Gametes and Fertilization: Maize as a Model System for Experimental Embryogenesis in Flowering Plants

Dumas, Christian; Mogensen, H. Lloyd

doi:10.2307/3869786

Cited by 29 publications

(29 citation statements)

References 33 publications

(52 reference statements)

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“…Transmission electron microscopy studies of sperm cells have revealed the subcellular organization of the sperm cells and their close association with the vegetative cell nucleus (for review, see Dumas and Mogensen, 1993;Weterings and Russell, 2004). However, such studies give only a static picture.…”

Section: Live Imaging Of Sperm Cell Dynamicsmentioning

confidence: 99%

Green Sperm. Identification of Male Gamete Promoters in Arabidopsis

2005

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Previously, in an effort to better understand the male contribution to fertilization, we completed a maize (Zea mays) sperm expressed sequence tag project. Here, we used this resource to identify promoters that would direct gene expression in sperm cells. We used reverse transcription-polymerase chain reaction to identify probable sperm-specific transcripts in maize and then identified their best sequence matches in the Arabidopsis (Arabidopsis thaliana) genome. We tested five different Arabidopsis promoters for cell specificity, using an enhanced green fluorescent protein reporter gene. In pollen, the AtGEX1 (At5g55490) promoter is active in the sperm cells and not in the progenitor generative cell or in the vegetative cell, but it is also active in ovules, roots, and guard cells. The AtGEX2 (At5g49150) promoter is active only in the sperm cells and in the progenitor generative cell, but not in the vegetative cell or in other tissues. A third promoter, AtVEX1 (At5g62580), was active in the vegetative cell during the later stages of pollen development; the other promoters tested (At1g66770 and At1g73350) did not function in pollen. Comparisons among GEX1 and GEX2 homologs from maize, rice (Oryza sativa), Arabidopsis, and poplar (Populus trichocarpa) revealed a core binding site for Dof transcription factors. The AtGEX1 and AtGEX2 promoters will be useful for manipulating gene expression in sperm cells, for localization and functional analyses of sperm proteins, and for imaging of sperm dynamics as they are transported in the pollen tube to the embryo sac.

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Section: Live Imaging Of Sperm Cell Dynamicsmentioning

confidence: 99%

Green Sperm. Identification of Male Gamete Promoters in Arabidopsis

2005

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“…In line with this idea, DcSERK expression was not detected prior to fertilization in developing carrot flowers, suggesting that embryogenic competence is not acquired before formation of the zygote in carrot (Schmidt et al, 1997). Experiments with isolated egg cells have also shown that fertilization is an absolute requirement for embryogenesis to proceed (Dumas and Mogensen, 1993;Faure et al, 1994). However, AtSERK1 is clearly expressed before meiosis during ovule development in gametophytic and sporophytic tissue.…”

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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“…Likewise, experimental studies on the early studies of embryogenesis have not been possible due to inadequate culture techniques for the isolated egg cells and young embryos. In the last few years, major progress has been made in the isolation of plant gametes (reviewed in Dumas and Mogensen, 1993). Simple and efficient techniques have been…”

Section: Introductionmentioning

confidence: 99%

Regeneration of Fertile Barley Plants from Mechanically Isolated Protoplasts of the Fertilized Egg Cell.

et al. 1994

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A simple procedure is described for the mechanical isolation of protoplasts of unfertilized and fertilized barley egg cells from dissected ovules. Viable protoplasts were isolated from m75% of the dissected ovules. Unfertilized protoplasts did not divide, whereas almost all fertilized protoplasts developed into microcalli. These degenerated when grown in medium only. When cocultivated with barley microspores undergoing microspore embryogenesis, the protoplasts of the fertilized egg cells developed into embryo-like structures that gave rise to fully fertile plants. On average, 75% of cocultivated protoplasts of fertilized egg cells developed into embryo-like structures. Fully fertile plants were regenerated from 4 0 % of the embryo-like structures. The isolation-regeneration techniques may be largely genotype independent, because similar frequencies were obtained in two different barley varieties with very different performance in anther and microspore culture. Protoplasts of unfertilized and fertilized eggs of wheat were isolated by the same procedure, and a fully fertile wheat plant was regenerated by cocultivation with barley microspores.

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Gametes and Fertilization: Maize as a Model System for Experimental Embryogenesis in Flowering Plants

Cited by 29 publications

References 33 publications

Green Sperm. Identification of Male Gamete Promoters in Arabidopsis

Green Sperm. Identification of Male Gamete Promoters in Arabidopsis

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

Regeneration of Fertile Barley Plants from Mechanically Isolated Protoplasts of the Fertilized Egg Cell.

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