Table 1. Top 10 Hexameric Sequence Elements Enriched in PBSs.

Rank	Motif	Exp.a	Obs.b	Ratioc	P Value (Enrichment)d	P Value (Distribution)e
PBS-Gs
1	CACGTG	52.69	1442	27.37	0	1
2	CGCGTG/CACGCG	15.54	145	9.33	1.36E-86	0.554
3	GCGCGT/ACGCGC	11.58	121	10.45	6.14E-78	0.369
4	CGCGCG	4.72	58	12.28	5.25E-42	0.0236
5	CACGTC/GACGTG	36.27	133	3.67	4.22E-35	0.7293
6	CGTGGC/GCCACG	29.04	116	3.99	4.83E-34	0.0140
7	TGACGT/ACGTCA	50.88	156	3.07	2.58E-32	0.115
8	GGGTCC/GGACCC	23.61	99	4.19	6.81E-31	0.744
9	GCGTGA/TCACGC	28.81	109	3.78	3.55E-30	0.865
10	ACGCGT	19.32	88	4.56	4.05E-30	0.0181
PBS-Ns
1	CGCGTG/CACGCG	11.00	83	7.55	1.28E-43	0.072
2	TGACGT/ACGTCA	36.01	136	3.78	3.93E-37	0.035
3	GCGCGT/ACGCGC	8.19	65	7.93	8.97E-36	0.145
4	CACGTC/GACGTG	25.67	87	3.39	1.97E-21	0.01
5	CACATG/CATGTG	79.28	172	2.17	1.42E-19	0.601
6	ACGCGT	13.67	54	3.95	1.43E-16	0.401
7	TGTCGT/ACGACA	44.02	104	2.36	1.10E-14	0.016
8	CGTCAT/ATGACG	39.66	94	2.37	1.64E-13	0.053
9	GACGTC	23.77	66	2.78	8.84E-13	0.482
10	CCACGT/ACGTGG	31.78	79	2.49	1.35E-12	0.127

^aMotifs expected in the Arabidopsis genome.

^bMotifs observed in PBS-Gs or PBS-Ns.

^cRatio of Exp. to Obs.

^dP value for motif enrichment (via binomial tests).

^eP value for comparing the distribution of G-boxes with each motif (via two-sample KS tests). P values ≤ 0.01 indicate the motifs whose distribution is significantly different from that of G-boxes.