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Emergence of apospory and bypass of meiosis via apomixis after sexual hybridisation and polyploidisation.

Hojsgaard D, Greilhuber J, Pellino M, Paun O, Sharbel TF, Hörandl E - New Phytol. (2014)

Bottom Line: Bypassing meiosis permits these triploid genotypes to form viable seed and new polyploid progeny.Apomixis is functional in triploids and associated with drastic meiotic abnormalities.Selection acts to stabilise developmental patterns and to tolerate endosperm dosage balance shifts which facilitates successful seed set and establishment of apomictic lineages.

View Article: PubMed Central - PubMed

Affiliation: Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, Georg August University of Göttingen, Untere Karspüle 2, D-37073, Göttingen, Germany.

No MeSH data available.


Related in: MedlinePlus

Male gametophyte development, viability, functionality and compatibility with female gametophytes to set seeds in Ranunculus. (a) Male gametophytes of a triploid hybrid during flowering showing aborted and immature to mature microspores (carrying one nucleus or two, with the generative one adsorbed to the inner microspore wall). (b) Box-and-whisker diagram for the proportion of viable male gametophytes at flowering among ploidy levels of interspecific hybrids and sexual parentals. Boxes represent first and third quartiles, and the band inside each box indicates the median. Whiskers correspond to 95% CI. Outliers and extreme values are represented by circles and stars, respectively. (c) Growing pollen tubes of functional male gametophytes on flower stigma and style (arrowheads) 120 min post-pollination; (d) ovule at flowering, 180 min post-pollination, showing the path of the pollen tube toward the embryo sac (whitish delineated) between integuments and the apparent delivery of male gametes into the synergids and egg cell zone (arrow). (e) Box-and-whisker diagram for the proportion of seeds formed by interspecific hybrids and sexual parental species among ploidy levels. Boxes, whiskers and outliers are represented as in (b). Genotypes: (a) G4; (c) G7; (d) J33. ii, inner integuments; •, chalazal pole; *, micropylar pole. Bars: (a) 10 μm; (c, d) 30 μm. 1Data from Hörandl (2008).
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fig02: Male gametophyte development, viability, functionality and compatibility with female gametophytes to set seeds in Ranunculus. (a) Male gametophytes of a triploid hybrid during flowering showing aborted and immature to mature microspores (carrying one nucleus or two, with the generative one adsorbed to the inner microspore wall). (b) Box-and-whisker diagram for the proportion of viable male gametophytes at flowering among ploidy levels of interspecific hybrids and sexual parentals. Boxes represent first and third quartiles, and the band inside each box indicates the median. Whiskers correspond to 95% CI. Outliers and extreme values are represented by circles and stars, respectively. (c) Growing pollen tubes of functional male gametophytes on flower stigma and style (arrowheads) 120 min post-pollination; (d) ovule at flowering, 180 min post-pollination, showing the path of the pollen tube toward the embryo sac (whitish delineated) between integuments and the apparent delivery of male gametes into the synergids and egg cell zone (arrow). (e) Box-and-whisker diagram for the proportion of seeds formed by interspecific hybrids and sexual parental species among ploidy levels. Boxes, whiskers and outliers are represented as in (b). Genotypes: (a) G4; (c) G7; (d) J33. ii, inner integuments; •, chalazal pole; *, micropylar pole. Bars: (a) 10 μm; (c, d) 30 μm. 1Data from Hörandl (2008).

Mentions: Male meiosis was apparently regular in synthetic diploids, but less than a half of mature microgametophytes (45.3%, ranging between 32.3% and 62.4%, Table S3) had polysaccharide vesicles in their cytoplasm, indicating viability. In triploids, male meiosis was clearly irregular: the progress through microsporogenesis was disturbed from the beginning and showed high amounts of cell abortion, ending with an average of < 20% viable microgametophytes (ranging between 10.6% and 25.9%; Fig. 2a,b, Table S3).


