geNorm–based ranking of the putative reference genes. (A) Genes were ranked from the least stable (on the left) to the most stable (on the right) according to their M value (Y axis). This classification was independently performed by using different sets of conditions: the ‘All conditions’ included the whole set of culture conditions studied by RT-qPCR in this work; the ‘C sources’ subset gathered the 18 samples obtained from growth on different sugars; the ‘Stress’ subset corresponded to 6 samples harvested during stress exposition; the ‘Germination’ subset included the 6 germination time points. For each set of conditions, the result of the classification was given below the X-axis (arbitrary colours attributed to each gene for the sake of clarity). (B) Result of the pairwise variation analysis between NFn and NFn+1 to determine the optimal number of genes for reliable normalization. Values below the 0.15 threshold mean that n genes might be sufficient.