Six-day-old WT and #5 seedlings were snap freezing and ground with liquid nitrogen and then dissolved in 400 µL of lysis buffer (20 mM Tris·HCl, pH 7.4, 150 mM NaCl, 5 mM MgCl2, 1 mM DTT, 100 µg/ml cycloheximide, and 1% [v/v] Triton X-100). The samples were incubated on ice for 10 min, centrifugated at 20,000g for 10 min at 4 ℃. For footprint preparation, 10 µL of RNase I (NEB) and 6 µL of DNase I (NEB) were added to 400 µL of lysate and incubated for 45 min at room temperature with gentle mixing. Illumina HiSeq 2500