Development And Application Of Simple Sequence Repeat In Houttuynia Cordata

Houttuynia cordata Thunb is perennial plant in the genus Houttuynia Saururaceae. It is distributed widely in the central, southeastern and southwestern regions of China. The agronomic characters, medicinal components and components’content of H. cordata Thunb from different geographical population are significantly different. Simple Sequence Repeat(SSR) marker is a molecular marker of short tandem repeat sequence. Its characters are high genetic diversity, rich information content and co-dominance. In this study, expressed sequence tag (EST)-SSR marker of H. cordata Thunb will be build base on EST. A part of markers will be screened and utilized of preliminary analysis of genetic diversity of H.cordata Thunb from different geographical populations. The main results are listed as follows:(1)That3487SSRs were be found in the EST of H. cordata Thunb, including1278dinucleotide repeats and1994trinucleotide repeats, their percentage was36.65%and57.18%, respectively. The SSRs character showed the main dinucleotide repeats and trinucleotide repeats were AC/GT and GAA/CTT, the percentage was86.70%and16.85%, respectively. That749SSRs length were longer than20bp and those of2189between12-20bp were found in the EST. This result showed SSR markers of H. cordata Thunb was rich information content.(2) EST-SSR markers of H. cordata Thunb had been developed. And polymerase chain reaction system and reaction conditions of some EST-SSR markers were explored. The best system was constituted of14.4μL ddH20、2μL10×buffer1.2μLMgCl2、0.5μLdNTP、0.35μL primes0.2μL Taq DNA polymerase and25ng/μL template. the best annealing temperature was between56℃and58℃.50pairs of primers were experiment, the result showed that28pairs of primers could be amplicated bands by using the PCR system and reaction condition. These primers were further tested in the populations of Rugao and Xiamen, which came from Jiangsu province and Fujian province, respectively.20pairs of primers had been shown some polymorphisms.(3) That17germplasm resources of H.cordata Thunb came from17differnet places in China were used to analyze their genomic genetic diversity by using the20pairs of primers. A total of141bands were generated, of which73bands were polymorphic bands (the percentage of polymorphic band, PPB=51.7%). The value of genetic similarity rate was0.6667-0.8936, the average value was0.7802. The results showed that17germplasm resources of H.cordata Thunb were be divided into two major group by clustering analysis, one was distributed in the midwest areas in China, the other was distributed in the mid-east region and southeast areas in China. And the genetic diversity of H.cordata Thunb was related with the environments in some way. Meanwhile, it was been confirmed that the EST-SSRs developed in this study could be valued in reseaching genetic diversity of H.cordata.