Abstract:The purification and characteristics of DNAs isolated from the broad-leaf species,Populus simonii,P.bolleana P.suaveolens,P.nigra var.italica,Ailanthus altissima,Paulownia fortunei,and Robinia pseudoacacia are reported in this paper.Analysis results of DNAs indicated that DNAs conform to the requirement as exogenous DNAs for genetic transformation of the molecular breeding of poplar.Purified DNAs show a typically ultraviolet absorption spectrum,the A(260)/A(280) and A(260)/A(230) ratio are 1.69—2.16 and 1.17-2.00 respectively.The melting temperature of DNAs are 68—78℃,therfore,those content of (G+C)% are 34.4-58.8% and thermal hyperchromic effect are 32-38%.DNAs were analysed by Sepharose 4B column chromatography.DNAs stain by EtBr in agrose gel present continul bands and major component molecular weight is about 40-1.0×106 dal (67.6-1.5 kb).While the restruction endonucleases Xho Ⅰ and EcoR Ⅰ digested DNAs,the visible division bands can‘t be found.But the polymeric DNAs in the starting caves disappeared.