Postmitotic ‘isodiametric’ cell growth in the maize root apex

Baluška, Frantǐsek; Kubica, Š.; Hauskrecht, M.

doi:10.1007/bf00195876

Cited by 92 publications

(57 citation statements)

References 11 publications

(7 reference statements)

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“…Cells in this region are undergoing rapid division, which keeps them short; because they are expanding in the transverse direction, they bec0m.e wider than long ( Fig. 4B; Baluska et al, 1990). This reduces the contribution of their lateral walls to plasmodesmatal diffusivity, even though the frequency of plasmodesmata in both transverse and longitudinal walls is still fairly high (Fig: 4A).…”

Section: Resultsmentioning

confidence: 98%

Nonvascular, Symplasmic Diffusion of Sucrose Cannot Satisfy the Carbon Demands of Growth in the Primary Root Tip of Zea mays L

1994

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Nonvascular, symplasmic transport of sucrose (Suc) was investigated theoretically in the primary root tip of maize (Zea mays 1.cv WF9 x Mo 17) seedlings. Symplasmic diffusion has been assumed to be the mechanism of transport of Suc to cells in the root apical meristem (R.T. Ciaquinta, W. Lin, N.L. Sadler, V.R. Franceschi [1983] Plant Physiol 72: 362-367), which grow apical to the end of the phloem and must build all biomass with carbon supplied from the shoot or kernel. We derived an expression for the growthsustaining Suc flux, which is the minimum longitudinal flux that would be required to meet the carbon demands of growth in the root apical meristem. We calculated this flux from data on root growth velocity, area, and biomass density, taking into account construction and maintenance respiration and the production of mucilage by the root cap. We then calculated the conductivity of the symplasmic pathway for diffusion, from anatomical data on cellular dimensions and the frequency and dimensions of plasmodesmata, and from two estimates of the diffusive conductance of a plasmodesma, derived from independent data. Then, the concentration gradients required to drive a growth-sustaining Suc flux by diffusion alone were calculated but were found not to be physiologically reasonable. We also calculated the hydraulic conductivity of the plasmodesmatal pathway and found that mass flow of Suc solution through plasmodesmata would also be insufficient, by itself, to satisfy the carbon demands of growth. However, much of the demand for water to cause cell expansion could be met by the water unloaded from the phloem while unloading Suc to satisfy the carbon demands of growth, and the hydraulic conductivity of plasmodesmata is high enough that much of that water could move symplasmically. Either our current understanding of plasmodesmatal ultrastructure and function is flawed, or alternative transport mechanisms must exist for Suc transport to the meristem.Understanding the control of plant growth and development must include an understanding of the transport of photoassimilates from sources into developing sinks. Transport of solutes through the differentiated phloem is explained well by quantitative treatments of Miinch's (1930) pressure flow hypothesis (Christy and Femer, 1973;Tyree et al., 1974a;Ross and Tyree, 1980), and experimental data are in reasonably good agreement with their predictions (cf. Zimmermann and Brown, 1971; Pickard et al.,

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Section: Resultsmentioning

confidence: 98%

Nonvascular, Symplasmic Diffusion of Sucrose Cannot Satisfy the Carbon Demands of Growth in the Primary Root Tip of Zea mays L

1994

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“…In cell-based terminology, therefore, the term "zone of cell elongation" should be reserved for root cells that grow in this strictly polar fashion. Significantly, our morphometric studies at the cellular leve1 showed that an abrupt decline of cellular widening coincided precisely with a prominent increase in the rate of cell lengthening, and this occurred at the base of the PIG region (BaluSka et al, 1990(BaluSka et al, , 1994Barlow et al, 1991). This occurrence provided the first hint that the newly formed postmitotic cells of the root may undergo some kind of preparatory phase wherein they adjust or reorganize their growth from the formerly slow, mitotic mode of growth to a rapid mode of elongation.…”

mentioning

confidence: 80%

“…This previously unrecognized region of the root, intercalated between the apical meristem and the zone of rapid cell elongation, was originally discovered as the result of a morphometric analysis of the breadthlength ratios of cells along the length of the maize root (BaluSka et al, 1990). The analysis indicated that as cells are displaced away from the root apex, their growth is adjusted in such a way that, in the immediate postmitotic region, approximately isodiametric (cuboidal) cellular shapes are obtained.…”

