Exploring the genetic diversity of wild cranberry populations in the Upper Midwest

Authors: RODRIGUEZ-BONILLA, LORRAINE - University Of Wisconsin; RODRIGUEZ-BONILLA, FABIAN - University Of Puerto Rico; MATUSINEC, DANIEL - University Of Wisconsin; Wiesman, Eric; SCHOVILLE, SEAN - University Of Wisconsin; ATUCHA, AMAYA - University Of Wisconsin; Zalapa, Juan

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2019
Publication Date: 1/11/2019
Citation: Rodriguez-Bonilla, L., Rodriguez-Bonilla, F., Matusinec, D., Wiesman, E.C., Schoville, S., Atucha, A., Zalapa, J.E. 2019. Exploring the genetic diversity of wild cranberry populations in the Upper Midwest. Crop Science. vol 59:2413-2428. https://doi.org/10.2135/cropsci2019.06.0367.
DOI: https://doi.org/10.2135/cropsci2019.06.0367

Interpretive Summary: Plant breeding continuously evolves to satisfy the needs of the growing population, but in many crops it has resulted in a decline of the genetic diversity available. Therefore, increasing knowledge of the range, genetic relationships, and diversity among crop wild relatives is essential for the efficient use of available germplasm in breeding programs. In cranberries (Vaccinium macrocarpon), most cultivars share the same genetic background based on only a few wild selections. This limits the breeding pool for selection to support the cranberry industry. Therefore, we studied 36 wild populations of V. macrocarpon and its closest wild relative V. oxycoccos across Wisconsin and Minnesota using 32 molecular markers. The set of markers clearly distinguished the two species of cranberries, and we found high diversity for both species. We demonstrated the presence of untapped and previously undiscovered cranberry diversity in natural areas of the states of Wisconsin and Minnesota. Moreover, a comparison between wild V. macrocarpon with a group of cultivated and experimental hybrids found a distinct separation between both groups, suggesting there is diversity in the wild that needs to be explored and incorporated into breeding programs. The results of our studies are the first to explore in depth the genetic diversity of wild cranberry populations in the Upper Midwestern U.S. and provide novel information to support researchers and collections to develop conservation efforts to protect one of the few North American native crops. Additionally, since all of these populations were sampled in Minnesota and Wisconsin, they might possess unique adaptations to the largest cranberry production area in the world, central Wisconsin. Due to the lack of exploration, Wisconsin growers have been forced to use cranberry cultivars developed for other growing areas. Therefore, the challenges faced by growers in our state are unique and include intense frost risk and cranberry fruit worm, among others. This study demonstrates the vast diversity and range of cranberry populations in two mostly unexplored and underutilized Midwest states. We believe that there could be many other states that possess wild areas with unique and unexplored populations that could be excellent targets not only to establish a germplasm collection, but also for the characterization and conservation high diversity cranberry areas, which may possess traits useful for the development of new breeding lines for cranberry production.

Technical Abstract: Plant breeding continuously evolves to satisfy the needs of the growing population, but in many crops it has resulted in a decline of the genetic diversity available. Therefore, increasing knowledge of the range, genetic relationships, and diversity among crop wild relatives (CWR) is essential for the efficient use of available germplasm in breeding programs. In cranberries (Vaccinium macrocarpon), most cultivars share the same genetic background based on only a few wild selections. This limits the breeding pool for selection to support the cranberry industry. Therefore, we studied 36 wild populations of V. macrocarpon and V. oxycoccos across Wisconsin and Minnesota using 32 simple sequence repeat (SSR) markers. Results found high levels of heterozygosity in both species, despite previous molecular markers studies revealing low genetic variation. In V. macrocarpon, a total number of 294 alleles and moderate to high levels of heterozygosity (HO=0.51, HT=0.66) were found. As expected for outcrossed polyploid species (4x), higher levels of heterozygosity (HO=0.81, HT=0.83) were found in V. oxycoccos compared to V. macrocarpon. A comparison between wild V. macrocarpon with a group of cultivated and experimental hybrids found a distinct separation between both groups, suggesting there is diversity in the wild that needs to be explored and incorporated into breeding programs. The results of our studies are the first to explore in depth the genetic diversity of wild cranberry populations in the Upper Midwestern U.S. and provide novel information to support in-situ conservation efforts to protect CWR of one of the few North American native crops.