Table 3.

Ranking of the reference gene and their expression stability values calculated by Normfinder

Ranking order	Species and cultivars of Forsythia		Organs of Forsythia plants		Developmental stages of Forsythia flower buds		Forsythia flower plants		Developmental stages of Forsythia fruits		Leaves of Forsythia plants treated with ABA		Leaves of Forsythia plants treated with PEG
	Gene	Stability	Gene	Stability	Gene	Stability	Gene	Stability	Gene	Stability	Gene	Stability	Gene	Stability
1	TIP	0.174	GAPDH	0.664	TIP	0.137	SDH	0.104	ACT	0.132	ACT	0.324	G6PD	0.036
2	UKN1	0.290	SDH	1.039	ACT	0.220	UKN1	0.139	TIP	0.140	TIP	0.491	UKN1	0.132
3	G6PD	0.323	G6PD	1.109	SDH	0.220	ACT	0.212	UKN1	0.143	PTB	0.533	SDH	0.182
4	ACT	0.410	PTB	1.182	G6PD	0.256	PTB	0.267	G6PD	0.148	UKN1	0.537	TIP	0.546
5	TUB	0.497	UKN1	1.357	UKN1	0.430	TIP	0.388	ABCT	0.263	G6PD	0.553	ACT	0.593
6	CYP	0.566	F-Box	1.488	CYP	0.561	TUB	0.524	PTB	0.341	SDH	0.591	MTP	0.647
7	SDH	0.626	TIP	1.803	GAPDH	0.818	MTP	0.575	MTP	0.397	TUB	0.665	TUB	0.700
8	PTB	0.724	ABCT	1.822	PTB	0.926	F-Box	0.641	SDH	0.432	MTP	0.912	CYP	0.792
9	F-Box	0.996	ACT	2.139	MTP	0.980	ABCT	0.901	F-Box	0.663	CYP	1.071	PTB	0.941
10	MTP	1.017	MTP	2.214	TUB	1.111	G6PD	0.912	TUB	1.071	F-Box	1.212	F-Box	1.096
11	GAPDH	1.732	CYP	2.252	F-Box	1.321	CYP	0.932	CYP	1.147	GAPDH	1.355	GAPDH	1.738
12	ABCT	2.337	TUB	2.503	ABCT	1.417	GAPDH	1.283	GAPDH	1.909	ABCT	2.268	ABCT	2.108

Stability values was calculated by Normfinder and the smaller the stability value, the more suitable it is as reference gene