Symbiodiniaceae ITS2 rDNA metabarcoding
The region of the internal transcribed spacer 2 (ITS2) nrDNA (~ 400 bp) was amplified by PCR with the specific primers SYM_VAR_5.8S2 and SYM_VAR_REV (Hume et al., 2018) linked to Illumina adapters following the 16S Metagenomic Sequencing Library Preparation Illumina protocol. Amplifications in triplicate were pooled and PCR clean-up was performed with the ProNex System. Illumina indexing primers (Nextera XT Index Kit  96 indexes, 384 samples) were added to 5 L of mixed purified PCR products, according to the manufacturer instructions. The products pooled in equimolar amounts (4 nM) and sequenced on the Illumina MiSeq platform using a MiSeq Reagent Kit v2 (500-cycles) paired-end run with 25% PhiX.