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Ovule culture and embryo rescue facilitate interspecific hybridisation in blueberry (Vaccinium spp.)
- Pathirana, R., Wiedow, C., Pathirana, S., Hedderley, D., Morgan, E., Scalzo, J., Frew, T., Timmerman-Vaughan, G.
- Acta horticulturae 2015 no.1083 pp. 123-132
- DNA, Vaccinium, blueberries, embryo culture, field experimentation, flow cytometry, greenhouses, hybrids, interspecific hybridization, males, microsatellite repeats, nuclear genome, ovule culture, ovules, ploidy, pollination, progeny, New Zealand
- About 80 blueberry (Vaccinium) accessions represent four species in New Zealand collections. They are highly heterogeneous and constitute a valuable resource as parental material for breeding. However, hybridisation between different species and ploidy levels does not produce viable seed in vivo. To increase the variation available to breeders, and to introgress characters from different species into parental breeding populations, interspecific, interploidy crosses were made. Ovules were cultured aseptically 14, 28 and 35 days after pollination. Embryos were dissected from the enlarged ovules and cultured on regeneration media. From fourteen of these crosses, more than 200 plants regenerated within 6-10 weeks. In ovulo embryo culture was more successful when the maternal parent had a lower ploidy than the male parent. Flow cytometry revealed that 4x Ã 6x crosses produced pentaploids, while the progeny of 4x Ã 5x and 5x Ã 6x crosses had nuclear DNA contents similar to that of the maternal parent. Random Amplified Polymorphic DNA and Simple Sequence Repeat marker analyses are being used to confirm the hybrid nature of these progenies. Hybrid plants are being propagated in vitro, acclimated in the greenhouse and established in field trials. Our study has demonstrated that in vitro ovule culture and embryo rescue can be used to overcome post-zygotic barriers to interspecific hybridisation between Vaccinium species with different ploidy levels.