Establish Of SSR And ISSR Fingerprints In New Populus Varieties (Clones)

Poplar is a general name of all tree species in genus Populus L. of family Salicaceae,about more than100species totally and more than53species in China. In recent years, withthe development of the poplar breeding, more than50new poplar varieties had introducedand selected by poplar breeders successively. But due to small differences in morphologybetween the same kinds of different clones, so it was difficult to distinguish them through themorphological characteristics. This not only affected the further genetic improvement ofpoplar varieties, also affected the correct application of good varieties. Therefore, applicationof molecular marker technology in the study of poplar species (clones) identification, toestablish a reliable poplar species (clones) of classification and evaluation system hadimportant significance. In this study, SSR and ISSR were used for genetic fingerprinting andidentification of5poplar cultivars, determination of the genetic relationships among thesevarieties. The main results are as follows:1.2DNA extracting methods for poplar leaves were compared in this study.The resultsshowed that the SDS method was better than the CTAB method. It could meet theamplification requirements of SSR and ISSR molecular markers.2. In this study, the effects of genomic DNA extraction from poplar leaves were studiedunder5different kinds of conditions for storing samples. The result showed that3differentkinds of conditions for storing samples (frozen at-80℃, natural withering and dried withsilica gel) were the better methods. We can adopt appropriate preservation methods accordingto the actual situation.3. Among36pairs of SSR primers,12pairs of primers which were presented apparentpolymorphism between the parents were determined as analysis of genetic diversity forPopulus cultivars (clones).125DNA fragments were amplified, of which111werepolymorphic (88.8%). Band size ranged from80bp to1000bp.10ISSR primers werescreened out from30ISSR primers and amplified using of PCR.102DNA bands wereamplified,73of them were polymorphic bands and the ratio of polymorphic bands was71.57%. Band size ranged from100bp to1000bp.4.3pairs of SSR primers and4ISSR primers were selected to construct DNA fingerprints of5poplar cultivars (clones) apparently. These fingerprints can be used foridentification of poplar varieties (clones).5. The SSR analysis showed that genetic similarity coefficient ranged from0.440to0.736between all the Populus cultivars (clones). The average genetic similarity coefficientwas0.573. High similarity coefficient existed between2new Populus hybrid cultivars andtheir male parent. The similarity coefficients were0.632and0.688. The ISSR analysisshowed that genetic similarity coefficient ranged from0.412to0.883between all the Populuscultivars (clones). The average genetic similarity coefficient was0.636. High similaritycoefficient existed between2new Populus hybrid cultivars and their male parent. Thesimilarity coefficients were0.735and0.883.6. Both SSR and ISSR data were used to analyse genetic relationship between Populuscultivars (clones). The result showed that genetic similarity coefficient ranged from0.467to0.775between all the Populus cultivars (clones). The average genetic similarity coefficientwas0.601. The dendrogram of5Populus varieties (clones) was the similar as the ISSR result.