title: small RNAs citrus protoplast
design: Total RNA was extracted from the callus-derived protoplast of Citrus reticulata Blanco using the Trizol regent separately following the manufacturerĄŻs instructions. The RNA quality was examined by gel electrophoresis and Bioanalyzer (Agilent2100). Small RNAs with 16-30nt in length were separated from the total RNAs by size fractionation with polyacrylamide gel electrophoresis. After PAGE purification and ligation of adaptors to their 5' and 3' ends, the small RNAs were reverse transcribed to cDNA using Superscript ˘ňreverse transcriptase (Invitrogen). The amplified products were purified by gel electrophoresis and sequenced via the Illumina Genome Analyzer at the Beijing Genomics Institute (BGI, Shenzhen, China).