Intersectional F1 hybrids of 4x vaccinium meriodionale (section pyxothamnus) and highbush blueberry, V. corymbosum (section cyanococcus)

Authors: Ehlenfeldt, Mark; LUTEYN, JAMES - New York Botanical Garden

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2020
Publication Date: 1/21/2021
Citation: Ehlenfeldt, M.K., Luteyn, J.L. 2021. Intersectional F1 hybrids of 4x vaccinium meriodionale (swartz) (section pyxothamnus) and highbush blueberry, V. corymbosum (section cyanococcus). HortScience. 56(3):318–323. https://doi.org/10.21273/HORTSCI15523-20.
DOI: https://doi.org/10.21273/HORTSCI15523-20

Interpretive Summary: Vaccinium meriodionale, a blueberry species native to high-altitude locations in Peru, Colombia, and Venezuela, is of considerable interest for its profuse, concentrated flowering and narrow-based plant structure, both of which may be useful in breeding for mechanical harvest. We attempted to combine these parents to try to make hybrids useful for improving conventional highbush blueberry cultivars. The first-generation hybrids with highbush blueberry were intermediate in morphology and notably vigorous. The hybrids displayed variable branching structure, dormancy, flowering abundance, and fruit wax. However, most appeared to be deciduous to semi-evergreen, with small, dark-colored fruit. Crosses of this hybrid back to highbush blueberry displayed good fertility and numerous offspring indistinguishable from conventional highbush at the seedling stage. Despite coming from exotic, wide crosses, the fertility of these hybrids suggests that they might be able to be conventionally utilized to improve cultivated blueberry without significant difficulty. This information will be of interest to blueberry researchers, geneticists, and breeders.

Technical Abstract: Vaccinium meriodionale (section Pyxothamnus), a tetraploid species native to high-altitude locations in Peru, Colombia, and Venezuela, is of considerable interest for its profuse, concentrated flowering and monopodial plant structure, both of which may be useful in breeding for mechanical harvest. Tetraploid V. meriodionale was successfully hybridized as a male with 4x V. corymbosum (section Cyanococcus, highbush blueberry). The first-generation hybrids with highbush blueberry selections were intermediate in morphology and notably vigorous. The 4x F1 hybrids displayed variable branching structure, dormancy, prolificacy, fruit wax, etc.; however, most appear to be deciduous to semi-evergreen, with small, dark-colored fruit. Backcrosses to 4x highbush using the F1 hybrids as females displayed good fertility, and these crosses have produced numerous offspring morphologically indistinguishable from 4x highbush at the seedling stage. Evaluations of male fertility found variation for pollen production and quality, but significantly found clones with good shed, high stainability, and almost complete tetrad production. The fertility of these hybrids suggests that this germplasm, despite deriving from intersectional hybrids, might be conventionally utilized without significant difficulty. These hybrids also have potential value for nascent V. meridionale breeding efforts occurring in South America.