The pooled PCR products were sequenced using a modified protocol for the Ion ProtonTM system (Thermo Fisher Scientific, Waltham, MA, United States). Briefly, the sequencing library was created by end-polishing the barcoded PCR products, followed by adapter ligation and amplification. The resulting library was quantified and its quality accessed with the Agilent Bioanalyzer (Agilent Technologies, Santa Clara, CA, United States). Eight microliters of the 100 pM library were then applied to Ion Sphere Particles to prepare the sequencing template. The template was amplified using Ion OneTouch 2. The Ion Sphere Particles with the amplified template were loaded onto an IonPI® chip and sequenced on the Ion Proton system per manufacturer’s instructions. Approximately, 41 million reads were generated from each sequencing run. Raw reads were generated as fastq files for bioinformatic analysis. Sequencing data has been made publicly available through GEO (Accession No. GSE111845).
