Studies On Genetic Diversity Of Paeonia Delavayi In Shangri-la

Paeonia delavayi,native to Southwest of China,has rich phenotypic variation.The plants with purple and yellow flowers were introduced into France in1884 and have been used widely in European and American gardens.Moreover,they have played great roles in Moutan cultivars breeding in France and the U.S.A.As a vulnerable plant,P.delavayi hasn't been protected effectively or developed in China.The taxonomy and genetic diversity research about it has never revealed main types of variation yet and the origin of variation has been a mystery.To supply fundamental data and theoretical direction of its protection and development,on basis of system investigation,the phenotypic variation and ISSR markers diversity have been studied on a population under the same ecological conditions.The results are as follows:There are complicated climatic and ecological conditions in Shangfi-la and it is typical of P.delavayi distribution zones.P.delavayi is widely distributed in Shangri-la.There was variation on height,length of current season stem,segment number,segment width,segment length,leaf length,leaf width,leafstalk length,petal number,flower size,flower number on one branch,pedicle length,carpel number,sepal numberand bract number of P. delavayi.Other thaits are significantly relative to height and flower color.Ten groups were listed as green,kelly,yellow,orange,secondary,red,magenta,purple,dark purple,pink flower groups in the population and low,medium and high types existed in a group except green flower group because of its limited number.Moreover,there were no low type in pueple and dark purple flower group.Through cluster analysis on basis of 24 traits,the ten groups were classified into two clusters.The five groups from green to secondary color were in Clusterâ… while the left five groups were in Clusterâ…¡.The short types of all groups gathered in one cluster.P.delavayi showed continuous variation on height,leaf length,leaf width,segment number,segment width,segment length,petal number,flower size and carpel number and it supported that Hong recognized only one species,P.delavayi.At the same time,the three species in the former taxonomic treatment were discussed further.The result showed segment width of leaf was susceptible to environmental factors especially light and P potanini wasn't able to be recognized on grounds of it.The plants with purple flowers,the short plants with yellow flowers and the other plants with yellow flowers showed significant difference on height,leaf width,segment number,segment length,petal number,flower size and carpel number of sepal bract.The paper identified that P.delavayi var.lutea and P.delavayi var.humilis as infraspecific taxa.ISSR markers revealed a total of 134 bands were amplified from 180 individuals of P.delavayi.A relatively high level of infraspeeific genetic diversity was revealed: PPB=80.6%,H=0.3506 and I=0.5034.The discriminant analysis showed that the classification accuracy among ten groups was 85.6%.The gene differation Gst was 0.2567 while the gene flow Nm was 1.4477.Gene exchange existed widely among groups,especially among thee groups with in-between color flowers.High gene flow existed between them and plants with yellow flowers or with purple flowers.Moreover,the cluster analysis revealed the ten groups gathered.The green,the kelly,the yellow flower groups had close relationship while the red and the dark purple flower groups comes closer and the margeta and the purple flower groups are closer.From the research above,it was summarized(1) P.delavayi population in Shangri-la had great genetic polymorphism;(2)flower color and height were leading factors in genetic diversity and there were ten flower color groups with 25 height types in them with great ornamental value;(3)gene exchange existed widely among groups and types and their relationship dependeded on difference of flower color and height,which helps guide cross-breeding.The paper(1) supports that Hong recognized only one species,P.delavayi.(2) identifies that P.delavayi var.lutea and P.delavayi var.humilis as infraspecific taxa.(3)reveals infraspecific variation of P.delavayi may originate from spontaneous hybridization between the infraspecific variaties.