title: Identification of Taxus microRNAs with high-throughput sequencing
design: Total RNA was extracted from the fresh leaves of  pot-cultivated T. mairei using Trizol (Invitrogen, Beijing,  China). The samples were then subjected to 15% denaturing  polyacrylamide gel electrophoresis (PAGE), after  which the small RNA fragments of 18–30 nucleotides  (nts) were isolated from the gel and purified. Next,  the small RNA molecules were ligated to a 5  adaptor  and a 3  adaptor sequentially and then converted  to DNA by reverse transcription polymerase chain  reaction (RT-PCR) (Fig. S1). Finally, approximately 20  μg products of RT-PCR were sequenced directly using  Illumina HiSeq 2000 according to the manufacturer’s  protocols.