Table 2.

The evaluation of candidate reference genes with NormFinder and BestKeeper¹.

Method		Ranking order (better-good-average)
	Rank1	1	2	3	4	5	6	7	8	9	10
	Organs/seedlings2
NormFinder	Gene3	ARF	EF1α	COX	GAPDH	RPL2	Actin	H3	18S rRNA	Tubα	CYP
	M1	0.131	0.203	0.365	0.373	0.382	0.389	0.427	0.582	0.678	0.703
BestKeeper	Gene3	18S rRNA	CYP	COX	Actin	RPL2	ARF	EF1α	H3	GAPDH	Tubα
	SD	0.58	0.72	0.94	1.07	1.07	1.08	1.10	1.13	1.28	1.58
	Heat
NormFinder	Gene3	ARF	RPL2	EF1α	CYP	H3	GAPDH	COX	18S rRNA	Actin	Tubα
	M1	0.212	0.228	0.238	0.387	0.424	0.454	0.500	0.757	0.850	0.928
BestKeeper	Gene3	Actin	18S rRNA	GAPDH	RPL2	ARF	H3	EF1α	CYP	COX	Tubα
	SD	0.57	0.60	0.77	0.92	0.93	0.95	1.10	1.11	1.16	1.67
	CdCl2
NormFinder	Gene3	CYP	RPL2	ARF	EF1α	H3	GAPDH	COX	Actin	18S rRNA	Tubα
	M1	0.625	0.65	0.75	0.751	0.765	0.791	0.836	0.91	0.987	1.621
BestKeeper	Gene3	ARF	EF1α	CYP	Actin	18S rRNA	RPL2	H3	GAPDH	COX	Tubα
	SD	0.37	0.49	0.53	0.54	0.62	0.98	1.05	1.22	1.33	2.09
	NaCl
NormFinder	Gene3	EF1α	ARF	CYP	GAPDH	H3	COX	Actin	18S rRNA	RPL2	Tubα
	M1	0.201	0.213	0.251	0.275	0.304	0.324	0.426	0.492	0.496	0.852
BestKeeper	Gene3	18S rRNA	ARF	COX	EF1α	Actin	GAPDH	CYP	H3	RPL2	Tubα
	SD	0.24	0.32	0.34	0.38	0.39	0.45	0.61	0.66	0.86	1.24
	NaHCO3
NormFinder	Gene3	RPL2	Actin	CYP	GAPDH	H3	COX	ARF	EF1α	Tubα	18S rRNA
	M1	0.253	0.454	0.48	0.485	0.489	0.57	0.832	1.184	1.273	1.407
BestKeeper	Gene3	Actin	RPL2	H3	GAPDH	COX	CYP	18S rRNA	ARF	EF1α	Tubα
	SD	0.64	0.74	0.86	0.89	1.02	1.06	1.11	1.22	1.45	2.13
	Na2CO3
NormFinder	Gene3	ARF	H3	RPL2	CYP	EF1α	Actin	Tubα	18S rRNA	COX	GAPDH
	M1	0.284	0.297	0.298	0.366	0.413	0.432	0.455	0.469	0.473	0.523
BestKeeper	Gene3	COX	Actin	ARF	GAPDH	H3	Tubα	CYP	RPL2	EF1α	18S rRNA
	SD	0.36	0.38	0.68	0.7	0.76	0.85	0.89	0.89	0.92	1.03

¹Lower stability value M1 obtained by NormFinder or SD obtained by BestKeeper indicates higher stability of housekeeping genes under each condition and is marked with bold text. ²These samples include leaves, stems, roots, flowers, and seedlings, as well as the leaves and roots under heat (37°C for 0, 1, 2, 4, 6, 8, 12, 24, and 48 h), heavy metal (200 μM CdCl₂ for 0, 1, 3, 6, 12, 24, and 48 h), salt (200 mM NaCl for 0, 1, 3, 6, 12, 24, and 48 h), and alkali (200 mM NaHCO₃ or 100 mM Na₂CO₃, treated for 0, 1, 3, 6, 12, 24, and 48 h) treatments. Three biological replicates were taken for different organs/seedlings, as well as leaves and roots at each time point of all stress treatments. ³Names of candidate reference genes refer to Table 1.