Vegetative Apical Meristems.

Medford, June I.

doi:10.1105/tpc.4.9.1029

Cited by 114 publications

(34 citation statements)

References 47 publications

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“…Many genes thought to be associated with the Arabidopsis transition to flowering have been cloned or are currently being cloned (Shannon and Meeks-Wagner 1991;Mandel et al 1992;Weigel et al 1992;Araki and Komeda 1993;Lee et al 1993). Ultimately, these transition-to-flowering genes will be analyzed in the context of the morphological changes which occur at the shoot apex (for a review of shoot apex terminology, see Medford 1992). Hence, an in-depth understanding of the morphological changes which occur during the transition to flowering is required.…”

Section: Introductionmentioning

confidence: 99%

Bi-directional inflorescence development in Arabidopsis thaliana: Acropetal initiation of flowers and basipetal initiation of paraclades

Hempel

Feldman

1994

Planta

117

163

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In this study we investigated Arabidopsis thaliana (L.) Heynh. inflorescence development by characterizing morphological changes at the shoot apex during the transition to flowering. Sixteen-hour photoperiods were used to synchronously induce flowering in vegetative plants grown for 30 d in non-inductive 8-h photoperiods. During the first inductive cycle, the shoot apical meristem ceased producing leaf primordia and began to produce flower primordia. The differentiation of paraclades (axillary flowering shoots), however, did not occur until after the initiation of multiple flower primordia from the shoot apical meristem. Paraclades were produced by the basipetal activation of buds from the axils of leaf primordia which had been initiated prior to photoperiodic induction. Concurrent with the activation of paraclades was the partial suppression of paraclade-associated leaf primordia, which became bract leaves. The suppression of bract-leaf primordia and the abrupt initiation of flower primordia during the first inductive photoperiod is indicative of a single phase change during the transition to flowering in photoperiodically induced Arabidopsis. Morphogenetic changes characteristic of the transition to flowering in plants grown continuously in 16-h photoperiods were qualitatively equivalent to the changes observed in plants which were photoperiodically induced after 30 d. These results suggest that Arabidopsis has only two phases of development, a vegetative phase and a reproductive phase; and that the production of flower primordia, the differentiation of paraclades from the axils of pre-existing leaf primordia and the elongation of internodes all occur during the reproductive phase.

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Section: Introductionmentioning

confidence: 99%

Bi-directional inflorescence development in Arabidopsis thaliana: Acropetal initiation of flowers and basipetal initiation of paraclades

Hempel

Feldman

1994

Planta

117

163

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“…Since the apical meristem in dicotyledonous plants is organised into layers or regions (see review of apical structure by Medford, 1992) giving rise to the epidermal and subepidermal and ground tissue respectively, and assuming that mutations are single cell events; the expression of mutations was envisaged as occurring via transitional chimeric meristems where, depending on the mutant cells fitness, it progressively displaces unmutated cells in its own somatic layer and in those of the other somatic layers. Lateral buds formed during this process would be homohistonts of either the parental cell lineage where the mutant cell was unfit and eliminated, or conversely of the mutant cell's lineage where the latter was fit.…”

Section: Introductionmentioning

confidence: 99%

Diplontic selection as a positive factor in determining the fitness of mutants of Dianthus ‘Mystère’ derived from x-irradiation of nodes in in vitro culture

1993

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X-irradiation of in vitro nodes of Dianthus 'Myst6re' resulted in the production of useful flower colour variants at a rate of approximately 2%. The breakdown of chimeras under diplontic selection and putative selection for fitness in the mutant homohistonts was facilitated by in vitro subculture. The resultant mutants were vigorous and most were stable although pleiotropy in respect to Alternaria disease was observed.Image analysis of leaf shape in the mutagenised progeny detected no significant differences in the population means for this character but significant increase in the standard deviation was correlated with increase in dose rate. Significant differences in means for leaf shape were detected between the control and selected flower colour-variant lines and between many of the lines indicating that the flower colour changes were occurring in a background of quantitative gene changes in the variants.The comparative advantages of this model of in vitro mutagenesis are discussed.

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“…Thus, the ballistic microtargeting technique is ready to be used in meristem studies . This could include cell fate studies or promoter studies of any apex-specific genes (Medford, 1992) . Microtargeting and transient expression of marker genes provide rapid localization with precise resolution, which allows us to distinguish between the meristem, its cell layers and the leaf primordia .…”

Section: Discussionmentioning

confidence: 99%

“…However, little is known about the biology of this tissue (as reviewed by Medford, 1992) . The reason for this gap in our knowledge is that the meristem is a tiny structure which makes biochemical or molecular biological studies very difficult.…”

Section: Introductionmentioning

confidence: 99%

Shoot apical meristems as a target for gene transfer by microballistics

et al. 1995

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The classical approach of gene transfer to a given plant species delivers the foreign gene to transformable cells and then puts the effort into generating plants . This approach is very difficult in many important crop plants, including cereals, and the results of regeneration are very genotype-dependent . In contrast, we use regenerable cells and try to transform them . Shoot apical meristems provide a tissue which regenerates in situ a fertile plant for most given genotypes or species. Transformation of meristem cells may lead to transgenic sectors in chimeras . These sectors may contribute to the gametes and, thus, to transgenic offspring, which then should be homohistonts and not sectorial chimeras like their parents . Our model plant for these studies is wheat . Microtargeting is a ballistic approach which is particularly suitable for the controlled delivery of microprojectiles to meristem cells in situ (Sautter et al ., 1991) . We summarize in this paper our experience with ballistic microtargeting of transgenes to wheat shoot apical meristem cells in situ .Abbreviations: GUS -,3-glucuronidase 45

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Vegetative Apical Meristems.

Cited by 114 publications

References 47 publications

Bi-directional inflorescence development in Arabidopsis thaliana: Acropetal initiation of flowers and basipetal initiation of paraclades

Bi-directional inflorescence development in Arabidopsis thaliana: Acropetal initiation of flowers and basipetal initiation of paraclades

Diplontic selection as a positive factor in determining the fitness of mutants of Dianthus ‘Mystère’ derived from x-irradiation of nodes in in vitro culture

Shoot apical meristems as a target for gene transfer by microballistics

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