Why Do Plant Cells Divide?

Jacobs, Thomas

doi:10.1105/tpc.9.7.1021

Cited by 92 publications

(60 citation statements)

References 54 publications

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“…This could be illustrated in Figure 6 because the kdsA gene seems to be re-induced in late G1 in synchronized BY-2 cells. Before entry in the S phase and subsequent mitosis, the cell must reach a critical size partly controlled at the G1/S cell cycle checkpoint (Jacobs, 1997;Polymenis and Schmidt, 1999). As a result, the synthesis of Kdo and mRG-II may be needed during G1 in association with cell growth before the commitment into the DNA replication process.…”

Section: Discussionmentioning

confidence: 99%

The Gene Expression and Enzyme Activity of Plant 3-Deoxy-D-Manno-2-Octulosonic Acid-8-Phosphate Synthase Are Preferentially Associated with Cell Division in a Cell Cycle-Dependent Manner

et al. 2003

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3-Deoxy-d-manno-2-octulosonic acid-8-phosphate (Kdo-8-P) synthase catalyzes the condensation of phosphoenolpyruvate with d-arabinose-5-phosphate to yield Kdo-8-P. Kdo-8-P is the phosphorylated precursor of Kdo, a rare sugar only found in the rhamnogalacturonan II pectic fraction of the primary cell walls of higher plants and of cell wall polysaccharides of some green algae. A cDNA named LekdsA (accession no. AJ294902) encoding tomato (Lycopersicon esculentum) Kdo-8-P synthase has been isolated. The recombinant protein rescued a kdsA thermosensitive mutant of Salmonella typhimurium impaired in the synthesis of a functional Kdo-8-P synthase. Using site-directed mutagenesis of LekdsA cDNA, the tomato Kdo-8-P synthase was shown to possess the same essential amino acids that form the active sites in the bacterial enzymes. The tomato kdsA gene expression and the relevant Kdo-8-P synthase activity were preferentially associated to dividing cells, in the course of the early development of tomato fruit and in meristematic tissues. Furthermore, the transcription of the kdsA gene was found to oscillate during the cell cycle in tobacco (Nicotiana tabacum) Bright-Yellow 2 synchronized cells with a maximum during mitosis.

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Section: Discussionmentioning

confidence: 99%

The Gene Expression and Enzyme Activity of Plant 3-Deoxy-D-Manno-2-Octulosonic Acid-8-Phosphate Synthase Are Preferentially Associated with Cell Division in a Cell Cycle-Dependent Manner

et al. 2003

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“…It has been suggested that formation of organ initials involves oriented cell expansion and cell wall modification, coupled with controlled cell division (Lyndon, 1990;Fleming et al, 1997;Jacobs, 1997;Meyerowitz, 1997). Therefore, we investigated ex- pression patterns of the GmEXP1 gene in secondary root initials by in situ hybridization analysis to test whether the gene is also involved in formation of the root initials.…”

Section: Gmexp1 Mrna Is Also Localized In the Secondary Root Initialsmentioning

confidence: 99%

Expression of an Expansin Gene Is Correlated with Root Elongation in Soybean

et al. 2003

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Expansin is a family of proteins that catalyze long-term expansion of cell walls and has been considered a principal protein that affects cell expansion in plants. We have identified the first root-specific expansin gene in soybean (Glycine max), GmEXP1, which may be responsible for root elongation. Expression levels of GmEXP1 were very high in the roots of 1-to 5-d-old seedlings, in which rapid root elongation takes place. Furthermore, GmEXP1 mRNA was most abundant in the root tip region, where cell elongation occurs, but scarce in the region of maturation, where cell elongation ceases, implying that its expression is closely related to root development processes. In situ hybridization showed that GmEXP1 transcripts were preferentially present in the epidermal cells and underlying cell layers in the root tip of the primary and secondary roots. Ectopic expression of GmEXP1 accelerated the root growth of transgenic tobacco (Nicotiana tabacum) seedlings, and the roots showed insensitivity to obstacle-touching stress. These results imply that the GmEXP1 gene plays an important role in root development in soybean, especially in the elongation and/or initiation of the primary and secondary roots.The root is a plant organ that has adapted to acquire water and nutrients from the environment (Schiefelbein et al., 1997). The root system has recently been the focus of interest as a useful system for understanding organ development because it is a relatively simple organ, its growth pattern is uniform, and it has a small number of differentiated cell types (Aeschbacher et al., 1994). Furthermore, the development of new roots (secondary or lateral roots) from an existing root (primary root) provides a novel opportunity to investigate cellular differentiation and development in plants.Although the primary and secondary roots share many basic structural features, they are different in their origin (Scheres et al., 1996). A basic feature of the root is its radial pattern, which is made up of concentric layers of tissues. Three fundamental types of the tissues are the epidermis, the cortex, and the vascular tissues (Esau, 1977;Dolan et al., 1993;Raven et al., 1999). In the longitudinal section, the root can be divided into three different regions: those of cell division, elongation, and maturation (specialization) (Dolan et al., 1993;Baluska et al., 1996;Howell, 1998;Raven et al., 1999). The region of cell division contains the root apical meristem, which carries out new cell divisions but does not elongate newly divided cells immediately. The cells derived from the region of cell division expand and elongate mostly in the region of elongation. After they have elongated, the cells begin to differentiate in the region of maturation, where root hairs and the secondary roots are initiated. The events of cell elongation and maturation occurring in the root have been suggested to be controlled by the extensibility of the cell wall and the turgor pressure inside the cell (Cosgrove, 1996).It has been proposed that development of the s...

