The DNA (200 ng) was digested using BcgI restriction enzyme (NEB, America) at 37C for 3 hours. Then, the above digestion products were ligated to the adaptors (Ada1, Ada2) overnight at 4using T4 DNA ligase (NEB, America). Subsequently, the above ligation products were amplified by PCR using Phusion High Fidelity DNA polymerase (NEB, America). The obtained PCR products were purified with QIAquick PCR purification kit (Qiagen, CA) and then sequenced with the Illumina Nova PE155 platform.