Development of method for preparing high molecular weight DNA from chrysanthemum

► An improved method for preparing high molecular weight DNA from chrysanthemum was firstly developed. ► A considerable yield of HMW-DNA more than 2 Mb was achieved. ► The improved method utilizes a modified buffer system including 1% (v/v) β-mercaptoethanol, 4 mM spermidine and 6% (w/v) PVP-40 and a centrifugal speed of 1600 × g to extract and suspend HMW-DNA. ► No difference on DNA fragment size was observed with different lysis times. The HMW-DNA can be partially digested to 23-80 kb in size.