A Study On The Genetic Diversity And Differentiation Of The Weed Humulus Scandens Populations In Shanghai

Humulus scandens is one of the major annual dioecious weeds found through China. Ten population and 381 individuals in Shanghai were sampled and genotyped using microsatellites to reveal the genetic structure and to provide suggestions on its control. After screening 62 primers of H. lupulus, 7 primers that produced reproducible and multiple alleles were selected to amplify DNA samples of all Humulus scandens populations. A total of 47 different SSR alleles were detected. The percentages of polymorphic loci in each population were 100% in P₁₀₀ level and almost 100% in P₉₅ level (except the FX and QP population). At population level, mean number of alleles per loci was 5.64. The average of expected heterozygosity was 0.5898, the average of obverse heterozygosity was 0.4391. Due to the deficiency of heterozygotes, positive inbreeding coefficients were found in each population.. Assuming Hardy-Weinberg equilibrium, the average gene diversity was estimated to be 0.600 within the population (He), and 0.635 at species level (H_T).The coefficient of genetic differentiation between populations (Gst) of H. scandens was 0.055, indicating that most of the genetic diversity was within populations.The genetic distance of populations was from 0.2789 to 0.0096, and the average was 0.1097. The genetic identity was from 0.7566 to 0.9904, and the average was 0.8981. Those data suggested that the ten H. scandens population had high genetic identity and low genetic differentiation, which may be due to the sexual reproduction and dioecious characteristic of H. scandens. Mantel tests of relationship between geographic and genetic distance matrices indicated no significant relationship between genetic distance and geographical distance (r=-0.0784, p=0.667).High genetic diversity and low genetic differentiation of H. scandens in Shanghai suggested that were of multiple origins and dispersal. High genetic diversity hints that biological control of this weed seems difficult and chemical or physical methods should be utilized to its control.