| Seed pumpkin(Cucurbita pepo L.),an herb of Cucurbita in Cucurbitaceae,with seed was the main edible organ.The production of seed-used pumpkin in China is mainly concentrated in Heilongjiang,Xinjiang and Inner Mongolia.It is an important cash crop and a distinctive export-oriented crop.Due to the late start of genetic breeding of seed-used pumpkin,there are few excellent seed-used pumpkin germplasm resources and narrow genetic background,which seriously limits the innovation and utilization of seed-used pumpkin breeding materials.The study on genetic diversity of seed-used pumpkin germplasm can provide a theoretical basis for parent selection,protection and identification of seed-used pumpkin germplasm.Since the experiment,48 seed-used pumpkin germplasm resources from four different regions have been used as research materials.These germplasm resources have been clustered and analyzed by observing and recording the phenotypic differences between germplasm during their growth.The DNA samples of 48 germplasm were amplified by 20 pairs of polymorphic primers.The diversity was analyzed based on the amplification results,and the fingerprint was established.The main test results are as follows:(1)The statistical analysis of genetic diversity parameters of botanical traits showed that the coefficient of variation of No.31 morphological traits ranged from 15.16% to86.00%.Among them,the largest coefficient of variation was leaf white spot(86%),and the smallest was growth habit(15.16%).Compared with quality traits,the genetic coefficient of variation of quantitative traits was lower as a whole.(2)Based on the cluster analysis of botanical characters,48 seed-used pumpkin germplasm were divided into 6 groups at the Euclidean distance of 7.67.The results of cluster analysis better reflected the morphological similarity among seed-used pumpkin germplasm.(3)After screening 20 pairs of primers,115 polymorphic alleles were amplified from48 seed-used pumpkin germplasm.The mean Shannon information index(I)of the locus was 1.36,the mean genetic diversity index(H)was 0.69 and the mean polymorphism information index(PIC)was 0.63,indicating that it has high polymorphism.Based on various indexes,five pairs of core primers that can completely distinguish 48 germplasm were selected to construct fingerprints.(4)The genetic diversity and genetic distance between populations were analyzed.The results showed that the Germplasm from Hulunbuir City,Inner Mongolia had the farthest genetic relationship with the Germplasm from Shanxi Province,and the Germplasm from Bayannur City,Inner Mongolia had the closest genetic relationship with the Germplasm from Gansu Province.The genetic diversity of Germplasm from Hulunbuir of Inner Mongolia is relatively poor,and the genetic diversity of Germplasm from Gansu Province is relatively rich.(5)The clustering results of 48 seed-used pumpkin Germplasm Based on SSR molecular markers showed that the 48 germplasm were divided into two categories with a genetic similarity coefficient of 0.66.Among them,the first category contained 46 germplasm and was divided into three subclasses with a genetic similarity coefficient of0.68.The first subclass contained 18 germplasm,the second subclass contained 10 germplasm,the third subclass contained 3 germplasm and the second subclass contained 2germplasm,The clustering results are closely related to the geographical origin of germplasm.The cluster analysis results of morphological markers and molecular markers were tested for consistency,and the correlation coefficient was 0.20,indicating that the two markers had low consistency in the classification of experiment materials in this study. |
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