add any search term you like to the search bar. For example, you could specify author, publication time, types of tissue or stress… or any combination of these. Just keep adding AND in between each term. For example: (Arabidopsis thaliana[organism]) AND “expression profiling by array” AND leaf
GEO provides an informative guide to how to download original records or curated datasets individually or in bulk. You can download data directly from Accession Viewer pages (eg this one) in SOFT, MINiML or TXT formats. Raw data is also available in TAR. You can also do bulk downloads via GEO’s FTP site. All files are compressed using gzip.
It’s also possible to access GEO programmatically in order to, for example, quickly retrieve CEL files from Arabidopsis stress experiments. Again, GEO provide a guide to this, although this is probably something better tackled with some pre-existing knowledge of programming.
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