Research On DNA Fingerprint Molecular Identification Techniques For Soybean Cultivars

Soybean is an important grain and oil dual-use crop in China,which is widely cultivated all over the country.With the rapid development of plant breeding technology,the number of soybean cultivars is increasing year by year,and more and more soybean cultivars are being applied for protection.Due to the similar soybean breeding objectives,some excellent parents are widely used,the basis of soybean breeding is relatively narrow,and the similarity between cultivars is getting higher and higher.Traditional phenotypic identification cannot identify cultivars accurately and effectively.Therefore,it is of great significance to develop a set of core SNP markers with high information content and construct SNP-DNA fingerprinting for rapid and accurate identification of soybean cultivars.In this study,300 soybean cultivars were genotyped by 9K liquid phase probe capture chip,and the threshold of genetic similarity coefficient for identifying soybean cultivars using SNP markers was proposed.The core SNP markers for soybean cultivar identification were screened by genetic algorithm,and DNA fingerprinting of 395 soybean cultivars were constructed,which can provide a basis for the establishment of molecular identification technology system of soybean cultivars and the construction of fingerprint database.The main results are as follows:1.The soybean 9K liquid phase probe capture chip was used to scan,analyze and evaluate 300 soybean cultivars,and the threshold of genetic similarity coefficient of different soybean cultivars was proposed.The results showed that the genetic similarity coefficient of unrelated cultivars was 61.4%,and the genetic similarity coefficient of related cultivars was 76.8%,there was a significant difference between the two.The genetic similarity coefficient in most of cultivars was less than 95%;the genetic similarity coefficient between the different individuals of the same cultivar was above 95%.Therefore,the genetic similarity coefficient of 95%was used as the threshold of different soybean cultivars.2.Population structure analysis of 300 soybean cultivars.Phylogenetic tree analysis showed that 300 soybean cultivars were divided into three groups,and the classification were related to the geographical origin of the cultivars.The principal component analysis showed that 300 cultivars were divided into three subgroups:the first subgroup consists of cultivars in the southern region,the second subgroup mainly includes cultivars in Huanghuai region,the third subgroup includes all cultivars in Northeast and some cultivars in Huanghuai region.The results showed that the genetic difference of soybean in Huanghuai region was the most obvious,and the genetic background of soybean cultivars in Southern and Huanghuai region was wide,while the genetic basis of soybean cultivars in Northeast region was relatively narrow.3.The screening of core SNP markers and the development of KASP markers:Genetic algorithm was used to analyze the genotype of 300 soybean released cultivars,and 70 SNPs were obtained.70 SNPs were evenly distributed on the chromosome,which could distinguish 100%of the cultivars.70 SNPs were transformed into KASP markers for genotyping,and SNPs with higher deletion rate were removed,48 core SNP loci for soybean cultivar identification were finally obtained.The accuracy of genotyping of core SNP loci was verified by another 95 cultivars.The results showed that the number of different loci among all cultivars was greater than or equal to 1,indicating that 48 core SNP loci can identify soybean cultivars accurately.4.The genotyping results of 48 core loci were converted into binary coded data,and SNP-DNA fingerprinting of 395 soybean cultivars was constructed,which provided a basis for authenticity and specific identification of soybean cultivars and an important method for cultivar protection.