The Cloning Of HMGR Gene Fragment And Analysis Of Genetic Relationship By ISSR Markers Of Houttuynia Cordata Thunb

HERBA HOUTTYNIAE, the whole plant of Houttuynia cordata Thunb., is a kind of traditional Chinese medicine and also a kind of delicious vegetable. It is the raw material resources of Yuxingcao injecting liquid. In current time, pharmacological experiments had proved that it had the function of antibacteria, anti-virus and diuresis, and could enhance body immunity. This thesis reviewed the research status of Houttuynia cordata. The active ingredients,pharmacological action and clinical application were analyzed and summarized. The results indicated that its biological activities were high; its effects were positive and worth being further popularized, but basic research should be conducted to develop new herbal preparations.Recently, the research of Houttuynia cordata have been focused on active ingredients,pharmacological action,planting technique and clinical application, but rarely on molecular level. The thesis studied the germplasm resources of Houttuynia cordata elementarily, the main content in this thesis were as below:Houttuynia cordata seeds have dormancy property. It is difficult to break the dormancy during the natural conditions. This study investigated effect on the seed in dormancy-breaking with different low temperature. Results showed that low temperature played a role in dormancy-breaking process. Treating the seed at 4℃for 8 days was the best treatment. It increased the germination viability and germination rate of seed up to 86.0%.4 pairs of degenerate primers were designed by using some internet database and biological software such as NCBI,DDBJ,Blockmaker,CodeHop and Primer Premier 5.0. Using the 4 pairs of designed primers to carry out RT-PCR, a cDNA fragment with length of 670 bp was cloned from the Houttuynia cordata seedling. The fragment was compared in the GenBank by Blast, and the results indicated that this fragment showed considerable identities with the HMGR genes of other plants. It demonstrated that the degenerate primers obtained from this programming are practicable, and also showed satisfied results and high positive rates.17 germplasm resources of Houttuynia Cordate were used as materials for analyzing their genome polymorphism by ISSR markers. 12 primers screened out from 50 primers were used for ISSR amplification. A total of 112 bands were generated, of which 95 bands were polymorphic bands (the percentage of polymorphic band, PPB=84.82%). The average number of DNA fragments produced by each primer was 9.33. Nei'similarity coefficients and genetic distances were calculated by using POPGENE software and the dendrogram were constructed by using UPGMA. 17 Houttuyniae materials were divided into three major groups while the genetic distance was 0.20.The results indicated that there actually existed much genetic diversity on molecular level among the germplasm resources of Houttyniae, the genuieness of Houttyniae was related with the environments in some way. The relationship between genuieness,genetic and environmental factors of Houttyniae were discussed.