N2 genomic DNA
The genomic DNA of each sample was randomly sheared into short fragments of about 350 bp, respectively. The obtained fragments were subjected to library construction using the NEBNext DNA Library Prep Kit, with strictly following the instructions. Briefly, as followed by end repairing, dA-tailing, and further ligation with NEBNext adapter, the required fragments (in 300-500 bp size) were PCR enriched by P5 and indexed P7 oligos. After purification and subsequent quality check, the resulted library is ready for sequencing.