During my doctoral studies at Cincinnati, I was also involved in microsatellite motif study conducted in Dr. Theresa Culley’s lab. Microsatellites, also known as simple sequence repeats (SSR) or short tandem repeats (STR), are typically defined as repeated sequences of 1-6 bases found throughout the nuclear and plastid genomes of eukaryotes. For many researchers, microsatellites continue to be the marker of choice for surveys of genetic diversity and structure, as well as paternity analysis and mating system estimates in which codominance is essential.
In this project we explored the relationship between microsatellite motif type and detectable genetic variation in plant populations, which is critical when a researcher determines which markers are associated with higher levels of genetic variation. To guide researchers in their choice of molecular markers, we conducted a literature review based on 6,616 microsatellite markers published from 1997-2012. We examined relationships between heterozygosity (He or Ho) and allele number (A) with the following marker characteristics: repeat type, motif length, repeat frequency, and microsatellite size, as well as their variations across taxa. Our results showed no significant differences in genetic variation between imperfect and perfect repeat types, but dinucleotide motif lengths exhibited significantly higher A, He, and Ho than most other motifs. Repeat frequency was positively correlated with A, He, and Ho, but correlations with microsatellite size were minimal or non-significant. We concluded that researchers should carefully consider their choices specific to the desired application; and if researchers aim to find high genetic variation, dinucleotide motif lengths with large repeat frequencies are recommended. Peer-Reviewed Publication