Relation between co-expression within the central arraylets to co-expression in the microarray data. Panel A shows gene expression as measured in the arraylets defined by the GSVD using a set of genes described in the main text (green – low expression, red – high expression). Only the 200 transcripts whose expression profile in the central arraylets 5–7 (boxed) is closest to that of HvCslF3 (as measured by Euclidean distance) are shown. The expression profiles for the same genes, in the space spanned by arrays, are shown in panel B. Approximate co-expression can be seen for some tissues (e.g. expression in anther, caryopsis and endosperm tends to be low, while expression in root, radicle and coloeptile tends to be higher). At the top of panel B we indicate, for each tissue, the standard deviation of expression values among the genes shown on the plot, scaled with the corresponding quantity for the whole dataset; i.e. values larger (smaller) than one indicate larger (smaller) variability than average. As expected (see text), variability in expression is smallest in those tissues represented in both datasets.