library_construction_protocol: 0.5 g of ten-day-old seedlings were ground with mortar and pestle in liquid nitrogen and homogenized in 10 mL of nuclei isolation buffer (0.25 M sucrose, 15 mM PIPES pH 6.8, 5 mM MgCl2, 60 mM KCl, 15 mM NaCl, 1 mM CaCl2, 0.9% Triton X-100, 1 mM PMSF, 1 X proteinase inhibitors Cocktail) for 15 min on ice. Debris were filtered through two layers of miracloth to get nuclei suspension, which was then cold centrifuged at 4,000 g for 10 min. Nuclei were resuspended in 500 µL of TM2 (50 mM Tris-HCl, 2 mM MgCl2, 0.25 M sucrose, 1 mM PMSF, 1 X proteinase inhibitors Cocktail). After cold centrifugation at 4,000 g for 5 min, nuclei were resuspended in 400 µL of MNase digestion buffer (50 mM Tris-HCl pH 7.5, 5 mM CaCl2, 0.25 M sucrose, 1 mM PMSF, 1X proteinase inhibitors Cocktail) with 1000 U/mL final concentration of MNase (New England Biolabs) and incubated at 37°C with agitation (1000 rpm on Thermomixer) for 10 min. Digestion was stopped by adding 40 µL of  0.5 mM EDTA and 20 µL of  10% SDS. Proteinase K and RNase A were added to remove proteins and RNAs before Phenol-chloroform extraction to get DNA. follow the instructions of Ovation Ultralow System V2 (Nugen) kit