DNA profiling of oaks (Quercus spp.)

Forensic botany demands tools to verify the value of plant-origin evidence brought into the process of criminal investigation. Molecular biology provides techniques for comparing material from the crime scene with other biological material of evidence. In this paper, we propose a set of seven markers based on Short Tandem Repeats (STRs) loci for DNA profiling of Quercus spp. STR markers of the highest observed heterozygosity were selected, according to available literature. Oaks were chosen due to their wide dissemination in the northern hemisphere. They served as an object of study to develop a method for obtaining comparable genetic profiles of plant evidence material.

In the study, we verified the specificity of primers towards selected species of oaks. Twenty-three species, including most of those previously studied, were investigated for the presence of selected loci. After DNA extraction, STR sequences were amplified using multiplex PCR, and amplification products were then analysed with capillary electrophoresis. The frequency of genotypes was tested with the χ² test.

Out of 23 investigated species of oak, full genetic profiles were obtained for 13 species.

An incomplete genetic profile may result from DNA degradation or lower homology in primer binding sites. Full profiles were successfully obtained for most of the species tested; however, deficient profiles were yielded in species for which a full profile was expected. This may be due to the loss in DNA quality caused by ageing processes of plant material and inappropriate storage conditions or method of preservation.