Abnormal meiosis in alfalfa, Medicago sativa: cytology of 2N egg and 4N pollen formation

Pfeiffer, T. W.; Bingham, E. T.

doi:10.1139/g83-021

Cited by 67 publications

(47 citation statements)

References 3 publications

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“…It is well known that unreduced gametes or meiotic restitution is of predominant importance in polyploidization and speciation. This phenomenon has been reported in alfalfa (Pfeiffer and Bingham, 1983), barley (Finch and Bennet, 1979), potato (Conicella et al, 1996), and other species in Triticeae (Tiwari et al, 2008;Zhang et al, 2008).…”

Section: Discussionsupporting

confidence: 70%

Mitotic and meiotic behavior of rye chromosomes in wheat - Psathyrostachys huashanica amphiploid x triticale progeny

Xie

Kang²,

Sparkes³

et al. 2013

Genet. Mol. Res.

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ABSTRACT. The dynamics of rye chromosomes during mitosis and meiosis was analyzed in a subset comprising 33 F 3 lines from the cross of wheat, Psathyrostachys huashanica amphiploid (AABBDDNsNs) and hexaploid triticale (AABBRR), as visualized by genomic in situ hybridization. The results indicated that 31 of the total lines contained 4-14 rye chromosomes. Twenty-eight combinations had more rye chromosomes than the F 1 hybrids, suggesting the occurrence of spontaneous quantitative increment. No P. huashanica chromosomes were detected in all of the combinations tested. Mitotic analysis showed that rye chromosomes progressed normally with the wheat counterparts without loss. However, abnormal meiosis was found in almost all lines. Similar progression between wheat and rye genomes appeared from interphase to metaphase I. It was at anaphase I that many rye univalents lagged behind those of wheat, followed by equational division. This resulted in the formation of chromosomal segments and micronuclei at telophase I or II. Micronuclei could also be generated from the immobilized univalents in the periphery of cells. Synapsis and translocations between wheat and rye genomes, chromosome bridges, and unreduced gametes were detected. Therefore, it is proposed that rye chromosome elimination may involve chromatid lagging, fragmentation and micronucleation, or the immobilization of certain univalents during meiosis instead of mitosis in the relatively advanced generations. This mechanism, together with spontaneous incremental increase of rye chromosome number, permitted the generation of various germplasms for wheat improvement.

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Section: Discussionsupporting

confidence: 70%

Mitotic and meiotic behavior of rye chromosomes in wheat - Psathyrostachys huashanica amphiploid x triticale progeny

Xie

Kang²,

Sparkes³

et al. 2013

Genet. Mol. Res.

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“…Lack of meiotic cytokinesis is also considered as one of the reasons for unreduced gamete formation (PFEIFFER and BINGHAM, 1983;RAY and TOKACH, 1992). In potatoes, analysis of microtubule cytoskeletons has revealed that meiotic nuclear restitution occurs by the fusion of nonsister nuclei, which depends on the absence of secondary interzonal microtubules and on the distance between nuclei (CONICELLA et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

Distribution of Microtubular Cytoskeletons and Organelle Nucleoids During Microsporogenesis in a 2n Pollen Producer of Hybrid Populus

Wang

Kang

2009

Silvae Genetica

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The distribution of microtubular cytoskeletons and organelle nucleoids during microsporogenesis in Populus simonii Carr. x P. nigra L. 'Tongliao' was studied by indirect immunofluorescence and 4',6-diamidino-2-phenylindole (DAPI) staining. Our purpose was to reveal the relationship between changes in microtubule and chromosome behavior and cytokinesis and to explain the mechanism of 2n pollen production. We observed stable frequencies of 2n pollen production, ranging from 1.56 % to 2.29 %, between 2006 and 2008. Moreover, conjoined pollen grains were also observed. Meiotic abnormalities, including univalents, lagging chromosomes and micronuclei, were observed during microsporogenesis. Triads and dyads were also detected in meiotic products. Parallel spindles in metaphase II were unable to fuse, owing to the existence of an organelle band. Regularly, in telophase II, primary phragmoplasts were organized between sister nuclei, and secondary phragmoplasts formed between non-sister nuclei. Cell plates were initiated by centrifugal expansion of phragmoplasts and cytoplasmic infurrowing started at the junctions between the microsporocyte wall and the expanded phragmoplasts. However, a secondary phragmoplast was absent in some microsporocytes. These observations suggest that the occurrence of 2n pollen may result from the partial failure of cytokinesis caused by the absence of secondary phragmoplasts in this hybrid.

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“…In this study, 2n pollen was 40-fold more frequent than 4n pollen. Production of 4n pollen is documented in alfalfa, corn and peas, and generally involves a failure of cytokinesis following meiosis (Pfeiffer and Bingham, 1983). Additional cytological study is needed to understand the mechanisms underlying 2n and 4n pollen production in Achillea.…”

Section: Production Of Unreduced Pollen In Natural Populationsmentioning

confidence: 99%

Unreduced gametes and neopolyploids in natural populations of Achillea borealis (Asteraceae)

2006

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Polyploidy is a major mechanism of speciation and adaptation, yet little is known about the origins of polyploids in natural species. I investigated gametic nonreduction and neopolyploid formation in natural tetraploid populations of Achillea borealis (Asteraceae), an autopolyploid complex consisting of tetraploid and hexaploid cytotypes. Cytological analyses of tetraploid populations revealed the occurrence of reduced (n ¼ 2x) as well as unreduced 'big' (2n ¼ 4x) and 'jumbo' (4n ¼ 8x) pollen grains, which were clearly distinguished by size. Production of unreduced pollen was monitored in two tetraploid populations in 1997 and 1998. Mean population-level frequencies of unreduced pollen ranged from 0.030 to 0.538%, with as few as one-third and as many as one-half of sampled plants producing unreduced grains. Eight individuals were found to produce 41% unreduced pollen, with highest observed frequencies of 7.0, 13.2 and 15.8%. Experimental crosses using high unreduced pollen producers as male parents generated viable seeds. However, the frequency of neohexaploids in the progeny of experimental crosses (0.388%) was similar to that observed in progeny of randomly selected, openpollinated control parents (0.465%). These results suggest that unreduced eggs are the most likely source of new polyploids. In spite of the inefficiency of unreduced pollen in unilateral sexual polyploidization, the overall rate of neohexaploid formation (one in 233) was several orders of magnitude greater than estimates of genic mutation rates.

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Abnormal meiosis in alfalfa, Medicago sativa: cytology of 2N egg and 4N pollen formation

Cited by 67 publications

References 3 publications

Mitotic and meiotic behavior of rye chromosomes in wheat - Psathyrostachys huashanica amphiploid x triticale progeny

Mitotic and meiotic behavior of rye chromosomes in wheat - Psathyrostachys huashanica amphiploid x triticale progeny

Distribution of Microtubular Cytoskeletons and Organelle Nucleoids During Microsporogenesis in a 2n Pollen Producer of Hybrid Populus

Unreduced gametes and neopolyploids in natural populations of Achillea borealis (Asteraceae)

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