Studies On Genetic Diversity Of Houttuynia Cordata Thunb In Hunan

Houttuynia cordata Thunb is perennial herbaceous plant and belongs to species of Houttuynia cordata Saururaceae. It is not only drugs but also food and has been formally identified as "one of great development of the potential resources" by the Ministry of Health. H.cordata Thunb was focused by more and more people, but with the demands constantly increasing, wild resources of H.cordata Thunb have gradually declined and can not meet production requirements. We collected 28 resources of H.cordata Thunb in Hunan in 2009,and measured and analyzed their genetic diversity from phenotypic characteristics and SRAP molecular markers respectively to provide a theoretical basis on selection and orientation culture. The main results are as follows:1. Rich phenotypic variation among the resources of H.cordata Thunb:the ecological environment has a great influence to Houttuynia, the mean variation coefficients of between populations accounted 1/2 whereas that of within population was 1/3 which the variations between populations were main variation source. The correlation analysis of phenotypic characteristics and habitat factor showed that the correlations between the majority of phenotypic characteristics and altitude and longitude were significant, only individual characteristics were significantly correlated with latitude. The result indicates that the altitude and longitude have a larger affect to phenotypic characteristics but the latitude has a less affected.2. The orthogonal design results of the SRAP-PCR reaction shows that:the optimum SRAP-PCR reaction system contained 40 ng DNA,0.1 mmol·L-1 dNTPs,2.0 mmol·L-1 Mg2+,37.5 ng·μL-1 primer,2U Taq polymerase in a total volume of 25μL and the optimal annealing temperature and cycling times was 53℃and 35 times.3. The molecular genetic diversity of the H.cordata Thunb resources:101 effective primer-combinations were screened from 340 primer-combinations. A total of 5296 bands were detected with those primers and 4781 of them were polymorphic and the percentage of polymorphy was 87.56%. The Gst was 0.51 and the Nm was 0.24 which the indicated that the gene exchange is low among H.cordata Thunb resources.4. Phenotypic and molecular clustering results show that:28 H.cordata Thunb resources can be divided into two groups with phenotypic clustering, the first group contains only the resource of 27,the second group can be divided into 4 subgroups which resources 11,9 and 18 were clustered into a subgroup, the rests were clustered into another; the 28 H. cordata Thunb resources can be divided into two groups with molecular clustering too, the first group only contains the resource of 27, the second group can be divided into 3 subgroups, resources 11 and 9 were clustered into a subgroup, the rests were clustered into another. The fact shows that phenotypic clustering and molecular clustering are similar.