title: control
design: Total RNA was extracted using hot borate method from sepals, petals and receptacles, and using hot phenol method from stamens and gynoecia as described previously (Wan and Wilkins, 1994; Xue et al., 2008). Poly (A)+ RNA was isolated with a Poly attract mRNA isolation system (Promega, Madison, WI ) and was used to synthesize the first strand cDNA using SuperScript ? reverse transcriptase and d(T)18VN primers (Invitrogen, Carlsbad, CA, USA). Second-strand cDNA was synthesized by nick translation with E. coli DNA ligase, E. coli DNA Polymerase I and RNase H (Invitrogen, Carlsbad, CA, USA). The double-stranded cDNA (ds cDNA) was purified with Qiagen PCR clean up kit (Qiagen, Hilden, Germany) and was subjected to 454 GS-FLX platform for transcriptome sequencing (Roche 454 Company, CT, USA).