DNA Barcodes for Wood Identification of Anatomically Similar Species of Genus Chamaecyparis

Abstract

The genus Chamaecyparis comprises seven species (C. formosensis, C. hodginsii, C. lawsoniana, C. nootkatensis (Callitropsis nootkatensis), C. obtusa, C. pisifera, and C. thyoides). Accurate species identification is necessary for proper use and economic value of wood. Species identification of woods is generally based on anatomical analysis; however, C. obtusa and C. pisifera wood have similar microscopic morphology, which makes species identification impossible. Therefore, the molecular identification of species in wood of the genus Chamaecyparis is required. In this study, six candidate DNA barcode genes (trnP-GGG, ycf1b, clpP, accD, ycf2, and rps16) in the chloroplast of Chamaecyparis were identified with nucleotide diversity values higher than the arbitrary value of 0.02. Each gene was evaluated for species identification using phylogenetic analysis by genes registered at NCBI (42 sequences each for trnP-GGG, ycf1b, clpP, accD, and ycf2, and 50 sequences for rps16). The genes trnP-GGG, clpP, and rps16 could not be distinguished between C. pisifera and C. formosensis. However, ycf1b, accD, and ycf2 could be distinguished between all Chamaecyparis species. These results suggest the use of the chloroplast genes ycf1b, accD, and ycf2 as DNA barcodes for species identification in Chamaecyparis, including C. obtusa and C. pisifera, based on the reported genetic information to date.