Fingerprinting Of Cassava Clones Based On AFSM Simplified Resequencing Technology

Cassava originated from Brazil.With the rapid economic development,cassava is widely cultivated in tropical and subtropical regions around the world.At present,it is widely planted in Guangxi,Guangdong,Fujian,Yunnan,Guizhou and Hainan provinces in China.Cassava storage roots are rich in starch.In China's industrial starch market,cassava starch shared about 10%and also is an important fuel ethanol and green chemical industrial material.Cassava is the main food crop for low-income farmers in tropical areas.65%of the world's total output is used to make human food,while cassava flour and cassava leaves are high-energy feed materials.Cassava starch and dried cassava slices can also be used as important raw materials for producing alcohol,citric acid,lysine,glutamic acid,tapioca protein,fructose,glucose,etc.The produced cassava products have great applications in various aspects such as food,beverage,medicine,textiles,paper making,etc.Cassava has a vast industrial use and food market.China's annual comprehensive output value is 20 billion yuan,and the import quota is several times the output.It is of great significance to maintain and develop the cassava industry.In the scientific research and variety promotion and utilization of cassava,it involves the preservation,management and character identification and evaluation of more than ten thousand germplasm resources,which is the material basis of cassava industrial utilization.With the rapid development of cassava breeding and new variety breeding,many excellent varieties have been cultivated.The construction of fingerprint based on SNP marker technology is helpful for further excavation and utilization of cassava genetic resources,as well as for the registration and protection of varieties,variety renewal and full utilization of variety resources.At the same time,it is of great significance for cassava variety specificity and authenticity identification and seed purity identification.In this study,AFSM simplified resequencing method with proprietary technology will be adopted to obtain SNP markers of 544 cassava germplasm materials.After a series of algorithm screening and population structure analysis,100 core SNP and INDEL loci were finally selected to construct cassava variety fingerprint.It is expected to be applied to cassava variety specificity and authenticity identification,seed purity identification,etc.,that will provide new technical basis for further mining and utilization of cassava genetic resources and variety registration and protection.The main research results are as follows:1.For 544 cassava samples,two EcoR?-Msp? and EcoR?-Hpa? libraries were respectively constructed according to AFSM simplified resequencing database requirements.After passing the final monoclonal detection,the corresponding EcoR?-Msp?and EcoR?-Hpa? libraries were mixed into two sequencing libraries.After double-ended sequencing of the two libraries,we obtained 650G of data in total.According to statistics,we selected a total of 1,641,026 SNP sites,which are relatively evenly distributed on 8 chromosomes of cassava genome.2.From the original 1641026 SNP and INDEL sites,SNPs with too high deletion rate and too high single mutation rate were removed through two-step filtration,and 6,886 SNPs and INDELs sites were finally retained to be fingerprint candidate sites.3.After calculating 6886 candidate SNPs by genetic algorithm,a fingerprint database composed of 100 SNPs and INDELs evenly distributed on chromosomes was finally obtained to distinguish all 544 samples.4.Through detection,100 SNPs and INDELs mutation sites can effectively distinguish 544 samples,and through clustering analysis by calculating genetic distance,it can be found that samples from similar sources can be clustered together according to the information of 100 SNPs and INDELs,which shows that the fingerprint calculated according to genetic algorithm is true and effective.5.According to the same AFSM genotyping method and the genetic algorithm obtained in this study,by calculating 284 potato SNP sites,we successfully constructed a potato fingerprint consisting of 100 SNPs,which verified the practicability of this fingerprint technique.