| Eucommia ulmoides,also known as Silk skin,Silk cotton,Sijin tree,endemic to China,is the only genus of plant in Eucommiaceae.As high impact on the industry,ecological and herbal medicines and other aspects,Eucommia has a great potential for development and utilization.With the further research on the utilization value of E.ulmoides,breeding of E.ulmoides has received considerable attention by domestic and overseas.Cross breeding is an efficient genetic improvement strategy based on genetic recombination,which greatly enriches the genetic variation of genetic groups,and it has significant important in forest breeding.In this study,based on the former research on 41 superior individuals that selected from hybrid progenies by sexual hybridization between superior varieties(clones)in E.Ulmoides,and constructed of high density genetic linkage map of Eucommia and identified of QTL analysis for important quantitative traits,phenotypic difference of the primary superior individuals in 5 to 7 years old was analyzed.Through correlation analysis results of phenotypic traits in 3-7 years old,the primary superior individuals were selected.The molecular markers closely linked to the target traits QTLs were selected to do molecular detection on superior individuals.In addition,the selection of superior individual plants was carried out to study the asexual propagation and the clone determination,so as to provide the experimental materials for the selection and evaluation of the later clones.The main results as follows:1.The CV of BN,BA,LY and CA in 5 years old of superior individuals were larger than other traits.The CV of the BA was the highest,up to 75.79%,while the CV of LVN was the smallest,which was only about 7.67%.2.The CV of CA,GC,LY and RC in 6 years old of superior individuals were larger than other traits.Compared to 5 years old,the previous sequence of phenotypic variation coefficient changed a little,but the variation of branch angle,branch number,branch diameter and chlorogenic acid content were the largest.The results showed that the sequence of phenotypic difference in 5-6 years old was not obvious,and phenotypic traits in 5-6 years old tended to be stable.3.The CV of TLN,LT,LY and CA in 7 years old of superior individuals were larger than other traits.Compared to 6 years old,the previous sequence of phenotypic variation coefficient changed a lot,only a small number of phenotypic variations had less variation.It indicated that the sequence of phenotypic difference in 6-7 years old was large,and the possibility for re-selection of primary individual individuals was of great potential.4.Correlation analysis of phenotypic traits in 5-7 years old of primary superior individuals were carried out at the same age,the results showed that tree height and ground diameter had a significant positive correlation in 5,6,7 years old of superior individuals,the same as chlorogenic acid and rutin content.In addition,Tree height and rutin content had a significant positive correlation in 5,6,7 years old of superior individuals,so did gutta-percha content and chlorogenic acid content,and correlation of other traits were not significant.Joint selection of superior individuals according to the correlation among traits can improve the selection efficiency of breeding.5.According to phenotypic data of superior individuals in 3 to 7 years old,correlation analysis among year-to-year showed that some traits in early stage of E.ulmoides(before 6 years old)were not related to other ages,and it is difficult to represent traits of other age,so it is not suitable for early selection.But correlation of phenotypic traits in 5-6 years old was higher than other year-to-year.Compared to 6-7 years old,the correlation reached extremely significant level,It was suggested that phenotypic traits of 6 years old were suitable for early selection of E.ulmoides.6.Through the results of correlation analysis between phenotypic data of 4-6 years old and the corresponding molecular marker effect value,the molecular marker or combinations with higher detection efficiency were selected for marker assisted selection.Combined with the phenotypic selection,the superior individuals with different target traits were chosen.Six markers or marker combinations were screened out,including molecular marker DZ200-350 related to tree height,marker combination(em15me23-360 and em12me11-300)related to ground diameter,marker em31me26-160 related to leaf yield,marker em49me3-150 related to leaf gutta-percha content,marker em10me28-170 related to chlorogenic acid content,marker em7me28-240 related to rutin content.7.Combined with the results of phenotypic selection and molecular marker assisted selection,18 plants with higher growth of tree height,11 plants with higher growth of ground diameter,17 plants with higher leaf yield,16 plants with higher content of gutta-percha,20 plants with higher content of chlorogenic acid and 17 plants with higher content of rutin were selected.Superior individuals with higher growth of tree height include 3-29,1-1,2-32,2-36,4-83,5-41,5-126,4-48,4-44,1-100,1-49,2-23,3-44,22-11,22-22,2-34,3-55,5-152.Superior individuals with higher growth of ground diameter include 3-55,5-33,5-41,5-54,5-126,7-46,16-40,22-11,22-22,23-14,25-82.Plants with higher leaf yield include 5-54,2-36,23-14,5-124,5-33,8-72,2-20,3-55,4-30,4-83,3-29,4-44,3-37,2-23,16-40,1-49,1-100.Plants with higher content of gutta-percha include 1-1,5-54,5-41,1-40,1-45,1-19,2-23,5-35,5-126,4-83,1-49,3-44,3-55,5-129,2-36,5-124.Superior individuals with higher content of chlorogenic acid include 1-1,1-40,2-36,1-45,1-100,1-49,7-46,5-35,4-89,22-11,2-23,1-19,5-33,16-40,5-152,5-126,6-30,5-54.Superior individuals with higher content of rutin include 1-1,1-49,2-36,5-129,2-32,5-152,5-124,4-44,17-27,5-126,5-149,5-33,3-44,23-14,1-45,4-48.8.The variation coefficient of annual branch length and branch diameter among annual clones were larger,indicating that there was a great difference in the initial germination vigor of grafted seedlings among different clones.Correlation analysis between tree height,ground diameter of superior individuals in 6 years old and annual branch length were not significant,and Correlation analysis between tree height,ground diameter of superior individuals in 6 years old and annual branch diameter were not significant.The difference of annual branch length and branch diameter reached extremely significant level,which was easy for the subsequent clonal selection. |
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