|Buteler, M -|
|Labonte, D -|
Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 1999
Publication Date: September 1, 1999
Citation: Buteler, M.I. Jarret, R.L. Labonte, D.R. Sequence characterization of microsatellites in diploid and polyploid ipomoea. Journal of theoretical and applied genetics; 1999. Theor. application genet; 99:123-132 (1999). Interpretive Summary: This report describes the results of a series of experiments conducted to isolate and characterize small pieces of the sweetpotato genetic material. These small pieces are known as microsatellites. The study revealed that in sweetpotato these microsatellites are highly variable and that the regions adjacent to the microsatellites are also highly variable. This information is relevant in that it provides an explanation for previously reported difficulties in utilizing microsatellites in genetic studies with sweetpotato.
Technical Abstract: The objectives of the present study were to evaluate the inheritance and nucleotide sequence profiles of microsatellite genetic markers in hexaploid sweetpotato (Ipomoea batatas (L.) Lam.) and its putative tetraploid and diploid ancestors, and to test possible microsatellite mutation mechanisms in polyploids by direct sequencing of alleles. Sixty-three microsatellite loci were isolated. Nine out of the 63 PCR primer pairs tested yielded a clearly discernible, heritable banding pattern. All of the primers which produced discernible banding patterns from I. batatas also amplified products of similar size in tetraploid and diploid I. trifida accessions. The sequence analysis of several alleles in the three species showed differences due to mutations in the repeat regions consistent with small differences in the repeat number. However, in some cases insertions/deletions and base substitutions in the microsatellite flanking regions were responsible for polymorphisms in both, polyploid and diploid species. These results provide strong empirical evidence that complex genetic mechanisms are responsible for SSR allelic variation in Ipomoea. Four I. batatas microsatellite loci showed polysomic segregation that fit tetraploid segregation ratios. To our knowledge this is the first report of segregation ratios for microsatellites markers in polyploids.