RNA was harvest using Trizol reagent (Qiagen)，1µg of total RNA was used for the construction of sequencing libraries. 1. Take a certain amount of total RNA samples, and use oligo dT beads to enrich mRNA with poly Atail;2. mRNA molecules were fragmented into small pieces;3. The fragmented mRNA was synthesized into first strand cDNA using random primers;4. The second strand cDNA was synthesized;5. The synthesized cDNA was subjected to end-repair and 3' adenylated. Adaptors were ligated tothe ends of these 3' adenylated cDNA fragments;6. PCR amplification and purification;7. Library quality control;8. Library circularization;9. The library was amplified to make DNA nanoball (DNB);10. Sequencing on DNBSEQ (DNBSEQ Technology) platform.