Using Simple Sequence Repeats (SSRs) to Measure Pollen Flow in a Flowering Dogwood Orchard

Abstract

Abstract Dispersal of flowering dogwood pollen in an orchard was evaluated by performing parentage analyses on open pollinated seedlings collected from a single maternal tree. Pollen sources for 45 seedling trees were established using three polymorphic simple sequence repeat (SSR) loci. Previous data suggest that Cornus florida pollen is typically limited to travel between closely situated trees. If this is true, breeding may be simplified by crossing trees through open pollination rather than more laborious current methods involving pollination cages. However, the expected leptokurtic distribution, in which the likelihood that pollen transfer will occur between trees decreases quickly as distance increases, was not seen. Although the majority of paternal trees were located within the 12 m (39.4 ft) radius of the study area, the trees most likely to have donated pollen were some of those located the greatest distance from the mother tree. Unusual pollen movement may be explained, in part, by asynchronous flowering times of trees within the study or by genetic similarities exhibited between the mother tree and potential pollen donors in the area. Additionally, andrenid and halictid bees, which were the predominant pollinators observed at this site, may have moved pollen farther than expected.