454 sequencing
RiboMinus Eukaryote Kit for RNA-Seq (Invitrogen) was used to deplete ribosomal RNA from pooled total RNA. Approximately 10 *g of processed total RNA were used for cDNA synthesis using M-MLV RTase cDNA Synthesis kit (TaKaRa, Dalian, China). A total of 10 *g cDNA were used for sequencing library construction at Beijing Institute of Genomics, Chinese Academy of Sciences as manufactory’s procedures.