Plasmodesmal Structure and Development

Roberts, Alison G.

doi:10.1002/9780470988572.ch1

Cited by 21 publications

(23 citation statements)

References 174 publications

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“…The origin of secondary PD is less clear (Roberts, 2005). Our current data, employing a range of imaging approaches, indicate that secondary PD arise in direct contact with existing PD during radial wall extension.…”

Section: Discussionmentioning

confidence: 63%

“…These profiles are also shown diagrammatically in Figure 7. With progressive extension of the tobacco trichome basal wall, the twinned pores become connected by a central cavity (Figure 7A), although it should be noted that in some species not all PD in a pit field become connected by central cavities (Roberts, 2005; Figure 7A). …”

Section: Formation Of Central Cavitiesmentioning

confidence: 99%

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Peeking into Pit Fields: A Multiple Twinning Model of Secondary Plasmodesmata Formation in Tobacco

et al. 2008

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In higher plants, plasmodesmata (PD) are major conduits for cell-cell communication. Primary PD are laid down at cytokinesis, while secondary PD arise during wall extension. During leaf development, the basal cell walls of trichomes extend radially without division, providing a convenient system for studying the origin of secondary PD. We devised a simple freeze-fracture protocol for examining large numbers of PD in surface view. In the postcytokinetic wall, simple PD were distributed randomly. As the wall extended, PD became twinned at the cell periphery. Additional secondary pores were inserted at right angles to these, giving rise to pit fields composed of several paired PD. During wall extension, the number of PD increased fivefold due to the insertion of secondary PD. Our data are consistent with a model in which a subset of the original primary PD pores function as templates for the insertion of new secondary PD, spatially fixing the position of future pit fields. Many of the new PD shared the same wall collar as the original PD pore, suggesting that new PD pores may arise by fissions of existing PD progenitors. Different models of secondary PD formation are discussed. Our data are supported by a computational model, Plasmodesmap, which accurately simulates the formation of radial pit fields during cell wall extension based on the occurrence of multiple PD twinning events in the cell wall. The model predicts PD distributions with striking resemblance to those seen on fractured wall faces.

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Section: Discussionmentioning

confidence: 63%

Section: Formation Of Central Cavitiesmentioning

confidence: 99%

Peeking into Pit Fields: A Multiple Twinning Model of Secondary Plasmodesmata Formation in Tobacco

et al. 2008

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“…On the one hand, PD are viewed as simple pores whose permeability is governed by diffusion (Liarzi and Epel, 2005), and on the other hand, they are viewed as complex structures that can facilitate selective trafficking of macromolecules (Lucas and Lee, 2004), features that are sometimes difficult to reconcile. However, it is clear that PD have a complex substructure (Roberts, 2005). For example, "sphincters" have been observed in the wall around the neck region of PD (Olesen, 1979), and connections have been observed between the desmotubule and PM at the neck region of the pore (Badelt et al, 1994).…”

Section: Discussionmentioning

confidence: 99%

“…Plasmodesmata (PD) are the functional units of the symplasm and occur at multiple interfaces between plant cells (Roberts, 2005;Maule, 2008). The basic structure of the PD pore reveals a plasma membrane (PM)-lined pore containing the desmotubule, an axial endoplasmic reticulum-derived structure that provides endomembrane continuity between cells (for review, see Maule, 2008).…”

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confidence: 99%

Evidence for Unidirectional Flow through Plasmodesmata

2009

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The leaf trichome of tobacco (Nicotiana tabacum) represents a unique secretory structure in which the basal trichome cell is connected to the epidermis by numerous plasmodesmata (PD). Small fluorescent probes microinjected into the basal trichome cell moved apically into distal trichome cells but not into the subtending epidermal cell. In marked contrast, the same probes moved apically into trichome cells when injected into the epidermal cell. Noninvasive methods of dye loading, including ester loading into the apical secretory cell by trichome "capping" and by infiltration of caged fluorescein, produced the same result. In transgenic tobacco plants constitutively expressing photoactivatable green fluorescent protein (PAGFP), activation of PAGFP above the epidermal/trichome (e/t) boundary resulted in movement of protein apically into the distal trichome cells but not across the e/t boundary, while PAGFP activated in the epidermal cell moved apically across the e/t boundary. Experiments with apoplastic tracers also revealed the presence of a distinct apoplastic barrier to solute movement at the e/t interface. These data point to unidirectional transport of solutes through PD. PAGFP activated in individual cells equidistant between the basal cell and the apical cell moved bidirectionally from these cells, suggesting that mass flow was not the driving force for unidirectional transport. We found that unidirectional transport across the e/t boundary was not affected by virus infection or by addition of the actin inhibitor latrunculin but could be dissipated completely by addition of sodium azide. Collectively, our data suggest that active, unidirectional transport of molecules may occur through PD located at unique interfaces in the plant.

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“…Most are formed during division between daughter cells, but can also develop later [Figs. 6(b) and 6(d)]; for a review, see Roberts (2005). Each plasmodesma contains a tubule related to the endoplasmic reticulum, i.e., the network of membranous tubules within the cytoplasm of a cell, connected to the nuclear membrane thereby offering a cytosolic and an endoplasmic reticulum pathway from cell to cell [ Fig.…”

Section: Anatomy and Physiology Of The Vascular Tissuesmentioning

confidence: 99%

Sap flow and sugar transport in plants

et al. 2016

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Green plants are Earth's primary solar energy collectors. They harvest the energy of the Sun by converting light energy into chemical energy stored in the bonds of sugar molecules. A multitude of carefully orchestrated transport processes are needed to move water and minerals from the soil to sites of photosynthesis and to distribute energy-rich sugars throughout the plant body to support metabolism and growth. The long-distance transport happens in the plants' vascular system, where water and solutes are moved along the entire length of the plant. In this review, the current understanding of the mechanism and the quantitative description of these flows are discussed, connecting theory and experiments as far as possible. The article begins with an overview of low-Reynolds-number transport processes, followed by an introduction to the anatomy and physiology of vascular transport in the phloem and xylem. Next, sugar transport in the phloem is explored with attention given to experimental results as well as the fluid mechanics of osmotically driven flows. Then water transport in the xylem is discussed with a focus on embolism dynamics, conduit optimization, and couplings between water and sugar transport. Finally, remarks are given on some of the open questions of this research field.

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Plasmodesmal Structure and Development

Cited by 21 publications

References 174 publications

Peeking into Pit Fields: A Multiple Twinning Model of Secondary Plasmodesmata Formation in Tobacco

Peeking into Pit Fields: A Multiple Twinning Model of Secondary Plasmodesmata Formation in Tobacco

Evidence for Unidirectional Flow through Plasmodesmata

Sap flow and sugar transport in plants

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