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Production of interspecific hybrids between Alstroemeria pelegrina L. var. rosea and A. magenta Bayer by ovule culture
Masahiro Mii
Euphytica
Interspecific hybrids were efficiently produced in the cross-incompatible combination between Alstroemeria pelegrina L. var. rosea and A. magenta Bayer by culturing immature ovules with placenta 7–14 days after pollination on 2 g/l Gelrite-solidified MS medium containing 3% (w/v)sucrose. The plants showed intermediate characteristics between the parents and their hybridity was confirmed by karyotype and DNA analyses. The mean number of chromosome association per PMC at metaphase I was 2.60I+6.70II, pollen stainability was20.8%, and they produced viable seeds after self-pollination. Furthermore, mature plants were obtained when the hybrids were backcrossed as male parents with both the parents. The backcross-progeny from A. pelegrina var. rosea × hybrids exhibited 3.8 to 79.7% pollen stainability and that from A. magenta × hybrids 78.8 to 98.3%. Almost all of these plants produced viable seeds after self-pollination, which implies that they can beutilized for breeding of novel cultiv...
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Homoeologous chromosome pairing in the distant hybrid Alstroemeria aurea×A. inodora and the genome composition of its backcross derivatives determined by fluorescence in situ hybridization with species-specific probes
Evert Jacobsen
Heredity, 1999
A distant hybrid between two diploid species (2n = 2x = 16), Alstroemeria aurea and A. inodora, was investigated for homoeologous chromosome pairing, crossability with A. inodora and chromosome transmission to its BC 1 offspring. Fluorescence in situ hybridization (FISH) with two species-specific probes, A001-I (A. aurea specific) and D32-13 (A. inodora specific), was used to analyse chromosome pairing in the hybrid and the genome constitution of its BC 1 progeny plants. High frequencies of associated chromosomes were observed in both genotypes of the F 1 hybrid, A1P2-2 and A1P4. In the former, both univalents and bivalents were found at metaphase I, whereas the latter plant also showed tri-and quadrivalents. Based on the hybridization sites of DNA probes on the chromosomes of both parental species, it was established that hybrid A1P4 contains a reciprocal translocation between the short arm of chromosome 1 and the long arm of chromosome 8 of A. inodora. Despite regular homoeologous chromosome pairing in 30% of the pollen mother cells, both hybrids were highly sterile. They were backcrossed reciprocally with one of the parental species, A. inodora. Two days after pollination, embryo rescue was applied and, eventually, six BC 1 progeny plants were obtained. Among these, two were aneuploids (2n = 2xǹ1 = 17) and four were triploids (2n = 3x = 24). The aneuploid plants had originated when the interspecific hybrid was used as a female parent, indicating that n eggs were functional in the hybrid. In addition, 2n gametes were also functional in the hybrid, resulting in the four triploid BC 1 plants. Of these four plants, three had received 2n pollen grains from the hybrid and one a 2n egg. Using FISH, homoeologous crossing over between the chromosomes of the two parental species in the hybrid was clearly detected in all BC 1 plants. The relevance of these results for the process of introgression and the origin of n and 2n gametes are discussed.
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Use of Flow Cytometric Measurement of Nuclear DNA Content to Assess Ploidy Level in Azalea
Peter Velguth
Hortscience, 1996
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Molecular and morphological characterization of new interspecific hybrids of alstroemeria originated from A. caryophylleae scented lines
Patricio Zapata
Euphytica, 2019
Alstroemeria is a genus native to South America from which many varieties of ornamental plants have been developed and introduced into the market. Interspecific hybridization followed by embryo rescue has been one of the most common breeding techniques to obtain new varieties. This study was aimed at obtaining alstroemeria hybrids through interspecific crosses using novel scented parental lines and assessing these hybrids. A total of 3669 embryos were rescued, from which 18 flowering plants were morphologically evaluated. Flower stem length ranged from 25 (14E07) to 83 cm (14A11) and most of the flowers showed pink/white colors with stripes over the inner tepals. Only 3 hybrids were perceived as scented and one of them (14E08) was evaluated through GC-MS analysis, detecting 9 VOCs, all of them monoterpenes. Molecular analysis using RAPD markers clustered two main groups: (A) hybrids with A. pelegrina as parental line and (B) hybrids coming from the crossing UC05 9 C3 and its reciprocal. Moreover through this analysis was possible to subcluster hybrids coming from different seasons. A protocol for obtaining alstroemeria hybrids was successfully developed for this species using molecular and phenotypic evaluation to provide information about their pedigree and to spot those traits which are attractive for the ornamental plant market.
