scholarly journals Reduced Cell Size and Cell Wall Components of Apple Softening before Ripening on the Tree

HortScience ◽  
2004 ◽  
Vol 39 (6) ◽  
pp. 1227-1230 ◽  
Author(s):  
Dong Geun Choi ◽  
Song Joong Yun

The softening of fruit dramatically reduces its market value, especially when this occurs on the tree before ripening. The causes of fruit softening, before ripening, were examined through anatomical and phytochemical comparative analyses between normal fruit, fruit softened on the tree, and stored fruit. The typical morphological changes that occurred with the fruit included early senescence and decreased firmness. The decrease in firmness of softening fruit was due to smaller cell sizes but larger intercellular spaces. The water and free sugar content of the fruit flesh, as well as the weight and sugar content of the cell walls, were significantly lower in softening fruit. Conversely, uronic acid levels and β-galactosidase activity were slightly higher in the softening compared to normal fruit, but the latter was lower than in stored fruit. The results indicated that reduced cell size and cell wall mass were major changes occurring during fruit softening on the tree before ripening, suggesting a difference in the softening mechanisms in ripening and stored fruit.

Author(s):  
WILLIAM S. YORK ◽  
ALAN G. DARVILL ◽  
MICHAEL MCNEIL ◽  
THOMAS T. STEVENSON ◽  
PETER ALBERSHEIM

Author(s):  
William S. York ◽  
Alan G. Darvill ◽  
Michael McNeil ◽  
Thomas T. Stevenson ◽  
Peter Albersheim

2018 ◽  
Vol 19 (9) ◽  
pp. 2691 ◽  
Author(s):  
Michael Ogden ◽  
Rainer Hoefgen ◽  
Ute Roessner ◽  
Staffan Persson ◽  
Ghazanfar Khan

Nutrients are critical for plants to grow and develop, and nutrient depletion severely affects crop yield. In order to optimize nutrient acquisition, plants adapt their growth and root architecture. Changes in growth are determined by modifications in the cell walls surrounding every plant cell. The plant cell wall, which is largely composed of complex polysaccharides, is essential for plants to attain their shape and to protect cells against the environment. Within the cell wall, cellulose strands form microfibrils that act as a framework for other wall components, including hemicelluloses, pectins, proteins, and, in some cases, callose, lignin, and suberin. Cell wall composition varies, depending on cell and tissue type. It is governed by synthesis, deposition and remodeling of wall components, and determines the physical and structural properties of the cell wall. How nutrient status affects cell wall synthesis and organization, and thus plant growth and morphology, remains poorly understood. In this review, we aim to summarize and synthesize research on the adaptation of root cell walls in response to nutrient availability and the potential role of cell walls in nutrient sensing.


IAWA Journal ◽  
2019 ◽  
Vol 40 (4) ◽  
pp. 845-870 ◽  
Author(s):  
Adya P. Singh ◽  
Yoon Soo Kim ◽  
Ramesh R. Chavan

ABSTRACT This review presents information on the relationship of ultrastructure and composition of wood cell walls, in order to understand how wood degrading bacteria utilise cell wall components for their nutrition. A brief outline of the structure and composition of plant cell walls and the degradation patterns associated with bacterial degradation of wood cell walls precedes the description of the relationship of cell wall micro- and ultrastructure to bacterial degradation of the cell wall. The main topics covered are cell wall structure and composition, patterns of cell wall degradation by erosion and tunnelling bacteria, and the relationship of cell wall ultrastructure and composition to wood degradation by erosion and tunnelling bacteria. Finally, pertinent information from select recent studies employing molecular approaches to identify bacteria which can degrade lignin and other wood cell wall components is presented, and prospects for future investigations on wood degrading bacteria are explored.


1995 ◽  
Vol 73 (S1) ◽  
pp. 384-387 ◽  
Author(s):  
R. Sentandreu ◽  
M. Sentandreu ◽  
M. V. Elorza ◽  
M. Iranzo ◽  
S. Mormeneo

Following synthesis of its individual components, the cell wall of Candida albicans is assembled extracellularly in two steps. First, a viscoelastic composite is formed by noncovalent interactions between mannoproteins and other wall components. Second, the initial network is consolidated by formation of covalent cross-linkages among the wall polymers. In both processes, specific proteins may regulate the final yeast or mycelial morphology. These proteins might carry out part of what could be called a morphogenetic code. Experimental results have shown that some mannoproteins form supramolecular complexes. They are secreted independently, but released together from cell walls by hydrolases. In C. albicans cell walls a transglutaminase activity has been detected that could be responsible for the formation of covalent bonds between structural proteins. Key words: fungal cell wall, construction, morphogenesis, protein interactions, noncovalent linkages, covalent linkages.


1979 ◽  
Vol 27 (4) ◽  
pp. 377 ◽  
Author(s):  
G Scurfield

Light microscopy, scanning electron microscopy, X-ray diffraction and differential thermal analysis have been used to examine the structure and mineralogical make-up of 79 Australian petrified woods. Initiation of petrifaction appears to rely on the provision of a substrate with inherent porosity, with the substrate components chemically rather inert and only slowly degraded at normal temperatures and pressures under conditions probably most often acid and tending to anaerobic, and the pores sufficiently large to allow access of an appropriate mineral in ionic or colloidal form in water. Stages in the process include entry of mineral solution into the wood via splits or checks, cell lumina, and other voids; permeation of cell walls; progressive dissolution of cell wall components beginning largely with lignin and accompanied by a build-up of a mineral framework adequate for maintaining the dimensional stability of the wood; mineral deposition in cell lumina after cell wall replacement as a continuous, intermittent, perhaps separate, but not obligatory event; mineral deposition in voids present or formed by dissolution of intercellular substance as a separate, but not obligatory event; and final lithification involving loss of water and perhaps replacement of one mineral by another.


1996 ◽  
Vol 121 (1) ◽  
pp. 132-136 ◽  
Author(s):  
C.M. Sean Carrington ◽  
Russell Pressey

Activity of ß-galactosidase II (EC 3.2.1.23), which can hydrolyze ß-galactan from tomato cell walls, increased markedly during ripening of `Roma' and `Rutgers' tomatoes (Lycopersicon esculentum Mill.). Activity of two other ß-galactosidase isozymes, incapable of galactan hydrolysis, was present in green fruit and remained unchanged throughout ripening. ß-Galactosidase II activity was not detectable in green fruit of either cultivar, appearing first at the breaker stage of `Roma' fruit and not until the pink stage of `Rutgers' fruit. Consistent with this, galactose loss from Na2CO3-soluble pectin (NSP) was detectable at an earlier stage in `Roma' vs. `Rutgers' fruit. A greater decline in NSP galactose was evident in `Roma' fruit compared to `Rutgers' fruit, in keeping with the higher levels and longer period of ß-galactosidase II expression in the former. Significant galactose loss from trans -1,2-diaminocyclohexane-N,N,N',N' -tetraacetic acid-soluble pectin, in contrast, was not seen until the last stage of ripening. These results indicate that the long-reported, net galactosyl loss from the cell walls of ripening tomatoes correlates with ß-galactosidase II activity. Nonetheless, the observation that softening commenced before ß-galactosidase II activity or galactose loss was detectable suggests some other basis for the earliest stages of ripening-related fruit softening in tomato.


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