Comparative analysis of two dna extraction protocols from fresh and dried wood of Cunninghamia lanceolata (Taxodiaceae)

Abstract

DNA was isolated from the sapwood, transition wood and heartwood of fresh and dried Cunninghamia lanceolata wood using two DNA extraction protocols: the modified CTAB method and the modified Qiagen kit. Our major objective was to (i) determine an optimized method for retrieving good quality and sufficient quantity of DNA from wood, and to (ii) investigate the effect of different radial positions of fresh and dried wood for DNA extraction. In comparison with the modified CTAB method, a greater quantity of higher quality DNA - both chloroplast and nuclear ribosomal DNA - was retrieved using the Qiagen kit protocol. The chloroplast DNA regions retrieved from both fresh and dried wood were successfully amplified using both protocols, but the PCR amplification for the rDNA-ITS region from the heartwood failed using both protocols. The quantity and purity of the DNA from the sapwood and transition wood (derived from nuclei and plastids in the parenchyma cells) was greater than that from the heartwood (derived mainly from amyloplasts). Due to the influence of the drying treatment, the quantity of DNA decreased by more than 50%. The optimized radial position for DNA extraction in the stem was demonstrated based on anatomical observation.