Genetic Diversity Analysis Of Section Aigeiros Clones Germplasm Resources Based On GBS Technology

Section Aigeiros poplar is the main poplar species cultivated in plantation,which has important economic value.In the national poplar germplasm resource bank of tiger forest paper company with limited liability had collected Populus euramericana clones form European and American.They are mainly from the excellent clones in the hybrid offspring of a few parents,they have little difference in morphological characteristics and relatively narrow genetic basis.Therefore,it is particularly important to carry out genetic diversity analysis and clonal germplasm identification of poplar germplasm resource bank.This study collected some clones in the national poplar germplasm resource bank as materials in order to developed SNP markers based on genetic by sequencing(GBS)technology and kompetitive allele specific PCR(KASP)markers.We constructed DNA fingerprints in order to provide technical support for the collection,and identification and utilization of poplar germplasm based on genotyping results.The main results are as follows:(1)Development of SNP markersA total of obtained 191Gb data and 426936306 sequences by GBS sequencing of 99 poplar samples.The success rate of sequencing sequence fragment alignment to the P.trichocarpa reference genome was 74.90%.After being filtered,148713 high quality SNP markers were obtained.Among six possible single base variations,C/T>G/A>A/T>A/C>G/T>C/G,the ratio of transition to transversion was 1.37:1.(2)Development of poplar core KASP markersA total of 57 specific markers were chose from 148713 SNPs,and they are distributed on 19 chromosomes of poplar uniformity,and without other SNP marker in the front and behind 50bp.There are 56 SNPs were transformed into KASP markers successfully of 57 SNP that were chose.56 KASP markers were verified and screened by 22 representative poplar samples.The results showed that 16 KASP markers were selected as core primers.The results of genotyping poplar clones by Power Marker software showed that the average deletion rate of 16 KASP markers was 0.110,the variation ranges of polymorphism information content(PIC)and heterozygous sites ratio(RH)were 0.550～0.700 and 0.000～0.310,and the average values were 0.650 and 0.120,indicating that the polymorphism of KASP core markers was high.We used the maximum likelihood method of IQtree software to make cluster analysis based on 148713 high-quality SNP markers,the results showed that the poplar clones were divided into four groups;We used the UPGMA algorithm of NTSYS-pc software to make cluster analysis based on the 16 KASP core genotyping results,the poplar clones were also clustered into four groups,and the two clustering results were basically the same,indicating that the developed KASP core markers are reliable.(3)Genetic diversity analysis and SNP fingerprint construction of poplar germplasm resourcesThe genetic diversity of all poplar populations was analyzed based on 148713 SNP markers result.The results showed that the number of different alleles,the NA、NE、I、HO、HE are 4.200、4.000、0.413 and 0.397.The genetic diversity based on KASP genotyping result.The results showed that the NA was 4.000,the NE was 3.000,the I was 0.077,the HO was 0.401 and the HE he was 0.434,indicating a high genetic diversity in the population.The results of genetic similarity coefficient analysis between the two showed that the genetic similarity coefficient of Zhonghan 17-1 and Zhonghan 17-2 was 1,which was likely to be the same germplasm.Based on the genotyping results,the fingerprint of poplar germplasm resources was constructed,and a unique two-dimensional code of fingerprint was encoded for each germplasm.The development of SNP marker method based on GBS sequencing is reliable,and the tested poplar germplasm has rich genetic diversity.The first set of KASP core markers of poplar has been developed,which provides a new idea for poplar genetic diversity analysis and fingerprint construction.