Apomixis: Molecular Strategies for the Generation of Genetically Identical Seeds without Fertilization

Koltunow, Anna M.; Bicknell, Ross; Chaudhury, Abed

doi:10.1104/pp.108.4.1345

Cited by 169 publications

(113 citation statements)

References 8 publications

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“…Somatic (sporophytic) cells surrounding the embryo sac can develop into an embryo, as occurs in apomixis (Koltunow, 1993;Koltunow et al, 1995), and reduced egg cells can initiate embryogenesis parthenogenetically in the absence of fertilization (Matzk et al, 1995;Matzk, 1996). Apomixis refers to asexual reproduction through seeds that involves the avoidance of meiosis and fertilization-independent embryo development (Grossniklaus, 2001).…”

Section: Are All Cells Of the Embryo Sac Competent To Form Embryos?mentioning

confidence: 99%

The ArabidopsisSomatic Embryogenesis Receptor Kinase 1Gene Is Expressed in Developing Ovules and Embryos and Enhances Embryogenic Competence in Culture

et al. 2001

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We report here the isolation of the Arabidopsis SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE 1 (AtSERK1) gene and we demonstrate its role during establishment of somatic embryogenesis in culture. The AtSERK1 gene is highly expressed during embryogenic cell formation in culture and during early embryogenesis. The AtSERK1 gene is first expressed in planta during megasporogenesis in the nucleus of developing ovules, in the functional megaspore, and in all cells of the embryo sac up to fertilization. After fertilization, AtSERK1 expression is seen in all cells of the developing embryo until the heart stage. After this stage, AtSERK1 expression is no longer detectable in the embryo or in any part of the developing seed. Low expression is detected in adult vascular tissue. Ectopic expression of the full-length AtSERK1 cDNA under the control of the cauliflower mosaic virus 35S promoter did not result in any altered plant phenotype. However, seedlings that overexpressed theAtSERK1 mRNA exhibited a 3- to 4-fold increase in efficiency for initiation of somatic embryogenesis. Thus, an increased AtSERK1 level is sufficient to confer embryogenic competence in culture.

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Section: Are All Cells Of the Embryo Sac Competent To Form Embryos?mentioning

confidence: 99%

The ArabidopsisSomatic Embryogenesis Receptor Kinase 1Gene Is Expressed in Developing Ovules and Embryos and Enhances Embryogenic Competence in Culture

et al. 2001

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“…A apomixia facultativa tal como registrada em S. fluminensis produz dois tipos de sementes férteis: (a) embriões apomíticos geneticamente idênticos ao genótipo materno e (b) embriões zigóticos geneticamente diferentes do genótipo materno (PANGSUBAN et al, 2009), e, dessa forma, a progenie dessas plantas é constituída por uma população variável de plantas, algumas das quais são clones da planta-mãe e outras são hibridos sexuais (KOLTUNOW et al, 1995).…”

Section: Discussionunclassified

“…A apomixia pode ser facultativa (a planta produz descendentes tanto de origem sexual quanto de origem apomítica) ou obrigatória (KOLTUNOW et al, 1995). Trata-se de um sistema reprodutivo pouco frequente, encontrado em cerca de 15% das famílias das angiospermas, presente principalmente nas famílias das Gramineae (Poaceae), Asteraceae e Rosaceae.…”

Section: Introductionunclassified

Apomixia facultativa em Smilax fluminensis Steud. (Smilacaceae), espécie dióica de fragmentos florestais, centro oeste do Brasil

2013

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RESUMO -Apomixia facultativa em Smilax fluminensis (Smilacaceae) foi estudada em duas populações naturais de Tangará da Serra, MT. A espécie apresenta inflorescências umbeliformes e flores inconspícuas. Foi avaliado o sistema reprodutivo de indivíduos femininos e masculinos de S. fluminensis em três episódios reprodutivos consecutivos, sendo a razão sexual entre esses indivíduos equilibrada. No sistema reprodutivo foi registrada a formação de frutos em todos os tratamentos: Polinização Cruzada (82,16%), Polinização Aberta (70,30%) e Apomixia (31,81%). A maioria dos frutos contados desenvolveu três sementes, e a formação de frutos com quatro sementes foi registrada em ambos os fragmentos florestais. Frutos com uma semente foi registrado em apenas um dos fragmentos, e no tratamento apomítico esse número foi cerca de duas vezes maior, em comparação com os demais tratamentos. As abelhas Halictus hesperus e Tetragona clavipes visitaram flores de ambos os sexos e foram consideradas polinizadoras pela sua frequência e comportamento. A apomixia facultativa de S. fluminensis é estratégia reprodutiva vantajosa, pois garante sua reprodução mesmo na ausência de polinizadores.Palavras-chave: Entomofilia; Razão sexual; Sistema reprodutivo. FACULTATIVE APOMIXIS IN Smilax fluminensis Steud. (Smilacaceae), DIOECIOUS SPECIES OF FOREST FRAGMENT, WEST CENTRAL BRAZIL

