Development and Characterization of Simple Sequence Repeat (SSR) Markers from the Genomic sequence of Sweetpotato [Ipomoea batatas L. (Lam) cv. Taizhong6]

Abstract

Background: Sweetpotato is a multifunctional root crop with many essential nutrients and bioactive compounds. Due to its genetic complexity and lack of genomic resources, efficient genetic studies, and cultivar development lags far behind other major crops. Simple sequence repeats (SSRs) offer an effective molecular marker technology for molecular-based breeding and for locating important loci in crop plants, but only a few have previously been developed in sweetpotato. Results: To further explore new SSR markers and accelerate its use in sweetpotato genetic studies, genome-wide characterization and development of SSR markers were performed using the recently published genome of sweetpotato cultivar, Taizhong6. In this study, a set of 2,431 primer pairs were developed from 133,727 SSRs identified in the sweetpotato genome using the Perl script MISA software. The average frequency was one SSR per 6.26 kb with dinucleotides (38.5%) being the most dominant repeat motif. The main motif types in all repeats were AT/AT, AAT/ATT, A/T, AAAT/ATTT, AAAAT/ATTTT and AAAAAT/ATTTTT accounting for 78.29% of the total SSRs. 50% of the 100 randomly selected primer pairs amplified 251 alleles and the average number of alleles was 5.02 alleles per locus with a range of 1 to 13 alleles. The UPGMA cluster analysis grouped the 24 sweetpotato materials into four clusters at a similarity coefficient of 0.68. Conclusion: The SSR markers currently developed will provide valuable genetic resources for germplasm identification, genetic diversity analysis, and functional genomics studies in sweetpotato and related species.