ethylene treatment
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).