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“…This suggests that ANT regulates the extent of cell proliferation, rather than the rate of cell proliferation, to control organ cell numbers. Cell size is regulated by the coordination of cell growth with cell proliferation in dividing cells, as well as by cell expansion in differentiated nondividing cells (20). The larger ant-1 cells partially compensated for the decrease in cell numbers and minimized the reduction in overall ant-1 organ growth (Fig.…”

Section: Effect Of Ant Function On Cell Proliferation and Cell Growthmentioning

confidence: 99%

Plant organ size control: AINTEGUMENTA regulates growth and cell numbers during organogenesis

Mizukami

Fischer

2000

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

762

700

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The control of cell proliferation during organogenesis plays an important role in initiation, growth, and acquisition of the intrinsic size of organs in higher plants. To understand the developmental mechanism that controls intrinsic organ size by regulating the number and extent of cell division during organogenesis, we examined the function of the Arabidopsis regulatory gene AINTEGUMENATA (ANT). Previous observations revealed that ANT regulates cell division in integuments during ovule development and is necessary for floral organ growth. Here we show that ANT controls plant organ cell number and organ size throughout shoot development. Loss of ANT function reduces the size of all lateral shoot organs by decreasing cell number. Conversely, gain of ANT function, via ectopic expression of a 35S::ANT transgene, enlarges embryonic and all shoot organs without altering superficial morphology by increasing cell number in both Arabidopsis and tobacco plants. This hyperplasia results from an extended period of cell proliferation and organ growth. Furthermore, cells ectopically expressing ANT in fully differentiated organs exhibit neoplastic activity by producing calli and adventitious roots and shoots. Based on these results, we propose that ANT regulates cell proliferation and organ growth by maintaining the meristematic competence of cells during organogenesis.A lthough plant growth is influenced greatly by external environmental factors, it appears that the intrinsic size of plant organs is determined by internal developmental factors. Evidence for intrinsic organ size control is seen by the remarkable uniformity of organ size among individuals within a species (e.g., Arabidopsis thaliana petal size) and by the conspicuous differences in organ size between related species (e.g., A. thaliana versus Brassica napus petal size). Previous genetic analysis has focused primarily on the role of polarized cell elongation in determining organ morphology (1, 2). However, disparity in size of a particular organ (e.g., petal) between species is primarily the result of differences in cell number, not cell size (3). Thus, the intrinsic organ size of a species is determined primarily by organ cell number. Population genetics has indicated that intrinsic plant organ size might be regulated by a polygenic system, and in some species quantitative trait loci that affect plant organ size have been studied (4). However, how intrinsic organ size is genetically controlled, or the nature of the developmental regulators involved in plant organ size control, is not well understood.The total cell number of an organ is determined by the number of divisions of undifferentiated stem cells [i.e., meristematic cells (5)]. During shoot development, lateral organs are initiated as primordia from apical and lateral meristems (6, 7). Although most cells in organ primordia are meristematic and proliferate, cells lose meristematic competence and withdraw from the cell cycle as organs develop. Thus, the maintenance of meristematic competence of cells is ...

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Why Do Plant Cells Divide?

Cited by 92 publications

References 54 publications

The Gene Expression and Enzyme Activity of Plant 3-Deoxy-D-Manno-2-Octulosonic Acid-8-Phosphate Synthase Are Preferentially Associated with Cell Division in a Cell Cycle-Dependent Manner

The Gene Expression and Enzyme Activity of Plant 3-Deoxy-D-Manno-2-Octulosonic Acid-8-Phosphate Synthase Are Preferentially Associated with Cell Division in a Cell Cycle-Dependent Manner

Expression of an Expansin Gene Is Correlated with Root Elongation in Soybean

Plant organ size control: AINTEGUMENTA regulates growth and cell numbers during organogenesis

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