design: Petals from 10-20 floral buds at FB5 were dissected and collected. Total RNA was extracted using Trizol Reagent (Invitrogen, Carlsbad, CA). rRNA depleted mRNAs were prepared by the Ribo-Zero Gold rRNA Removal Kit. All RNA sequencing libraries were constructed using the NEBNext Ultra Directional RNA Library Prep Kit. The double-strand cDNA libraries were sequenced on an Illumina Hi-Seq 2000 sequencing platform.