A modified non-liquid nitrogen protocol for extraction of high-quality genomic DNA from the inner bark tissues of Dalbergia cochinchinensis (Fabaceae)
Dalbergia cochinchinensis (Fabaceae) is known as Thai rosewood. It is a Thai native and widespread throughout Thailand. Due to it being a hardwood tree, it became a valuable hardwood tree species for its commercial value for luxury furniture and as a first-class prime timber, which has made it a potentially endangered species. For genetic studies of this tree, we tested four protocols of genomic DNA extraction from the inner bark based on the sodium dodecyl sulfate method and two protocols of the cetyltrimethyl ammonium bromide method, . We evaluated the quantity, purity, and integrity of the extracted genomic DNA from 15 genotypes of D. cochinchinensis using PCR amplification and restriction enzyme digestion to develop a protocol for this species. We found that optimal concentrations of lithium chloride and polyvinylpyrrolidone could improve the quantity and quality of DNA in the extraction buffer without using liquid nitrogen. The highest concentration of high-quality DNA was obtained with protocol M5 (392 ng/µL DNA and a purity ratio of A260/A280 equal to 1.96). In contrast, the commercial Nucleospin Plant II Mini Kit provided the lowest yield of 13.94 ng/µL DNA, with a low purity ratio of A260/A280 (1.58). Start codon targeted \ and sequence-related amplified polymorphism fingerprints further demonstrated that protocol M5 developed for inner bark tissue samples gives good DNA quality and quantity for genetic studies of D. cochinchinensis.