Evaluation of five protocols for DNA extraction from leaves of Malus sieversii, Vitis vinifera, and Armeniaca vulgaris.

Leaves of Malus sieversii, Vitis vinifera, and Armeniaca vulgaris contain substantial amounts of secondary metabolites, which limit the high-quality DNA extraction performance. In this study, five extraction protocols were compared for their ability to produce good quality DNA from fresh and dried (with silica gel) leaves of these species. The modified protocol of Dellaporta et al., using polyvinylpyrrolidone to bind the phenolic compounds and a high molar concentration of potassium acetate to inhibit co-precipitation of polysaccharides with DNA, produced the best DNA quality for all species tested. DNA extracted by this method had a 1.77-1.96 A260/280 nm ratio and successful amplification of the 18S ribosomal DNA gene. DNA concentrations of dried leaves were lower than those obtained from fresh leaves, which was likely due to aspects of the drying procedure. All five methods for grapevine produced DNA of obvious better quality from green canes compared to leaves, due to the relatively low content of secondary metabolites in the former. For grapevine and apricot, three methods can be equally used to obtain DNA of good quality: the Doyle and Doyle modified method using CTAB and high concentration of NaCl, the Jobes et al. modified method, and the sodium dodecyl sulfate mini preparation method of Edwards et al. The protocol of Jobes et al. using LiCl for RNA removal showed the best results for most of the M. sieversii samples examined.