Interspecific hybridization history of Vaccinium berry crops and potential in wild relatives

Wild species have been extensively used as a reservoir of genetic variability in plant breeding. Both blueberries and cranberries are crops from the highly diverse Vaccinium genus that have benefited from interspecific hybridizations throughout their domestication history. In this review, we compiled all documented interspecific hybridizations performed for blueberry and cranberry aiming to guide future breeding efforts. We report the traits of interest, success and failure of crosses, and give the taxonomic sections of the species involved. Out of the 500 species listed in Vaccinium, only 42 have been tested for hybridization so far. Successful crosses with fertile progenies have been reported across distantly related sections. Considering the polyphyletic nature of Vaccinium, the definition of crop wild relatives for these crops could be expanded to incorporate other genera. This review highlights the enormous potential of the wild gene pools for breeding of Vaccinium berry crops, and the need to characterize these species and establish germplasm collections to face the agricultural challenges ahead.