Genetic Diversity Studies Of Sagittaria Gramineain Yalu River Estuary Wetland

Sagittaria graminea(Alismaceae), a perennial aquatic herb, originating in North America, is an exotic species found in wetland of Yalv River in recent years. S. graminea is the first discovered species in China and other countries of East Asia. So far, it has been little known about the way of its introduction and its potential ecological risk. This paper selects the Yalu River Estuary Wetland in 5 populations as experimental materials, the introduction of Wuhan Botanical Garden ornamental S. graminea as control.This experiment mainly use 12 random primers(E33M47, E32M50 and E41M47 etc.)to amplify of two regions of S. graminea. 220 distinct bands were obtained, and 18 bands were amplified from each primer. Among all the ampilified bands, 84 bands were the common bands of the individuals from the two regions, counting for 38.18 %, and 136 bands were polymorphic, counting for 61.82 %. The way of the introduction of S. graminea in Yalu River Estuary Wetland were deduced and analyzed via the analysis of the genetic diversity and genetic structure of S. graminea from natural populations in Yalu River Estuary Wetland.The results are as follows:From the species level, the genetic diversity in both regions was rich,the percentage of polymorphic loci(P)was 52.94 % in Yalu River Estuary Wetland and 56.62 % in Wuhan Botanical Garden; the Nei’s gene diversity(h)was 0.2155 in Yalu River Estuary Wetland and 0.2482 in Wuhan; the Shannon diversity index(I)was 0.3093 in Yalu River Estuary Wetland and 0.3535 in Wuhan. Therefore, the genetic diversity in both regions was not rich. For the 7 populations in 2 regions, the percentage of polymorphic loci(P)was 97.79 %, the Nei’s gene diversity(h) was 0.3541, the Shannon diversity index(I)was 0.5294, indicating that higher genetic differentiation of S. graminea existed in different regions. At the population level, the percentage of polymorphic loci(P)was 39.71 % in Yalu River Estuary Wetland and 52.94 % in Wuhan; the Nei’s gene diversity(h)was 0.1784 in Yalu River Estuary Wetland and 0.2355 in Wuhan; the Shannon diversity index(I)was 0.2536 in Yalu River Estuary Wetland and 0.3353 in Wuhan., which indicated that the genetic diversity in both regions was not rich at the level of population. The genetic differentiation among population between Yalu River Estuary Wetland and Wuhan was different, the maen Gst was 0.1719 in Yalu River Estuary Wetland and 0.0512 in Wuhan Botanical Garden, indicating that the genetic diversity of S. graminea in Yalu River Estuary Wetland was lower than that in Wuhan, and the genetic diversity in both regions was not high. The gene flow(Nm=2.4088)of S. graminea in Yalu River Estuary Wetland was significantly different from that(Nm=9.2644)in Wuhan Botanical Garden, indicating that the differentiation of S. graminea in Yalu River Estuary Wetland was higher than that in Wuhan Botanical Garden. The different gene flow in the two regions further certified the genetic diversity of S. graminea in Yalu River Estuary Wetland was lower than that in Wuhan Botanical Garden.From the genetic identity. The genetic identity in both regions was not rich The genetic identity of S. graminea was 0.9238-0.9668 in Yalu River Estuary Wetland and 0.9668 in Wuhan Botanical Garden. The genetic identity of S. graminea between the two populations was 0.5186-0.6095, indicating that the genetic identity of S. graminea in both Yalu River Estuary Wetland and Wuhan was high. But the genetic identity of S. graminea in Yalu River Estuary Wetland was lower than that in Wuhan, indicating that there was obvious difference between the S. graminea in Yalu River Estuary Wetland and Wuhan.The analysis results showed that the genetic diversity of S. graminea either in Yalu River Estuary Wetland or in Wuhan was low. There was no gene exchange between S. graminea in Yalu River Estuary Wetland and S. graminea in Wuhan. It is known that S. graminea in Wuhan was introduced from abroad, and our results showed that the genetic diversity of S. graminea in Yalu River Estuary Wetland was lower than that in Wuhan, which indicated that the introduction of S. graminea in Yalu River Estuary Wetland was probably disposable.