Expression analysis of PDI and PDI-like genes in developing caryopses. Relative (A, C and E) and absolute (B, D and F) quantification of the expression level in developing caryopses collected between 5 and 38 DPA (days post anthesis) of nine PDI and PDI-like genes. The 14 cDNA pools (two biological replicates, seven developing caryopsis samples) were tested in triplicate and normalized using the geometric average of the relative expression of the two reference genes encoding Cell division control protein and ADP-ribosylation factor. The relative expression levels of the nine genes (A, C and E) were referred to that of a calibrator set to the value one, which was represented by the developmental stage with the lowest expression. The absolute expression levels of the nine genes were expressed as number of cDNA copies per μg of reverse transcribed total RNA (B, D and F). Normalized values of relative and absolute expressions of the nine genes are given as average ± SD.