Somatic hybridization in Citrus: navel orange (C. sinensis Osb.) and grapefruit (C. paradisi Macf.)

Abstract

Protoplasts of navel orange, isolated from embryogenic nucellar cell suspension culture, were fused with protoplasts of grapefruit isolated from leaf tissue. The fusion products were cultured in the hormone-free medium containing 0.6 M sucrose. Under the culture conditions, somatic embryogenesis of navel orange protoplasts was suppressed, while cell division of grapefruit mesophyll protoplasts was not induced. Six embryoids were obtained and three lines regenerated to complete plants through embryogenesis. Two of the regenerated lines exhibited intermediate morphological characteristics of the parents in the leaf shape. Chromosome counts showed that these regenerated plants had expected 36 chromosomes (2n=2x=18 for each parent). The rDNA analysis using biotin-labeled rRNA probes confirmed the presence of genomes from both parents in these plants. This somatic hybridization system would be useful for the practical Citrus breeding.

Culturing embryogenic protoplasts of ?Hamlin? sweet orange in calcium alginate beads

“…To distinguish beads, they visually marked the nurse culture beads by the addition of charcoal. In Citrus, the only plants regenerated from leaf mesophyll protoplasts have been those from somatic hybridization experiments where the other parental protoplast source was an embryogenic cell line Ohgawara et al 1989;Ohgawara et al 1991). If the embryogenic stimulation of the leaf mesophyll protoplasts was due to cocultivation, rather than treatment with a fusagen, then the cocultivation of Ca-alginate embedded leaf mesophyll protoplasts with embryogenic cells might be adequate for regeneration.…”

Production of Somatic Hybrids and Cybrids in the Rutaceae Family and Application to Citrus Breeding.

“…Through the interspecific somatic hybridization, we obtained the regenerated plants resembling mesophyll parent besides the somatic hybrids, which had 18 chromosomes [3,5] . Restriction endonuclease analysis revealed that the regenerated plants were cybrids possessed nuclear genomes of mesophyll cells and mitochondrial genomes of nucellar cells.…”

“…In 1985, we established a somatic hybridization system using Trovita orange (Citrus sinensis) nuceller cells and trifoliate orange (Poncirus trifoliata) mesophyll cells [1] , and applied this system to Citrus species including sterile cultivars [2][3][4][5] . All of the somatic hybrids that flowered showed fertility of both pollen and ovule [6][7][8], and were available to produce triploid plants [8,9].…”

Regeneration of Intergeneric Somatic Hybrids by Electrical Fusion between Citrus and Its Wild Relatives: Mexican Lime (Citrus aurantifolia) and Java Feroniella (Feroniella lucida) or Tabog (Swinglea glutinosa).

“…Since the first somatic hybrid plants of citrus between Citrus sinensis^nd Poncirus trifoliata were regenerated by Ohgawara et al (10), a number of additional somatic hybrids among Citrus and related genera have been reported (1,2,3,7,8,11). Vardi et al (16) has reported the production of cybrid citrus plants.…”