Evaluation of reference genes for real-time RT-PCR expression studies in the plant pathogen Pectobacterium atrosepticum

Table 2 Ranking of reference genes by geNorm

Genes	Average expression stability M	Pairwise variations V
ffh	0.334	-
recA	0.334	0.118
proC	0.371	0.166
gyrA	0.533	0.288
16S	0.909	-

Ranking of the most stably expressed genes from top to bottom and determination of the optimal number of genes needed for normalisation. The average expression stability value M was obtained by calculating the M for each gene and excluding the gene with the highest M (lowest stability) for the next calculation round. The optimal number of reference genes needed for normalisation is determined by the pairwise variation (V) between the normalisation factors. The cut-off value of V was set to 0.15, below which the inclusion of another reference gene has no significant effect, as suggested by Vandesompele et al. [6].

ISSN: 1471-2229