Occurrence of 2n gametes in the F1 hybrids of Oriental × Asiatic lilies (Lilium) : Relevance to intergenomic recombination and backcrossing

Occurrence of 2n gametes in the F1 hybrids of Oriental × Asiatic lilies (Lilium) : Relevance to intergenomic recombination and backcrossing

Cytological modes of the origin of 2n gametes were investigated in six different genotypes of F^sub 1^ hybrids between Oriental and Asiatic (OA) lilies (Lilium, 2n = 2x = 24). Chromosome pairing between the parental genomes was very low, the average frequency range from 0.3 to 1.2 bivalents per cell...

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Bibliographic Details
Published in:Euphytica Vol. 143; no. 1-2; pp. 67 - 73
Main Authors: BARBA-GONZALEZ, R, LIM, K.-B, RAMANNA, M. S, VISSER, R. G. F, VAN TUVL, J. M
Format: Journal Article
Language:English
Published: Dordrecht Springer 2005
Springer Nature B.V
Subjects:
Agronomy. Soil science and plant productions
Biological and medical sciences
Fundamental and applied biological sciences. Psychology
Genetics and breeding of economic plants
Genotypes
Hybrids
Pollen
Monocotyledones
Recombination
intergenomic recombination
Backcross
first division restitution
genomic in situ hybridization
Liliaceae
Angiospermae
Genetic improvement
Fluorescence in situ hybridization
F1 hybrid
Unreduced gamete
Lilium
Herbaceous plant
Spermatophyta
Genome
unreduced gametes
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Summary:Cytological modes of the origin of 2n gametes were investigated in six different genotypes of F^sub 1^ hybrids between Oriental and Asiatic (OA) lilies (Lilium, 2n = 2x = 24). Chromosome pairing between the parental genomes was very low, the average frequency range from 0.3 to 1.2 bivalents per cell among the genotypes. Within a genotype the frequency of bivalents varied from 0 to 6 in some cases. The normally occurring haploid pollen grains were totally sterile. In contrast, in different genotypes, variable percentages of 2n pollen were found and shown to be fertile as estimated from pollen germination. A cytological analysis of Metaphase I and subsequent stages of meiosis using genomic in situ hybridization (GISH) revealed that there was intergenomic recombination between the alien genomes. Following Metaphase I stage, three different types of abnormal cytological events led to the formation of 2n pollen: (i) Post-Metaphase I division (PMI), (ii) Post-Metaphase II division (PMII) and (iii) Asymmetric Cytokinesis of the pollen mother cell followed by chromosome division. All three cytological events led to first division restitution (FDR) gametes. Based on in vitro pollen germination it was proved for two genotypes that 2n pollen was viable only during the first day of anthesis. It was possible to use 2n pollen successfully for backcrossing. Implications of 2n pollen for intergenomic recombination in BC^sub 1^ progenies are discussed.[PUBLICATION ABSTRACT]
ISSN:0014-2336
1573-5060
DOI:10.1007/s10681-005-2657-1