Phylogenetic relationship of 30 plant STK genes (4 from chestnut rose and 26 from other plant species). The STK genes from other plant species were based on the following strategy: amino acid sequences of chestnut rose STK genes were used as a query in BLASTp searches against GenBank database, the produced top 100 sequences were used for filter out highly homologous sequences (> 85% identity) within a plant species. The remained sequences were used for phylogenetic analysis. Drosiphila Pelle gene was used as outgroup in this study. Rosa 1 comprises STK1 and STK7 genes; Rosa 2 comprises STK2 and STK8 genes; Rosa3 comprises STK3 and STK4 genes; Rosa4 comprises STK5, STK6 and STK9 genes. The trees were constructed by the neighbor-joining method by PAUP* 4.0 software. Bootstrap values (1000 replicates) with only values > 50% were shown on the branches.