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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #316461

Title: Cybridization of grapefruit with 'Dancy' mandarin leads to improved fruit characteristics

item SATPUTE, ADITI - University Of Florida
item Chen, Chunxian
item GMITTER, FRED - University Of Florida
item LING, PAUL - University Of Florida
item YU, OIBIN - University Of Florida
item GROSSER, MELINDA - University Of Florida
item CHASE, CHRISTINE - University Of Florida
item GROSSER, JUDE - University Of Florida

Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2015
Publication Date: 9/18/2015
Citation: Satpute, A., Chen, C., Gmitter, F., Ling, P., Yu, O., Grosser, M., Chase, C., Grosser, J. 2015. Cybridization of grapefruit with 'Dancy' mandarin leads to improved fruit characteristics. Journal of the American Society for Horticultural Science. 140(5):427-435.

Interpretive Summary: Cybridization is a process of combination of a nuclear genome and an organelle genome of different sources, generating a new genotype (cybrid) and likely resulting in some phenotypic changes due to introduction of a new organelle genome and stimulation of new gene interactions. Cybrids generated from the fusion of citrus protoplast are valuable materials for further comparison of these changes, and use as advanced selections for potential release if some desired traits are significantly improved. Therefore, cybridization should be an additional approach to plant breeding.

Technical Abstract: In cybridization, new combinations of nuclear and cytoplasmic genes result in a unique genotype that may bring cellular, physical, physiological and biochemical changes to the plant. This has been demonstrated in unexpected cybrids generated from the fusion of citrus protoplasts in two independent experiments. The first experiment was conducted to generate potentially seedless triploids by fusing diploid protoplasts of embryogenic 'Dancy' mandarin (Citrus reticulata Blanco) suspension culture cells with haploid 'Ruby Red' grapefruit (Citrus paradisi Macfad.) protoplasts derived from tetrad stage microspores. After multiple attempts, only one triploid was recovered, but several diploid plants with typical grapefruit morphology were also regenerated. In the second experiment, protoplasts derived from embryogenic 'Dancy' mandarin suspension culture were fused with non-embryogenic protoplasts from 'Duncan' grapefruit leaves in an effort to produce an allotetraploid somatic hybrid. The fruits from the resulting trees resembled grapefruit in morphology and fruit type, and maintained excellent quality throughout the summer, when commercial grapefruit rapidly loses quality. Fruits on these trees remained firm with exceptional sweetness and good flavor into August, and without seed germination. The regenerants obtained in the protoplast fusion experiments were confirmed as cybrids by genetic marker analyses. The test grapefruit were identical to commercial 'Ruby Red' grapefruit at seven nuclear SSR marker loci, but identical to 'Dancy' with respect to a mitochondrial intron marker. The plastid genomes of individual trees originated from either fusion partner. In the first experiment, haploid 'Ruby Red' protoplast preparations must have also contained contaminant diploid protoplasts. Apart from the value of altered fruit quality attributes in the marketplace, these plants provide an opportunity to understand the contributions of cytoplasmic organelle genetics to important citrus fruit breeding objectives.