Table 2.

Candidate reference genes ranked according to their expression stability as determined by NormFinder.

Root		Stem		Leaf		Different organs		PLBs		Microtubers
Ranking	Stability value	Ranking	Stability value	Ranking	Stability value	Ranking	Stability value	Ranking	Stability value	Ranking	Stability value
GUSB	0.011	UBQ	0.005	PP2A	0.007	GUSB	0.009	MDH	0.012	GUSB	0.008
EF1-α	0.004	MDH	0.004	GAPDH	0.006	ACT	0.008	EF1-α	0.011	GAPDH	0.006
GAPDH	0.004	TIP41	0.003	APT	0.005	APT	0.006	TIP41	0.009	TIP41	0.004
APT	0.003	GAPDH	0.003	TIP41	0.005	UBQ	0.006	PP2A	0.008	PP2A	0.004
UBQ	0.003	TUB	0.002	GUSB	0.004	MDH	0.005	GUSB	0.006	TUB	0.003
MDH	0.002	ACT	0.002	ACT	0.003	GAPDH	0.005	GAPDH	0.006	UBQ	0.003
TUB	0.002	EF1-α	0.002	TUB	0.003	TUB	0.001	APT	0.004	ACT	0.002
ACT	0.001	PP2A	0.001	EF1-α	0.003	PP2A	0.001	UBQ	0.002	EF1-α	0.002
PP2A	0.001	APT	0.001	MDH	0.003	EF1-α	0.001	TUB	0.002	MDH	0.002
TIP41	0.001	GUSB	0.001	UBQ	0.003	TIP41	0.001	ACT	0.001	APT	0.001
Best combination	Stability value	Best combination	Stability value	Best combination	Stability value	Best combination	Stability value	Best combination	Stability value	Best combination	Stability value
PP2A/TIP41	0.001	APT/GUSB	0.001	MDH/UBQ	0.002	EF1-α/TIP41	0.000	ACT/TUB	0.001	ACT/APT	0.001
Most stable	Stability value	Most stable	Stability value	Most stable	Stability value	Most stable	Stability value	Most stable	Stability value	Most stable	Stability value
TIP41	0.001	GUSB	0.001	UBQ	0.003	TIP41	0.001	ACT	0.001	APT	0.001