Cross-breeding And Hybrid Analysis By SSR Markers Between Populus Nigra And P.szechuanica, P.yunnanensis

Poplar are important species for industrial timber and ecological environment protection because they are rapid growth, strong resistance, wide accommodation. For a long time tree breeders of the world have made great efforts in poplar crossing and acquired remarkable achievements. Especially many excellent new poplar strains were bred and widely planted from intersectional crossing between Sect. Aigeiros and Sect. Tacamahaca. But most of the parental trees were Populus deltoids and P. cathayana , P. simonii, P. ussuriensis. It is little reported about the cross among P. nigra, P. yunnanensis, P. szechuanica. So the artificial crossing between Populus nigra and P. szechuanica, P. yunnanensis was carried out in room and some hybrids were got from the two crosses. Growth-testing and the traits of leaves were carried out ,in the same time the hybrids were indentified by SSR markers,The results are as follows:1. The crossability between Populus nigra and P. szechuanica, P.yunnanensis is high and the fruit set rate 10 days after pollination of the two crosses reached 92.88% and 82.14% respectively, and the germination rate of hybrid seeds is 80% and 50% .2. The average seedling height and collar diameter of the Populus nigra×P. szechuanica are 44.3cm and 5.50mm, while the Populus nigra×P. szechuanica are 42.2cm and 5.37mm. the growth increment of the two hybrids is near in this year. the average height of hybrids from Populus nigra×P. szechuanica is little taller than the hybrids from Populus nigra×P. yunnanensis .3. The seedling height variance coefficient of Populus nigra×P. szechuanica and Populus nigra×P.szechuanica are 14.5% and 19.01%, the collar diameter variance coefficient are 10.7%和16.1% recpectively. The large variations in seedling height is useful for selection.4. Significant differences were found in the hybrids leaves and the leaf traits of hybrids exposed polymorphism.5. Using SSR markers to identify the hybrids, the results showed that the hybrids have not only parents chracteristics DNA bands, but also new genetic character, so the hybrids have genetic variation.6.Clustering analysis of the hybrids was carried using SSR method, it indicated that there are 2/3 of the hybrids from Populus nigra×P.yunnanensis is close to female parent, the other are near to male parent. There are half of the hybrids from Populus nigra×P.yunnanensis is close to female parent, the other is near to male parent.