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Occurrence of numerically unreduced (2n) gametes in Alstroemeria interspecific hybrids and their significance for sexual polyploidisation
Evert Jacobsen
Euphytica, 2003
The F1 hybrids of seven diploid Alstroemeria species (2n=2x=16) were investigated for the production of numerically unreduced (2n) gametes and their mode of origin. Based on a survey of 17 interspecific hybrid combinations,consisting of 119 genotypes, it was found that the F1 hybrids of Chilean-Brazilian species mostly produced first division restitution (FDR) 2n gametes. These F1 hybrids were self-pollinated in order to obtain F2 seeds, which was an indication that the F1 plants also produced 2neggs simultaneously. All the F2 progeny plants were typical allotetraploids, most of which formed 16 bivalents and a small proportion formed multivalents during metaphase I stages of meiosis. Through genomic in situ hybridisation (GISH) it was proved that multivalent formation in F2plants, derived from A. inodora ×A. pelegrina hybrid, was due to homoeologous recombination but not from reciprocal translocations. In order to test the segregation pattern of the recombinant chromosomes, an F3 po...
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Meiotic behaviour of individual chromosomes in allotriploid Alstroemeria hybrids
Evert Jacobsen
Heredity, 2004
Chromosome association and chiasma formation were studied in pollen mother cells at metaphase I of four allotriplod BC1 plants (2n ¼ 3x ¼ 24) obtained from the backcross of the hybrid Alstroemeria aurea  A. inodora with its parent A. inodora. We distinguished the chromosomes of both parental species by genomic in situ hybridization (GISH), whereas the individual chromosomes were identified on the basis of their multicolour FISH banding patterns obtained after a second hybridization with two species-specific satellite repeats as probes. All the four BC1 plants possessed two genomes of A. inodora and one of A. aurea. Variable numbers of recombinant chromosomes, resulting from meiotic recombination in the interspecific hybrid, were present in these plants. The homologous A. inodora chromosomes generally formed bivalents, leaving the homoeologous A. aurea chromosomes unassociated. High frequencies of trivalents were observed for the chromosome sets that contained recombinant chromosomes, even when the recombinant segments were small. Chromosome associations in the trivalents were restricted to homologous segments. The implications of the absence of homoeologous chromosome pairing on gamete constitution and prospects for introgression in Alstroemeria are discussed.
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Direct Potting of Ornamental Grasses using Two Division Sizes
Mark Brand
Hortscience, 1996
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Early postfertilization ovule culture in Alstroemeria L. and barriers to interspecific hybridization
Evert Jacobsen
Euphytica, 1995
An early postfertilization ovule culture technique in Alstroemeria was described in which young ovules were cultured in vitro two days after pollination. This resulted in the direct production of seedlings in a normally incongruous cross combination. A histological study of the in vitro cultured ovules revealed the development of the embryo inside the ovule in the absence of normal endosperm. The in vivo grown ovules showed a total breakdown of the developing seed within four weeks after pollination due to a postfertilization barrier. This ovule culture technique was applied in a diallel cross of seven Alstroemeria species, five from Chile and two from Brazil. The selfings and the reciprocal crosses between the Brazilian species A. inodora and A. brasiliensis were congruous and gave seed set. The cross A. inodora × A. pelegrina gave viable seeds. In all other 39 combinations no viable seeds were harvested. In those cross combinations both pre-and postfertilization barriers were found. After early ovule culture hybrid plants were obtained in 27 of the 39 incongruous species combinations of the diallel.
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Interspecific Hybridization in Woody Ornamentals: How to Deal with Barriers?
Erik Van Bockstaele
V International Symposium on In Vitro Culture and Horticultural Breeding, 2006
For diverse reasons, interspecific hybridization was attempted in several woody ornamental genera (Rhododendron, Hydrangea, Hibiscus, Buddleia and Ligustrum), and yielded information on the occurrence and the overcoming of multiple crossing barriers. Prezygotic barriers (inhibition of pollen tube growth) were absent in all genera except Rhododendron. The first signals of postzygotic incongruity were the malformation of endosperm and the inhibition of germination. In order to replace the endosperm and allow maturation of the hybrid embryo and thus solve the lack of endosperm, in vitro media were established for all genera mentioned, mostly resulting in a significant increase of germination rates compared to in vivo germination. After germination, incompatibility between the plastome and nuclear genome may inhibit chloroplast development and chlorophyll formation. As a result, albinism is observed, mainly in interspecific Rhododendron and Hibiscus hybrids. Many hybrids are not viable, and growth aberrations caused by 'hybrid' vigor have been observed in Rhododendron and Hibiscus. Although flowering hybrids have so far only been obtained in the genera Buddleia and Hibiscus, preliminary research efforts with regard to fertility restoring through polyploidization were already performed in all genera. Proof was found for the occurrence of 2n gametes in Rhododendron, that might be a more recommendable tool for allopolyploidization than somatic chromosome doubling.
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Asymbiotic in Vitro Propagation of Temperate Terrestrial Orchids (Orchidaceae)
Paul Read
HortScience: a publication of the American Society for Horticultural Science
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