Uridine, a cell division factor in pea roots

Smit, Gerrit; Koster, Charlotte C.; Schripsema, Jan; Spaink, Herman P.; Brussel, Audrey; Kijne, Jan W.

doi:10.1007/bf00041176

Cited by 63 publications

(27 citation statements)

References 10 publications

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“…Transport of AGO9 RNA (itself maternally biased in endosperm) (Dataset S2) from somatic companion cells mediates small RNA-dependent transposon silencing necessary for specification of gametophyte precursor cells (48), and maternally deposited AGO3 may likewise influence transposon silencing in the endosperm. Although the significance of converting cytidine to uridine by cytoplasmic cytidine deaminase proteins in the chalazal endosperm is not clear, picomolar concentrations of uridine enhance cell division responses to auxin and cytokinin in root cortical cells (49).…”

Section: Discussionmentioning

confidence: 99%

Regulation of imprinted gene expression in Arabidopsis endosperm

Hsieh

Shin²,

Uzawa³

et al. 2011

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

314

551

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Imprinted genes are expressed primarily or exclusively from either the maternal or paternal allele, a phenomenon that occurs in flowering plants and mammals. Flowering plant imprinted gene expression has been described primarily in endosperm, a terminal nutritive tissue consumed by the embryo during seed development or after germination. Imprinted expression in Arabidopsis thaliana endosperm is orchestrated by differences in cytosine DNA methylation between the paternal and maternal genomes as well as by Polycomb group proteins. Currently, only 11 imprinted A. thaliana genes are known. Here, we use extensive sequencing of cDNA libraries to identify 9 paternally expressed and 34 maternally expressed imprinted genes in A. thaliana endosperm that are regulated by the DNA-demethylating glycosylase DEMETER, the DNA methyltransferase MET1, and/or the core Polycomb group protein FIE. These genes encode transcription factors, proteins involved in hormone signaling, components of the ubiquitin protein degradation pathway, regulators of histone and DNA methylation, and small RNA pathway proteins. We also identify maternally expressed genes that may be regulated by unknown mechanisms or deposited from maternal tissues. We did not detect any imprinted genes in the embryo. Our results show that imprinted gene expression is an extensive mechanistically complex phenomenon that likely affects multiple aspects of seed development.

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Section: Discussionmentioning

confidence: 99%

Regulation of imprinted gene expression in Arabidopsis endosperm

Hsieh

Shin²,

Uzawa³

et al. 2011

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

314

551

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“…The expression pattern is reminiscent of the signal gradient hypothesis, in which opposing signal gradients from the vasculature and from NF signaling at the epidermis would delimit the cellular landscape to form a nodule (Smit et al, 1995;Heidstra et al, 1997;van Spronsen et al, 2001). Because MtCLE13 is induced by cytokinin, its expression pattern presumably reflects an internal cytokinin gradient in the cortex.…”

Section: Nodule-related Mtcle12 and Mtcle13 Expression Is Linked Withmentioning

confidence: 99%

“…Opposite preexisting and NF-induced signal gradients have been proposed to rule the cortical cell responses (Smit et al, 1995;Heidstra et al, 1997;van Spronsen et al, 2001). Uridine and ethylene are diffusive signals originating from the vasculature that have been identified as positive and negative regulators, respectively.…”

mentioning

confidence: 99%

CLE Peptides Control Medicago truncatula Nodulation Locally and Systemically

Mortier

Herder²,

Whitford³

et al. 2010

Plant Physiology

302

409

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The CLAVATA3/embryo-surrounding region (CLE) peptides control the fine balance between proliferation and differentiation in plant development. We studied the role of CLE peptides during indeterminate nodule development and identified 25 MtCLE peptide genes in the Medicago truncatula genome, of which two genes, MtCLE12 and MtCLE13, had nodulation-related expression patterns that were linked to proliferation and differentiation. MtCLE13 expression was up-regulated early in nodule development. A high-to-low expression gradient radiated from the inner toward the outer cortical cell layers in a region defining the incipient nodule. At later stages, MtCLE12 and MtCLE13 were expressed in differentiating nodules and in the apical part of mature, elongated nodules. Functional analysis revealed a putative role for MtCLE12 and MtCLE13 in autoregulation of nodulation, a mechanism that controls the number of nodules and involves systemic signals mediated by a leucine-rich repeat receptor-like kinase, SUNN, which is active in the shoot. When MtCLE12 and MtCLE13 were ectopically expressed in transgenic roots, nodulation was abolished at the level of the nodulation factor signal transduction, and this inhibition involved long-distance signaling. In addition, composite plants with roots ectopically expressing MtCLE12 or MtCLE13 had elongated petioles. This systemic effect was not observed in transgenic roots ectopically expressing MtCLE12 and MtCLE13 in a sunn-1 mutant background, although nodulation was still strongly reduced. These results suggest multiple roles for CLE signaling in nodulation.

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“…These divide, and some of them (those that are not infected) will form the nodule meristem. The spatial localization of pericycle activation next to protoxylem poles may require an inducing factor, termed stele factor and thought to perhaps be uridine, coming from the protoxylem, or it may be caused by inhibition of the response of cells near the protophloem poles (100,142,151). mRNA encoding 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase, which catalyzes the final step of ethylene synthesis, has been shown by in situ hybridization to be enriched in cells adjacent to the protophloem poles (74).…”

Section: Growth Dynamics Of Bacterial Populations Inside Infection Thmentioning

confidence: 99%

Infection and Invasion of Roots by Symbiotic, Nitrogen-Fixing Rhizobia during Nodulation of Temperate Legumes

Gage

2004

Microbiol Mol Biol Rev

774

532

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Bacteria belonging to the genera Rhizobium, Mesorhizobium, Sinorhizobium, Bradyrhizobium, and Azorhizobium (collectively referred to as rhizobia) grow in the soil as free-living organisms but can also live as nitrogen-fixing symbionts inside root nodule cells of legume plants. The interactions between several rhizobial species and their host plants have become models for this type of nitrogen-fixing symbiosis. Temperate legumes such as alfalfa, pea, and vetch form indeterminate nodules that arise from root inner and middle cortical cells and grow out from the root via a persistent meristem. During the formation of functional indeterminate nodules, symbiotic bacteria must gain access to the interior of the host root. To get from the outside to the inside, rhizobia grow and divide in tubules called infection threads, which are composite structures derived from the two symbiotic partners. This review focuses on symbiotic infection and invasion during the formation of indeterminate nodules. It summarizes root hair growth, how root hair growth is influenced by rhizobial signaling molecules, infection of root hairs, infection thread extension down root hairs, infection thread growth into root tissue, and the plant and bacterial contributions necessary for infection thread formation and growth. The review also summarizes recent advances concerning the growth dynamics of rhizobial populations in infection threads

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Uridine, a cell division factor in pea roots

Cited by 63 publications

References 10 publications

Regulation of imprinted gene expression in Arabidopsis endosperm

Regulation of imprinted gene expression in Arabidopsis endosperm

CLE Peptides Control Medicago truncatula Nodulation Locally and Systemically

Infection and Invasion of Roots by Symbiotic, Nitrogen-Fixing Rhizobia during Nodulation of Temperate Legumes

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