design: Total RNA was obtained from floret frozen powder (100mg) using RNeasy Plant Mini Kit (Qiagen), digested by RQ1 DNase (Promega) and purified by standard procedures (phenol/chloroform treatment and sodium acetate/isopropanol precipitation). RNA was checked for quality (agarose gel electrophoresis; A260/A280 ratio >1.8; NanoDrop ND-1000, Thermo Fisher Scientific) and integrity (RIN>8; BioAnalyzer 2100, Agilent Technologies). cDNA libraries were prepared using the Universal Plus mRNA-Seq kit (Tecan Genomics, Redwood City, CA) and assessed with a Qubit 2.0 fluorometer (Invitrogen, Carlsbad, CA) and the Agilent Bioanalyzer DNA assay. Sequencing was performed on the NovaSeq 6000 (Illumina, San Diego, CA) in paired-end 150 bp mode. Primary bioinformatic analysis includes base calling, demultiplexing and adapter masking (Illumina BCLConvert v3.9.31).