Objective This paper aims at investigating the genetic variation and genetic relationship of 33 samples of 22 Populus species.

Method 40 primer combinations screened from 72 of SRAP (Sequence-related Amplified Polymorphism) markers were used to analyze the genetic variation and the genetic relationship of Populus.

Result The results showed that 40 pairs of primer combinations produced 487 clear bands, and there were 441 polymorphic bands with a ratio of 90.55%. The dendrogram generated by UPGMA showed the genetic relationship among 33 samples. The genetic similarity among 33 samples varied from 0.448 6 to 0.910 3; the maximum average genetic distance among sections in Populus was between Sect. Leuce Duby and Turanga, which was 0.3777. The 33 samples were classified into four major groups by cluster analysis using UPGMA. This result was in accordance with the previous classification based on conventional methods. Phylogenetic tree showed that all samples in Sect. Leuce Duby formed a separate branch, while Sect. Tacamahaca, Aigeiros and Turanga formed another branch, which may indicate that Sect. Leuce Duby have rather distant phylogenetic relationships with the others and the genetic relationship among the other three sections was closer.

Conclusion Different poplar species have high polymorphism in SRAP sites, and SRAP could be a potentially useful marker technique for genetic variation and genetic relationship study in Populus germplasm. The results would provide a theoretical basis for studying the classification, identification and systematic evolution of Populus.