The Protective Layer as an Extension of the Apoplast

IAWA Journal ◽  
1993 ◽  
Vol 14 (2) ◽  
pp. 163-171 ◽  
Author(s):  
J. R. Barnett ◽  
P. Cooper ◽  
Lynda J. Bonner
Keyword(s):  
Cell Wall ◽  
Protective Layer ◽  
Xylem Parenchyma ◽  
Pit Membrane ◽  
Parenchyma Cells ◽  
Deep Supercooling ◽  
Dying Cells ◽  
Tylose Formation ◽  
Universal Application

The protective layer between the cell wall and plasmalemma of xylem parenchyma cells has variously been suggested to be involved in protection of the protoplast from attack by autolytic enzymes from neighbouring, dying cells, tylose formation, deep supercooling of xylem, and strengthening of the pit. None of these ideas has universal application to all species in which parenchyma cells possess a protective layer. It is proposed instead, that the protective layer is primarily laid down in order to preserve apoplastic continuity around the protoplast of a lignified cell, bringing the entire plasmalemma surface, and not just that part of it in contact with the porous pit membrane, into contact with the apoplast. If this is so, then other functions may be coincidental, or have arisen secondarily.

Primary Function of the Protective Layer in Contact Cells: Buffer Against Oscillations in Hydrostatic Pressure in the Vessels?

IAWA Journal ◽  
1988 ◽  
Vol 9 (3) ◽  
pp. 285-288 ◽  
Author(s):  
Aart J.E. van Bel ◽  
Christiaan van der Schoot
Keyword(s):  
Hydrostatic Pressure ◽  
Osmotic Pressure ◽  
Protective Layer ◽  
Xylem Parenchyma ◽  
Primary Function ◽  
Parenchyma Cells ◽  
Tylose Formation

In the literature it has been suggested that the protective layer, deposited along the wall between xylem parenchyma and vessels, is involved in tylose formation as part of an antipathogenic response. Yet, in a number of cases, the presence of a protective layer is not related with tylose development. It is proposed here, that the protective layer primarily acts as a buffer against hydrostatic oscillations in the vessels. As the hydrostatic pressure in the vessels becomes less negative, the xylem cells will increasingly withdraw water from the apoplast. Once the hydrostatic pressure has surpassed a certain limit, the protective layer is unable to withstand the osmotic pressure of the parenchyma cells and the latter will bulge into the vessels giving rise to the formation of tyloses.

scholarly journals EFFECT OF CALCIUM CHELATORS ON WALL STRUCTURE AND DEEP SUPERCOOLING OF XYLEM PARENCHYMA OF PEACH

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1080a-1080
Author(s):  
Michael Wisniewski ◽  
Glen Davis
Keyword(s):  
Cell Wall ◽  
Oxalic Acid ◽  
Enzyme Hydrolysis ◽  
Wall Structure ◽  
Xylem Parenchyma ◽  
Sodium Phosphate Buffer ◽  
Pit Membrane ◽  
Deep Supercooling ◽  
Integral Role ◽  
Xylem Tissue

The pit membrane of xylem parenchyma of peach plays an important role in deep supercooling. Enzyme hydrolysis of xylem tissue indicated that the pit membrane is rich in pectin. The objective of the present study was to determine if removal of calcium from the cell wall would effect deep supercooling by loosening the cell wall. Current year shoots of `Loring' peach were infiltrated with oxalic acid, EGTA, or sodium phosphate buffer for 24-48 hours and then prepared for either ultrastructural analysis or differential thermal analysis. The use of 5-50 mM oxalic acid resulted in a distinct reduction in the size of the low-temperature exotherm (LTE) with increasing concentration. Oxalic acid also produced a loosening and swelling of the pit membrane. The use of EGTA (100 mM) or NaP04 (150 mM) produced only a slight shift in the LTE to warmer temperatures when compared to fresh tissues. Heat treatments (30-100°C) also resulted in a gradual shift of the LTE to warmer temperatures. The data indicate that cross-linking of pectins may play a role in defining the pore structure of the pit membrane and that this area of the cell wall plays an integral role in deep supercooling of peach wood.

