Research On Crossing Compatibility And Karyotype Analysis In Paeonia

Paeonia lactiflora is widely distributed in China and is widely recognized as an excellent material for landscaping and flower production.Cross breeding has always been one of the hotspots in the breeding of paeonia lactiflora,and is an important method to cultivate new varieties.The study of chromosome karyotype is very important for the origin and evolution of plants,the identification of genetic relationship and the selection of hybrid combinations.This study select 20 kinds of peony as parents,hybridization between group and group,the determination of different combination of seed-setting rate,so as to select affinity good cross combinations;The karyotype of some hybrid parents was studied,and the genetic relationship between cultivars was revealed by the clustering analysis of karyotype similarity coefficient;Karyotype analysis was carried out on the progenies of the two hybrids,and the authenticity of the hybrids was preliminarily identified,which provide cytological basis for the utilization of Paeonia resources and the cultivation of new varieties.The main results are as follows:1.Selection of hybrid parents: in this study,20 species of Paeonia lactiflora were selected from 5types of flowers(single petal type,osmanthus type,rose type,table and court type,composite type)and 5major color series(white,pink,purple,red and complex color)for intergroup and intergroup hybridization.These include 2 wild P.lactiflora from northeast China,11 cultivated P.lactiflora,2 Chinese Chinese tree peony and 5 Japanese tree peony.2.The research on crossing compatibility of intersection crosses in Paeonia.There were seed in intersection crosses test,and the cross compatibility are good.Of the 10 cross combinations with ‘Fen Yu Nu' as female parent and cultivated P.lactiflora as male parent,‘Fen Yu Lou' had the highest seed-setting rate and the best compatibility.Among the 5 crosses with ‘Fen Yu Nu' as male parent and cultivated P.lactiflora as female parent,the seed-setting rate with single petal female parent was the highest.There was a great difference in the combination seeds of 8 hybrid combinations with wild P.lactiflora as male parent and cultivated P.lactiflora as female parent,and the compatibility between ‘Sheng Tao Hua' and wild P.lactiflora was best.Five better father-parent materials.were selected: ‘Fen Yu Lou',‘Shao Nv Zhuang',‘Hong Ling Jin Xing',‘Hua Hong Chong Lou',‘Tao Hua Shi'.Two good maternal materials were selected:‘Sheng Tao Hua' and ‘Zi Lian Wang Yue'.3.There was a difference in seed-setting rate between 'Fenyunu' and cultivated Paeonia lactiflora inpositive and negative intersection crosses.The reverse crossing rate of ‘Zi Lian Wang Yue' and‘Sheng Tao Hua' and ‘Fen Yu Nu' is much higher than that of normal crossing,but the reverse crossing rate of ‘Shao Nv Zhuang',‘Hua Hong Chong Lou',‘Xi Shi Fen' and ‘Fen Yu Nu' is lower than that of normal crossing.4.The research on crossing compatibility of intra-sectional crosses in Paeonia.The results of 19 groups with P.Lactiflora as female parent and P.Suffruticosa as male parent showed that theintra-sectional genetic relationship was far away and there was cross incompatibility.Four seed-bearing combinations were selected:‘Zi Lian Wang Yue'בFeng Dan Bai',‘Fen Yu Nu' בDao Jin',‘Zi Lian Wang Yue' בBa Qian Dai Chun' and‘Tao Hua Shi'בBa Qian Dai Chun'.5.Karyotype analysis of hybrid parents.The chromosome number of all 14 P.lactiflora species was2n=10,diploid,and the karyotypes were all symmetrical type 2A.The karyotype formula is2n=2x=6m+2sm+2st and 2n=2x=8m+2st.In lonly variety,the nuclear asymmetry coefficient,average arm ratio and evolution index were the lowest,while those in rose variety were the largest,and those in light color were more primitive than those in dark color.In the principal component analysis of the three karyotype parameters,the contribution rate of the longest chromosome / The shortest chromosome was the highest.6.The karyotype similarity coefficient and evolutionary distance of 14 species of P.Lactiflora were calculated and analyzed,and the variation range of karyotype similarity of cultivars of P.Lactiflora was larger than that of cultivars of P.Suffruticosa,indicating that the karyotype diversity among cultivars of P.Suffruticosa was higher,while that among cultivars of P.Lactiflora was lower.Karyotype approximate coefficient cluster analysis divided 14 species of Paeonia into two categories.The first category includs all the paeonia lactiflora varieties,and the nine species of paeonia lactiflora were grouped into two groups.The first group included: paeonia lactiflora,Paeonia obovata,‘Fen Yu Nu' and‘Zi Lian Wang Yue'.The second group includes:‘Sheng Tao Hua','‘Hua Hong Chong Lou',‘Xi Shi Fen',‘Fen Yu Lou'and ‘Fen Mian Tao Hua'.The second category includs all the tree peony varieties,and the five peony varieties were grouped into two groups.The first group includes:‘Feng Dan Bai';The second group includes:‘Ba Qian Dai Chun',‘Hua Wang',‘Fang Ji' and ‘Dao Jin' and the analysis results were consistent with the traditional classification.7.Karyotype analysis of hybrid progenies : the chromosome number of hybrids was 2n=10,diploid and 2A karyotype,which were the same as the parent.The relative length range,arm ratio range,centromeric index range and nuclear asymmetry coefficient of chromosomes were all between parental parent,and the karyotype formula was the same as that of paternal parent.