mentioning

confidence: 99%

Specialized Zones of Development in Roots: View from the Cellular Level

Baluška¹,

Volkmann²,

Barlow³

1996

Plant Physiology

133

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“…42 In 1990 Baluška et al 43 invented the term transition zone to describe a unique part of the maize root apex, in which cells after leaving the meristem and before entering the elongation zone undergo slow isotropic-like growth, but do not still elongate, in fact resembling meristematic cells in many aspects. In particular, the apical part (distal) of this region seems to be characterized mainly by cells that optionally can reenter the cell cycle, whereas cells of the basal (proximal) part of this zone are able to readily enter into the fast cell elongation region.…”

Section: The Root Transition Zonementioning

confidence: 99%

NO signaling is a key component of the root growth response to nitrate inZea maysL.

Trevisan

Manoli

Quaggiotti

2014

Plant Signaling & Behavior

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To search for nutrients and water, roots need to efficiently explore large soil volumes. To this aim they generate complex root systems, allowing them to maximize their resource allocation efficiency. 1 Despite the vital importance of roots, the difficulty in accessing intact root systems for analysis, particularly under field conditions, have slowed down the breeding programs for plant's adaptation to environmental restrictions. 2,3 The capacity of plants to take up nutrients and water is mainly determined by changes in the architecture of the root system. 1 Three major processes affect the overall architecture of the root system: the rate of cell division, the rate of cell differentiation, and the extent of expansion and elongation of cells. [4][5][6] Disturbs in any of these 3 processes can affect the whole root-system architecture and the capacity of plants to survive and develop in adverse environments (Giehl et al. 7 and references therein).The root system results from the coordinated control of both genetic endogenous programs (regulating growth and organogenesis) and the action of abiotic and biotic environmental stimuli. 8,9 The dynamic control of the overall root system architecture (RSA) throughout time finally determines root plasticity and allows plants to efficiently adapt to environmental constraints. 10 The soil-environment from which plants extract nutrients and water is extremely heterogeneous, both spatially and temporally. 11 Among the nutrients present in soil, nitrate (NO 3 − ) may vary by an order of magnitude within centimeters or over the course of a day. 12 The effects of NO 3 − on the root system are complex and depend on several factors, such as the concentration available to the plant, the endogenous nitrogen status and the sensitivity of the species. 10,13,14 A considerable part of the studies aimed to unravel the mechanisms controlling RSA growth and development in response to nitrate have been focused on lateral roots (LR), 8,13,[15][16][17][18][19][20] while the nitrate-regulation of the primary root growth is still unclear. Beside NO 3 − , auxin has been demonstrated to strongly affect and control the LR development, [21][22][23][24] and an increasing number of studies suggests an overlap between auxin and NO 3 − signaling pathways in controlling LR development. [25][26][27][28][29][30][31][32][33] NO 3 -has a Doubtful Role in Regulating the Growth of Primary RootsDespite the high amount of reports published on nitrate effects on root elongation, the lack of univocal results makes it difficult to clearly decipher this response ( Table 1). In Arabidopsis thaliana, inhibition of primary root growth has been observed when nitrate is applied homogeneously at high concentrations (50 mM) for 7 d, but not in a range between 0.1 and 10 mM. 35 On the contrary, in this same species Linkohr et al. 36 showed an inhibition of primary root elongation with the increase of nitrate concentration already beyond 0.01 mM, but in this case seedlings were IAA, indole-3-acetic acid; SNP, sodium n...

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Postmitotic ‘isodiametric’ cell growth in the maize root apex

Cited by 92 publications

References 11 publications

Nonvascular, Symplasmic Diffusion of Sucrose Cannot Satisfy the Carbon Demands of Growth in the Primary Root Tip of Zea mays L

Nonvascular, Symplasmic Diffusion of Sucrose Cannot Satisfy the Carbon Demands of Growth in the Primary Root Tip of Zea mays L

Specialized Zones of Development in Roots: View from the Cellular Level

NO signaling is a key component of the root growth response to nitrate inZea maysL.

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