Presence of supercooling-facilitating (anti-ice nucleation) hydrolyzable tannins in deep supercooling xylem parenchyma cells in Cercidiphyllum japonicum

Planta ◽  
2011 ◽  
Vol 235 (4) ◽  
pp. 747-759 ◽  
Author(s):  
Donghui Wang ◽  
Jun Kasuga ◽  
Chikako Kuwabara ◽  
Keita Endoh ◽  
Yukiharu Fukushi ◽  
...  
Keyword(s):  
Ice Nucleation ◽  
Xylem Parenchyma ◽  
Hydrolyzable Tannins ◽  
Cercidiphyllum Japonicum ◽  
Parenchyma Cells ◽  
Deep Supercooling

NITROGEN IN WOOD AND ITS ROLE IN WOOD DETERIORATION

1966 ◽  
Vol 44 (11) ◽  
pp. 1539-1554 ◽  
Author(s):  
Ellis B. Cowling ◽  
William Merrill
Keyword(s):  
Cell Wall ◽  
Continuous Process ◽  
Wood Fiber ◽  
Significant Loss ◽  
Chemical Form ◽  
Present Knowledge ◽  
Xylem Parenchyma ◽  
Fiber Cells ◽  
Parenchyma Cells ◽  
Wood Deterioration

Based on present knowledge of the origin, amounts, chemical form, and distribution of nitrogen (N) in wood, hypotheses are proposed to explain radial gradients in N content that exist across the xylem cylinder of tree stems: (1) N in the cytoplasm of developing wood cells is diluted by apposition of cell wall substances; (2) after maturation of wood fiber cells, N in their cytoplasm is removed by elution into the transpiration stream; (3) death of xylem parenchyma cells during aging of sapwood and formation of heartwood is accompanied by removal of much of the N in their cytoplasm. Hypotheses 2 and 3 above suggest strongly that trees possess an internal recycling mechanism for conservation and reuse of the N in the cytoplasm of xylary cells.Although the supply of N in wood is meager, wood-destroying fungi readily metabolize the carbon-rich constituents of wood and produce large fruiting structures that release vast numbers of spores in nature. To account for these capacities, we postulate that these fungi employ one or more of the following three mechanisms: (1) preferential allocation of N obtainable from wood to substances and pathways highly efficient in the use of wood constituents; (2) reuse of N obtainable from wood by a dynamic and continuous process of autolysis and reuse without significant loss of N; (3) utilization of N sources outside the wood itself, for example, by fixation of atmospheric N.

scholarly journals Change of supercooling capability in solutions containing different kinds of ice nucleators by flavonol glycosides from deep supercooling xylem parenchyma cells in trees

Cryobiology ◽  
2011 ◽  
Vol 63 (3) ◽  
pp. 157-163 ◽  
Author(s):  
Chikako Kuwabara ◽  
Jun Kasuga ◽  
Donghui Wang ◽  
Yukiharu Fukushi ◽  
Keita Arakawa ◽  
...  
Keyword(s):  
Flavonol Glycosides ◽  
Xylem Parenchyma ◽  
Parenchyma Cells ◽  
Deep Supercooling ◽  
Ice Nucleators

22. Identification of anti-ice nucleation substances in tree xylem with deep supercooling xylem parenchyma cells

Cryobiology ◽  
2007 ◽  
Vol 55 (3) ◽  
pp. 330-331 ◽  
Author(s):  
Jun Kasuga ◽  
Keita Arakawa ◽  
Yasuyuki Hashidoko ◽  
Seizo Fujikawa
Keyword(s):  
Ice Nucleation ◽  
Xylem Parenchyma ◽  
Parenchyma Cells ◽  
Deep Supercooling

Ultrastructural observations on pit membrane alterations and associated effects in elm xylem tissues infected by Ceratocystis ulmi

1978 ◽  
Vol 56 (20) ◽  
pp. 2567-2588 ◽  
Author(s):  
G. B. Ouellette
Keyword(s):  
Protective Layer ◽  
Cavity Formation ◽  
Bordered Pit ◽  
Fibrillar Material ◽  
Host Cytoplasm ◽  
Pit Membrane ◽  
Bordered Pits ◽  
Parenchyma Cells

Gradations in the degree of pit membrane alteration in tissues infected by Ceratocystis ulmi (Buism.) C. Moreau and collected at various intervals after inoculation are described. Membranes of bordered pit pairs are coated and apparently impregnated with bands or masses of osmiophilic material; this coating may be thick and stratified and the pit cavities completely occluded. Similar osmiophilic material also occurs in decreasing amounts over and within membranes of simple or half-bordered pits and within the adjacent protective layer. Various degrees of distention and cavity formation in these pit membranes are associated with the osmiophilic material. Products released into vessels from disintegrating pit membranes seem to be sparse. Host cytoplasm in contiguous parenchyma cells can have diverse reactions.Examination of specimens at various angles established the interrelationship between osmiophilic material and remnants of pit membranes. Variously oriented lamellar-like structures and a fibrillar material intermixed with a more amorphous one characterize the osmiophilic material. The significance of these observations is discussed.

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