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“…In contrast, all four meiotically derived nuclei participate in the formation of the tetrasporic female gametophyte, generating a chimeric haploid multicellular entity that incorporates both maternally derived alleles into distinct gametophytic cells. Other alternative pathways of sexual development include many forms of multiple embryogenesis within the same ovule ( polyembryony) (Koltunow et al 1995), natural formation of unreduced gametes at variable frequencies (Harlan and de Wet 1975;Bretagnolle and Thompson 1995;Brownfield and Köhler 2011), and autonomous development of the egg cell by parthenogenesis (Kimber and Riley 1963).…”

Section: Reproductive Versatility In Flowering Plantsmentioning

confidence: 99%

Reproductive Versatility and the Epigenetic Control of Female Gametogenesis

Vielle‐Calzada

Hernandez-Lagana

Rodríguez-Leal

et al. 2012

Cold Spring Harbor Symposia on Quantitative Biology

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Each year, plants and animals perform the task of repopulating the planet through patterns of courtship and mating that have a unifying and compelling logic: the production of offspring. Although life of nearly all organisms is organized around sex and breeding, Darwinian thinking focused more on the struggle for existence than on evolutionary significance of this frantic race to reproduce. In Darwin's own words, "We do not know the final cause of sexuality; why new beings should be produced by the union of the two sexual elements. The whole subject is hidden in darkness. . ." (Darwin 1862). In plants, a major consequence of this search for survival is the evolution of a multitude of reproductive alternatives that have intrigued botanists, geneticists, and evolutionary biologists for more than 100 years. Because sexually derived genetic diversity is interpreted as essential for adaptation, it is often thought that sex is necessary for the perpetuation of a species; however, many organismsincluding several hundred families of flowering plants-are going efficiently about propagating their kind without bothering with meiosis and mating. Whereas many plants can undergo vegetative propagation, through the production of stolons, bulbs, or rhizomes, for example, many others have developed methods to produce an embryo from a single cell whose nucleus is not formed by the fusion of two gametes, offering a direct developmental and evolutionary challenge to sexual reproduction. Recent evidence suggests that epigenetic mechanisms that control transcriptional silencing of DNA repetitive elements and heterochromatin are crucial for the acquisition of cell identity in the ovule, opening the possibility that the developmental distinction between sexual development and apomixis might have evolved as an adaptive response to evolutionary forces that modulate structural variation and reproductive versatility in flowering plants.The emergence of all plants is derived from a common ancestor that endosymbiotically acquired a photosynthetic bacterium capable of transforming light into energy, an evolutionary event that changed the surface of the planet by progressively transforming an environment dominated by cyanobacteria (blue-green bacteria) into a habitat predominantly occupied by photosynthetic multicellular organisms. Although fossilized spores suggest that land plants appeared more than 450 million years ago, the establishment of their life cycle through the alternation of haploid and diploid generations remains an unsolved mystery. In contrast to green algae and mosses, in which the gametophytic (haploid) phase is free-living and temporally dominant, flowering plants have a reduced and ephemeral gametophyte that forms male and female gametes and is necessary to ensure sexual reproduction.Plants have evolved a characteristic life strategy with alternating diploid and haploid phases (or generations), continuous postembryonic development that derives in the formation of aerial and underground meristems, and the absence of a germli...

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Apomixis: Molecular Strategies for the Generation of Genetically Identical Seeds without Fertilization

Cited by 169 publications

References 8 publications

The ArabidopsisSomatic Embryogenesis Receptor Kinase 1Gene Is Expressed in Developing Ovules and Embryos and Enhances Embryogenic Competence in Culture

The ArabidopsisSomatic Embryogenesis Receptor Kinase 1Gene Is Expressed in Developing Ovules and Embryos and Enhances Embryogenic Competence in Culture

Apomixia facultativa em Smilax fluminensis Steud. (Smilacaceae), espécie dióica de fragmentos florestais, centro oeste do Brasil

Reproductive Versatility and the Epigenetic Control of Female Gametogenesis

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