A re-examination of the mechanisms of 2n gamete formation in potato and its implications for breeding

Ramanna, M.S.

doi:10.1007/bf00038921

Cited by 119 publications

(84 citation statements)

References 32 publications

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“…Recent molecular studies have even revealed a polyploid origin of some classically considered diploid species, such as maize and soybean [141,142]. It has been suggested that functioning of the unreduced gametes produced through meiotic restitution may have been a major mechanism for the widespread occurrence of polyploidy in nature [24,137,139,[143][144][145][146][147][148][149][150], see 26 for a review]. Meiotic restitution may also be a significant driving force behind speciation in plants.…”

Section: Meiotic Restitution and Polyploidiza-tionmentioning

confidence: 99%

Meiosis-Driven Genome Variation in Plants

Cai¹,

Xu²

2007

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Meiosis includes two successive divisions of the nucleus with one round of DNA replication and leads to the formation of gametes with half of the chromosomes of the mother cell during sexual reproduction. It provides a cytological basis for gametogenesis and inheritance in eukaryotes. Meiotic cell division is a complex and dynamic process that involves a number of molecular and cellular events, such as DNA and chromosome replication, chromosome pairing, synapsis and recombination, chromosome segregation, and cytokinesis. Meiosis maintains genome stability and integrity over sexual life cycles. On the other hand, meiosis generates genome variations in several ways. Variant meiotic recombination resulting from specific genome structures induces deletions, duplications, and other rearrangements within the genic and non-genic genomic regions and has been considered a major driving force for gene and genome evolution in nature. Meiotic abnormalities in chromosome segregation lead to chromosomally imbalanced gametes and aneuploidy. Meiotic restitution due to failure of the first or second meiotic division gives rise to unreduced gametes, which triggers polyploidization and genome expansion. This paper reviews research regarding meiosis-driven genome variation, including deletion and duplication of genomic regions, aneuploidy, and polyploidization, and discusses the effect of related meiotic events on genome variation and evolution in plants. Knowledge of various meiosis-driven genome variations provides insight into genome evolution and genetic variability in plants and facilitates plant genome research.

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Section: Meiotic Restitution and Polyploidiza-tionmentioning

confidence: 99%

Meiosis-Driven Genome Variation in Plants

Cai¹,

Xu²

2007

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“…However, the presence of 2n gametes may allow a species to overcome stylar, ploidy and EBN barriers. 2n gametes result from meiotic distortions affecting micro-or macro-sporogenesis (Peloquin et al 1989;Ramanna 1979). In potato, wild species are scrutinized for their contribution to variability in traditional farmer's fields and to current plant breeding efforts in the search for traits that make potato cultivars tolerant or resistant to diverse diseases (Chen et al 2003) and abiotic stresses such as drought and frost.…”

Section: Introductionmentioning

confidence: 99%

Hybridization between wild and cultivated potato species in the Peruvian Andes and biosafety implications for deployment of GM potatoes

Scurrah¹,

Celis-Gamboa²,

Chumbiauca³

et al. 2008

Euphytica

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The nature and extent of past and current hybridization between cultivated potato and wild relatives in nature is of interest to crop evolutionists, taxonomists, breeders and recently to molecular biologists because of the possibilities of inverse gene flow in the deployment of genetically-modified (GM) crops. This research proves that natural hybridization occurs in areas of potato diversity in the Andes, the possibilities for survival of these new hybrids, and shows a possible way forward in case of GM potatoes should prove advantageous in such areas.

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“…All meiotic stages of the pollen mother cells were examined. The occurrence of parallel and/or fused spindles during Metaphase II, followed by dyad formation identified the FDR mode of 2n pollen formation (Mok and Peloquin, 1975;Ramanna, 1979). Pollen staining was in accordance with Quinn et a!.…”

Section: Plant Materialsmentioning

confidence: 75%

“…The benefits of such hybridisations aimed to capture novel genetic diversity are directly related to the meiotic mechanism responsible for diplandroid formation. At present, three meiotic mechanisms have been identified that lead to male 2n gametes in the diploid potato species: parallel and/or fused spindles at metaphase II (First Division Restitution or FDR), premature cytokinesis I, and premature cytokinesis II (Second Division Restitution or SDR) (Mok and Peloquin, 1975;Ramanna, 1979). The discovery of synaptic genes (Iwanaga and Peloquin, 1979) of the diploid parent's heterozygosity intact to the tetraploid offspring (Okwuagwa and Peloquin, 1981).…”

Section: Introductionmentioning

confidence: 99%

Genetic recombination in a diploid synaptic mutant and a Solanum tuberosum × S. chacoense diploid hybrid

Douches

Quirós

1988

Heredity

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A diploid synaptic mutant, M6 with the genotype sy3/sy3,ps/ps, was identified as heterozygous for four enzyme-coding loci, and for the tuber flesh colour locus (Y). Through 4x-2 x crosses, half-tetrad analysis was applied to determine the ability of the M6 clone to transmit its heterozygosity to tetraploid offspring. On the average, an 8903 per cent reduction in recombination was found within the chromosome segments sampled, resulting in 98 per cent transmission of heterozygosity. Cytological observations of microsporogenesis revealed frequent pachytene associations and a high proportion of univalents at diakinesis. These findings show that chromosome pairing in M6 is mostly desynaptic. Diploid and 4x-2x testcrosses were made to study recombination in a 2n-pollen producing diploid hybrid T704 (ps/ps); S. tuberosum L. x S. chacoense Bitt. For the loci compared, recombination was reduced 3456 per cent on the average. This hybrid transmitted on the average 892 per cent of its heterozygosity which was significantly higher than the value previously observed in non-hybrid individuals. Unlike M6, T704 produced both viable n and 2n pollen. In addition, cytological examination of PMCs indicate normal bivalent associations. It is suggested that genomic differentiation between S. tuberosum and S. chacoense could account for the reduced recombination levels.

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A re-examination of the mechanisms of 2n gamete formation in potato and its implications for breeding

Cited by 119 publications

References 32 publications

Meiosis-Driven Genome Variation in Plants

Meiosis-Driven Genome Variation in Plants

Hybridization between wild and cultivated potato species in the Peruvian Andes and biosafety implications for deployment of GM potatoes

Genetic recombination in a diploid synaptic mutant and a Solanum tuberosum × S. chacoense diploid hybrid

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