Trizol法 After the samples were qualified, the eukaryotic mRNA was enriched with magnetic beads with Oligo dT. mRNA was then randomly interrupted by fragmentation buffer. Using mRNA as template, the first strand of cDNA was synthesized with six-base random hexamers, and then the second strand of cDNA was synthesized by adding buffer, dNTPs and DNA polymerase I. AMPure XP beads were then used to purify double-stranded cDNA. The purified double-stranded cDNA was then end-repaired, A tail was added and sequencing joints were connected. Then AMPure XP beads were used for fragment size selection, and finally PCR enrichment was performed to obtain the final cDNA library.