design: 2-step PCR with first reaction using 1:1 mixture of forward primers S615F_Cerco (GTTAAAAAGCTCGTAGTTG) and S615F_Phyt (GTTAAAARGCTCGTAGTCG) and a single reverse primer S963R_Phyt (CAACTTTCGTTCTTGATYAAA); the second reaction with primers S615F_Cer (GTTAAAARGCTCGTAGTYG) and reverse S947R_Cer (AAGARGAYATCCTTGGTG).  PCRs were performed in triplicate, cleaned using a Qiagen MinElute Purification kit. Libraries were prepared using a TruSeq DNA PCR-free LT Kit (Illumina)