Chimonanthus praecox open flower stage
For each stage, three individual flowers from three individual plants were randomly chosen and total RNA samples were extracted from each flower by using RNA isolation kits (W6771; Watson Biotechnologies Inc.).The quality and quantity of total RNA was analyzed using an UltrasecTM 2100 pro UV/Visible Spectrophotometer (Amersham Biosciences, Uppsala, Sweden) and gel electrophoresis. Then, samples of three individuals were pooled within each stage in equal amounts to generate one mixed sample per stage by RNA pooling. These three mixed RNA samples of each flower stage were subsequently used in cDNA library construction and Illumina deep sequencing.  Three cDNA libraries were prepared following TruSeqTM RNA sample preparation Kit from Illumina (San Diego, CA USA), using 5μg of total RNA. Shortly, messenger RNA was isolated with polyA selection by oligo (dT) beads and and fragmented using fragmentation buffer. cDNA synthesis, end repair, A-base addition and ligation of the Illumina-indexed adaptors were performed according to Illumina’s protocol. Libraries were then size selected for cDNA target fragments of 300–500 bp on 2% Low Range Ultra Agarose followed by PCR amplified using Phusion DNA polymerase (NEB) for 15 PCR cycles. After quantified by TBS380, Paired-end libraries were sequenced with the Illumina HiSeqTM 2000 (2 × 100bp read length) in Shanghai Majorbio Bio-pharm Biotechnology Co., Ltd. (Shanghai, China).