Molecular identification of Fitzroya cupressoides, Sequoia sempervirens, and Thuja plicata wood using taxon-specific rDNA-ITS primers

Abstract

The nuclear ribosomal DNA internal transcribed spacer (rDNA-ITS) region was PCR amplified and sequenced from the wood of three specimens of Fitzroya cupressoides, nine specimens of Sequoia sempervirens, and ten specimens of Thuja plicata. The full lengths of the ITS regions are 1110 bp for F. cupressoides, 1096 bp for S. sempervirens, and 1138 bp for T.plicata, and thus in the range of 975 bp to 1125 bp which is reported for members of the Cupressaceae. Length variation of ITS regions is due to differences in the length of the spacer region ITS 1. Intraspecific variations of the sequences of rDNA-ITS regions were one bp in F. cupressoides, and 18 bp in S. sempervirens and T. plicata. Based on the interspecific sequence divergence of the ITS region, taxon-specific primers were designed for the detection of F. cupressoides, S. sempervirens and T. plicata.The primer sequences were selected from the highly divergent ITS 1 spacer. The specificity of the primers was checked by lengths and sequence of the amplicons, and the primers detected the target organism, solely, across 40 conifer species. Our data establish the molecular basis for DNA-based wood identification in these species.