design: Total RNA was extracted using a Trizol RNA extraction kit (TaKaRa, Dalian, China) and treated with DNase I (TaKaRa, Dalian, China). The ribosomal RNA-depleted RNA-Seq library was constructed and sequenced using the Nova-PE150 strategy by Novogene Company, Beijing. The cDNA library was subjected to a paired-end (150 bp) sequencing analysis using the HiSeq 2500 platform (Illumina, USA) and raw reads were obtained.