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Length polymorphisms of simple sequence repeat DNA in soybean
M S Akkaya1, A A Bhagwat, P B Cregan
1Soybean and Alfalfa Research Laboratory, United States Department of Agriculture, Beltsville Agricultural Research Center, Maryland 20705-2350.
Genetics
|December 1, 1992
Summary
Soybean simple sequence repeat (SSR) DNA analysis revealed limited (CA)n and (GT)n repeats but abundant (AT)n repeats. These (AT)n repeats offer a promising source for developing polymorphic genetic markers in soybean.
Area of Science:
- Plant genetics
- Molecular biology
- Genomics
Background:
- Simple sequence repeats (SSRs) are valuable genetic markers in many species.
- Soybean [Glycine max (L.) Merr.] genome characterization for SSRs is crucial for genetic studies.
Purpose of the Study:
- To investigate the presence and extent of SSR DNA length polymorphism in soybean.
- To evaluate the potential of different SSR types as genetic markers in soybean.
Main Methods:
- Bioinformatic search of GenBank for SSRs.
- Polymerase chain reaction (PCR) amplification using SSR-flanking primers.
- Screening of a soybean DNA library.
- Sequencing of positive clones.
Main Results:
- No (CA)n or (GT)n SSRs with n > 8 were found; the longest was (CA)9.
- Five (AT)n SSRs (n=14-27) and one (ATT)n SSR (n=14-27) were detected.
- PCR amplification revealed 6, 7, and 8 alleles at three loci, demonstrating codominant segregation.
Conclusions:
- Soybean has a lower abundance of (CA)n SSRs compared to the human genome.
- (CA)n SSRs are unlikely to be an abundant source of genetic markers in soybean.
- (AT)n SSRs are abundant and suitable for developing highly polymorphic genetic markers in soybean.