Towards the Identification of Candidate Genes for Pollen Morphological Traits in Rubus L. Using Association Mapping

Rubus L. species display considerable morphological and genetic variability. Traditional taxonomic methods, which rely primarily on the observation of external characters, are often insufficient to resolve this complexity. Consequently, molecular biology tools are being increasingly employed. This study aimed to identify markers associated with candidate genes responsible for four selected pollen morphological traits—namely, the length of the polar axis, length of the ectoaperture, distance between the apices of two ectocolpi, and equatorial diameter—using association mapping. Based on the available literature, this is the first report of association mapping used to identify candidate genes for pollen morphological traits in Rubus L. Sixteen Rubus species and the complete set of possible markers (65534) were analyzed. Association mapping enabled the identification of 44 markers that are statistically significantly associated with all four morphological traits under consideration. The ten markers with the highest total LOD value for four pollen morphological traits allowed the distinction of six species: Rubus bifrons, Rubus caesius, Rubus idaeus, Rubus radula, Rubus saxatilis, and Rubus scissus. The results demonstrate that the proposed comprehensive approach of analyzing all possible markers may serve as an effective tool for detecting markers linked to genes controlling important traits, not only in Rubus species but potentially in other taxa as well.