CYTOGENETICS OF VACCINIUM DARROWI X V. ARBOREUM HYBRIDS AND THEIR OPEN-POLLINATED DERIVATIVES
Vaccinium darrowi, a low-growing, evergreen blueberry native in the southeastern United States, is the species that was crossed with northern highbush blueberry to produce the southern highbush cultivars. Vaccinium arboreum, the sparkleberry, also native in the southeastern U. S., is a small tree that can reach 8 m in height. Unlike highbush blueberry, sparkleberry can tolerate soils that are prone to drought, contain little organic matter, and have a pH as high as 6.0. More than 100 V. darrowi x V. arboreum F1 hybrids (both parents diploid) were grown for five years in a field that also contained tetraploid V. corymbosum and hexaploid V. ashei cultivars. Meiotic studies of 5 F1 hybrids showed that they were diploid and that univalents normally outnumbered bivalents during Metaphase I. There were lagging chromosomes and chromatin bridges at Anaphase I. The F1 hybrids flowered abundantly but were very low in pollen production, pollen staining and in production of open-pollinated seed. Of eight open-pollinated progeny of the F1 hybrids that were studied during meiosis, seven were tetraploid and one was pentaploid. The tetraploid progeny probably originated when unreduced gametes from the F1 interspecific hybrids united with normal gametes from tetraploid highbush. Although fertility and chromosome pairing were higher in the tetraploid open-pollinated progeny than in their diploid F1 parents, study of meiosis still revealed some univalent chromosomes, lagging chromosomes, and chromatin bridges. Despite chromosome pairing problems, introgression of V. arboreum genes into highbush cultivars could be useful, especially where late ripening, higher vigor, and increased ability to grow on upland soils are desirable.
San Martin, J. and Lyrene, P.M. (2003). CYTOGENETICS OF VACCINIUM DARROWI X V. ARBOREUM HYBRIDS AND THEIR OPEN-POLLINATED DERIVATIVES. Acta Hortic. 626, 101-103
blueberry, blueberry breeding, sparkleberry, interspecific hybridization