Each genomic DNA sample, amounting to 1 microg, was randomly fragmented using an ultrasonic processor (Covaris, US). The resulting fragmented DNA molecules then underwent an extensive series of procedures. Initially, these fragments were subjected to end repair treatment utilizing the End Repair Mix, which encompassed end repairing, 5'-phosphorylation, dA-tailing, and subsequent purification steps. Then, the repaired DNAs were then ligated with Illumina adaptors using a T-A ligation method to adenylate their 3' ends.