Table 1.

Ranking of the candidate reference genes, listed from most to least stable, in the samples from grapevine somatic embryo aggregates cultured in DM1 differentiation medium, as based on the geNorm, NormFinder and BestKeeper software programs

Rank order	geNorm		NormFinder		BestKeepera
	Gene name	M value	Gene name	Stability value	Gene name	Pearson correlation (r)
1	EF1-α(m)	0.346	EF1-α(m)	0.115	UBQ-L40	0.978
2	GAPDH(m)	0.346	GAPDH(m)	0.155	EF1-α(m)	0.963
3	AP47	0.411	AP47	0.212	GAPDH(m)	0.951
4	MDH(m)	0.465	TIP41	0.277	α-Tubulin	0.934
5	UBQ-L40	0.490	EF1-α	0.290	AP47	0.924
6	EF1-α	0.517	UBQ-L40	0.316	UBQ-10(m)	0.923
7	TIP41	0.539	MDH(m)	0.341	MDH(m)	0.911
8	α-Tubulin	0.566	UBQ-10(m)	0.374	EF1-α	0.905
9	UBQ-10(m)	0.588	SAND	0.389	TIP41	0.847
10	SAND	0.620	α-Tubulin	0.448	SAND	0.785
11	PP2A	0.654	PP2A	0.478
12	Actin	0.690	Actin	0.508
13	β-Tubulin	0.732	β-Tubulin	0.656
14	UBC	0.789	UBC	0.702
15	Cyclophilin	0.843	Cyclophilin	0.725

^aBestKeeper is able to analyze a maximum of ten genes; therefore, the five worst-ranked candidates in previous analyses by geNorm and NormFinder (PP2A, Actin, β-Tubulin, UBC and Cyclophilin) were excluded from the studied data sets