Molecular and morphological evidences for hybrid origin of Kushui Rose

Natural hybridization plays a significant role in evolution of the genus of Rosa , e.g., Kushui Rose ( R. Sertate x R. Rugosa ) is always considered as a natural hybrid of R. sertata and the cultivated rose R. rugosa . In order to test the hybrid origin of Kushui Rose, we conducted molecular sequences analysis and morphological traits examination in its related taxa in the genus. Although Principal component analysis (PCA) of Morphological characteristics revealed Kushui Rose was intermediate between R. rugosa and R. willmottiae , and also and R. sertata , but the unambiguous sequence additivities of nuclear DNAs (ITS and GAPDH ) as well as the incongruence between nuclear and chloroplast gene trees revealed the hybrid origin of Kushui Rose from R. rugosa and R. willmottiae rather than R. sertata . Further, the cluster relationships in concatenated chloroplast (cpDNA) trees ( psbA-trnH , trnL-F , and trnS-G ) implied that R. willmottiae and R. rugosa respectively acted as its maternal parent and paternal parent during its homoploidization speciation. Here our study could provide a more reasonable orientation for further study in conservation biology of the hybrid species as well as in its agronomy traits with heterosis effect.