Characterization of highly variable (GA/CT) n microsatellites in the bur oak, Quercus macrocarpa

Area of Science:

• Genomics
• Molecular Ecology
• Botany

Background:

• Wind-pollinated temperate trees like bur oak (Quercus macrocarpa) present challenges for studying pollination and parentage.
• Developing reliable genetic markers is crucial for understanding population dynamics and reproductive strategies in these species.

Purpose of the Study:

• To evaluate the utility of polymerase chain reaction (PCR)-based microsatellite analysis for bur oak parentage and pollination studies.
• To identify and characterize microsatellite loci suitable for genetic marker development in Quercus macrocarpa.

Main Methods:

• Construction and screening of a bur oak genomic library for (CA/GT)n and (GA/CT)n dinucleotide repeats.
• Sequencing of positive clones to identify repeat motif abundance and characteristics.
• Genotyping of adult bur oaks and offspring at selected (GA/CT)n microsatellite loci to assess polymorphism and inheritance.

Main Results:

• An estimated 3x10^5 dinucleotide repeats exist per bur oak genome.
• The (GA/CT)n motif was more abundant and showed longer repeat lengths than (CA/GT)n, indicating better marker potential.
• Three (GA/CT)n microsatellite loci exhibited Mendelian inheritance and high polymorphism (11-20 alleles, 0.66-0.75 heterozygosity) in a natural population.

Conclusions:

• Abundant and highly polymorphic (GA/CT)n microsatellites are identified in the bur oak genome.
• These genetic markers demonstrate significant potential for applications in studies of parentage, pollination, and gene flow in temperate trees.
• PCR-based microsatellite analysis is a valuable tool for ecological and evolutionary research in Quercus species.