[BioC] ToggleProbe() and Arabidopsis annotation file ath1121501.db.

[Song Li]

Hi All,

I was loading Arabidopsis ath1121501.db package using some old code to
check my results from several years back. I got the following message:

"""
Warning: All Arabidopsis packages now require you to use the
  toggleProbes() method in order to expose multiple mappings.
"""

I googled and find in the AnnotationDbi document:

"""
In many probe packages, some probes are known to map to multiple genes.
The reasons for this can be biological as happens in the arabidopsis packages,
"""

My question is:

1) What is happening  biologically in the Arabidopsis package?
2) Does the warning message means that if I don't use "toggleProbes()"
I only get probes that map to single gene? Is this true for other
packages?

Thanks,
Song Li
-- 
Postdoctoral Associate
IGSP
Duke University