Research Of Genetic Diversity Of Paspalum Dilatatum

Paspalum dilatatum is a high quality forage grasses that widely distributed in tropical and subtropical areas,and it is also one of the suitable for growing in warm type forage grasses in natural pasture of Guizhou Province.6 kinds of different populations of Paspalum dilatatum were chosen as materials in this study,and we studied its genetic diversity from morphology,ISSR molecule marker technology and drought resistance to provide a theoretical basis for gene discovery,genetic improvement and new variety breeding of Paspalum dilatatum.The results showed that:Variable coefficient of 10 morphological traits in 6 Paspalum dilatatum were range from9.76 to 56.08,stem length,ratio of length and diameter,fresh weight and dry weight of plant,of which variable coefficient were larger than 50%,and variable coefficient of leaf moisture content was minimum.Some traits in 10 morphological traits had a extremely significant correlation.The results of principal component analysis in 10 morphological traits showed that the accumulative contribution rate of the first 2 principal components was 88.903%,and the contribution rate of the first principal component was 58.765%,which were composed of height,stem diameter,leaf width,blade length and stem length,the contribution rate of the second principal component was30.138%,which was the concentrated expression of leaf length,ratio of length and diameter,fresh weight and dry weight.Clustering analysis with 10 phenotypic characters of tested Paspalum dilatatum,when genetic distance was 2,6 different populations of Paspalum dilatatum could be divided into 4groups.The genetic distance between Paspalum dilatatum from America and other areas was the largest,we clustered them as a group.And Paspalum dilatatum from Vietnam could be clustered as a group,and other 4 kinds of Paspalum dilatatum in Guizhou Province were clustered as a group.As a result of analysis,there exists a certain correlation between genetic distance and geographic location of Paspalum dilatatum.We screened 15 primers amplified by PCR from 50 ISSR peimers by ISSR molecule markertechnology,and detected the average of number of allele(na),effective number of allele(ne),Nei's genetic diversity index(H)and Shannon diversity index(I)in 6 Paspalum dilatatum was1.23,1.15,0.08 and 0.12.The genetic diversity among populations was population A> population D> population F> population B> population E> population C.The genetic structure analysis of 6 Paspalum dilatatum indicated that total genetic diversity of tested material and genetic diversity among populations was 0.2996 and 0.0831,and the genetic variation of Paspalum dilatatum was mainly existed in populations.We detected the gene flow among Paspalum dilatatum populations were smaller on the level of ISSR molecular markers,and the gene flow was 0.1919< 1.We detected the genetic similarity coefficient based on ISSR molecular markers and clustered by UPGMA,when genetic similarity coefficient was 0.83,the tested materials could be divided into 4 group,population D(valley in Anlong)and population E(grass slop in Anlong)were clustered as a group,because of the genetic relationship between 2 populations was closest,and then they clustered as a group with population F,population B(Dushan)were clustered as a group,population C(Vietnam)were clustered as a group and population A(America)were clustered as a group.The clustering results were similar to the clustering results according to morphological traits,which showed that the Paspalum dilatatum populations in different geographic locations had some genetic differentiation,and the main reason for the differentiation should be related to the geographic distance.We studied drought resistance of 6 different populations of Paspalum dilatatum by setting different time gradients of drought stress,and evaluated drought resistance of different materials according to soluble protein,MDA content,POD activity,CAT activity,soluble sugar content,chlorophyll content,plant height drought resistance coefficient and wilting rate resistance coefficient,comprehensive analyzed the drought resistance among tested materials by the average subordinative function method was:population A(Americ),population D(Anlong Valley),population F(Meitan),population E(Anlong grass slop),population C(Vietnam),population B(Dushan).