Study On The Cyclocarya Paliurus Natural Populations Structure And Genetic Diversity Based On Issr And SSR Markers

Cyclocarya paliurus is used as ornamental plant in subtropical regions,due to its beautiful shape,and copper coins-like fruits.Moreover,it is regarded as an important medicinal woody plant because of its diverse biological activities,such as antihypertensive,hypoglycemic and hypolipidemic etc..In this study,the natural populations of C.paliurus were investigated.Also,in order to provide the scientific basis for the development and utilization of germplasm resources,the genetic diversity and genetic structure of natural populations for C.paliurus were analyzed by molecular markers and morphological markers.Main results are as follows:1.The characteristics of C.paliurus natural populationsInvestigation based on 30 natural populations found 22 smaller populations(the number of individuals of population was less than 20)and 5 larger ones(the number of individuals in population was more than 30).The distribution pattern of diameter at the breast height(DBH)for total investigated individuals showed "L" type.Of all DBH size class,the ration of 33.5% in20-30 cm occupied the highest group,followed by 23.0% in 30-40 cm.There were a plenty of seedlings under most of populations with forest gap(with sufficient sunlight),inferring strong ability of natural regeneration.2.Variation of seed morphology among populationsStudies on seed morphology(1000-seed weight,volume,diameter,thickness)revealed that the coefficient of variation was no more than 30%,and Shannon-weaver genetic diversity index(H)was less than 1.0,indicating that the genetic diversity of seed morphology among populations was low.3.Population genetic analysis based on ISSR marker120 polymorphic fragments from 244 individuals of 29 populations were amplified by 9ISSR primers.The percentage of polymorphic band(PPB)ranged from 22.5% to 84.1%(averaged 55%).Analysis of molecular variance analysis showed that the degree of genetic differentiation among populations was low,and 82% of the genetic variation occurred within populations.The value of gene flow(Nm)among populations was 1.335.The genetic consistency coefficient(GS)among populations ranged from 0.841 to 0.969,and 5 clusters were identified within 26 natural populations at GS of 0.906.The principal coordinate analysis(PCA)suggested that 26 natural populations could be divided into 3 regions on the two-dimensional level.4.Population genetic analysis based on SSR marker24 polymorphic fragments were amplified by 6 pairs of SSR primer for 244 individuals of29 populations.The percentage of polymorphic band(PPB)ranged from 66.7% to 100%(averaged 94.83%).Analysis of molecular variance analysis showed that the degree of geneticdifferentiation among populations was low,and 91% of the genetic variation occurred within populations.The value of gene flow(Nm)among populations was 1.182.The genetic consistency coefficient(GS)among populations ranged from 0.741 to 0.993,and 5 clusters were identified within 26 natural populations at GS of 0.930.The principal coordinate analysis(PCA)suggested that 26 natural populations could be divided into 3 regions on the two-dimensional level.5.Population genetic analysis combining ISSR and SSR markersAMOVA analysis,PCA correlation analysis,UPGMA cluster analysis and STRUCTURE analysis showed low genetic differentiation among natural populations.Mantel test showed that there was no significant correlation between distribution region of natural populations and geographical location.