Pollen-mediated gene flow in managed fields of lowbush blueberry

Authors: Rowland, Lisa; Ogden, Elizabeth; BELL, DANIEL - University Of Maine; DRUMMOND, FRANK - University Of Maine

Submitted to: Canadian Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2019
Publication Date: 2/1/2020
Citation: Rowland, L.J., Ogden, E.L., Bell, D.J., Drummond, F.A. 2020. Pollen-mediated gene flow in managed fields of lowbush blueberry. Canadian Journal of Plant Science. https://doi.org/10.1139/cjps-2019-0109.
DOI: https://doi.org/10.1139/cjps-2019-0109

Interpretive Summary: Lowbush blueberry production, which makes up about twenty-five percent of the total blueberry production in the U.S., is from managed wild fields in Maine. Individual plants of wild lowbush blueberry are quite variable in terms of yield, and we are investigating possible causes of these yield differences, including the distance that pollen is dispersed. Lowbush blueberry is pollinated by native bees and by rented honey bees. If the bees carry pollen only very short distances, plants might tend to be pollinated by themselves or by the nearest neighboring plants. We have shown previously that near neighbors are very closely related (like siblings) about 30% of the time, thus crosses from the nearest neighbors could result in low yields due to inbreeding. In this study, we used molecular markers to perform paternity analyses on seedlings from open pollinated individuals and tested whether the father plants that provided pollen tended to be the nearest neighbors to the mother plants or whether self-pollination was occurring. We found that pollen was typically transferred by bees from plants outside the nearest neighborhood and that self-pollination was uncommon. Our results suggest that pollen dispersal by bees is over longer distances in lowbush blueberry and so inbreeding likely does not contribute to yield differences among plants. This information will be useful to other scientists interested in improving yields in lowbush blueberry.

Technical Abstract: Pollen-mediated gene flow was analyzed in two managed fields of lowbush blueberry, Vaccinium angustifolium Ait., in Maine. Seedlings derived from open-pollinated crosses of two mother plants, one from each of the two fields, were genotyped using simple sequence repeat (SSR) markers. The mother plants, the four to five nearest neighbor plants, and a group of 23-24 plants further away from the site of fruit collection were genotyped as well. The paternity of 70 seedlings produced by the mother plants, 35 from each field, was analyzed using FAMOZ to determine if each seedling was most likely a result of a self-cross, a cross with one of the nearest neighbors, or a cross from outside the nearest neighborhood. Approximately 91-97% of the seedlings appeared to result from crosses with plants outside the nearest neighborhood, whereas 0% appeared to have resulted from self-crosses. This suggests that the primary pollinators of lowbush blueberry, native bees and honey bees, routinely collect and move pollen from distances greater than the adjacent neighbors of the plants receiving the pollen.