| Eucommia ulmoides Oliv is an important and strategic resource for China.E.ulmoides is a valuable species and extensively distributed.About 99% of the world’s resources of E.ulmoides distributed in China.However,the collection,reservation,and utilization of E.ulmoides is an inefficient state due to the frequent exchange of germplasm resources.With the transformation of the cultivation of E.ulmoides into the improved varietie,gradually,some cultivations perform ordinary germplasm.The groups face the crisis and the distributions further shrink and even disappear,including the genetic diversity may be disappear.For protecting and utilizing of E.ulmoides resource,the population genetic diversity and genetic structure of the E.ulmoides germplasms from gene pool were performed by using nine SSR primers.An optimal sampling strategy to construct the core collection of E.ulmoides male and female resources was discussed based on phenotypic data,including genetic distance,sampling methods,sampling proportions and cluster selections.The core collection and QR code fingerprint were constructed based on molecular marker data.The final core collection was found based on phenotypic and molecular marker data.The main contents and results are as follows:(1)The genetic diversity of E.ulmoides existed the high level polymorphism.The exchange on genetic level of E.ulmoides is sufficient.E.ulmoides has low genetic differentiation among populations.The Shannon’s information index(I),expected Heterozygosity(He),observed Heterozygosity(Ho),polymorphism information content(PIC),and gene flow(Nm)ranged from 1.242 to 1.675,0.644 to 0.777,0.379 to 0.762,0.712 to 0.84 and 1.473 to 3.002,with a mean of 1.452,0.720,0.720,0.791 and 2.378,respectively.The results indicated that all locus showed the high levels of polymorphism.The number of alleles(Na),effective number of alleles(Ne).Shannon’s information index(I),expected Heterozygosity(He),observed Heterozygosity(Ho)was 3.444~10.333(mean 5.823),2.397~4.919(mean 3.809),0.952~1.762(mean1.452),0.511~0.748(mean 0.713),0.544~0.789(mean 0.653),respectively,which indicated that the genetic diversity of population existed the high level polymorphism.The population genetic structure was assessed and the optimum peak of ΔK at K = 2 showed that all populations were classified into two different genetic clusters.The cluster I(red cluster)and cluster II(green cluster)included 28 and 14 populations,respectively.Analysis of molecular variance(AMOVA)showed that the most of the genetic variation within populations(96%),more than that among populations(4%).E.ulmoides has low genetic differentiation(Fst=0.041).The clustering analysis indicated also a low level of population differentiation.The average genetic distance and genetic identity of E.ulmoides is 0.30 and 0.72,respectively,which indicated the high similarity among populations.A high genetic differentiation within populations was revealed,suggessting that more individuals from different populations should be collected to protect the genetic diversity of E.ulmoides.(2)The male core collection of E.ulmoides was constructed based on phenotypic data.33 accessions were selected by combining the preferred method,mahalanobis distance,10% sampling proportion,and single distance clustering method.The final sampling proportion was 10.8%.The value of MD,VD,CR,VR were 0%,86.36%,100% and 157.62%,respectively,and there was not significant correlation between the core collection and total collection by T-test(0.05).The accord rate of mean,maximum,minimum and genetic diversity index of the core collection and total collection were 88.89%~100%,100%,100%,and 88.55%~98.54%,respectively.The male core collection of 33 accessions could satisfactorily represent the phenotypic variation of 306 E.ulmoides germplasms.(3)The female core collection of E.ulmoides was constructed based on phenotypic data.46 accessions were selected by combining the preferred method,euclidean distance,10% sampling proportion,and median distance clustering method.The final sampling proportion was 11.6%.The value of MD,VD,CR,VR were 0%,92.59%,100% and 147.14%,respectively,and there was not significant correlation between the core collection and total collection by T-test(0.05).The accord rate of mean,maximum,minimum and genetic diversity index of the core collection and total collection were 96.05%~100%,100%,100%,and 85.78%~99.52%,respectively.The female core collection of 46 accessions could satisfactorily represent the phenotypic variation of 395 E.ulmoides germplasms.(4)The core collection of E.ulmoides was constructed based on molecular marker data.189 of 887 collection samples were obtained based on allele number maximize strategy.The sampling proportion was 21.3%.In the total collection,number of allele(n),average number of allele(Na),average effective number of allele(Ne),average Shannon’s information index(I),average observed Heterozygosity(Ho),average expected Heterozygosity(He),Nei’s diversity index(H),average genotype numbers(Ng)and average polymorphism information content(PIC)of nine SSR locus were 107,11.889,5.096,1.812,0.658,0.795,0.925,46.889 and 0.795,respectively.While the core collection were 107,11.889,5.937,1.970,0.677,0.821,0.939,46.889 and 0.821,respectively.The core collection samples contained all the alleles and genotypes of total collection.Some genetic diversity indexes increase while the genetic redundancy was removed.T-test analysis suggested that there was not a significant correlation between eight evaluation parameters of core collection and total collection,which was further confirmed by the results from PCoA analysis.The nine genetic diversity index above-mentioned of reserve collection were 93,10.333,4.877,1.753,0.653,0.787,0.919,36.111 and 0.787,respectively.The reserve collection samples contained the 86.9% alleles and 77% genotypes of total collection.All the genetic diversity indexes decrease while the high genetic diversity samples were removed.T-test analysis suggested that there was not a significant correlation between eight evaluation parameters of reserve collection and total collection.The genetic diversity of 189 core collections well represent the 887 total collections.(5)The final core collection of E.ulmoides was constructed based on phenotypic data and molecular marker data.245 of 887 collection samples were obtained based on phenotypic data and molecular marker data.The sampling proportion was 27.6%.245 accessions could satisfactorily represent the phenotypic variation and genetic variation of E.ulmoides germplasms.The final core collection had better effect on the phenotypic and genetic diversity of the original germplasm.(6)Molecular fingerprint and two-dimensional code identification system of 854 E.ulmoides germplasms was constructed.854 of 887 varieties can be distinguished based on nine SSR locus.Two-dimensional code was generated by SSR results in QR-code software.The results can provide useful information for collection,management,protection and utilization of E.ulmoides. |
PDF Full Text Request