Cell divisions in cotyledons after germination: localization, time course and utilization for a mutagenesis assay

Fridlender, Marcelo; Lev‐Yadun, Simcha; Babůrek, I.; Angelis, Karel J.; Levy, Avraham A.

doi:10.1007/bf00196573

Cited by 16 publications

(13 citation statements)

References 28 publications

(40 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…74. Tobacco cotyledons can be used to determine the ICR frequency because the development (number of cells and patterns of divisions) of this organ is well understood (29). Based on the frequency and size of blue sectors in cotyledons (data not shown), we estimate that ICR occurs in the 10 Ϫ6 range͞genome in the presence of RuvC and in the 10 Ϫ7 range in WT tobacco.…”

Section: Expression Of Ruvc In Plantsmentioning

confidence: 97%

Stimulation of homologous recombination in plants by expression of the bacterial resolvase RuvC

Shalev

Sitrit

Avivi-Ragolski

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Targeted gene disruption exploits homologous recombination (HR) as a powerful reverse genetic tool, for example, in bacteria, yeast, and transgenic knockout mice, but it has not been applied to plants, owing to the low frequency of HR and the lack of recombinogenic mutants. To increase the frequency of HR in plants, we constructed transgenic tobacco lines carrying the Escherichia coli RuvC gene fused to a plant viral nuclear localization signal. We show that RuvC, encoding an endonuclease that binds to and resolves recombination intermediates (Holliday junctions) is properly transcribed in these lines and stimulates HR. We observed a 12-fold stimulation of somatic crossover between genomic sequences, a 11-fold stimulation of intrachromosomal recombination, and a 56-fold increase for the frequency of extrachromosomal recombination between plasmids cotransformed into young leaves via particle bombardment. This stimulating effect may be transferred to any plant species to obtain recombinogenic plants and thus constitutes an important step toward gene targeting.Gene targeting (GT) involves the disruption or replacement of an endogenous allele by one manipulated in vitro. This replacement requires that after transfection into the target cell the transgene recombines with the target allele by homologous recombination (HR) by virtue of sharing extensive sequence similarity, rather than integrating randomly by illegitimate recombination. As HR occurs efficiently in many lower eukaryotes such as budding yeast and in bacteria, GT has proved to be a very powerful reverse genetic tool to study gene function. The GT technology is also now routine, if not still laborious in the generation of transgenic knockout mice, and has provided models for human genetic disease and the role of homeotic genes in development (1).The mechanism of HR has long been an elusive, yet fascinating, problem. Studies in prokaryotes and lower eukaryotes have provided much insight into the nature of this process, the recombination intermediates, the genes, and the proteins involved (2-4). The basic steps of HR are listed below together with the proteins required in Escherichia coli: (i) initiation of HR by a DNA double-strand break and͞or single-strand DNA formation by the RecBCD complex; (ii) exchange of DNA strands, including homology recognition and strand displacement, done by RecA-like proteins; (iii) heteroduplex extension, with branch or bubble migration, performed by RuvA plus RuvB or RecG to yield a recombination intermediate, a four-way DNA junction named the Holliday junction; and (iv) resolution of this heteroduplex Holliday junction by the endonuclease RuvC. Steps iii and iv have only very recently been elucidated: in E. coli the RuvA and RuvB proteins (encoded on one operon) have been shown to form a complex promoting ATP-dependent branch migration of Holliday junctions, a process of high importance for the formation of heteroduplex DNA. A second operon encodes RuvC and the orf-26 gene; RuvC is the endonuclease that binds specifi...

show abstract

Section: Expression Of Ruvc In Plantsmentioning

confidence: 97%

Stimulation of homologous recombination in plants by expression of the bacterial resolvase RuvC

Shalev

Sitrit

Avivi-Ragolski

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…the process of cell proliferation in the cotyledon is more complicated than the simple exponential proliferation described in earlier studies of post-germinative epigeal cotyledon (tobacco) development, which used a macerating procedure (Fridlender et al 1996). The unequal cell division results in heterogeneity of cell size in the palisade tissue (Figs.…”

Section: Cell Division and Cell Size During Cotyledon Growthmentioning

confidence: 97%

“…Nelson (1932) held that, in Cucurbita , the cells of all the cotyledon tissues divide, and they only begin to expand after the cessation of division. However, the role of division and cell expansion in expansion of the epigeal cotyledon remains unclear (Fridlender et al 1996). This controversy might be due to the unreliability of observations based on cross sections.…”

Section: Introductionmentioning

confidence: 99%

Cell division and cell enlargement in isolated Cucurbita cotyledons grown in darkness and in light

Stoynova-Bakalova

Petrov

Tsukaya

2002

Journal of Plant Research

View full text Add to dashboard Cite

The spatial and temporal patterns of post-embryonal cell growth and cell division were characterised in excised cotyledons of vegetable marrow ( Cucurbita pepo L. var. giromontia Alef.) incubated in water. The concurrent roles of these two processes in cotyledon growth were determined using paradermal sections of the first palisade layer of developing cotyledons. Tissue specificity was observed in the pattern of cell division. The daughter cells derived from an initial cell, which had already differentiated before imbibition of the seeds, were tightly packed in a cluster, which enabled us to monitor cell division during early cotyledon development. Heterogeneity of cell size was recognised during the process of cell proliferation in the cluster, suggesting that cell division is uncoupled from control of cell size. There was significantly more cell division in the marginal part of the cotyledons than in other parts, suggesting high activity of the marginal meristem. Light enhanced cell and cotyledon enlargement, but had no effect on the number of divisions. This study elucidated the cellular basis of post-germinative Cucurbita cotyledon morphogenesis and development.

show abstract

“…However, the heat treatment was imposed when seedlings were 2 weeks old, 15 which is after the end of cell division in cotyledons. 21 This suggests that there is a mechanistic correlation between orgDNA transfer and nuclear division. Because the nuclear membrane disappears during mitosis, cell division may provide easier access of orgDNA fragments to nuclear chromosomes.…”

Section: The Role Of Cell Division In Orgdna Transfer To Nucleusmentioning

confidence: 99%

Nuclear genome diversity in somatic cells is accelerated by environmental stress

Wang

Lloyd

Timmis

2012

Plant Signaling & Behavior

View full text Add to dashboard Cite

show abstract

Cell divisions in cotyledons after germination: localization, time course and utilization for a mutagenesis assay

Cited by 16 publications

References 28 publications

Stimulation of homologous recombination in plants by expression of the bacterial resolvase RuvC

Stimulation of homologous recombination in plants by expression of the bacterial resolvase RuvC

Cell division and cell enlargement in isolated Cucurbita cotyledons grown in darkness and in light

Nuclear genome diversity in somatic cells is accelerated by environmental stress

Contact Info

Product

Resources

About