Emergence of apospory and bypass of meiosis via apomixis after sexual hybridisation and polyploidisation.

Hojsgaard D, Greilhuber J, Pellino M, Paun O, Sharbel TF, Hörandl E - New Phytol. (2014)

Male gametophyte development, viability, functionality and compatibility with female gametophytes to set seeds in Ranunculus. (a) Male gametophytes of a triploid hybrid during flowering showing aborted and immature to mature microspores (carrying one nucleus or two, with the generative one adsorbed to the inner microspore wall). (b) Box-and-whisker diagram for the proportion of viable male gametophytes at flowering among ploidy levels of interspecific hybrids and sexual parentals. Boxes represent first and third quartiles, and the band inside each box indicates the median. Whiskers correspond to 95% CI. Outliers and extreme values are represented by circles and stars, respectively. (c) Growing pollen tubes of functional male gametophytes on flower stigma and style (arrowheads) 120 min post-pollination; (d) ovule at flowering, 180 min post-pollination, showing the path of the pollen tube toward the embryo sac (whitish delineated) between integuments and the apparent delivery of male gametes into the synergids and egg cell zone (arrow). (e) Box-and-whisker diagram for the proportion of seeds formed by interspecific hybrids and sexual parental species among ploidy levels. Boxes, whiskers and outliers are represented as in (b). Genotypes: (a) G4; (c) G7; (d) J33. ii, inner integuments; •, chalazal pole; *, micropylar pole. Bars: (a) 10 μm; (c, d) 30 μm. 1Data from Hörandl (2008).
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4260133&req=5

fig02: Male gametophyte development, viability, functionality and compatibility with female gametophytes to set seeds in Ranunculus. (a) Male gametophytes of a triploid hybrid during flowering showing aborted and immature to mature microspores (carrying one nucleus or two, with the generative one adsorbed to the inner microspore wall). (b) Box-and-whisker diagram for the proportion of viable male gametophytes at flowering among ploidy levels of interspecific hybrids and sexual parentals. Boxes represent first and third quartiles, and the band inside each box indicates the median. Whiskers correspond to 95% CI. Outliers and extreme values are represented by circles and stars, respectively. (c) Growing pollen tubes of functional male gametophytes on flower stigma and style (arrowheads) 120 min post-pollination; (d) ovule at flowering, 180 min post-pollination, showing the path of the pollen tube toward the embryo sac (whitish delineated) between integuments and the apparent delivery of male gametes into the synergids and egg cell zone (arrow). (e) Box-and-whisker diagram for the proportion of seeds formed by interspecific hybrids and sexual parental species among ploidy levels. Boxes, whiskers and outliers are represented as in (b). Genotypes: (a) G4; (c) G7; (d) J33. ii, inner integuments; •, chalazal pole; *, micropylar pole. Bars: (a) 10 μm; (c, d) 30 μm. 1Data from Hörandl (2008).
Mentions: Male meiosis was apparently regular in synthetic diploids, but less than a half of mature microgametophytes (45.3%, ranging between 32.3% and 62.4%, Table S3) had polysaccharide vesicles in their cytoplasm, indicating viability. In triploids, male meiosis was clearly irregular: the progress through microsporogenesis was disturbed from the beginning and showed high amounts of cell abortion, ending with an average of < 20% viable microgametophytes (ranging between 10.6% and 25.9%; Fig. 2a,b, Table S3).

Bottom Line: Bypassing meiosis permits these triploid genotypes to form viable seed and new polyploid progeny.Apomixis is functional in triploids and associated with drastic meiotic abnormalities.Selection acts to stabilise developmental patterns and to tolerate endosperm dosage balance shifts which facilitates successful seed set and establishment of apomictic lineages.

View Article: PubMed Central - PubMed

Affiliation: Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, Georg August University of Göttingen, Untere Karspüle 2, D-37073, Göttingen, Germany.

No MeSH data available.


Related in: MedlinePlus