| Sugar beet(Beta vulgaris L.)is an important sugar and cash crop in China,belonging to the genus Amaranthaceae and sugar beet.The aim of this study was to establish an accurate and scientific sampling strategy for SSR molecular marker genetic analysis of sugar beet germplasm resources,and to assess the kinship of the sugar beet materials tested in this study.The main results were as follows.The main results were as follows.1.27 pairs of core primers were screened.Eight beet materials were screened for247 pairs of sugar beet SSR primers,from which 27 pairs of polymorphic primers were selected for use as sugar beet molecular markers.These 27 primer pairs amplified 103 total bands,including 95 polymorphic bands,with a polymorphism ratio of 90.43% and a polymorphism information content(PIC)range of 0.549-0.983,with an average PIC value of 0.841 for each primer pair;to verify the polymorphism of the primers between populations,56 different DNA pairs from M206 were selected for PCR amplification.The total number of bands amplified was 3,all of which were polymorphic,and the percentage of polymorphism was 100%.2.The best sampling strategy for exploring the genetic diversity of sugar beet germplasm resources using SSR molecular markers was determined.Four different sugar beet germplasm resources were used as materials,and the amplification results were analysed and compared using SSR molecular markers in three treatments: single DNA samples,fixed DNA mixes,and random gradient mixes of the four germplasm resources.The results showed that:(1)all four germplasm resources were rich in genetic variation,and the established sampling strategy could be used to study the genetic variation of different germplasm resource populations of sugar beet;(2)the number of alleles increased gradually with the increase in the number of single DNA plants,and reached a peak at 20 or 30 plant mixes,while the number of alleles in 40 or50 plant mixes decreased.(3)When using SSR to analyse the genetic diversity of sugar beet germplasm resources,a high frequency(>90%)of alleles could be detected in a random sample of 20 individual plants per population,and the sampling gradient was reproducible.The results of the study provide a strong theoretical basis for further research on the sampling strategy of sugar beet and its closely related populations.3.The genetic diversity and clustering analysis of the 33 existing good polyembryonic sugar beet germplasm resources were carried out according to the optimal sampling strategy.The results showed that a total of 173 bands were amplified by 37 SSR primer pairs,of which 141 were polymorphic bands,with a polymorphism percentage of 81.5% and an average of 4.68 bands per primer pair.The average number of valid alleles amplified per primer pair was 1.9281,the Shannon's diversity index was0.6817,the Nei's expected heterozygosity was 0.4767,the inter-population genetic differentiation index Fst was 0.1814,and the inter-population gene flow Nm was 1.1283.At a genetic distance of 0.150,the material was divided into two subgroups,with No.32(2B32)as a separate subgroup and the others as a subgroup.The results showed that there was a certain degree of genetic differentiation among the present participant groups,and the genetic base of sugar beet was narrow and closely related.The present study was used to understand the genetic differences among sugar beet germplasm resources,and to provide a theoretical basis for the evaluation and utilization of polyembryonic sugar beet germplasm resources and breeding in China. |
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