Rachel Foster

University of Illinois, Urbana-Champaign, Urbana, Illinois, United States

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Publications (6)13.51 Total impact

  • Frederick Meins · Rachel Foster
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    ABSTRACT: Tissues derived from the leaf lamina of Nicotiana tabacum L. cv. Havana 425 plants require cytokinin for continuous proliferation in culture, whereas tissues derived from the cortex of the stem are cytokinin autotrophic. Both phenotypes persist when the two types of cells are cloned, indicating that leaf- and cortex-derived cells are determined to express different cytokinin requirements in culture. We showed that cultures derived from leaf and cortex tissues of plants regenerated from cloned leaf and cortex cells exhibit the cytokinin requirement of comparable tissues of seed-grown plants. This provides direct evidence that plant cells can undergo transdetermination and that this process has an epigenetic basis.
    No preview · Article · Feb 1986 · Differentiation
  • Frederick Meins Jr · Rachel Foster
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    ABSTRACT: Tissues cultured from the leaf lamina of wild-type Nicotiana tabacum L. cv. “Havana 425” plants require an exogenous source of cytokinin for rapid growth. In contrast, leaf tissues of plants heterozygous or homozygous for the partially dominant, monogenic habituated leaf (H1-1) trait, exhibit a cytokinin-autotrophic phenotype in culture. Here we show that the H1 trait can arise in culture. Cytokinin autotrophic variants were obtained by culturing wild-type tissues of leaf lamina successively on media containing reduced concentrations of the cytokinin, kinetin. Plants regenerated from clones of these variants exhibited the H1 phenotype, which segregated in breeding tests as expected for a dominant, monogenic trait. This trait, designated H1-2, is inherited at a different locus than the H1-1 trait described earlier. Our results show that cytokinin mutants can arise in cell culture and that at least two genes regulate the cytokinin requirement of cultured tobacco tissues.
    No preview · Article · Jan 1986 · Developmental Genetics
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    Frederick Meins · Rachel Foster
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    ABSTRACT: Cytokinin requiring cells of Nicotiana tabacum L. cv "Havana 425" can be induced in culture to become cytokinin autotrophic. This process is known as cytokinin habituation. Earlier we showed that pith parenchyma tissue consists of inducible cells, which habituate at high rates when treated with cytokinin, and noninducible cells, which remain cytokinin requiring under these conditions. The inducible and noninducible phenotypes are determined states that arise during the development of the tobacco plant and are inherited by individual cells. Here we show that pith tissue of plants regenerated from cloned lines of noninducible cells exhibits the inducible phenotype indicating that noninducible cells, or their descendants, can become inducible. This change in competence for habituation appears to have an epigenetic basis; it is reversible, occurs at high rates, and depends on the developmental state of the cells. The habituated state occurs in two forms that can be distinguished by their difference in developmental potential. Habituated cells derived from inducible pith cells give rise to normal plants whose leaf and pith tissues require cytokinin for growth in culture. In contrast, habituated cells obtained by transferring noninducible cells on media with progressively lower cytokinin concentrations give rise to plants whose leaf and pith tissues exhibit a cytokinin-habituated phenotype in culture.
    Full-text · Article · Apr 1985 · Developmental Biology
  • Frederick Meins Jr · Rachel Foster · Joseph D. Lutz
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    ABSTRACT: Cultured leaf tissues of Nicotiana tabacum L. cv. “Havana 425” normally require an exogenous source of cytokinin for rapid growth; stem-cortex tissues do not—ie, they exhibit the cytokinin-habituated phenotype. We found that plants regenerated from cloned cortex and leaf tissues from one particular plant differed in leaf-tissue phenotype: Leaf tissues derived from leaf cells exhibited the normal, nonhabituated phenotype, whereas leaf tissues derived from cortex cells were cytokinin-habituated. This difference in leaf phenotype was not found using leaf and cortex cells from six other donor plants. The inheritance of the habituated leaf trait was studied in tissues from cortex-derived plants and hybrids between these plants and normal plants. F1 hybrids were intermediate between the parental types in degree of habituation. No differences were found between reciprocal hybrids. These results suggest that the habituated leaf trait is an incompletely dominant, nuclear trait. Both parental and intermediate phenotypes were recovered in the F2 progeny. The frequency of habituated leaf progeny in the F2 and backcross populations provide evidence that the trait is regulated at a single genetic locus.
    No preview · Article · Jan 1983 · Developmental Genetics
  • Frederick Meins · Rachel Foster · Joseph Lutz
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    ABSTRACT: After transferring leaf, pith, and stemcortex tissues ofNicotiana tabacum L. cv. "Havana 425" from a complete medium containing auxin and cytokinin to an inductive medium with auxin deleted, there is lag phase of approx. 14d followed by a linear phase in which the rate of bud initiation is constant. The incidence of buds formed is very low, approx. one bud per 10(3) or 10(4) cells. Statistical analysis of the distribution of buds among explants and subcloning experiments provide evidence that the paucity of buds results from neither negative interactions among bud forming centers nor a paucity of cells with the potential for organogenesis. Our results are consistent with the hypothesis that the frequency of bud initiation is determined by the availability of competent cells, by position effects, or by a combination of both mechanisms.
    No preview · Article · Nov 1982 · Planta
  • Frederick Meins · Joseph Lutz · Rachel Foster
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    ABSTRACT: Pith tissue of Nicotiana tabacum L. cv. "Havana 425" exhibits a gradient in its tendency to habituate for cytokinin on an auxin-containing medium at 35° C, about 10° C above the standard culture temperature. Explants of pith from below the 8th to 11th internode, counting from the bottom of the plant, rarely habituate for cytokinin; explants from above this threshold habituate rapidly. The explants must also be above a critical size, about 20-30 mg, to habituate. There was a pronounced interaction between size and position effects; the threshold position for cytokinin habituation shifted upward with decreasing explant size.
    No preview · Article · Nov 1980 · Planta