Data on pre-processed gene expression levels in Arabadopsis thaliana plants as measured by Affymetrix microarray technology Data relate to 12 arrays, three of which are allocated to each of four treatments in a two-by-two factorial design: strain (calcium-resistant or wild-type); calcium challenge (low or high) Rows (1 to 22810) correspond to genes Column 1 gives the name of each gene Columns 2 to 13 correspond to arrays as follows: 2 to 4: calcium-resistant strain, low calcium challenge 5 to 7: calcium-resistant strain, high calcium challenge 8 to 10: wild-type strain, low calcium challenge 11 to 13: wild-type strain, high calcium challenge