Occurrence of numerically unreduced (2n) gametes in Alstroemeria interspecific hybrids and their significance for sexual polyploidisation |
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Authors: | MS Ramanna AGJ Kuipers E Jacobsen |
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Institution: | (1) Laboratory of Plant Breeding, Wageningen University and Research Center, P.O. Box 386, 6700 AJ Wageningen, The Netherlands |
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Abstract: | 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 population from one genotype, P6C49-6, was investigated. The recombinant chromosomes
assorted independently from each other supporting the hypothesis that the segregation of chromosomes in ring quadrivalents
did not behave like those in translocation heterozygotes. It was concluded that in allopolyploids of Alstroemeria,bilateral sexual polyploidisation could accomplish genetic recombination by both homoeologous crossing-over as well as through
the assortment of chromosomes.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | Alstroemeria genomic in situ hybridisation homoeologous recombination interspecific hybridisation unreduced gametes |
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